ASN RSS https://amnat.org/ Latest press releases and announcements from the ASN en-us Mon, 30 Mar 2020 05:00:00 GMT 60 “Floral trait evolution of angiosperms on Pacific islands” https://amnat.org/an/newpapers/July-Hetherington-Rauth.html Molly C. Hetherington-Rauth and Marc T. J. Johnson (July 2020) Insect pollinated plants evolve smaller flowers on some (sub)tropical islands and in and in specific plant families Read the Article (Just Accepted)Islands often play host to “unusual” organisms. For example, giant tortoises, swimming iguanas, flightless birds, and tame animals are all features commonly associated with animals inhabiting islands. These unusual suites of traits, such as gigantism and tame behavior, are referred to as island syndromes and have been well characterized for island animals; however, the presence of island syndromes for plants has been poorly studied. One observation repeatedly made by naturalists, including Charles Darwin and Alfred Russel Wallace, is that island plants have small, non-showy flowers compared to plants living on the mainland. An often-cited explanation for this is that islands typically have less diverse pollinator communities and often lack large pollinators compared to mainland pollinator communities. Despite this explanation, it has yet to be tested whether island plants do, in fact, evolve small flowers. In this study, Hetherington-Rauth and Johnson put these historical claims to the test by examining island plants from across seven tropical and subtropical island systems in the Pacific Ocean. Using herbarium specimens, they measured the flowers of 556 plant species found on islands, as well as their closest living mainland relatives. Contrary to naturalists’ predictions, they find that on average island plants did not evolve smaller flowers relative to mainland plants; however, the study did find that on specific islands, including the Gal&aacute;pagos Islands where Darwin visited, plants did evolve smaller flowers. The study also found that certain plant families tended to evolve smaller flowers. The authors conclude that no general island syndrome exists for flower size, but instead floral morphology likely evolves in response to the features of specific islands and the differing evolutionary history among plant families. Abstract Animals frequently evolve unique suites of traits on islands, but whether plants evolve comparable island syndromes remains unresolved. Here we test the prediction based on natural history observations that insect pollinated plants evolve smaller flowers on islands than mainland communities. We examined 556 plant species representing 136 phylogenetically independent contrasts between island and mainland sister taxa. We focused on endemic taxa originating from the Americas associated with seven tropical and subtropical islands of the Pacific Ocean. Contrary to conventional wisdom, flowers were not on average smaller on islands than the mainland. On specific archipelagos (the Galápagos Islands and Revillagigedo Islands), however, island taxa did evolve smaller flowers. Divergence in flower size between island and mainland taxa also varied among taxonomic families, such that some plant families evolved smaller flowers on islands, other families evolved larger flowers on islands, while some families exhibited no divergence in flower size between island and mainland taxa. Overall, our results show that there is no general island syndrome for flower size, but instead the evolution of floral morphology is complex and context dependent, depending on variation among islands and plant families. Our results also suggest that if island floras are typically dominated by small flowered species, as suggested by natural history observations, then ecological filtering is a more likely explanation of this pattern than evolutionary divergence post-colonization. We propose future studies that could disentangle the relative roles of ecological filtering and evolution in the distribution of floral traits on islands. More forthcoming papers &raquo; <p>Molly C. Hetherington-Rauth and Marc T. J. Johnson (July 2020)</p> <p><b>Insect pollinated plants evolve smaller flowers on some (sub)tropical islands and in and in specific plant families </b></p> <p><i><a href="https://dx.doi.org/10.1086/709018">Read the Article</a></i> (Just Accepted)</p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">I</span>slands often play host to &ldquo;unusual&rdquo; organisms. For example, giant tortoises, swimming iguanas, flightless birds, and tame animals are all features commonly associated with animals inhabiting islands. These unusual suites of traits, such as gigantism and tame behavior, are referred to as island syndromes and have been well characterized for island animals; however, the presence of island syndromes for plants has been poorly studied.</p> <p>One observation repeatedly made by naturalists, including Charles Darwin and Alfred Russel Wallace, is that island plants have small, non-showy flowers compared to plants living on the mainland. An often-cited explanation for this is that islands typically have less diverse pollinator communities and often lack large pollinators compared to mainland pollinator communities. Despite this explanation, it has yet to be tested whether island plants do, in fact, evolve small flowers.</p> <p>In this study, Hetherington-Rauth and Johnson put these historical claims to the test by examining island plants from across seven tropical and subtropical island systems in the Pacific Ocean. Using herbarium specimens, they measured the flowers of 556 plant species found on islands, as well as their closest living mainland relatives. </p><p>Contrary to naturalists&rsquo; predictions, they find that on average island plants did not evolve smaller flowers relative to mainland plants; however, the study did find that on specific islands, including the Gal&aacute;pagos Islands where Darwin visited, plants did evolve smaller flowers. The study also found that certain plant families tended to evolve smaller flowers. The authors conclude that no general island syndrome exists for flower size, but instead floral morphology likely evolves in response to the features of specific islands and the differing evolutionary history among plant families.</p> <hr /><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>nimals frequently evolve unique suites of traits on islands, but whether plants evolve comparable island syndromes remains unresolved. Here we test the prediction based on natural history observations that insect pollinated plants evolve smaller flowers on islands than mainland communities. We examined 556 plant species representing 136 phylogenetically independent contrasts between island and mainland sister taxa. We focused on endemic taxa originating from the Americas associated with seven tropical and subtropical islands of the Pacific Ocean. Contrary to conventional wisdom, flowers were not on average smaller on islands than the mainland. On specific archipelagos (the Galápagos Islands and Revillagigedo Islands), however, island taxa did evolve smaller flowers. Divergence in flower size between island and mainland taxa also varied among taxonomic families, such that some plant families evolved smaller flowers on islands, other families evolved larger flowers on islands, while some families exhibited no divergence in flower size between island and mainland taxa. Overall, our results show that there is no general island syndrome for flower size, but instead the evolution of floral morphology is complex and context dependent, depending on variation among islands and plant families. Our results also suggest that if island floras are typically dominated by small flowered species, as suggested by natural history observations, then ecological filtering is a more likely explanation of this pattern than evolutionary divergence post-colonization. We propose future studies that could disentangle the relative roles of ecological filtering and evolution in the distribution of floral traits on islands. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Fri, 27 Mar 2020 05:00:00 GMT “Caching in or falling back at the Sevilleta: the effects of body size and seasonal uncertainty on desert rodent foraging” https://amnat.org/an/newpapers/July-Yeakel.html Justin D. Yeakel, Uttam Bhat, and Seth D. Newsome (July 2020) Foraging rodents balance risk and rewards. A new model explores balancing food choices when monsoonal onset is uncertain Read the Article (Just Accepted) Foraging in an unpredictable environment is risky business, especially for small endotherms unable to carry around significant body fat stores. In deserts throughout the American Southwest, diverse groups of rodents circumvent these risks by either foraging for lower quality fallback foods, such as grass leaves, or by maintaining caches of higher quality grass seeds. While both of these strategies mitigate the uncertainty associated with an increasingly unpredictable monsoonal growing season, the specific fitness advantages of these behaviors depends on both the rodent&#39;s body size as well as the variability and associated risks of resource acquisition. In a new study by Justin Yeakel and Uttam Bhat at the University of California Merced, and Seth Newsome at the University of New Mexico, the authors use a mathematical model to explore the fitness advantages associated with different foraging strategies and caching behaviors in environments with increasingly unpredictable growing seasons. Specifically they examine the role of fallback foods – less preferred foods available during periods of scarcity – and maintaining caches of different sizes for rodent consumers varying in body size by an order of magnitude (10 to 200 grams). Because larger consumers can maintain a larger proportion of body mass as fat storage, the role of fallback foods and cache size is very context-dependent. The authors find that less productive environments magnify the expected role of fallback foods in consumer diets, regardless of body size, which may lead to increased competition. They also report that, while maintaining a large cache can make up for the uncertainty associated with unpredictable monsoons, the benefits provided by maintaining large caches are primarily realized by large consumers. Consequently, it is the smaller rodent consumers that may be expected to first feel the effects of increasingly unpredictable monsoons in a future defined by a changing climate. Abstract Foraging in uncertain environments requires balancing the risks associated with finding alternative resources against potential gains. In aridland environments characterized by extreme variation in the amount and seasonal timing of primary production, consumers must weigh the risks associated with foraging for preferred seeds that can be cached against fallback foods of low nutritional quality (e.g., leaves) that must be consumed immediately. Here we explore the influence of resource-scarcity, body size, and seasonal uncertainty on the expected foraging behaviors of caching rodents in the northern Chihuahaun Desert by integrating these elements with a Stochastic Dynamic Program (SDP) to determine fitness-maximizing foraging strategies. We demonstrate that resource-limited environments promote dependence on fallback foods, reducing the likelihood of starvation while increasing future risk exposure. Our results point to a qualitative difference in the use of fallback foods and the fitness benefits of caching at the threshold body size of 50&nbsp;g. Above this 50&nbsp;g body-size threshold, we observe large fitness gains associated with the maintenance of even a modest-sized cache, whereas similar gains for smaller consumers require maintenance of unrealistically large caches. This suggests that larger-bodied consumers that cache may be less sensitive to the future uncertainties in monsoonal onset predicted by global climate scenarios, whereas smaller consumers, regardless of caching behavior, may be at greater risk. More forthcoming papers &raquo; <p>Justin D. Yeakel, Uttam Bhat, and Seth D. Newsome (July 2020)</p> <p><b>Foraging rodents balance risk and rewards. A new model explores balancing food choices when monsoonal onset is uncertain </b></p> <p><i><a href="https://dx.doi.org/10.1086/709019">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">F</span>oraging in an unpredictable environment is risky business, especially for small endotherms unable to carry around significant body fat stores. In deserts throughout the American Southwest, diverse groups of rodents circumvent these risks by either foraging for lower quality fallback foods, such as grass leaves, or by maintaining caches of higher quality grass seeds. While both of these strategies mitigate the uncertainty associated with an increasingly unpredictable monsoonal growing season, the specific fitness advantages of these behaviors depends on both the rodent&#39;s body size as well as the variability and associated risks of resource acquisition.</p> <p>In a new study by Justin Yeakel and Uttam Bhat at the University of California Merced, and Seth Newsome at the University of New Mexico, the authors use a mathematical model to explore the fitness advantages associated with different foraging strategies and caching behaviors in environments with increasingly unpredictable growing seasons. Specifically they examine the role of fallback foods &ndash; less preferred foods available during periods of scarcity &ndash; and maintaining caches of different sizes for rodent consumers varying in body size by an order of magnitude (10 to 200 grams). Because larger consumers can maintain a larger proportion of body mass as fat storage, the role of fallback foods and cache size is very context-dependent.</p> <p>The authors find that less productive environments magnify the expected role of fallback foods in consumer diets, regardless of body size, which may lead to increased competition. They also report that, while maintaining a large cache can make up for the uncertainty associated with unpredictable monsoons, the benefits provided by maintaining large caches are primarily realized by large consumers. Consequently, it is the smaller rodent consumers that may be expected to first feel the effects of increasingly unpredictable monsoons in a future defined by a changing climate.</p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">F</span>oraging in uncertain environments requires balancing the risks associated with finding alternative resources against potential gains. In aridland environments characterized by extreme variation in the amount and seasonal timing of primary production, consumers must weigh the risks associated with foraging for preferred seeds that can be cached against fallback foods of low nutritional quality (e.g., leaves) that must be consumed immediately. Here we explore the influence of resource-scarcity, body size, and seasonal uncertainty on the expected foraging behaviors of caching rodents in the northern Chihuahaun Desert by integrating these elements with a Stochastic Dynamic Program (SDP) to determine fitness-maximizing foraging strategies. We demonstrate that resource-limited environments promote dependence on fallback foods, reducing the likelihood of starvation while increasing future risk exposure. Our results point to a qualitative difference in the use of fallback foods and the fitness benefits of caching at the threshold body size of 50&nbsp;g. Above this 50&nbsp;g body-size threshold, we observe large fitness gains associated with the maintenance of even a modest-sized cache, whereas similar gains for smaller consumers require maintenance of unrealistically large caches. This suggests that larger-bodied consumers that cache may be less sensitive to the future uncertainties in monsoonal onset predicted by global climate scenarios, whereas smaller consumers, regardless of caching behavior, may be at greater risk.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Fri, 27 Mar 2020 05:00:00 GMT “Elder barn owl nestlings flexibly redistribute parental food according to siblings’ need or in return for allopreening” https://amnat.org/an/newpapers/July-Ducouret-A.html Pauline Ducouret, Andrea Romano, Amélie N. Dreiss, Patrick Marmaroli, Xavier Falourd, Manon Bincteux, and Alexandre Roulin (July 2020) Allofeeding can be driven by kin selection and reciprocity, and depends on environmental conditions in barn owl chicks Read the Article (Just Accepted) Abstract Kin selection and reciprocation of biological services are distinct theories invoked to explain the origin and evolutionary maintenance of altruistic and cooperative behaviors. Although these behaviors are considered as non-mutually exclusive, the cost-to-benefit balance to behave altruistically or to reciprocally cooperate, and the conditions promoting a switch between such different strategies have rarely been tested. Here we examined the association between allofeeding, allopreening and vocal solicitations in wild barn owl (Tyto alba) broods under different food abundance conditions: natural food provisioning, and after an experimental food supplementation. Allofeeding was mainly performed by elder nestlings (hatching is asynchronous) in prime condition, especially when the cost of forgoing a prey was small (when parents allocated more prey to the food donor and after food supplementation). Nestlings preferentially shared food with siblings that emitted very intense calls, thus potentially increasing indirect fitness benefits, or the ones that provided extensive allopreening to the donor, thus possibly promoting direct benefits from reciprocation. Finally, allopreening was mainly directed towards older siblings, perhaps to maximize the probability of being fed in return. Helping behavior among relatives can therefore be driven by both kin selection and direct cooperation, although it is dependent on the contingent environmental conditions. More forthcoming papers &raquo; <p>Pauline Ducouret, Andrea Romano, Amélie N. Dreiss, Patrick Marmaroli, Xavier Falourd, Manon Bincteux, and Alexandre Roulin (July 2020) </p> <p><b>Allofeeding can be driven by kin selection and reciprocity, and depends on environmental conditions in barn owl chicks </b></p> <p><i><a href="https://dx.doi.org/10.1086/709106">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">K</span>in selection and reciprocation of biological services are distinct theories invoked to explain the origin and evolutionary maintenance of altruistic and cooperative behaviors. Although these behaviors are considered as non-mutually exclusive, the cost-to-benefit balance to behave altruistically or to reciprocally cooperate, and the conditions promoting a switch between such different strategies have rarely been tested. Here we examined the association between allofeeding, allopreening and vocal solicitations in wild barn owl (<i>Tyto alba</i>) broods under different food abundance conditions: natural food provisioning, and after an experimental food supplementation. Allofeeding was mainly performed by elder nestlings (hatching is asynchronous) in prime condition, especially when the cost of forgoing a prey was small (when parents allocated more prey to the food donor and after food supplementation). Nestlings preferentially shared food with siblings that emitted very intense calls, thus potentially increasing indirect fitness benefits, or the ones that provided extensive allopreening to the donor, thus possibly promoting direct benefits from reciprocation. Finally, allopreening was mainly directed towards older siblings, perhaps to maximize the probability of being fed in return. Helping behavior among relatives can therefore be driven by both kin selection and direct cooperation, although it is dependent on the contingent environmental conditions. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Fri, 27 Mar 2020 05:00:00 GMT “Quantifying the contribution of habitats and pathways to a spatially structured population facing environmental change” https://amnat.org/an/newpapers/July-Sample.html Christine Sample, Joanna A. Bieri, Benjamin Allen, Yulia Dementieva, Alyssa Carson, Connor Higgins, Sadie Piatt, Shirley Qiu, Summer Stafford, Brady J. Mattsson, Darius J. Semmens, Jay E. Diffendorfer, and Wayne E. Thogmartin (July 2020) A new metric quantifies a habitat’s contribution to population growth in the face of environmental change Read the Article (Just Accepted) There are few places in the world unaffected by humans. Conservation of species in this human-altered environment, which continues to change at a rapid pace, is difficult. Migratory species offer particular challenges because they use multiple habitats over the course of their migration, and these habitats can span several geopolitical boundaries. Consequently, the observed population level in any given location may depend on environmental changes and management actions in far-away areas. A key question is this: Which habitats are most important to the survival and growth of a population facing environmental change? Using a network model, a team of mathematicians and ecologists from the United States and Austria have developed a metric to assess the importance of habitats and movement pathways used by a population. Their metric predicts which habitats and pathways are most critical to short-term population growth. As a case study, the team has investigated the migratory population of monarch butterflies in eastern North America. They find that the central breeding region is the most critical node of the migratory network under small to moderate disturbances. Conditions in Mexico, the sole wintering habitat, become increasingly important when the habitat undergoes very large harmful changes. The metric can be applied to a wide variety of animal populations, and can help wildlife managers proactively target the most critical areas for conservation. Abstract The consequences of environmental disturbance and management are difficult to quantify for spatially structured populations, because changes in one location carry through to other areas due to species movement. We develop a metric, G, for measuring the contribution of a habitat or pathway to network-wide population growth rate in the face of environmental change. This metric is different than other contribution metrics as it quantifies effects of modifying vital rates for habitats and pathways in perturbation experiments. Perturbation treatments may range from small degradation or enhancement to complete habitat or pathway removal. We demonstrate the metric using a simple metapopulation example and a case study of eastern monarch butterflies. For the monarch case study, the magnitude of environmental change influences ordering of node contribution. We find that habitats within which all individuals reside during one season are the most important to short-term network growth under complete-removal scenarios. Whereas the central breeding region contributes most to population growth over all but the strongest disturbances. The metric G provides for more efficient management interventions that proactively mitigate impacts of expected disturbances to spatially structured populations. More forthcoming papers &raquo; <p>Christine Sample, Joanna A. Bieri, Benjamin Allen, Yulia Dementieva, Alyssa Carson, Connor Higgins, Sadie Piatt, Shirley Qiu, Summer Stafford, Brady J. Mattsson, Darius J. Semmens, Jay E. Diffendorfer, and Wayne E. Thogmartin (July 2020) </p> <p><b>A new metric quantifies a habitat’s contribution to population growth in the face of environmental change </b></p> <p><i><a href="https://dx.doi.org/10.1086/709009">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span>here are few places in the world unaffected by humans. Conservation of species in this human-altered environment, which continues to change at a rapid pace, is difficult. Migratory species offer particular challenges because they use multiple habitats over the course of their migration, and these habitats can span several geopolitical boundaries. Consequently, the observed population level in any given location may depend on environmental changes and management actions in far-away areas. A key question is this: Which habitats are most important to the survival and growth of a population facing environmental change? </p><p>Using a network model, a team of mathematicians and ecologists from the United States and Austria have developed a metric to assess the importance of habitats and movement pathways used by a population. Their metric predicts which habitats and pathways are most critical to short-term population growth. As a case study, the team has investigated the migratory population of monarch butterflies in eastern North America. They find that the central breeding region is the most critical node of the migratory network under small to moderate disturbances. Conditions in Mexico, the sole wintering habitat, become increasingly important when the habitat undergoes very large harmful changes. The metric can be applied to a wide variety of animal populations, and can help wildlife managers proactively target the most critical areas for conservation. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span>he consequences of environmental disturbance and management are difficult to quantify for spatially structured populations, because changes in one location carry through to other areas due to species movement. We develop a metric, <i>G</i>, for measuring the contribution of a habitat or pathway to network-wide population growth rate in the face of environmental change. This metric is different than other contribution metrics as it quantifies effects of modifying vital rates for habitats and pathways in perturbation experiments. Perturbation treatments may range from small degradation or enhancement to complete habitat or pathway removal. We demonstrate the metric using a simple metapopulation example and a case study of eastern monarch butterflies. For the monarch case study, the magnitude of environmental change influences ordering of node contribution. We find that habitats within which all individuals reside during one season are the most important to short-term network growth under complete-removal scenarios. Whereas the central breeding region contributes most to population growth over all but the strongest disturbances. The metric <i>G</i> provides for more efficient management interventions that proactively mitigate impacts of expected disturbances to spatially structured populations. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 25 Mar 2020 05:00:00 GMT “Climate change and thermoregulatory consequences of activity time in mammals” https://amnat.org/an/newpapers/July-Bonebrake.html Timothy C. Bonebrake, Enrico Rezende, and Francisco Bozinovic (July 2020) Climate change and thermoregulatory 🧥 consequences of activity time 🌙☀️ in mammals 🐭 Read the Article (Just Accepted) Will nocturnal or diurnal mammals be more vulnerable to global warming? Recent studies have shown that mammal species are shifting their activity patterns in response to human disturbance and also that such shifts could conceivably be one way for mammals to mitigate future warming impacts, e.g. shifts from hot diurnal hours to cooler nocturnal hours. However, to date there is little understanding of the global implications of such shifts or how different traits might filter such climatic variation. Supported by a Universitas 21 fellowship, Timothy Bonebrake (The University of Hong Kong) worked on this question in Santiago, Chile, with Francisco Bozinovic and Enrico Rezende at the Pontificia Universidad Católica de Chile. To address this issue, the team developed a modeling framework for evaluating the consequences of nocturnal and diurnal activity for climate change implications. Using this model, the team found that, broadly, nocturnal mammals may see increased habitable thermal space with future warming while diurnal species will likely see decreased habitable space. Importantly, traits such as thermal conductance and body size will determine how individual species are affected by warming. Nocturnal small mammals tend to be smaller and have lower thermal conductance than diurnal species – features that will likely have key implications for climate change vulnerability. These results are particularly important in a world of rapidly changing climates (global warming) and light (artificial night light). With multiple drivers of anthropogenic change globally, diurnal and nocturnal mammals will face unique challenges. An understanding of underlying physiological patterns that structure environmental change responses will hopefully aid in the conservation of these diverse species. Abstract Activity times structure the thermal environments experienced by organisms. In mammals, species shift from being nocturnal to diurnal and vice versa but the thermal consequences of variable activity patterns remain largely unexplored. Here we used theoretical thermoregulatory polygons bounded by estimates of basal metabolic rates (BMR), maximum metabolic rates (MMR) and thermal conductance (C) in small mammals to explore the metabolic consequences of exposure to global scale day-time and night-time temperatures. Model predictions indicated higher metabolic scope for activity for nocturnal species at low latitudes and that reduced minimum C and larger body size increased the geographic range in which nocturnality was advantageous. Consistent with predictions, within rodents, nocturnal species have low C. However, nocturnal mammals tend to be smaller than diurnal species likely reflecting the importance of additional factors driving body size. Projections of warming impacts on small mammals suggest that diurnal species could lose habitable space globally. Conversely, warming could lift cool temperature constraints on nocturnal species and increase habitable space, suggesting that a shift towards nocturnal niches might be favored in a warming world. Taken together these findings demonstrate the importance of energetic considerations for endotherms in managing global change impacts on nocturnal and diurnal species. Cambio climático y las consecuencias termorregulatorias del tiempo de actividad en mamíferos Los periodos de actividad estructuran los ambientes térmicos que experimentan los organismos. En mamíferos, las especies pasan de ser nocturnas a diurnas y viceversa, sin embargo, las consecuencias térmicas de los patrones de actividad variables permanecen inexploradas. Aquí, utilizamos polígonos de termorregulación teóricos delimitados por estimaciones de las tasas metabólicas basales (BMR), las tasas metabólicas máximas (MMR) y la conductancia térmica (C) en pequeños mamíferos para explorar las consecuencias metabólicas de la exposición a diferentes temperaturas diurnas y nocturnas a escala mundial. Las predicciones de los modelos indican una mayor expansividad metabólica en las especies nocturnas de latitudes bajas, y que una reducción en C y un mayor tamaño corporal aumentan el rango geográfico en el cual la nocturnidad es ventajosa. De acuerdo con las predicciones, dentro de los roedores, las especies nocturnas tienen una C baja. Sin embargo, los mamíferos nocturnos tienden a ser más pequeños que las especies diurnas, lo que probablemente refleja la importancia de factores adicionales que determinan el tamaño corporal. Las proyecciones de los impactos del calentamiento global en los mamíferos pequeños sugieren que las especies diurnas podrían perder espacio habitable a nivel mundial. Por el contrario, el calentamiento global podría relajar las restricciones debidas a temperaturas frías sobre las especies nocturnas y aumentar el espacio habitable, lo que sugiere que un cambio hacia nichos nocturnos podría verse favorecido en un planeta en proceso de calentamiento. En conjunto, estos hallazgos demuestran la importancia de las consideraciones energéticas para comprender los impactos del cambio global en las especies nocturnas y diurnas de endotermos. More forthcoming papers &raquo; <p>Timothy C. Bonebrake, Enrico Rezende, and Francisco Bozinovic (July 2020) </p> <p><b>Climate change and thermoregulatory 🧥 consequences of activity time 🌙☀️ in mammals 🐭 </b></p> <p><i><a href="https://dx.doi.org/10.1086/709010">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">W</span>ill nocturnal or diurnal mammals be more vulnerable to global warming? Recent studies have shown that mammal species are shifting their activity patterns in response to human disturbance and also that such shifts could conceivably be one way for mammals to mitigate future warming impacts, e.g. shifts from hot diurnal hours to cooler nocturnal hours. However, to date there is little understanding of the global implications of such shifts or how different traits might filter such climatic variation. </p><p>Supported by a Universitas 21 fellowship, Timothy Bonebrake (The University of Hong Kong) worked on this question in Santiago, Chile, with Francisco Bozinovic and Enrico Rezende at the Pontificia Universidad Católica de Chile. To address this issue, the team developed a modeling framework for evaluating the consequences of nocturnal and diurnal activity for climate change implications. Using this model, the team found that, broadly, nocturnal mammals may see increased habitable thermal space with future warming while diurnal species will likely see decreased habitable space. Importantly, traits such as thermal conductance and body size will determine how individual species are affected by warming. Nocturnal small mammals tend to be smaller and have lower thermal conductance than diurnal species – features that will likely have key implications for climate change vulnerability. </p><p>These results are particularly important in a world of rapidly changing climates (global warming) and light (artificial night light). With multiple drivers of anthropogenic change globally, diurnal and nocturnal mammals will face unique challenges. An understanding of underlying physiological patterns that structure environmental change responses will hopefully aid in the conservation of these diverse species. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>ctivity times structure the thermal environments experienced by organisms. In mammals, species shift from being nocturnal to diurnal and vice versa but the thermal consequences of variable activity patterns remain largely unexplored. Here we used theoretical thermoregulatory polygons bounded by estimates of basal metabolic rates (<i>BMR</i>), maximum metabolic rates (<i>MMR</i>) and thermal conductance (<i>C</i>) in small mammals to explore the metabolic consequences of exposure to global scale day-time and night-time temperatures. Model predictions indicated higher metabolic scope for activity for nocturnal species at low latitudes and that reduced minimum <i>C</i> and larger body size increased the geographic range in which nocturnality was advantageous. Consistent with predictions, within rodents, nocturnal species have low <i>C</i>. However, nocturnal mammals tend to be smaller than diurnal species likely reflecting the importance of additional factors driving body size. Projections of warming impacts on small mammals suggest that diurnal species could lose habitable space globally. Conversely, warming could lift cool temperature constraints on nocturnal species and increase habitable space, suggesting that a shift towards nocturnal niches might be favored in a warming world. Taken together these findings demonstrate the importance of energetic considerations for endotherms in managing global change impacts on nocturnal and diurnal species. </p> <h4>Cambio climático y las consecuencias termorregulatorias del tiempo de actividad en mamíferos</h4> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">L</span>os periodos de actividad estructuran los ambientes térmicos que experimentan los organismos. En mamíferos, las especies pasan de ser nocturnas a diurnas y viceversa, sin embargo, las consecuencias térmicas de los patrones de actividad variables permanecen inexploradas. Aquí, utilizamos polígonos de termorregulación teóricos delimitados por estimaciones de las tasas metabólicas basales (<i>BMR</i>), las tasas metabólicas máximas (<i>MMR</i>) y la conductancia térmica (<i>C</i>) en pequeños mamíferos para explorar las consecuencias metabólicas de la exposición a diferentes temperaturas diurnas y nocturnas a escala mundial. Las predicciones de los modelos indican una mayor expansividad metabólica en las especies nocturnas de latitudes bajas, y que una reducción en <i>C</i> y un mayor tamaño corporal aumentan el rango geográfico en el cual la nocturnidad es ventajosa. De acuerdo con las predicciones, dentro de los roedores, las especies nocturnas tienen una <i>C</i> baja. Sin embargo, los mamíferos nocturnos tienden a ser más pequeños que las especies diurnas, lo que probablemente refleja la importancia de factores adicionales que determinan el tamaño corporal. Las proyecciones de los impactos del calentamiento global en los mamíferos pequeños sugieren que las especies diurnas podrían perder espacio habitable a nivel mundial. Por el contrario, el calentamiento global podría relajar las restricciones debidas a temperaturas frías sobre las especies nocturnas y aumentar el espacio habitable, lo que sugiere que un cambio hacia nichos nocturnos podría verse favorecido en un planeta en proceso de calentamiento. En conjunto, estos hallazgos demuestran la importancia de las consideraciones energéticas para comprender los impactos del cambio global en las especies nocturnas y diurnas de endotermos. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 25 Mar 2020 05:00:00 GMT “Dispersal predicts hybrid zone widths across animal diversity: Implications for species borders under incomplete reproductive isolation” https://amnat.org/an/newpapers/July-McEntee.html Jay P. McEntee, J. Gordon Burleigh, and Sonal Singhal (July 2020) Read the Article (Just Accepted) Why do species’ geographic ranges have limits? When you think of your favorite species, whether it be a wildflower or a songbird, you might also think about where you have to go in the world to see them. Historically, researchers have focused on how geographic limits are affected by dispersal (or how organisms move), abiotic conditions like temperature or precipitation, and biotic conditions like competition. This study explores an alternate factor: hybridization, or mating between different species. This study re-analyzes previously published data from over 130 animal hybridizing pairs in which one species meets another species in a geographically narrow zone of hybridization, or hybrid zone. These hybrid zones correspond with range edges. Based on existing theory, the authors make two predictions for what factors might explain the widths of hybrid zones. First, animals that disperse less should have narrower hybrid zones than animals that move more. Second, the more genetically different two animal species are, the narrower their hybrid zone should be.  Together, these two factors explained ~40% of the variation in the width of hybrid zones, with dispersal being a much bigger factor that genetic difference. This study emphasizes the importance of dispersal in hybrid zones and, more generally, in defining species' limits. This study’s origins lie in a graduate student reading group of an important text on hybrid zones (John Endler’s Geographic Variation, Speciation, and Clines). Two of the authors were concurrently studying hybrid zones in the field while participating in this reading group; this analysis includes their earlier studies. Their discussions with the third author prompted the comparative approach employed in this study. Abstract Hybrid zones occur as range boundaries for many animal taxa. One model for how hybrid zones form and stabilize is the tension zone model, a version of which predicts that hybrid zone widths are determined by a balance between random dispersal into hybrid zones and selection against hybrids. Here, we examine whether random dispersal and proxies for selection against hybrids (genetic distances between hybridizing pairs) can explain variation in hybrid zone widths across 131 hybridizing pairs of animals. We show that these factors alone can explain ~40% of the variation in zone width among animal hybrid zones, with dispersal explaining far more of the variation than genetic distances. Patterns within clades were idiosyncratic. Genetic distances predicted hybrid zone widths particularly well for reptiles, while this relationship was opposite tension zone predictions in birds. Lastly, the data suggest that dispersal and molecular divergence set lower bounds on hybrid zone widths in animals, indicating there are geographic restrictions on hybrid zone formation. Overall, our analyses reinforce the fundamental importance of dispersal in hybrid zone formation, and more generally in the ecology of range boundaries. More forthcoming papers &raquo; <p>Jay P. McEntee, J. Gordon Burleigh, and Sonal Singhal (July 2020) </p> <p><i><a href="https://dx.doi.org/10.1086/709109">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">W</span>hy do species’ geographic ranges have limits? When you think of your favorite species, whether it be a wildflower or a songbird, you might also think about where you have to go in the world to see them. Historically, researchers have focused on how geographic limits are affected by dispersal (or how organisms move), abiotic conditions like temperature or precipitation, and biotic conditions like competition. This study explores an alternate factor: hybridization, or mating between different species. This study re-analyzes previously published data from over 130 animal hybridizing pairs in which one species meets another species in a geographically narrow zone of hybridization, or hybrid zone. These hybrid zones correspond with range edges. Based on existing theory, the authors make two predictions for what factors might explain the widths of hybrid zones. First, animals that disperse less should have narrower hybrid zones than animals that move more. Second, the more genetically different two animal species are, the narrower their hybrid zone should be.  Together, these two factors explained ~40% of the variation in the width of hybrid zones, with dispersal being a much bigger factor that genetic difference. This study emphasizes the importance of dispersal in hybrid zones and, more generally, in defining species' limits. </p><p>This study’s origins lie in a graduate student reading group of an important text on hybrid zones (John Endler’s <i>Geographic Variation, Speciation, and Clines</i>). Two of the authors were concurrently studying hybrid zones in the field while participating in this reading group; this analysis includes their earlier studies. Their discussions with the third author prompted the comparative approach employed in this study.</p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">H</span>ybrid zones occur as range boundaries for many animal taxa. One model for how hybrid zones form and stabilize is the tension zone model, a version of which predicts that hybrid zone widths are determined by a balance between random dispersal into hybrid zones and selection against hybrids. Here, we examine whether random dispersal and proxies for selection against hybrids (genetic distances between hybridizing pairs) can explain variation in hybrid zone widths across 131 hybridizing pairs of animals. We show that these factors alone can explain ~40% of the variation in zone width among animal hybrid zones, with dispersal explaining far more of the variation than genetic distances. Patterns within clades were idiosyncratic. Genetic distances predicted hybrid zone widths particularly well for reptiles, while this relationship was opposite tension zone predictions in birds. Lastly, the data suggest that dispersal and molecular divergence set lower bounds on hybrid zone widths in animals, indicating there are geographic restrictions on hybrid zone formation. Overall, our analyses reinforce the fundamental importance of dispersal in hybrid zone formation, and more generally in the ecology of range boundaries. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 25 Mar 2020 05:00:00 GMT ASN Election https://amnat.org/announcements/ASNElections.html The ASN 2020 Elections are open through April 30 for the offices of President and Vice President. Email was sent to ASN member to access the election website. Please let us know if you think you are a member and you did not receive the email. The election website randomizes the order for each person voting. The names below are in alphabetical order.The PRESIDENT leads the ASN Executive Council and selects the membership of the award and officer nomination committees. The President selects the President’s Award for the “best” paper in The American Naturalist in the past year, gives the ASN Presidential Address and presents the Society’s awards at the annual meeting, and represents the ASN in multiple other ways through the year. The President serves on the Executive Council for five years, including one year as President-Elect and three years as a Past-President. Judith Bronstein The ASN represents everything I love most in science. From the first time I opened Am Nat as a college junior and realized how an ecologist could spend her life, to the ASN stand-alone meetings that have energized and reinvigorated my research, to the final paper I handled as Am Nat Editor in Chief, the ASN has occupied the center of my career. My research focuses on the ecology and evolution of interspecific interactions, particularly on mutualisms. My career-long goal has been to build a solid conceptual foundation for the study of these poorly understood interactions. Using a combination of field observations, experiments, and theory, my lab examines how population processes, abiotic conditions, and the community context determine net effects of interactions for each participant species. I received my BA from Brown University, and my MSc and PhD in Ecology and Evolutionary Biology from the University of Michigan. I currently hold the rank of University Distinguished Professor in the Department of Ecology and Evolutionary Biology at the University of Arizona, with a joint appointment in the Department of Entomology. I’ve received several other university honors, including a Distinguished Career Teaching Award, as well as a Distinguished Service Award from the National Science Foundation. I was elected Fellow of the Ecological Society of America in 2016. I’ve served as an NSF Program Officer and in leadership positions for the Ecological Society of America and the Smithsonian Institution, but my most relevant service has been to the ASN. I served as Secretary in 2004-2006. I joined the American Naturalist Editorial Board in 2004, became one of the three Editors in 2010, and then served as the (first and only female) Editor in Chief from 2013 to 2017. I’m particularly proud of the efforts we made to diversify the Editorial Board during this period. I initiated the popular “Countdown” series that highlights significant but overlooked Am Nat papers of the past. Melding my interests in diversity and Am Nat’s own history, I was lead author on a 2018 paper highlighting the biographies and contributions of its earliest women authors. The landscape of science, scientific societies, publishing, and the world itself are all changing rapidly. ASN can and must continue to show the intellectual leadership it’s been demonstrating so effectively in recent years, while remaining the model egalitarian and diverse organization that it’s recently become. Further, we will be experiencing some critical personnel transitions in the next few years, notably in both the Managing Editor and Editor in Chief positions at Am Nat. I think it’s fair to say that I know ASN and our flagship journal inside and out. I believe that I can gently spearhead pragmatic responses to the challenges and opportunities ahead. Rebecca Safran It is a tremendous honor to be nominated to serve as the President of ASN. I view ASN as my home society, given its focus on integrative research in ecology, evolution, behavior and genetics and its emphasis on natural history. As an integrative evolutionary ecologist, my research program is broadly centered on the question of how population differentiation and reproductive isolation evolves through individual-level comparative and experimental studies. For this work, I have the pleasure of working with a talented group of student researchers at the University of Colorado and a large network of collaborators who, in collection, enable us to combine a variety of tools and perspectives to address questions related to evolutionary process and resulting pattern at different scales of analysis. Our field work is primarily focused on one of the most widespread species of bird: the barn swallow, where we are able to conduct work as far away as small villages in the Gansu Province of China, kibbutzim in Israel, centuries-old barns in central Europe and in barns, bridges, and culverts just north of our campus here in Boulder, Colorado. I have been proud to be in service to ASN through ongoing membership of the editorial board of the American Naturalist since 2014, organization of an ASN Spotlight Session at a recent annual meeting [2017], and as a committee member and chair of the Young Investigator Award [2014 -2017, chaired in 2017]. As far as other leadership and organizational experiences, I have also had the pleasure of co-leading two National Evolutionary Synthesis Center working groups [2000 – 2014] as well as to co-chair [2017] and chair [2019] the second and third Gordon Research Conferences on Speciation. I also co-founded and currently co-direct an initiative on Science Communication [Inside the Greenhouse] which is associated with several integrative courses (e.g., I have been teaching a film and climate change class for the past ten years) as well as internship opportunities, and public events that highlight diverse and inclusive ways of adaptation to climate change. Through these endeavors, I have come to appreciate and value truly integrative and interdisciplinary endeavors, which to me, characterizes our society as a whole. If elected, I would be committed to expanding resources for professional development, including workshops and financial support for meeting attendance. Professional development workshops could include, for example, topics related to publishing, science communication, diversity and inclusion, and data management. Further, I would like to provide opportunities for integrating across fields, the stated mission of the ASN. This may involve the establishment of working groups focused on synthesis projects, and help with forming cross-disciplinary collaborations.The VICE-PRESIDENT organizes the Vice-President’s Symposium for the annual meeting and edits the special supplement to The American Naturalist that contains the papers derived from the VP Symposium. The Vice-President is also the Society’s liaison for the organizers of the annual meeting. The Vice-President serves as a member of the Executive Council for three years, two as a regular member and one as ex officio member.&nbsp; Deepa Agashe I want to know how organisms adapt to new environments, and how adaptive processes influence molecular evolution. Current themes in my lab include understanding: (1) dietary niche shifts in insect pests, (2) the evolution of the bacterial translation machinery, (3) the evolutionary consequences of new mutations, and (4) the evolution of host-bacterial associations. I completed my Bachelors in Microbiology at Abasaheb Garware College Pune, India (2003); and my PhD in Ecology, Evolution and Behaviour at the University of Texas at Austin (2009). After a postdoctoral fellowship at Harvard University, I started my independent group in Bangalore in 2012. I recently received a Women Excellence Award (for female scientists under 40) from the President of India and have successfully competed for several national and international research grants and fellowships. I count my efforts to increase the visibility of evolutionary biology in India as my most important service. I have organized several meetings and student workshops (e.g. the long-running ICTS Schools on Population Genetics and Evolution), and participated in various outreach efforts (e.g. public Science Caf&eacute; talks, radio and television programs, and talks at smaller colleges and Universities in the country). I also serve as associate editor of Molecular Biology and Evolution (since 2015) and Evolution (since 2020); on the diversity committee of the ASN (since 2018); and the international committee of the SSE (since 2018). The ASN and the American Naturalist are quite special for me: my first paper was published in the American Naturalist, and experiencing peer review at its best (thanks to AE George Gilchrist) shaped how I approach my current roles as reviewer and editor. I also won the Editor’s award for best student paper, and the book grant from ASN let me buy truly beautiful books that I could not otherwise afford. Since then, I have continued to enjoy the high quality of science that is discussed at ASN meetings and published in the American Naturalist. I hope to connect the ASN to the Indian community and increase the breadth and reach of the ASN. This link would be mutually beneficial, given the incredible biodiversity in my part of the world but the relatively small local community of evolutionary biologists and ecologists. For the VP symposium, I would like to consider two areas: how to bridge across micro and macro-evolution, and the early evolution and establishment of host-microbiome interactions. .Stuart West I am an evolutionary biologist who studies social behaviours such as cooperation, altruism, spite and sex allocation. I use a mixture of techniques including theory, experiments and across species comparative studies, across organisms ranging from bacteria to birds. I am the Professor of Evolutionary Biology, Oxford, UK. I have spent my research career at Oxford, Imperial College London (UK), Cambridge (UK) and the Smithsonian Tropical Research Institute (Panama). I have been awarded EMBO Membership (2014), Society for the Study of Evolution, Non-North American Vice President (2007), Zoological Society of London Scientific Medal (2007), Phillip Leverhulme Prize (2006), Royal Society University Research Fellowship (2002) and a BBSRC David Phillips Research Fellowship (1998). I have had editorial duties at: American Naturalist; Animal Behaviour; Annu. Rev. Ecol. Evol & Syst.; Behavioural Ecology; Evolution; Evolution and Human Behaviour; Journal of Evolutionary Biology; and Philosophical Transactions of the Royal Society (special editions). My panel activities have included the Athena Swan (Equality Challenge Unit, UK), European Research Council, Natural Environment Research Council (UK) and Zoology Society London Awards Committee (UK). I have served two terms as an Associate Editor at the American Naturalist (2005-2008 & 2008-2011), and am a regular contributor to the journal. It would be an honour to serve the ASN. I would suggest a VP symposium that brings together researchers examining the genetic architecture and population genetics of social traits, with those using behavioural and evolutionary ecology (phenotypic) approaches. We have recently had success in communicating complex ideas with short animations on YouTube, and I would like to apply this to the symposium. &nbsp; <p>The ASN 2020 Elections are open through April 30 for the offices of President and Vice President. Email was sent to ASN member to access the election website. Please <a href="mailto:asn@press.uchicago.edu">let us know</a> if you think you are a member and you did not receive the email. The election website randomizes the order for each person voting. The names below are in alphabetical order.</p><p>The PRESIDENT leads the ASN Executive Council and selects the membership of the award and officer nomination committees. The President selects the President&rsquo;s Award for the &ldquo;best&rdquo; paper in The American Naturalist in the past year, gives the ASN Presidential Address and presents the Society&rsquo;s awards at the annual meeting, and represents the ASN in multiple other ways through the year. The President serves on the Executive Council for five years, including one year as President-Elect and three years as a Past-President.</p> <p style="text-align: center;"><strong>Judith Bronstein</strong><strong> </strong></p> <p>The ASN represents everything I love most in science. From the first time I opened <em>Am Nat</em> as a college junior and realized how an ecologist could spend her life, to the ASN stand-alone meetings that have energized and reinvigorated my research, to the final paper I handled as <em>Am Nat </em>Editor in Chief, the ASN has occupied the center of my career. My research focuses on the ecology and evolution of interspecific interactions, particularly on mutualisms. My career-long goal has been to build a solid conceptual foundation for the study of these poorly understood interactions. Using a combination of field observations, experiments, and theory, my lab examines how population processes, abiotic conditions, and the community context determine net effects of interactions for each participant species.</p> <p>I received my BA from Brown University, and my MSc and PhD in Ecology and Evolutionary Biology from the University of Michigan. I currently hold the rank of University Distinguished Professor in the Department of Ecology and Evolutionary Biology at the University of Arizona, with a joint appointment in the Department of Entomology. I&rsquo;ve received several other university honors, including a Distinguished Career Teaching Award, as well as a Distinguished Service Award from the National Science Foundation. I was elected Fellow of the Ecological Society of America in 2016. I&rsquo;ve served as an NSF Program Officer and in leadership positions for the Ecological Society of America and the Smithsonian Institution, but my most relevant service has been to the ASN. I served as Secretary in 2004-2006. I joined the <em>American Naturalist</em> Editorial Board in 2004, became one of the three Editors in 2010, and then served as the (first and only female) Editor in Chief from 2013 to 2017. I&rsquo;m particularly proud of the efforts we made to diversify the Editorial Board during this period. I initiated the popular &ldquo;Countdown&rdquo; series that highlights significant but overlooked <em>Am Nat</em> papers of the past. Melding my interests in diversity and <em>Am Nat</em>&rsquo;s own history, I was lead author on a 2018 paper highlighting the biographies and contributions of its earliest women authors.</p> <p>The landscape of science, scientific societies, publishing, and the world itself are all changing rapidly. ASN can and must continue to show the intellectual leadership it&rsquo;s been demonstrating so effectively in recent years, while remaining the model egalitarian and diverse organization that it&rsquo;s recently become. Further, we will be experiencing some critical personnel transitions in the next few years, notably in both the Managing Editor and Editor in Chief positions at <em>Am Nat</em>. I think it&rsquo;s fair to say that I know ASN and our flagship journal inside and out. I believe that I can gently spearhead pragmatic responses to the challenges and opportunities ahead.</p> <p style="text-align: center;"><strong>Rebecca Safran</strong></p> <p>It is a tremendous honor to be nominated to serve as the President of ASN. I view ASN as my home society, given its focus on integrative research in ecology, evolution, behavior and genetics and its emphasis on natural history. As an integrative evolutionary ecologist, my research program is broadly centered on the question of how population differentiation and reproductive isolation evolves through individual-level comparative and experimental studies. For this work, I have the pleasure of working with a talented group of student researchers at the University of Colorado and a large network of collaborators who, in collection, enable us to combine a variety of tools and perspectives to address questions related to evolutionary process and resulting pattern at different scales of analysis. Our field work is primarily focused on one of the most widespread species of bird: the barn swallow, where we are able to conduct work as far away as small villages in the Gansu Province of China, kibbutzim in Israel, centuries-old barns in central Europe and in barns, bridges, and culverts just north of our campus here in Boulder, Colorado.</p> <p>I have been proud to be in service to ASN through ongoing membership of the editorial board of the <em>American Naturalist</em> since 2014, organization of an ASN Spotlight Session at a recent annual meeting [2017], and as a committee member and chair of the Young Investigator Award [2014 -2017, chaired in 2017]. As far as other leadership and organizational experiences, I have also had the pleasure of co-leading two National Evolutionary Synthesis Center working groups [2000 &ndash; 2014] as well as to co-chair [2017] and chair [2019] the second and third Gordon Research Conferences on Speciation. I also co-founded and currently co-direct an initiative on Science Communication [Inside the Greenhouse] which is associated with several integrative courses (e.g., I have been teaching a film and climate change class for the past ten years) as well as internship opportunities, and public events that highlight diverse and inclusive ways of adaptation to climate change. Through these endeavors, I have come to appreciate and value truly integrative and interdisciplinary endeavors, which to me, characterizes our society as a whole.</p> <p>If elected, I would be committed to expanding resources for professional development, including workshops and financial support for meeting attendance. Professional development workshops could include, for example, topics related to publishing, science communication, diversity and inclusion, and data management. Further, I would like to provide opportunities for integrating across fields, the stated mission of the ASN. This may involve the establishment of working groups focused on synthesis projects, and help with forming cross-disciplinary collaborations.</p><p>The VICE-PRESIDENT organizes the Vice-President&rsquo;s Symposium for the annual meeting and edits the special supplement to <em>The American Naturalist</em> that contains the papers derived from the VP Symposium. The Vice-President is also the Society&rsquo;s liaison for the organizers of the annual meeting. The Vice-President serves as a member of the Executive Council for three years, two as a regular member and one as ex officio member.&nbsp;</p> <p style="text-align: center;"><strong>Deepa Agashe</strong></p> <p>I want to know how organisms adapt to new environments, and how adaptive processes influence molecular evolution. Current themes in my lab include understanding: (1) dietary niche shifts in insect pests, (2) the evolution of the bacterial translation machinery, (3) the evolutionary consequences of new mutations, and (4) the evolution of host-bacterial associations.</p> <p>I completed my Bachelors in Microbiology at Abasaheb Garware College Pune, India (2003); and my PhD in Ecology, Evolution and Behaviour at the University of Texas at Austin (2009). After a postdoctoral fellowship at Harvard University, I started my independent group in Bangalore in 2012. I recently received a Women Excellence Award (for female scientists under 40) from the President of India and have successfully competed for several national and international research grants and fellowships.</p> <p>I count my efforts to increase the visibility of evolutionary biology in India as my most important service. I have organized several meetings and student workshops (e.g. the long-running ICTS Schools on Population Genetics and Evolution), and participated in various outreach efforts (e.g. public Science Caf&eacute; talks, radio and television programs, and talks at smaller colleges and Universities in the country). I also serve as associate editor of <em>Molecular Biology and Evolution</em> (since 2015) and <em>Evolution</em> (since 2020); on the diversity committee of the ASN (since 2018); and the international committee of the SSE (since 2018).</p> <p>The ASN and the <em>American Naturalist a</em>re quite special for me: my first paper was published in the <em>American Naturalist</em>, and experiencing peer review at its best (thanks to AE George Gilchrist) shaped how I approach my current roles as reviewer and editor. I also won the Editor&rsquo;s award for best student paper, and the book grant from ASN let me buy truly beautiful books that I could not otherwise afford. Since then, I have continued to enjoy the high quality of science that is discussed at ASN meetings and published in the <em>American Naturalist.</em></p> <p>I hope to connect the ASN to the Indian community and increase the breadth and reach of the ASN. This link would be mutually beneficial, given the incredible biodiversity in my part of the world but the relatively small local community of evolutionary biologists and ecologists. For the VP symposium, I would like to consider two areas: how to bridge across micro and macro-evolution, and the early evolution and establishment of host-microbiome interactions.</p> <p style="text-align: center;">.<strong>Stuart West</strong></p> <p>I am an evolutionary biologist who studies social behaviours such as cooperation, altruism, spite and sex allocation. I use a mixture of techniques including theory, experiments and across species comparative studies, across organisms ranging from bacteria to birds.</p> <p>I am the Professor of Evolutionary Biology, Oxford, UK. I have spent my research career at Oxford, Imperial College London (UK), Cambridge (UK) and the Smithsonian Tropical Research Institute (Panama). I have been awarded EMBO Membership (2014), Society for the Study of Evolution, Non-North American Vice President (2007), Zoological Society of London Scientific Medal (2007), Phillip Leverhulme Prize (2006), Royal Society University Research Fellowship (2002) and a BBSRC David Phillips Research Fellowship (1998).</p> <p>I have had editorial duties at: <em>American Naturalist; Animal Behaviour; Annu. Rev. Ecol. Evol &amp; Syst.; Behavioural Ecology; Evolution; Evolution and Human Behaviour; Journal of Evolutionary Biology; and Philosophical Transactions of the Royal Society</em> (special editions). My panel activities have included the Athena Swan (Equality Challenge Unit, UK), European Research Council, Natural Environment Research Council (UK) and Zoology Society London Awards Committee (UK).</p> <p>I have served two terms as an Associate Editor at the <em>American Naturalist </em>(2005-2008 &amp; 2008-2011), and am a regular contributor to the journal.</p> <p>It would be an honour to serve the ASN. I would suggest a VP symposium that brings together researchers examining the genetic architecture and population genetics of social traits, with those using behavioural and evolutionary ecology (phenotypic) approaches. We have recently had success in communicating complex ideas with short animations on YouTube, and I would like to apply this to the symposium.<br /> &nbsp;</p> Tue, 24 Mar 2020 05:00:00 GMT Evolution Meeting Canceled https://amnat.org/announcements/Donation.html The 2020 Evolution Meeting is canceled due to COVID19. I&#39;ve been asked for a link to help us deal with the costs of the canceled contracts. There&#39;s an option here that will help all three societies support the Evolution Meetings: https://payments.evolutionsociety.org/donate&nbsp; Many thanks to Howard Rundle and Mitch Cruzan for the hard work of organizing. <p>The 2020 Evolution Meeting is canceled due to COVID19. I&#39;ve been asked for a link to help us deal with the costs of the canceled contracts.</p> <p>There&#39;s an option here that will help all three societies support the Evolution Meetings: <a href="https://payments.evolutionsociety.org/donate">https://payments.evolutionsociety.org/donate&nbsp;</a></p> <p>Many thanks to Howard Rundle and Mitch Cruzan for the hard work of organizing.</p> Wed, 18 Mar 2020 05:00:00 GMT 2020 IDEA Award Winners https://amnat.org/announcements/ANNIdeaAwa.html The American Society of Naturalists, the Society for the Study of Evolution, and the Society of Systematic Biologists are pleased to announce the recipients of the inaugural Inclusiveness, Diversity, Equity, and Access (IDEA) Award, Dr. Scott Edwards and Dr. Richard Kliman. The ASN/SSE/SSB Inclusiveness, Diversity, Equity, and Access (IDEA) Award was created in 2019 by the American Society of Naturalists (ASN), the Society for the Study of Evolution (SSE), and the Society of Systematic Biologists (SSB). The IDEA Award is given to a person at any career stage who has strengthened the ecology and evolutionary biology community by promoting inclusiveness and diversity in our fields. The award can also be presented to a group. The recipient will receive a plaque at the annual meeting of ASN/SSB/SSE and a $1000 honorarium. Dr. Edwards and Dr. Kliman were selected for their steadfast commitment to increasing diversity, equity, and inclusion of underrepresented minorities in evolutionary biology. In 2001, they started the Undergraduate Diversity at Evolution (UDE) program to provide funding and mentorship for students to attend the annual Evolution meeting. Since its inception, nearly 250 US and international undergraduates have had the opportunity to participate. Thank you to Dr. Edwards and Dr. Kliman for your commitment and contributions to the community! &nbsp; <p>The American Society of Naturalists, the Society for the Study of Evolution, and the Society of Systematic Biologists are pleased to announce the recipients of the inaugural Inclusiveness, Diversity, Equity, and Access (IDEA) Award, <strong>Dr. Scott Edwards and Dr. Richard Kliman. </strong></p> <p>The ASN/SSE/SSB Inclusiveness, Diversity, Equity, and Access (IDEA) Award was created in 2019 by the American Society of Naturalists (ASN), the Society for the Study of Evolution (SSE), and the Society of Systematic Biologists (SSB). The IDEA Award is given to a person at any career stage who has strengthened the ecology and evolutionary biology community by promoting inclusiveness and diversity in our fields. The award can also be presented to a group. The recipient will receive a plaque at the annual meeting of ASN/SSB/SSE and a $1000 honorarium.</p> <p><strong>Dr. Edwards and Dr. Kliman</strong> were selected for their steadfast commitment to increasing diversity, equity, and inclusion of underrepresented minorities in evolutionary biology. In 2001, they started the <a href="http://www.evolutionsociety.org/content/education/undergraduate-diversity-at-evolution.html">Undergraduate Diversity at Evolution</a> (UDE) program to provide funding and mentorship for students to attend the annual Evolution meeting. Since its inception, nearly 250 US and international undergraduates have had the opportunity to participate.</p> <p>Thank you to Dr. Edwards and Dr. Kliman for your commitment and contributions to the community!</p> <p>&nbsp;</p> Mon, 09 Mar 2020 05:00:00 GMT “Investigating the dynamics of elk population size and body mass in a seasonal environment using a mechanistic integral projection model” https://amnat.org/an/newpapers/Aug-Lachish-A.html Shelly Lachish, Ellen E. Brandell, Meggan E. Craft, Andrew P. Dobson, Peter J. Hudson, Daniel R. MacNulty, and Tim Coulson (Aug 2020) Novel bioenergetic integral projection model reveals how size-demog assoc shape pop dynamics in a seasonal environment Read the Article (Just Accepted) Abstract Environmentally-mediated changes in body size often underlie population responses to environmental change, yet this is not a universal phenomenon. Understanding when phenotypic change underlies population responses to environmental change is important for obtaining insights and robust predictions of population dynamics in a changing world. We develop a dynamic integral projection model that mechanistically links environmental conditions to demographic rates and phenotypic traits (body size) via changes in resource availability and individual energetics. We apply the model to the northern Yellowstone elk population and explore population responses to changing patterns of seasonality, incorporating the interdependence of growth, demography and density-dependent processes operating through population feedback on available resources. We found that small changes in body size distributions can have large impacts on population dynamics but need not cause population responses to environmental change. Environmental changes that altered demographic rates directly, via increasing or decreasing resource availability, led to large population impacts in the absence of substantial changes to body size distributions. In contrast, environmentally-driven shifts in body-size distributions could occur with little consequence for population dynamics when the effect of environmental change on resource availability was small and seasonally-restricted, and when strong density-dependent processes counteracted expected population responses. These findings highlight that a robust understanding of how body-size-demography associations influence population responses to environmental change will require knowledge of the shape of the relationship between phenotypic distributions and vital rates, the population status with regard to its carrying capacity, and importantly the nature of the environmentally-driven change in body size and carrying capacity. More forthcoming papers &raquo; <p>Shelly Lachish, Ellen E. Brandell, Meggan E. Craft, Andrew P. Dobson, Peter J. Hudson, Daniel R. MacNulty, and Tim Coulson (Aug 2020) </p> <p><b>Novel bioenergetic integral projection model reveals how size-demog assoc shape pop dynamics in a seasonal environment </b></p> <p><i><a href="https://dx.doi.org/10.1086/708723">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">E</span>nvironmentally-mediated changes in body size often underlie population responses to environmental change, yet this is not a universal phenomenon. Understanding when phenotypic change underlies population responses to environmental change is important for obtaining insights and robust predictions of population dynamics in a changing world. We develop a dynamic integral projection model that mechanistically links environmental conditions to demographic rates and phenotypic traits (body size) via changes in resource availability and individual energetics. We apply the model to the northern Yellowstone elk population and explore population responses to changing patterns of seasonality, incorporating the interdependence of growth, demography and density-dependent processes operating through population feedback on available resources. We found that small changes in body size distributions can have large impacts on population dynamics but need not cause population responses to environmental change. Environmental changes that altered demographic rates directly, via increasing or decreasing resource availability, led to large population impacts in the absence of substantial changes to body size distributions. In contrast, environmentally-driven shifts in body-size distributions could occur with little consequence for population dynamics when the effect of environmental change on resource availability was small and seasonally-restricted, and when strong density-dependent processes counteracted expected population responses. These findings highlight that a robust understanding of how body-size-demography associations influence population responses to environmental change will require knowledge of the shape of the relationship between phenotypic distributions and vital rates, the population status with regard to its carrying capacity, and importantly the nature of the environmentally-driven change in body size and carrying capacity. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 04 Mar 2020 06:00:00 GMT “Experimental hybridization studies suggest that pleiotropic alleles commonly underlie adaptive divergence between natural population” https://amnat.org/an/newpapers/Aug-Thompson.html Ken A. Thompson (Aug 2020) A synthesis of experimental hybridization studies suggests highly pleiotropic alleles are often used for adaptation Read the Article (Just Accepted) A&nbsp;longstanding and fundamental mystery in evolutionary biology surrounds the question of whether the mutation of a single gene tends to affect few or many traits at a time. For example, do mutations that affect how large an organism grows also tend to affect other traits like behavior or pigmentation? A new article by Ken Thompson, a Ph.D. candidate at the University of British Columbia, appearing in The&nbsp;American Naturalist, sheds new light on this unresolved question. Understanding the extent of pleiotropy—when a single gene affects many traits—is important because it tells us about the conditions under which evolution proceeds. In addition, knowledge of pleiotropy’s extent is critically important for applied studies of genome editing or genetic engineering. Normally, testing for pleiotropy is extremely labor-intensive. For decades, scientists have been inducing single mutations into hundreds or thousands of plants or animals to study the number of traits that are changed. In his article in The&nbsp;American Naturalist, Thompson leverages a prediction from evolutionary theory—based in simple geometric principles of genetics developed by Ronald Fisher in the 1930s—to conduct an indirect test of whether pleiotropy is widespread. Using data generated from experimental hybridization studies of naturally occurring plants and animals—where different species or subspecies are crossed in the lab—Thompson tests a specific prediction that only holds when genes are pleiotropic. The results of his analysis provide evidence that the mutations that cause evolution in nature typically have a high degree of pleiotropy. This work could have implications for gene-editing studies by making it clear that simple genetic changes might often affect many more traits than just the one where changes are desired. Abstract The alleles used for adaptation can pleiotropically affect traits under stabilizing selection. The fixation of alleles with deleterious pleiotropic side-effects causes compensatory alleles to be favoured by selection. Such compensatory alleles might segregate in interpopulation hybrids, resulting in segregation variance for traits where parents have indistinguishable phenotypes. If adaptation typically involves pleiotropy and compensation, then the segregation variance for traits under stabilizing selection is expected to increase with the magnitude of adaptive phenotypic divergence between parents. This prediction has not been tested empirically, and I gathered data from experimental hybridization studies to evaluate it. I found that pairs of parents which are more phenotypically divergent beget hybrids with more segregation variance in traits for which the parents are statistically indistinguishable. This result suggests that adaptive divergence between pairs of natural populations proceeds via pleiotropy and compensation, and that deleterious transgressive segregation variance accumulates systematically as populations diverge. More forthcoming papers &raquo; <p>Ken A. Thompson (Aug 2020) </p> <p><b>A synthesis of experimental hybridization studies suggests highly pleiotropic alleles are often used for adaptation </b></p> <p><i><a href="https://dx.doi.org/10.1086/708722">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>&nbsp;longstanding and fundamental mystery in evolutionary biology surrounds the question of whether the mutation of a single gene tends to affect few or many traits at a time. For example, do mutations that affect how large an organism grows also tend to affect other traits like behavior or pigmentation? A new article by Ken Thompson, a Ph.D. candidate at the University of British Columbia, appearing in <i>The&nbsp;American Naturalist</i>, sheds new light on this unresolved question. </p><p>Understanding the extent of pleiotropy—when a single gene affects many traits—is important because it tells us about the conditions under which evolution proceeds. In addition, knowledge of pleiotropy’s extent is critically important for applied studies of genome editing or genetic engineering. </p><p>Normally, testing for pleiotropy is extremely labor-intensive. For decades, scientists have been inducing single mutations into hundreds or thousands of plants or animals to study the number of traits that are changed. </p><p>In his article in <i>The&nbsp;American Naturalist</i>, Thompson leverages a prediction from evolutionary theory—based in simple geometric principles of genetics developed by Ronald Fisher in the 1930s—to conduct an indirect test of whether pleiotropy is widespread. Using data generated from experimental hybridization studies of naturally occurring plants and animals—where different species or subspecies are crossed in the lab—Thompson tests a specific prediction that only holds when genes are pleiotropic. </p><p>The results of his analysis provide evidence that the mutations that cause evolution in nature typically have a high degree of pleiotropy. This work could have implications for gene-editing studies by making it clear that simple genetic changes might often affect many more traits than just the one where changes are desired. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span>he alleles used for adaptation can pleiotropically affect traits under stabilizing selection. The fixation of alleles with deleterious pleiotropic side-effects causes compensatory alleles to be favoured by selection. Such compensatory alleles might segregate in interpopulation hybrids, resulting in segregation variance for traits where parents have indistinguishable phenotypes. If adaptation typically involves pleiotropy and compensation, then the segregation variance for traits under stabilizing selection is expected to increase with the magnitude of adaptive phenotypic divergence between parents. This prediction has not been tested empirically, and I gathered data from experimental hybridization studies to evaluate it. I found that pairs of parents which are more phenotypically divergent beget hybrids with more segregation variance in traits for which the parents are statistically indistinguishable. This result suggests that adaptive divergence between pairs of natural populations proceeds via pleiotropy and compensation, and that deleterious transgressive segregation variance accumulates systematically as populations diverge. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 04 Mar 2020 06:00:00 GMT “Optimal network architectures for spatially structured populations with heterogeneous diffusion” https://amnat.org/an/newpapers/July-Ruiz-Herrera-A.html Alfonso Ruiz-Herrera and Pedro J. Torres (July 2020) We derive new management guidelines to maximize the population size in networks. The degree of mobility is the key Read the Article (Just Accepted) Abstract The motivation of this paper is to derive new management guidelines to maximize the overall population size in popular strategies such as Marine Protected Areas and the construction of Ecological corridors. These guidelines are based on the identification of the network architecture(s) for which the total population size is maximized. Describing the biological role of the typical network variables in the fate of the population is a classical problem with many practical applications. This paper suggests that the optimal network architecture relies heavily on the degree of mobility of the population. The recommended network architecture for populations with reduced mobility (in the absence of cost of dispersal and landscapes made up of many sources) is a graph where a patch has routes towards any other patch with lower growth rates. However, for highly mobile populations, there are many possible network architectures for which the total population size is maximized, e.g., any cyclic graph. We have paid special attention to species with symmetric movement in heterogeneous landscapes. A striking result is that the network architecture does not have any influence on the total population size for highly mobile populations when any pair of different patches can be connected by a sequence of paths. More forthcoming papers &raquo; <p>Alfonso Ruiz-Herrera and Pedro J. Torres (July 2020) </p> <p><b>We derive new management guidelines to maximize the population size in networks. The degree of mobility is the key </b></p> <p><i><a href="https://dx.doi.org/10.1086/708806">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span>he motivation of this paper is to derive new management guidelines to maximize the overall population size in popular strategies such as Marine Protected Areas and the construction of Ecological corridors. These guidelines are based on the identification of the network architecture(s) for which the total population size is maximized. Describing the biological role of the typical network variables in the fate of the population is a classical problem with many practical applications. This paper suggests that the optimal network architecture relies heavily on the degree of mobility of the population. The recommended network architecture for populations with reduced mobility (in the absence of cost of dispersal and landscapes made up of many sources) is a graph where a patch has routes towards any other patch with lower growth rates. However, for highly mobile populations, there are many possible network architectures for which the total population size is maximized, e.g., any cyclic graph. We have paid special attention to species with symmetric movement in heterogeneous landscapes. A striking result is that the network architecture does not have any influence on the total population size for highly mobile populations when any pair of different patches can be connected by a sequence of paths. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 04 Mar 2020 06:00:00 GMT 2020 American Naturalist Student Paper Award https://amnat.org/announcements/ANNStuPaperAwa.html The American Naturalist 2020 Student Paper Award is for work that was published in 2019 and that was performed primarily by the first author and primarily while she or he was an undergraduate or graduate student. There were seventy eligible papers. The Editors of the journal, in consultation with Associate Editors, examine all student-authored papers in the journal to select an outstanding contribution that advances the journal’s goals of changing the way people think about organismal biology (including but not limited to ecology, evolution, and behavior) by providing new conceptual insights. &nbsp; The recipient of the 2020 Student Paper Award is Chuliang Song, for his paper “On the consequences of the interdependence of stabilizing and equalizing mechanisms” (American Naturalist, November 2019, 194 (5):627-639), co-authored with Gy&ouml;rgy Barab&aacute;s and Serguei Saavedra. Over the past decades, ecology has seen the emergence of what is now called Modern Coexistence Theory that provides an elegant interpretation and synthesis of mechanisms that can facilitate long-term coexistence of species. Song and colleagues present an exceptionally clearly written evaluation of MCT, comparing two- versus multi-species models, and comparing phenomenological versus more mechanistic models.&nbsp; With wonderfully lucid writing, they help clarify a number of key ideas of MCT, the relationships between various permutations of the theory, and some inconsistencies that people studying MCT need to keep in mind.&nbsp; Their critical appraisal of a major idea in ecology will affect the way ecologists think about species coexistence. They also do an excellent job of introducing the topic to readers who are not theoretical ecologists, making MCT accessible to a wider array of readers.Silas B. Tittes, for his paper “Grow where you thrive, or where only you can survive? An analysis of performance curve evaluation in a clade with diverse habitat affinities”, with co-authors Joseph F. Walker, Lorena Torres-Mart&iacute;ez and Nancy C. Emery (American Naturalist 193 (4):530-544). In this paper, Tittes and colleagues develop a novel Bayesian analytical tool for quantifying performance curves (e.g., how fitness varies across a gradient of environmental conditions). Their new method has the key benefit that it facilitates comparisons between different performance curve estimates (e.g., from different species). They then use this method to analyze growth chamber experimental data for a clade of vernal pool plants, that partition different soil moisture conditions in nature. Despite the differences in species’ distribution in the wild, in the laboratory these plants all have similar performance curves, with optimal performance often occurring at water conditions where a given species is rare or absent. The insight is that abiotic performance alone is not a good guide (contrary to many environmental niche modeling approaches), but rather biotic interactions such as competition must play a key role. This paper is outstanding for its merger of an innovative and sophisticated statistical toolkit with laboratory experimental data, field data on species distributions, all placed within a phylogenetic context, to address a core question in evolutionary ecology: what factors dictate species’ distributions? Daniel I. Bolnick, Editor-in-Chief Russell Bonduriansky, Editor Jennifer Lau, Editor Alice Winn, Editor with the editors who handled some of the 2019 papers, Judith Bronstein, former Editor-in-Chief Yannis Michilakis, former Editor <p><em>The American Naturalist </em>2020 Student Paper Award is for work that was published in 2019 and that was performed primarily by the first author and primarily while she or he was an undergraduate or graduate student. There were seventy eligible papers. The Editors of the journal, in consultation with Associate Editors, examine all student-authored papers in the journal to select an outstanding contribution that advances the journal&rsquo;s goals of changing the way people think about organismal biology (including but not limited to ecology, evolution, and behavior) by providing new conceptual insights.<br /> &nbsp;<br /> The recipient of the 2020 Student Paper Award is <strong>Chuliang Song</strong>, for his paper &ldquo;<a href="https://www.journals.uchicago.edu/doi/full/10.1086/705347">On the consequences of the interdependence of stabilizing and equalizing mechanisms</a>&rdquo; (<em>American Naturalist</em>, November 2019, 194 (5):627-639), co-authored with Gy&ouml;rgy Barab&aacute;s and Serguei Saavedra. Over the past decades, ecology has seen the emergence of what is now called Modern Coexistence Theory that provides an elegant interpretation and synthesis of mechanisms that can facilitate long-term coexistence of species. Song and colleagues present an exceptionally clearly written evaluation of MCT, comparing two- versus multi-species models, and comparing phenomenological versus more mechanistic models.&nbsp; With wonderfully lucid writing, they help clarify a number of key ideas of MCT, the relationships between various permutations of the theory, and some inconsistencies that people studying MCT need to keep in mind.&nbsp; Their critical appraisal of a major idea in ecology will affect the way ecologists think about species coexistence. They also do an excellent job of introducing the topic to readers who are not theoretical ecologists, making MCT accessible to a wider array of readers.</p><p><strong>Silas B. Tittes</strong>, for his paper &ldquo;<a href="https://www.journals.uchicago.edu/doi/full/10.1086/701827">Grow where you thrive, or where only you can survive? An analysis of performance curve evaluation in a clade with diverse habitat affinities</a>&rdquo;, with co-authors Joseph F. Walker, Lorena Torres-Mart&iacute;ez and Nancy C. Emery (<em>American Naturalist </em>193 (4):530-544). In this paper, Tittes and colleagues develop a novel Bayesian analytical tool for quantifying performance curves (e.g., how fitness varies across a gradient of environmental conditions). Their new method has the key benefit that it facilitates comparisons between different performance curve estimates (e.g., from different species). They then use this method to analyze growth chamber experimental data for a clade of vernal pool plants, that partition different soil moisture conditions in nature. Despite the differences in species&rsquo; distribution in the wild, in the laboratory these plants all have similar performance curves, with optimal performance often occurring at water conditions where a given species is rare or absent. The insight is that abiotic performance alone is not a good guide (contrary to many environmental niche modeling approaches), but rather biotic interactions such as competition must play a key role. This paper is outstanding for its merger of an innovative and sophisticated statistical toolkit with laboratory experimental data, field data on species distributions, all placed within a phylogenetic context, to address a core question in evolutionary ecology: what factors dictate species&rsquo; distributions?</p> <p>Daniel I. Bolnick, Editor-in-Chief<br /> Russell Bonduriansky, Editor<br /> Jennifer Lau, Editor<br /> Alice Winn, Editor</p> <p>with the editors who handled some of the 2019 papers,</p> <p>Judith Bronstein, former Editor-in-Chief<br /> Yannis Michilakis, former Editor</p> Mon, 02 Mar 2020 06:00:00 GMT “Where is natural history in ecological, evolutionary, and behavioral science?” https://amnat.org/an/newpapers/July-Travis.html Joseph Travis (July 2020) Read the Article (Just Accepted) There is an inherent tension between natural history, the careful observation of nature, and experimental science, the search for general principles of cause and effect. This tension is especially taut in the sciences that study nature’s variety: ecology, evolutionary biology, and behavioral biology. This paper examines the role that natural history plays in the scientific process, asking a series of questions about that role. Can scientists rely on observations in natural history to test scientific predictions? If experiments are necessary, how can natural history affect the relevance of experiments? In particular, the paper examines the pros and cons of two different approaches to science in these disciplines. Should scientists begin with an important hypothesis and find the best organism with which to test it? This is the foundation of what is called “question-driven science.” Alternatively, should scientists work from the opposite direction, that is, be careful natural historians so that they can ask which important hypothesis is most suited for testing with a particular organism? The paper offers a synthesis of these approaches, suggesting that strong science is built by having a command of natural history so that the scientist allows nature to tell her or him or them which question to ask instead of demanding that nature answer the question she, he, or they find most interesting. The Pine Barrens Treefrog, Hyla andersoni, is found in acidic ponds and seeps in three separate regions of the eastern US: southern New Jersey, the eastern border between the Carolinas, and an area of west Florida and southwest Alabama. In the latter two areas, it is found almost entirely in small, shallow seepages. If we want to conclude that the species is a specialist in such habitats, what must we do? Is it enough to say that we find them only in such habitats? Ought we to survey, quantitatively, all kinds of habitats in which frogs occur so that we can be sure where H.&nbsp;andersoni is not? If we wish to understand why H.&nbsp;andersoni is found only in acidic seeps, should we transplant them to different habitats, even at the risk of causing high mortality in those habitats? Does our answer change if we remember that this species is endangered? This is an even more contrived example than the ones in the text of the paper, but it illustrates the tension between relying on natural history and using natural history as our foundation for scientific investigation. Abstract Natural history is the careful observation of nature, wherever nature is. Ultimately, it is what ecological, evolutionary, and behavioral science are supposed to explain. It is difficult to use natural history alone to test hypotheses in these fields because of the complex paths between process and pattern. Few patterns are predicted by one and only one hypothesis, so experiments are almost always necessary. However, the robustness of experimental results depends on how well experimental conditions reflect the integration of natural history. Natural history also plays a vital role in how well we can apply Krogh’s principle to our work. Krogh’s principle is that scientists begin with an important hypothesis and find a system (organism, habitat, species interaction) with which to test it. However, natural history is essential for knowing if the question applies to the system or if we are forcing the question on the system. There is value in beginning one’s research not by identifying an interesting question and searching for the right system but with identifying an interesting system in which to ask the right question. This approach carries the danger of parochialism, which can only be avoided by having a command of theory as well as natural history. A command of both areas allows nature to tell us which question to ask instead of demanding that nature answer the question we find most interesting. More forthcoming papers &raquo; <p>Joseph Travis (July 2020) </p> <p><i><a href="https://dx.doi.org/10.1086/708765">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span>here is an inherent tension between natural history, the careful observation of nature, and experimental science, the search for general principles of cause and effect. This tension is especially taut in the sciences that study nature’s variety: ecology, evolutionary biology, and behavioral biology. This paper examines the role that natural history plays in the scientific process, asking a series of questions about that role. Can scientists rely on observations in natural history to test scientific predictions? If experiments are necessary, how can natural history affect the relevance of experiments? In particular, the paper examines the pros and cons of two different approaches to science in these disciplines. Should scientists begin with an important hypothesis and find the best organism with which to test it? This is the foundation of what is called “question-driven science.” Alternatively, should scientists work from the opposite direction, that is, be careful natural historians so that they can ask which important hypothesis is most suited for testing with a particular organism? The paper offers a synthesis of these approaches, suggesting that strong science is built by having a command of natural history so that the scientist allows nature to tell her or him or them which question to ask instead of demanding that nature answer the question she, he, or they find most interesting. </p> <hr /><p><i>The Pine Barrens Treefrog, </i>Hyla andersoni<i>, is found in acidic ponds and seeps in three separate regions of the eastern US: southern New Jersey, the eastern border between the Carolinas, and an area of west Florida and southwest Alabama. In the latter two areas, it is found almost entirely in small, shallow seepages. If we want to conclude that the species is a specialist in such habitats, what must we do? Is it enough to say that we find them only in such habitats? Ought we to survey, quantitatively, all kinds of habitats in which frogs occur so that we can be sure where </i>H.&nbsp;andersoni<i> is not? If we wish to understand why </i>H.&nbsp;andersoni<i> is found only in acidic seeps, should we transplant them to different habitats, even at the risk of causing high mortality in those habitats? Does our answer change if we remember that this species is endangered? This is an even more contrived example than the ones in the text of the paper, but it illustrates the tension between relying on natural history and using natural history as our foundation for scientific investigation. </i></p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">N</span>atural history is the careful observation of nature, wherever nature is. Ultimately, it is what ecological, evolutionary, and behavioral science are supposed to explain. It is difficult to use natural history alone to test hypotheses in these fields because of the complex paths between process and pattern. Few patterns are predicted by one and only one hypothesis, so experiments are almost always necessary. However, the robustness of experimental results depends on how well experimental conditions reflect the integration of natural history. Natural history also plays a vital role in how well we can apply Krogh’s principle to our work. Krogh’s principle is that scientists begin with an important hypothesis and find a system (organism, habitat, species interaction) with which to test it. However, natural history is essential for knowing if the question applies to the system or if we are forcing the question on the system. There is value in beginning one’s research not by identifying an interesting question and searching for the right system but with identifying an interesting system in which to ask the right question. This approach carries the danger of parochialism, which can only be avoided by having a command of theory as well as natural history. A command of both areas allows nature to tell us which question to ask instead of demanding that nature answer the question we find most interesting. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Fri, 28 Feb 2020 06:00:00 GMT “Looking for mimicry in a snake assemblage using deep learning” https://amnat.org/an/newpapers/July-de-Solan-A.html Thomas de Solan, Julien Pierre Renoult, Philippe Geniez, Patrice David, and Pierre-Andre Crochet (July 2020) Read the Article (Just Accepted) Abstract Batesian mimicry is a canonical example of evolution by natural selection, popularized by highly colorful species resembling unrelated models with astonishing precision. However, Batesian mimicry could also occur in inconspicuous species and rely on subtle resemblance. Although potentially widespread, such instances have been rarely investigated, such that the real frequency of Batesian mimicry has remained largely unknown. To fill this gap, we developed a new approach using deep learning to quantify visual resemblance between putative mimics and models from photographs. We applied this method to Western Palearctic snakes. Potential nonvenomous mimics were revealed by an excess of resemblance to sympatric venomous snakes compared to random expectations. We found that 8% of the non-venomous species were potential mimics, although they resembled their models imperfectly. This study is the first to quantify the frequency of Batesian mimicry in a whole community of vertebrates, and shows that even concealed species can act as potential models. Our approach should prove useful to detect mimicry in other communities, and more generally it highlights the benefits of deep learning for quantitative studies of phenotypic resemblance. More forthcoming papers &raquo; <p>Thomas de Solan, Julien Pierre Renoult, Philippe Geniez, Patrice David, and Pierre-Andre Crochet (July 2020)</p> <p><i><a href="https://dx.doi.org/10.1086/708763">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">B</span>atesian mimicry is a canonical example of evolution by natural selection, popularized by highly colorful species resembling unrelated models with astonishing precision. However, Batesian mimicry could also occur in inconspicuous species and rely on subtle resemblance. Although potentially widespread, such instances have been rarely investigated, such that the real frequency of Batesian mimicry has remained largely unknown. To fill this gap, we developed a new approach using deep learning to quantify visual resemblance between putative mimics and models from photographs. We applied this method to Western Palearctic snakes. Potential nonvenomous mimics were revealed by an excess of resemblance to sympatric venomous snakes compared to random expectations. We found that 8% of the non-venomous species were potential mimics, although they resembled their models imperfectly. This study is the first to quantify the frequency of Batesian mimicry in a whole community of vertebrates, and shows that even concealed species can act as potential models. Our approach should prove useful to detect mimicry in other communities, and more generally it highlights the benefits of deep learning for quantitative studies of phenotypic resemblance. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 26 Feb 2020 06:00:00 GMT “Correlated evolution of sex allocation and mating system in wrasses and parrotfishes” https://amnat.org/an/newpapers/July-Hodge.html Jennifer R. Hodge, Francesco Santini, and Peter C. Wainwright (July 2020) Size advantage drives the evolution of sex change in an iconic group of sex changing fishes (Labridae) Read the Article (Just Accepted) An organism that changes functional sex during the course of its reproductive life is known as a sequential hermaphrodite. This type of sex change occurs in a variety of animals and plants, but among vertebrate animals it is only found in some fishes. Theory predicts that sequential hermaphroditism should evolve in animals when, for a given sex, reproduction is more effective at a certain size (the size-advantage model). For example, when large males maintain social status by monopolizing access to resources or females, the reproductive success of small males is suppressed, and sex change from female to male is predicted. This is the theory, but until now we lacked empirical evidence that sex change evolves as a consequence of size advantage. Working at the University of California, Davis, Jennifer Hodge and colleagues analyzed the different forms of sex allocation and mating expressed by wrasses and parrotfishes – the second largest family of marine fishes and a model system for studies of sequential hermaphroditism. Accounting for evolutionary history, they find that female-to-male sex change has evolved in response to mating systems characterized by male size advantage. They also find that the mating system with the strongest male size advantage favors the most pronounced expression of hermaphroditism in which all males are derived via sex change. Once evolved, this combination of mating and sex allocation is rarely lost. The authors suggest the reason that male size advantage is able to alter selection in favor of sex change in fishes is likely because their gonads develop from a single type of tissue, rather than from two as in most vertebrates, resulting in plastic sex determination. This study provides important insight into why sex change evolves and the mechanisms that are required to sustain it. Abstract In accordance with predictions of the size-advantage model, comparative evidence confirms that protogynous sex change is lost when mating behavior is characterized by weak size advantage. However, we lack comparative evidence supporting the adaptive significance of sex change. Specifically, it remains unclear whether increasing male size advantage induces transitions to protogynous sex change across species, as it can within species. We show that in wrasses and parrotfishes (Labridae), the evolution of protogynous sex change is correlated with polygynous mating, and that the degree of male size advantage expressed by polygynous species influences transitions between different types of protogynous sex change. Phylogenetic reconstructions reveal strikingly similar patterns of sex allocation and mating system evolution with comparable lability. Despite the plasticity of sex determination mechanisms in labrids, transitions trend towards monandry (all males derived from sex-changed females), with all observed losses of protogyny accounted for by shifts in the timing of sex change to prematuration. Likewise, transitions in mating system trend from the ancestral condition of lek-like polygyny toward greater male size advantage, characteristic of haremic polygyny. The results of our comparative analyses are among the first to confirm the adaptive significance of sex change as described by the size-advantage model. More forthcoming papers &raquo; <p>Jennifer R. Hodge, Francesco Santini, and Peter C. Wainwright (July 2020) </p> <p><b>Size advantage drives the evolution of sex change in an iconic group of sex changing fishes (Labridae) </b></p> <p><i><a href="https://dx.doi.org/10.1086/708764">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>n organism that changes functional sex during the course of its reproductive life is known as a sequential hermaphrodite. This type of sex change occurs in a variety of animals and plants, but among vertebrate animals it is only found in some fishes. Theory predicts that sequential hermaphroditism should evolve in animals when, for a given sex, reproduction is more effective at a certain size (the size-advantage model). For example, when large males maintain social status by monopolizing access to resources or females, the reproductive success of small males is suppressed, and sex change from female to male is predicted. This is the theory, but until now we lacked empirical evidence that sex change evolves as a consequence of size advantage. </p> <p>Working at the University of California, Davis, Jennifer Hodge and colleagues analyzed the different forms of sex allocation and mating expressed by wrasses and parrotfishes – the second largest family of marine fishes and a model system for studies of sequential hermaphroditism. Accounting for evolutionary history, they find that female-to-male sex change has evolved in response to mating systems characterized by male size advantage. They also find that the mating system with the strongest male size advantage favors the most pronounced expression of hermaphroditism in which all males are derived via sex change. Once evolved, this combination of mating and sex allocation is rarely lost. The authors suggest the reason that male size advantage is able to alter selection in favor of sex change in fishes is likely because their gonads develop from a single type of tissue, rather than from two as in most vertebrates, resulting in plastic sex determination. </p> <p>This study provides important insight into why sex change evolves and the mechanisms that are required to sustain it. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">I</span>n accordance with predictions of the size-advantage model, comparative evidence confirms that protogynous sex change is lost when mating behavior is characterized by weak size advantage. However, we lack comparative evidence supporting the adaptive significance of sex change. Specifically, it remains unclear whether increasing male size advantage induces transitions to protogynous sex change across species, as it can within species. We show that in wrasses and parrotfishes (Labridae), the evolution of protogynous sex change is correlated with polygynous mating, and that the degree of male size advantage expressed by polygynous species influences transitions between different types of protogynous sex change. Phylogenetic reconstructions reveal strikingly similar patterns of sex allocation and mating system evolution with comparable lability. Despite the plasticity of sex determination mechanisms in labrids, transitions trend towards monandry (all males derived from sex-changed females), with all observed losses of protogyny accounted for by shifts in the timing of sex change to prematuration. Likewise, transitions in mating system trend from the ancestral condition of lek-like polygyny toward greater male size advantage, characteristic of haremic polygyny. The results of our comparative analyses are among the first to confirm the adaptive significance of sex change as described by the size-advantage model. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 26 Feb 2020 06:00:00 GMT “The ecology of individual differences empirically applied to space-use and movement tactics” https://amnat.org/an/newpapers/July-Webber.html Quinn M. R. Webber, Michel P. Laforge, Maegwin Bonar, Alec L. Robitaille, Christopher Hart, Sana Zabihi, and Eric Vander Wal (July 2020) Individuals display plasticity in movement strategies across a resource availability gradient Read the Article (Just Accepted) How do animals use space to find the best food? Movement is the mechanism by which animals find and access profitable foraging habitat. Animal movement is therefore shaped by the environment an individual animal experiences. Because individual animals experience different environments, we might expect individuals to vary in their movement tactics, but these tactics are predicted to vary as a function of the distribution of food resources. Contemporary behavioral ecology preoccupies itself with understanding meaningful consistent variation among individuals to understand how individual behavioral variation, or animal personality, is likely to result in individuals being consistent in their movement strategies across contexts. It is through the lens of animal plasticity and consistent differences that Webber, Laforge, and colleagues tested how free-ranging caribou on the island of Newfoundland, Canada, adjusted their movement patterns as a function of the distribution of profitable habitat, high-quality spring vegetation. Specifically, they tested the hypothesis that individuals that experience densely aggregated foraging habitats should move more slowly and intensively in a small localized area. By contrast, when foraging habitats are distributed more evenly across the landscape, individuals should move faster and more linearly throughout their range. As predicted, individuals adjust their movements as a function of resource distribution. In addition, individual caribou also display consistent differences in their movement behaviors, suggesting the fastest moving individuals in one context are the fastest moving individuals in a different context. The authors highlight how behavioral consistency and plasticity are important aspects of the movement ecology framework. By linking variation in resource distribution across landscapes to individual consistency and plasticity in movement behavior, the authors bridge concepts from the fields of animal personality and movement ecology. Abstract Movement provides a link between individual behavioral ecology and the spatial and temporal variation in an individual’s landscape. Individual variation in movement traits is an important axis of animal personality, particularly in the context of foraging ecology. We tested whether individual caribou (Rangifer tarandus) displayed plasticity in movement and space-use behavior across a gradient of resource aggregation. We quantified first-passage time and range-use ratio as proxies for movement-related foraging behavior and examined how these traits varied at the individual level across a foraging resource gradient. Our results suggest that individuals adjusted first-passage time, but not range-use ratio, to maximize access to high-quality foraging resources. First-passage time was repeatable and intercepts for first-passage time and range-use ratio were negatively correlated. Individuals matched first-passage time, but not range-use ratio, to the expectations of our patch-use model that maximized access to foraging resources, a result that suggests that individuals acclimated their movement patterns to accommodate both intra- and inter-annual variation in foraging resources on the landscape. Collectively, we highlight repeatable movement and space-use tactics, and provide insight into how individual plasticity in movement interacts with landscape processes to affect the distribution of behavioral phenotypes, and potentially fitness and population dynamics. More forthcoming papers &raquo; <p>Quinn M. R. Webber, Michel P. Laforge, Maegwin Bonar, Alec L. Robitaille, Christopher Hart, Sana Zabihi, and Eric Vander Wal (July 2020) </p> <p><b>Individuals display plasticity in movement strategies across a resource availability gradient </b></p> <p><i><a href="https://dx.doi.org/10.1086/708721">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">H</span>ow do animals use space to find the best food? Movement is the mechanism by which animals find and access profitable foraging habitat. Animal movement is therefore shaped by the environment an individual animal experiences. Because individual animals experience different environments, we might expect individuals to vary in their movement tactics, but these tactics are predicted to vary as a function of the distribution of food resources. Contemporary behavioral ecology preoccupies itself with understanding meaningful consistent variation among individuals to understand how individual behavioral variation, or animal personality, is likely to result in individuals being consistent in their movement strategies across contexts. </p> <p>It is through the lens of animal plasticity and consistent differences that Webber, Laforge, and colleagues tested how free-ranging caribou on the island of Newfoundland, Canada, adjusted their movement patterns as a function of the distribution of profitable habitat, high-quality spring vegetation. Specifically, they tested the hypothesis that individuals that experience densely aggregated foraging habitats should move more slowly and intensively in a small localized area. By contrast, when foraging habitats are distributed more evenly across the landscape, individuals should move faster and more linearly throughout their range. As predicted, individuals adjust their movements as a function of resource distribution. In addition, individual caribou also display consistent differences in their movement behaviors, suggesting the fastest moving individuals in one context are the fastest moving individuals in a different context. The authors highlight how behavioral consistency and plasticity are important aspects of the movement ecology framework. By linking variation in resource distribution across landscapes to individual consistency and plasticity in movement behavior, the authors bridge concepts from the fields of animal personality and movement ecology. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">M</span>ovement provides a link between individual behavioral ecology and the spatial and temporal variation in an individual’s landscape. Individual variation in movement traits is an important axis of animal personality, particularly in the context of foraging ecology. We tested whether individual caribou (<i>Rangifer tarandus</i>) displayed plasticity in movement and space-use behavior across a gradient of resource aggregation. We quantified first-passage time and range-use ratio as proxies for movement-related foraging behavior and examined how these traits varied at the individual level across a foraging resource gradient. Our results suggest that individuals adjusted first-passage time, but not range-use ratio, to maximize access to high-quality foraging resources. First-passage time was repeatable and intercepts for first-passage time and range-use ratio were negatively correlated. Individuals matched first-passage time, but not range-use ratio, to the expectations of our patch-use model that maximized access to foraging resources, a result that suggests that individuals acclimated their movement patterns to accommodate both intra- and inter-annual variation in foraging resources on the landscape. Collectively, we highlight repeatable movement and space-use tactics, and provide insight into how individual plasticity in movement interacts with landscape processes to affect the distribution of behavioral phenotypes, and potentially fitness and population dynamics. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 25 Feb 2020 06:00:00 GMT “Species differences in phenology shape coexistence” https://amnat.org/an/newpapers/July-Blackford.html Christopher Blackford, Rachel M. Germain, and Benjamin Gilbert (July 2020) Manipulation of species’ phenologies overturns competitive hierarchies with implications for coexistence Read the Article (Just Accepted) Species in ecological communities often show striking differences in phenology – the seasonal timing of important life events. The phenology of one species is likely to affect its ability to coexist with other species but ecological theory has contrasting predictions on if species with similar phenologies are more, or less likely to coexist with each other. On one hand, differences in phenology could reduce competition for resources. On the other hand, a species with early phenology could reduce resources available to later species and thus limit coexistence. To resolve these contrasting predictions, researchers from the University of Toronto and the University of British Columbia performed a greenhouse experiment on two competing annual grass species (Vulpia microstachys and V.&nbsp;microflora) to test how phenological separation of germination timing, affected coexistence. By manipulating the relative germination timing of these species, they were able to observe how phenological separation affects coexistence. They found early germination provided a competitive advantage, and thus phenological differences reduced within-year coexistence. However, through modelling they found that when the identity of the early germinating species changed across growing seasons, it was possible for phenological separation to increase coexistence. Overall, this research clarifies how phenological differences structure competitive interactions and highlight the need to quantify year-to-year variation in these differences to better understand species coexistence. Abstract Ecological theory produces opposing predictions about whether differences in the timing of life history transitions, or ‘phenology’, promote or limit coexistence. Phenological separation is predicted to create temporal niche differences, increasing coexistence, yet phenological separation could also competitively favor one species, increasing fitness differences and hindering coexistence. We experimentally manipulated relative germination timing, a critical phenological event, of two annual grass species, Vulpia microstachys and V.&nbsp;octoflora, to test these contrasting predictions. We parameterized a competition model to estimate within-season niche differences, fitness differences, and coexistence, and to estimate coexistence when year-to-year fluctuations of germination timing occur. Increasing germination separation caused parallel changes in niche and fitness differences, with the net effect of weakening within-year coexistence. Both species experienced a competitive advantage by germinating earlier and a four-day head start allowed the generally inferior competitor to exclude the otherwise superior competitor. The overall consequence of germination separation was to limit coexistence within a given year, although year-to-year variation in relative timing of germination was sufficient to support long-term coexistence. Our results clarify how phenological differences structure competitive interactions and highlight the need to quantify year-to-year variation in these differences to better understand species coexistence. More forthcoming papers &raquo; <p>Christopher Blackford, Rachel M. Germain, and Benjamin Gilbert (July 2020) </p> <p><b>Manipulation of species’ phenologies overturns competitive hierarchies with implications for coexistence </b></p> <p><i><a href="https://dx.doi.org/10.1086/708719">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">S</span>pecies in ecological communities often show striking differences in phenology – the seasonal timing of important life events. The phenology of one species is likely to affect its ability to coexist with other species but ecological theory has contrasting predictions on if species with similar phenologies are more, or less likely to coexist with each other. On one hand, differences in phenology could reduce competition for resources. On the other hand, a species with early phenology could reduce resources available to later species and thus limit coexistence. </p><p>To resolve these contrasting predictions, researchers from the University of Toronto and the University of British Columbia performed a greenhouse experiment on two competing annual grass species (<i>Vulpia microstachys</i> and <i>V.&nbsp;microflora</i>) to test how phenological separation of germination timing, affected coexistence. By manipulating the relative germination timing of these species, they were able to observe how phenological separation affects coexistence. They found early germination provided a competitive advantage, and thus phenological differences reduced within-year coexistence. However, through modelling they found that when the identity of the early germinating species changed across growing seasons, it was possible for phenological separation to increase coexistence. </p><p>Overall, this research clarifies how phenological differences structure competitive interactions and highlight the need to quantify year-to-year variation in these differences to better understand species coexistence. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">E</span>cological theory produces opposing predictions about whether differences in the timing of life history transitions, or ‘phenology’, promote or limit coexistence. Phenological separation is predicted to create temporal niche differences, increasing coexistence, yet phenological separation could also competitively favor one species, increasing fitness differences and hindering coexistence. We experimentally manipulated relative germination timing, a critical phenological event, of two annual grass species, <i>Vulpia microstachys</i> and <i>V.&nbsp;octoflora</i>, to test these contrasting predictions. We parameterized a competition model to estimate within-season niche differences, fitness differences, and coexistence, and to estimate coexistence when year-to-year fluctuations of germination timing occur. Increasing germination separation caused parallel changes in niche and fitness differences, with the net effect of weakening within-year coexistence. Both species experienced a competitive advantage by germinating earlier and a four-day head start allowed the generally inferior competitor to exclude the otherwise superior competitor. The overall consequence of germination separation was to limit coexistence within a given year, although year-to-year variation in relative timing of germination was sufficient to support long-term coexistence. Our results clarify how phenological differences structure competitive interactions and highlight the need to quantify year-to-year variation in these differences to better understand species coexistence. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 25 Feb 2020 06:00:00 GMT “Maternal investment, ecological lifestyle, and brain evolution in sharks and rays” https://amnat.org/an/newpapers/June-Mull.html Christopher G. Mull, Kara E. Yopak, and Nicholas K. Dulvy (June 2020) Shark and ray brain organization varies along a gradient reflecting size, maternal investment, and ecological lifestyle Read the Article (Just Accepted) While the drivers of brain size evolution have received lots of attention over the past several decades, there has been considerably less examination of the correlates of brain organization evolution – the relative size of the five major regions that comprise vertebrate brains. Because the relative size of a brain region potentially reflects its importance, most studies have looked for ecological or behavioral correlates of brain organization while ignoring the effects of life history (the rate of growth, maturation, and form of reproduction). Chondrichthyans (sharks, rays, and chimaeras) are an often overlooked yet remarkably diverse group. Their lineage represents the oldest jawed vertebrates and comprises more than 1,200&nbsp;species that inhabit every aquatic habitat on earth and exhibit most described reproductive modes, from egg-laying to placental live-bearing. They also mark the evolutionary origin of the vertebrate brain archetype characterized by five distinct regions, including the first true cerebellum. Because of their diversity, chondrichthyans are an excellent group for tackling fundamental questions about brain evolution. A new study led by Christopher Mull with colleagues from Simon Fraser University and the University of North Carolina Wilmington tackled these questions by collecting and examining the brains of 100&nbsp;species of chondrichthyans spanning every major order, ecological lifestyle, and reproductive mode. They found that brain organization varies across a series of axes rather than distinctly with ecology. Deep-water species tended to have low levels of maternal investment, with small brains predominantly comprised of medulla – important for non-visual sensory integration. Species with higher levels of maternal investment inhabiting shallow complex habitats, such as reefs, have relatively large brains comprised predominantly of telencephalon – important for higher cognitive functions such as spatial learning. For the first time, the researchers demonstrate that both ecological lifestyle and maternal investment are independently associated with brain organization. These findings highlight the need for a more holistic approach to understanding the evolution of brain size and organization across vertebrates. Abstract Across vertebrates increased maternal investment (via increased pre- and postnatal provisioning) is associated with larger relative brain size, yet it remains unclear how brain organization is shaped by life history and ecology. Here, we tested whether maternal investment and ecological lifestyle are related to variation in brain size and organization across 100 chondrichthyans. We hypothesized that brain size and organization would vary with level of maternal investment and habitat depth and complexity. We found that chondrichthyan brain organization varies along four main axes, according to: (1) absolute brain size, (2) relative diencephalon and mesencephalon size, (3) relative telencephalon and medulla size, and (4) relative cerebellum size. Increased maternal investment is associated with larger relative brain size, while ecological lifestyle is informative for variation between relative telencephalon and medulla size, and relative cerebellum size after accounting for the independent effects of reproductive mode. Deep-water chondrichthyans generally provide low levels of yolk-only (lecithotrophic) maternal investment and have relatively small brains, predominantly comprised of medulla (a major portion of the hindbrain). Whereas, matrotrophic chondrichthyans – which provide maternal provisioning beyond the initial yolk-sac – found in coastal, reef, or shallow oceanic habitats have large relative brain sizes, predominantly comprised of telencephalon (a major portion of the forebrain). We demonstrated, for the first time, that both ecological lifestyle and maternal investment are independently associated with brain organization in a lineage with diverse life history strategies and reproductive modes. More forthcoming papers &raquo; <p>Christopher G. Mull, Kara E. Yopak, and Nicholas K. Dulvy (June 2020) </p> <p><b>Shark and ray brain organization varies along a gradient reflecting size, maternal investment, and ecological lifestyle </b></p> <p><i><a href="https://dx.doi.org/10.1086/708531">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">W</span>hile the drivers of brain size evolution have received lots of attention over the past several decades, there has been considerably less examination of the correlates of brain organization evolution &ndash; the relative size of the five major regions that comprise vertebrate brains. Because the relative size of a brain region potentially reflects its importance, most studies have looked for ecological or behavioral correlates of brain organization while ignoring the effects of life history (the rate of growth, maturation, and form of reproduction).</p> <p>Chondrichthyans (sharks, rays, and chimaeras) are an often overlooked yet remarkably diverse group. Their lineage represents the oldest jawed vertebrates and comprises more than 1,200&nbsp;species that inhabit every aquatic habitat on earth and exhibit most described reproductive modes, from egg-laying to placental live-bearing. They also mark the evolutionary origin of the vertebrate brain archetype characterized by five distinct regions, including the first true cerebellum. Because of their diversity, chondrichthyans are an excellent group for tackling fundamental questions about brain evolution.</p> <p>A new study led by Christopher Mull with colleagues from Simon Fraser University and the University of North Carolina Wilmington tackled these questions by collecting and examining the brains of 100&nbsp;species of chondrichthyans spanning every major order, ecological lifestyle, and reproductive mode. They found that brain organization varies across a series of axes rather than distinctly with ecology. Deep-water species tended to have low levels of maternal investment, with small brains predominantly comprised of medulla &ndash; important for non-visual sensory integration. Species with higher levels of maternal investment inhabiting shallow complex habitats, such as reefs, have relatively large brains comprised predominantly of telencephalon &ndash; important for higher cognitive functions such as spatial learning. For the first time, the researchers demonstrate that both ecological lifestyle and maternal investment are independently associated with brain organization. These findings highlight the need for a more holistic approach to understanding the evolution of brain size and organization across vertebrates.</p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>cross vertebrates increased maternal investment (via increased pre- and postnatal provisioning) is associated with larger relative brain size, yet it remains unclear how brain organization is shaped by life history and ecology. Here, we tested whether maternal investment and ecological lifestyle are related to variation in brain size and organization across 100 chondrichthyans. We hypothesized that brain size and organization would vary with level of maternal investment and habitat depth and complexity. We found that chondrichthyan brain organization varies along four main axes, according to: (1) absolute brain size, (2) relative diencephalon and mesencephalon size, (3) relative telencephalon and medulla size, and (4) relative cerebellum size. Increased maternal investment is associated with larger relative brain size, while ecological lifestyle is informative for variation between relative telencephalon and medulla size, and relative cerebellum size after accounting for the independent effects of reproductive mode. Deep-water chondrichthyans generally provide low levels of yolk-only (lecithotrophic) maternal investment and have relatively small brains, predominantly comprised of medulla (a major portion of the hindbrain). Whereas, matrotrophic chondrichthyans &ndash; which provide maternal provisioning beyond the initial yolk-sac &ndash; found in coastal, reef, or shallow oceanic habitats have large relative brain sizes, predominantly comprised of telencephalon (a major portion of the forebrain). We demonstrated, for the first time, that both ecological lifestyle and maternal investment are independently associated with brain organization in a lineage with diverse life history strategies and reproductive modes.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Thu, 13 Feb 2020 06:00:00 GMT “A new method to reconstruct quantitative food webs and nutrient flows from isotope tracer addition experiments” https://amnat.org/an/newpapers/June-Lopez-Sepulcre.html Andrés López-Sepulcre, Matthieu Bruneaux, Sarah M. Collins, Rana El-Sabaawi, Alexander S. Flecker, and Steven A. Thomas (June 2020) Unveiling the circle of life using isotopes and Bayesian statistics Read the Article (Just Accepted) Nutrient cycles underpin all ecosystem processes and services, from productivity to water quality. While ecologists and biogeochemists have a pretty good idea of the main players and general patterns of different nutrient cycles, precisely quantifying the travel of nutrients among different parts of a given ecosystem remains challenging. One way that ecologists have approached this is by performing isotope tracer addition experiments. These experiments consist of slowly dripping small amounts of a rare isotopic form of the nutrient in question (a variation of the same element with an unusually high number of neutrons). Tracking their increase in different organisms during the experimental addition gives us an idea of how fast nutrients flow from one component of the ecosystem to the other. Despite giving us important insights on the dynamics of elements in ecosystems, these experiments lacked a framework that would allow us to quantify nutrient flows statistically, and therefore compare different experiments rigorously. This is important in understanding how nutrient cycles are affected by a variety of factors. In this article, L&oacute;pez-Sepulcre and colleagues develop a mathematical framework to analyze isotope tracer additions statistically and illustrate it by comparing the nitrogen cycle of two montane tropical streams of the island of Trinidad differing in their light availability. Abstract Understanding how nutrients flow through food webs is central in ecosystem ecology. Tracer addition experiments are powerful tools to reconstruct nutrient flows by adding an isotopically enriched element into an ecosystem, and tracking its fate through time. Historically, the design and analysis of tracer studies have varied widely, ranging from descriptive studies to modeling approaches of varying complexity. Increasingly, isotope tracer data is being used to compare ecosystems and analyze experimental manipulations. Currently, a formal statistical framework for analyzing such experiments is lacking, making it impossible to calculate the estimation errors associated with the model fit, the interdependence of compartments, or the uncertainty in the diet of consumers. In this paper we develop a method based on Bayesian Hidden Markov Models, and apply it to the analysis of 15N-NH4+ tracer additions in two Trinidadian streams in which light was experimentally manipulated. Through this case study, we illustrate how to estimate N fluxes between ecosystem compartments, turnover rates of N within those compartments, and the associated uncertainty. We also show how the method can be used to compare alternative models of food web structure, calculate the error arround derived parameters, and make statistical comparisons between sites or treatments. Une nouvelle m&eacute;thode de reconstruction quantitative des r&eacute;seaux trophiques et des flux de nutriments &agrave; partir d’exp&eacute;riences d’ajout de traceurs isotopiques Comprendre la mani&egrave;re dont les nutriments circulent au sein des r&eacute;seaux trophiques est essentiel en &eacute;cologie des &eacute;cosyst&egrave;mes. Les exp&eacute;riences d’ajout de traceur – consistant &agrave; ajouter un &eacute;l&eacute;ment pr&eacute;sentant un enrichissement isotopique dans un &eacute;cosyst&egrave;me et &agrave; suivre son devenir au cours du temps – constituent un outil puissant pour reconstruire les flux de nutriments. Historiquement, ces donn&eacute;es ont &eacute;t&eacute; analys&eacute;es en recourant &agrave; m&eacute;thodes diverses, allant d’&eacute;tudes descriptives jusqu’&agrave; des mod&eacute;lisations plus ou moins complexes. Les donn&eacute;es de traceurs isotopiques sont de plus en plus utilis&eacute;es pour comparer des &eacute;cosyst&egrave;mes et analyser des manipulations exp&eacute;rimentales. Actuellement, il n’existe toujours pas de cadre statistique formel pour analyser ce type de donn&eacute;es, ce qui rend impossible le calcul des erreurs d’estimation associ&eacute;es avec l’ajustement des mod&egrave;les, de l’interd&eacute;pendance des compartiments, ou encore de l’incertitude des r&eacute;gimes alimentaires des consommateurs. Dans cet article, nous pr&eacute;sentons une m&eacute;thode bay&eacute;sienne bas&eacute;e sur des mod&egrave;les de Markov cach&eacute;s, et nous l’appliquons &agrave; l’analyse d’ajouts du traceur 15N-NH4+ dans deux cours d’eau de l’&icirc;le de la Trinit&eacute; dans lesquels l’exposition lumineuse a &eacute;t&eacute; manipul&eacute;e exp&eacute;rimentalement. Dans cette &eacute;tude, nous montrons comment estimer les flux d’azote entre les compartiments de l’&eacute;cosyst&egrave;me, les taux de renouvellement d’azote au sein de ces compartiments et les incertitudes associ&eacute;es. Nous montrons &eacute;galement que cette m&eacute;thode peut &ecirc;tre utilis&eacute;e pour comparer des mod&egrave;les de structures alternatives de r&eacute;seaux trophiques, calculer l’erreur des param&egrave;tres d&eacute;riv&eacute;s, et r&eacute;aliser des comparaisons statistiques entre des sites ou des traitements. More forthcoming papers &raquo; <p>Andrés López-Sepulcre, Matthieu Bruneaux, Sarah M. Collins, Rana El-Sabaawi, Alexander S. Flecker, and Steven A. Thomas (June 2020) </p> <p><b>Unveiling the circle of life using isotopes and Bayesian statistics </b></p> <p><i><a href="https://dx.doi.org/10.1086/708546">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">N</span>utrient cycles underpin all ecosystem processes and services, from productivity to water quality. While ecologists and biogeochemists have a pretty good idea of the main players and general patterns of different nutrient cycles, precisely quantifying the travel of nutrients among different parts of a given ecosystem remains challenging. One way that ecologists have approached this is by performing isotope tracer addition experiments. These experiments consist of slowly dripping small amounts of a rare isotopic form of the nutrient in question (a variation of the same element with an unusually high number of neutrons). Tracking their increase in different organisms during the experimental addition gives us an idea of how fast nutrients flow from one component of the ecosystem to the other. Despite giving us important insights on the dynamics of elements in ecosystems, these experiments lacked a framework that would allow us to quantify nutrient flows statistically, and therefore compare different experiments rigorously. This is important in understanding how nutrient cycles are affected by a variety of factors. In this article, L&oacute;pez-Sepulcre and colleagues develop a mathematical framework to analyze isotope tracer additions statistically and illustrate it by comparing the nitrogen cycle of two montane tropical streams of the island of Trinidad differing in their light availability.</p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">U</span>nderstanding how nutrients flow through food webs is central in ecosystem ecology. Tracer addition experiments are powerful tools to reconstruct nutrient flows by adding an isotopically enriched element into an ecosystem, and tracking its fate through time. Historically, the design and analysis of tracer studies have varied widely, ranging from descriptive studies to modeling approaches of varying complexity. Increasingly, isotope tracer data is being used to compare ecosystems and analyze experimental manipulations. Currently, a formal statistical framework for analyzing such experiments is lacking, making it impossible to calculate the estimation errors associated with the model fit, the interdependence of compartments, or the uncertainty in the diet of consumers. In this paper we develop a method based on Bayesian Hidden Markov Models, and apply it to the analysis of <span style="font-size:70%; position:relative; top:-0.5em;">15</span>N-NH<span style="font-size:70%; position:relative; bottom:-0.3em;">4</span><span style="font-size:70%; position:relative; top:-0.5em;">+</span> <!-- $^{15}$N-NH$_4^+$ --> tracer additions in two Trinidadian streams in which light was experimentally manipulated. Through this case study, we illustrate how to estimate N fluxes between ecosystem compartments, turnover rates of N within those compartments, and the associated uncertainty. We also show how the method can be used to compare alternative models of food web structure, calculate the error arround derived parameters, and make statistical comparisons between sites or treatments.</p> <h4>Une nouvelle m&eacute;thode de reconstruction quantitative des r&eacute;seaux trophiques et des flux de nutriments &agrave; partir d&rsquo;exp&eacute;riences d&rsquo;ajout de traceurs isotopiques</h4> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">C</span>omprendre la mani&egrave;re dont les nutriments circulent au sein des r&eacute;seaux trophiques est essentiel en &eacute;cologie des &eacute;cosyst&egrave;mes. Les exp&eacute;riences d&rsquo;ajout de traceur &ndash; consistant &agrave; ajouter un &eacute;l&eacute;ment pr&eacute;sentant un enrichissement isotopique dans un &eacute;cosyst&egrave;me et &agrave; suivre son devenir au cours du temps &ndash; constituent un outil puissant pour reconstruire les flux de nutriments. Historiquement, ces donn&eacute;es ont &eacute;t&eacute; analys&eacute;es en recourant &agrave; m&eacute;thodes diverses, allant d&rsquo;&eacute;tudes descriptives jusqu&rsquo;&agrave; des mod&eacute;lisations plus ou moins complexes. Les donn&eacute;es de traceurs isotopiques sont de plus en plus utilis&eacute;es pour comparer des &eacute;cosyst&egrave;mes et analyser des manipulations exp&eacute;rimentales. Actuellement, il n&rsquo;existe toujours pas de cadre statistique formel pour analyser ce type de donn&eacute;es, ce qui rend impossible le calcul des erreurs d&rsquo;estimation associ&eacute;es avec l&rsquo;ajustement des mod&egrave;les, de l&rsquo;interd&eacute;pendance des compartiments, ou encore de l&rsquo;incertitude des r&eacute;gimes alimentaires des consommateurs. Dans cet article, nous pr&eacute;sentons une m&eacute;thode bay&eacute;sienne bas&eacute;e sur des mod&egrave;les de Markov cach&eacute;s, et nous l&rsquo;appliquons &agrave; l&rsquo;analyse d&rsquo;ajouts du traceur <span style="font-size:70%; position:relative; top:-0.5em;">15</span>N-NH<span style="font-size:70%; position:relative; bottom:-0.3em;">4</span><span style="font-size:70%; position:relative; top:-0.5em;">+</span> <!-- $^{15}$N-NH$_4^+$ --> dans deux cours d&rsquo;eau de l&rsquo;&icirc;le de la Trinit&eacute; dans lesquels l&rsquo;exposition lumineuse a &eacute;t&eacute; manipul&eacute;e exp&eacute;rimentalement. Dans cette &eacute;tude, nous montrons comment estimer les flux d&rsquo;azote entre les compartiments de l&rsquo;&eacute;cosyst&egrave;me, les taux de renouvellement d&rsquo;azote au sein de ces compartiments et les incertitudes associ&eacute;es. Nous montrons &eacute;galement que cette m&eacute;thode peut &ecirc;tre utilis&eacute;e pour comparer des mod&egrave;les de structures alternatives de r&eacute;seaux trophiques, calculer l&rsquo;erreur des param&egrave;tres d&eacute;riv&eacute;s, et r&eacute;aliser des comparaisons statistiques entre des sites ou des traitements.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Thu, 13 Feb 2020 06:00:00 GMT “Evolutionary pathways to communal and cooperative breeding in Carnivores” https://amnat.org/an/newpapers/June-Federico-A.html Valentine Federico, Dominique Allainé, Jean-Michel Gaillard, and Aurélie Cohas (June 2020) The coevolution between the constitutive traits of cooperative highlights the importance of delayed dispersal Read the Article (Just Accepted) Abstract In animal societies, individuals can cooperate in a variety of tasks, including rearing young. Such cooperation is observed in complex social systems, including communal and cooperative breeding. In mammals, both these social systems are characterized by delayed dispersal and alloparenting, whereas only cooperative breeding involves reproductive suppression. While the evolution of communal breeding has been linked to direct fitness benefits of alloparenting, the direct fitness cost of reproductive suppression has led to the hypothesis that the evolution of cooperative breeding is driven by indirect fitness benefits accrued through raising the offspring of related individuals. To decipher between the evolutionary scenarios leading to communal and cooperative breeding in carnivores, we investigated the coevolution among delayed dispersal, reproductive suppression, and alloparenting. We reconstructed ancestral states and transition rates between these traits. We found that cooperative breeding and communal breeding evolved along separate pathways, with delayed dispersal as the first step for both of them. The three traits coevolved, enhancing and stabilizing each other, which resulted in cooperative social systems being stable as opposed to intermediate configurations. These findings promote the key role of coevolution among traits to stabilize cooperative social systems, and highlight the specificities of evolutionary patterns of sociality in carnivores. More forthcoming papers &raquo; <p>Valentine Federico, Dominique Allainé, Jean-Michel Gaillard, and Aurélie Cohas (June 2020) </p> <p><b>The coevolution between the constitutive traits of cooperative highlights the importance of delayed dispersal </b></p> <p><i><a href="https://dx.doi.org/10.1086/708639">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">I</span>n animal societies, individuals can cooperate in a variety of tasks, including rearing young. Such cooperation is observed in complex social systems, including communal and cooperative breeding. In mammals, both these social systems are characterized by delayed dispersal and alloparenting, whereas only cooperative breeding involves reproductive suppression. While the evolution of communal breeding has been linked to direct fitness benefits of alloparenting, the direct fitness cost of reproductive suppression has led to the hypothesis that the evolution of cooperative breeding is driven by indirect fitness benefits accrued through raising the offspring of related individuals. To decipher between the evolutionary scenarios leading to communal and cooperative breeding in carnivores, we investigated the coevolution among delayed dispersal, reproductive suppression, and alloparenting. We reconstructed ancestral states and transition rates between these traits. We found that cooperative breeding and communal breeding evolved along separate pathways, with delayed dispersal as the first step for both of them. The three traits coevolved, enhancing and stabilizing each other, which resulted in cooperative social systems being stable as opposed to intermediate configurations. These findings promote the key role of coevolution among traits to stabilize cooperative social systems, and highlight the specificities of evolutionary patterns of sociality in carnivores. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Thu, 13 Feb 2020 06:00:00 GMT “Host transcriptional responses to high- and low-virulent avian malaria parasites” https://amnat.org/an/newpapers/June-Videvall.html Elin Videvall, Vaidas Palinauskas, Gediminas Valkiūnas, and Olof Hellgren (June 2020) Host transcriptional responses show major differences to high- and low-virulent avian malaria parasites Read the Article (Just Accepted) When hosts are infected with pathogens, does the severity of the outcome depend on the host, the pathogen, or both? For example, does a mild infection result from a strong and efficient host response that is able to suppress the pathogen? Or is the host response directly related to the ability of the pathogen to proliferate? Scientists from Lund University, Sweden, and the Nature Research Center, Lithuania, aimed to evaluate these questions in a bird–malaria system. They sequenced the expression levels of all genes in Eurasian siskins and measured their response to two closely related lineages of the same malaria parasite species. The birds showed large transcriptional responses to the high-virulent lineage Plasmodium relictum SGS1, but low responses to the low-virulent lineage Plasmodium relictum GRW4. The milder infection of GRW4 could therefore not be explained by a forceful host response suppressing the parasite, and the intensity of malaria infection could also not be explained by higher gene expression levels prior to infection. These results shed light on the different transcriptional response strategies used by hosts during malaria infection and open the door for further exploratory questions into the mechanisms that prevent low-virulent pathogens from proliferating. Abstract The transcriptional response of hosts to genetically similar pathogens can vary substantially, with important implications for disease severity and host fitness. A low pathogen load can theoretically elicit both high and low host responses, as the outcome depends on both the effectiveness of the host at suppressing the pathogen and the ability of the pathogen to evade the immune system. Here, we investigate the transcriptional response of Eurasian siskins (Spinus spinus) to two closely related lineages of the malaria parasite Plasmodium relictum. Birds were infected with either the high-virulent lineage P.&nbsp;relictum SGS1, the low-virulent sister lineage P.&nbsp;relictum GRW4, or sham-injected (controls). Blood samples for RNA-sequencing were collected at four time points during the course of infection, totaling 76 transcriptomes from 19 birds. Hosts infected with SGS1 experienced up to 87% parasitemia, major transcriptome shifts throughout the infection, and multiple genes showed strong correlation with parasitemia. In contrast, GRW4-infected hosts displayed low parasitemia (maximum 0.7%) with a minor transcriptional response. We further demonstrate that the baseline gene expression levels of hosts prior to infection were irrelevant as immunocompetence markers as they could not predict future pathogen load. This study shows that the magnitude of the host transcriptional response can differ markedly to related parasites with different virulence, and it enables a better understanding of the molecular interactions taking place between hosts and parasites. More forthcoming papers &raquo; <p>Elin Videvall, Vaidas Palinauskas, Gediminas Valkiūnas, and Olof Hellgren (June 2020) </p> <p><b>Host transcriptional responses show major differences to high- and low-virulent avian malaria parasites </b></p> <p><i><a href="https://dx.doi.org/10.1086/708530">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">W</span>hen hosts are infected with pathogens, does the severity of the outcome depend on the host, the pathogen, or both? For example, does a mild infection result from a strong and efficient host response that is able to suppress the pathogen? Or is the host response directly related to the ability of the pathogen to proliferate? </p><p>Scientists from Lund University, Sweden, and the Nature Research Center, Lithuania, aimed to evaluate these questions in a bird–malaria system. They sequenced the expression levels of all genes in Eurasian siskins and measured their response to two closely related lineages of the same malaria parasite species. The birds showed large transcriptional responses to the high-virulent lineage <i>Plasmodium relictum</i> SGS1, but low responses to the low-virulent lineage <i>Plasmodium relictum</i> GRW4. The milder infection of GRW4 could therefore not be explained by a forceful host response suppressing the parasite, and the intensity of malaria infection could also not be explained by higher gene expression levels prior to infection. These results shed light on the different transcriptional response strategies used by hosts during malaria infection and open the door for further exploratory questions into the mechanisms that prevent low-virulent pathogens from proliferating. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span>he transcriptional response of hosts to genetically similar pathogens can vary substantially, with important implications for disease severity and host fitness. A low pathogen load can theoretically elicit both high and low host responses, as the outcome depends on both the effectiveness of the host at suppressing the pathogen and the ability of the pathogen to evade the immune system. Here, we investigate the transcriptional response of Eurasian siskins (<i>Spinus spinus</i>) to two closely related lineages of the malaria parasite <i>Plasmodium relictum</i>. Birds were infected with either the high-virulent lineage <i>P.&nbsp;relictum</i> SGS1, the low-virulent sister lineage <i>P.&nbsp;relictum</i> GRW4, or sham-injected (controls). Blood samples for RNA-sequencing were collected at four time points during the course of infection, totaling 76 transcriptomes from 19 birds. Hosts infected with SGS1 experienced up to 87% parasitemia, major transcriptome shifts throughout the infection, and multiple genes showed strong correlation with parasitemia. In contrast, GRW4-infected hosts displayed low parasitemia (maximum 0.7%) with a minor transcriptional response. We further demonstrate that the baseline gene expression levels of hosts prior to infection were irrelevant as immunocompetence markers as they could not predict future pathogen load. This study shows that the magnitude of the host transcriptional response can differ markedly to related parasites with different virulence, and it enables a better understanding of the molecular interactions taking place between hosts and parasites. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Thu, 13 Feb 2020 06:00:00 GMT “Beyond pairwise interactions: multispecies character displacement in Mexican freshwater fish communities” https://amnat.org/an/newpapers/June-Roth-Monzon.html Andrea J. Roth-Monzón, Mark C. Belk, J. Jaime Zúñiga-Vega, and Jerald B. Johnson (June 2020) Read the Article (Just Accepted) For a long time, scientists have studied how competition can shape species traits. Most researchers have focused on pairs of competing species, thereby using a simple system to understand the evolutionary effects of competition. However, our understanding of how traits change when more than two species are interacting is still at a beginning stage. Most natural communities consist of several species living together and potentially interacting. Previous research suggests that when multiple species interact, trait evolution can take different pathways due to the addition of complex ecological interactions. There is still much to learn from studying these more complex competitive interactions.The authors of this paper studied a community of four species of livebearing fishes in northwest Mexico. They focused on how competition affects body shape. They asked if body shape differs among sites where no competitors are present, sites where only one competitor is present, and sites where two or more competitors are present. They discovered that body shape of all three species converged towards a similar morphology when co-occurring with competitors. They also found that when competing with two or more species, body shape is intermediate with respect to the body shape of the species with no competitors and with one competitor. Their results stand in contrast to the pattern of character divergence typically observed when only two species are competing. Abstract Competition has long been recognized as a central force in shaping evolution, particularly through character displacement. Yet research on character displacement is biased as it has focused almost exclusively on pairs of interacting species, while ignoring multispecies interactions. Communities are seldom so simple that only pairs of species interact, and it is not clear if inferences from pairwise interactions are sufficient to explain patterns of phenotypes in nature. Here we test for character displacement in a natural system of freshwater fishes in western Mexico that contains up to four congeneric species of the genus Poeciliopsis. We analyzed body shape differences between populations with different numbers of competitors while accounting for confounding environmental variables. Surprisingly, we found evidence for convergent character displacement in populations of P.&nbsp;prolifica, P.&nbsp;viriosa, and P.&nbsp;latidens. We also found that the convergence in body shape was not consistently in the same direction, meaning that when three or more competitors co-occurred, we did not find more extreme body shapes compared to when there were only two competitors. Instead, when three or more competitors co-occur, body shape was intermediate to the shape found with a pair of species or no competitor present. This intermediate shape suggests that evolution in multispecies communities likely occurs in response to several competitors, rather than to simple pairwise interactions. Overall, our results suggest that competition among multiple species is more complex than simple pairwise competitive interactions.M&aacute;s all&aacute; de las interacciones pareadas: desplazamiento de caracteres multiespec&iacute;fico en una comunidad de peces dulceacu&iacute;colas Mexicanos La competencia ha sido reconocida durante mucho tiempo como una fuerza central en la configuraci&oacute;n de la evoluci&oacute;n, particularmente a trav&eacute;s del desplazamiento de caracteres. Sin embargo, la investigaci&oacute;n en el desplazamiento de caracteres esta sesgada, puesto que se ha centrado casi de manera exclusiva en las interacciones entre pares de especies, mientras ignora las interacciones multiespec&iacute;ficas. Las comunidades rara vez son tan simples para que solo pares de especies interact&uacute;en, y a&uacute;n no es claro si las inferencias obtenidas de las interacciones pareadas son suficientes para explicar patrones fenot&iacute;picos en la naturaleza. Aqu&iacute; nos enfocamos en examinar el desplazamiento de caracteres en un sistema natural de peces dulceacu&iacute;colas en el oeste de M&eacute;xico que contiene hasta cuatro especies congen&eacute;ricas del g&eacute;nero Poeciliopsis. Analizamos diferencias en la forma del cuerpo entre poblaciones con diferentes n&uacute;mero de competidores mientras consideramos variables ambientales. Sorprendentemente, encontramos evidencia de desplazamiento de caracteres convergente en las poblaciones de P.&nbsp;prolifica, P.&nbsp;viriosa, y P.&nbsp;latidens. Tambi&eacute;n encontramos que la convergencia en la forma del cuerpo no fue consistente en la misma direcci&oacute;n, es decir, que cuando tres o m&aacute;s competidores coocurren, no se encuentran formas corporales m&aacute;s extremas como cuando se compara con la coocurrencia de solo dos competidores. Es m&aacute;s, cuando tres o m&aacute;s competidores coocurren, la forma de cuerpo es intermedia a la forma encontrada con un par de especies o en la ausencia de competidores. Esta forma corporal intermedia sugiere que la evoluci&oacute;n en comunidades multiespec&iacute;ficas probablemente emerja en respuesta a la presencia de varios competidores, en lugar de a simples interacciones pareadas. En general, nuestros resultados sugieren que la competencia entre m&uacute;ltiples especies es m&aacute;s compleja que las interacciones competitivas pareadas. More forthcoming papers &raquo; <p>Andrea J. Roth-Monzón, Mark C. Belk, J. Jaime Zúñiga-Vega, and Jerald B. Johnson (June 2020) </p> <p><i><a href="https://dx.doi.org/10.1086/708513">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">F</span>or a long time, scientists have studied how competition can shape species traits. Most researchers have focused on pairs of competing species, thereby using a simple system to understand the evolutionary effects of competition. However, our understanding of how traits change when more than two species are interacting is still at a beginning stage. Most natural communities consist of several species living together and potentially interacting. Previous research suggests that when multiple species interact, trait evolution can take different pathways due to the addition of complex ecological interactions. There is still much to learn from studying these more complex competitive interactions.</p><p>The authors of this paper studied a community of four species of livebearing fishes in northwest Mexico. They focused on how competition affects body shape. They asked if body shape differs among sites where no competitors are present, sites where only one competitor is present, and sites where two or more competitors are present. They discovered that body shape of all three species converged towards a similar morphology when co-occurring with competitors. They also found that when competing with two or more species, body shape is intermediate with respect to the body shape of the species with no competitors and with one competitor. Their results stand in contrast to the pattern of character divergence typically observed when only two species are competing. </p> <hr /><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">C</span>ompetition has long been recognized as a central force in shaping evolution, particularly through character displacement. Yet research on character displacement is biased as it has focused almost exclusively on pairs of interacting species, while ignoring multispecies interactions. Communities are seldom so simple that only pairs of species interact, and it is not clear if inferences from pairwise interactions are sufficient to explain patterns of phenotypes in nature. Here we test for character displacement in a natural system of freshwater fishes in western Mexico that contains up to four congeneric species of the genus <i>Poeciliopsis</i>. We analyzed body shape differences between populations with different numbers of competitors while accounting for confounding environmental variables. Surprisingly, we found evidence for convergent character displacement in populations of <i>P.&nbsp;prolifica</i>, <i>P.&nbsp;viriosa</i>, and <i>P.&nbsp;latidens</i>. We also found that the convergence in body shape was not consistently in the same direction, meaning that when three or more competitors co-occurred, we did not find more extreme body shapes compared to when there were only two competitors. Instead, when three or more competitors co-occur, body shape was intermediate to the shape found with a pair of species or no competitor present. This intermediate shape suggests that evolution in multispecies communities likely occurs in response to several competitors, rather than to simple pairwise interactions. Overall, our results suggest that competition among multiple species is more complex than simple pairwise competitive interactions.</p><h4>M&aacute;s all&aacute; de las interacciones pareadas: desplazamiento de caracteres multiespec&iacute;fico en una comunidad de peces dulceacu&iacute;colas Mexicanos</h4> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">L</span>a competencia ha sido reconocida durante mucho tiempo como una fuerza central en la configuraci&oacute;n de la evoluci&oacute;n, particularmente a trav&eacute;s del desplazamiento de caracteres. Sin embargo, la investigaci&oacute;n en el desplazamiento de caracteres esta sesgada, puesto que se ha centrado casi de manera exclusiva en las interacciones entre pares de especies, mientras ignora las interacciones multiespec&iacute;ficas. Las comunidades rara vez son tan simples para que solo pares de especies interact&uacute;en, y a&uacute;n no es claro si las inferencias obtenidas de las interacciones pareadas son suficientes para explicar patrones fenot&iacute;picos en la naturaleza. Aqu&iacute; nos enfocamos en examinar el desplazamiento de caracteres en un sistema natural de peces dulceacu&iacute;colas en el oeste de M&eacute;xico que contiene hasta cuatro especies congen&eacute;ricas del g&eacute;nero <i>Poeciliopsis</i>. Analizamos diferencias en la forma del cuerpo entre poblaciones con diferentes n&uacute;mero de competidores mientras consideramos variables ambientales. Sorprendentemente, encontramos evidencia de desplazamiento de caracteres convergente en las poblaciones de <i>P.&nbsp;prolifica</i>, <i>P.&nbsp;viriosa</i>, y <i>P.&nbsp;latidens</i>. Tambi&eacute;n encontramos que la convergencia en la forma del cuerpo no fue consistente en la misma direcci&oacute;n, es decir, que cuando tres o m&aacute;s competidores coocurren, no se encuentran formas corporales m&aacute;s extremas como cuando se compara con la coocurrencia de solo dos competidores. Es m&aacute;s, cuando tres o m&aacute;s competidores coocurren, la forma de cuerpo es intermedia a la forma encontrada con un par de especies o en la ausencia de competidores. Esta forma corporal intermedia sugiere que la evoluci&oacute;n en comunidades multiespec&iacute;ficas probablemente emerja en respuesta a la presencia de varios competidores, en lugar de a simples interacciones pareadas. En general, nuestros resultados sugieren que la competencia entre m&uacute;ltiples especies es m&aacute;s compleja que las interacciones competitivas pareadas.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 12 Feb 2020 06:00:00 GMT “The benefits of help in cooperative birds – non-existent or difficult to detect?” https://amnat.org/an/newpapers/June-Downing.html Philip A. Downing, Ashleigh S. Griffin, and Charlie K. Cornwallis (June 2020) Helpers benefit breeder reproductive success in cooperative birds Read the Article (Just Accepted) Live long and reproduce, a lot. This is a good way of passing on genes to future generations. But in a variety of species, from hairy-faced hover wasps to grey-crowned babblers (pictured), some individuals give up their opportunity to reproduce and help raise the offspring of others. Why do this? Evolutionary theory has the answer: help when you can pass on more genes this way than by reproducing yourself. For this to work, your help must boost the reproductive success of individuals with whom you share genes. Only part of this solution has empirical support. Helpers are typically related to those they help, but they don’t always boost their reproductive success. To make sense of the inconsistent evidence, researchers from the University of Lund in Sweden and Oxford University in the UK used a statistical technique called meta-analysis. This allowed them to synthesize the results of studies on 19 bird species where helping has been studied in remarkable detail. When considered together, the result is clear. Helpers indeed boost the reproductive success of their relatives. Inconsistencies between studies arise because of the methodological techniques used to measure the reproductive boost. So, live long and reproduce lots? Sure, but it&#39;s not the only way to effectively pass on your genes. Abstract In birds that breed cooperatively in family groups, adult offspring often delay dispersal to assist the breeding pair in raising their young. Kin selection is thought to play an important role in the evolution of this breeding system. However, evidence supporting the underlying assumption that helpers increase the reproductive success of breeders is inconsistent. In 10/19 species where the effect of helpers on breeder reproductive success has been estimated while controlling for the effects of breeder and territory quality, no benefits of help were detected. Here we use phylogenetic meta-analysis to show that the inconsistent evidence for helper benefits across species is explained by study design. After accounting for low sample sizes and the different study designs used to control for breeder and territory quality, we found that helpers consistently enhanced the reproductive success of breeders. Therefore, the assumption that helpers increase breeder reproductive success is supported by evidence across cooperatively breeding birds. More forthcoming papers &raquo; <p>Philip A. Downing, Ashleigh S. Griffin, and Charlie K. Cornwallis (June 2020) </p> <p><b>Helpers benefit breeder reproductive success in cooperative birds </b></p> <p><i><a href="https://dx.doi.org/10.1086/708515">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">L</span>ive long and reproduce, a lot. This is a good way of passing on genes to future generations. But in a variety of species, from hairy-faced hover wasps to grey-crowned babblers (pictured), some individuals give up their opportunity to reproduce and help raise the offspring of others. Why do this? Evolutionary theory has the answer: help when you can pass on more genes this way than by reproducing yourself. For this to work, your help must boost the reproductive success of individuals with whom you share genes. Only part of this solution has empirical support. Helpers are typically related to those they help, but they don&rsquo;t always boost their reproductive success.</p> <p>To make sense of the inconsistent evidence, researchers from the University of Lund in Sweden and Oxford University in the UK used a statistical technique called meta-analysis. This allowed them to synthesize the results of studies on 19 bird species where helping has been studied in remarkable detail. When considered together, the result is clear. Helpers indeed boost the reproductive success of their relatives. Inconsistencies between studies arise because of the methodological techniques used to measure the reproductive boost. So, live long and reproduce lots? Sure, but it&#39;s not the only way to effectively pass on your genes.</p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">I</span>n birds that breed cooperatively in family groups, adult offspring often delay dispersal to assist the breeding pair in raising their young. Kin selection is thought to play an important role in the evolution of this breeding system. However, evidence supporting the underlying assumption that helpers increase the reproductive success of breeders is inconsistent. In 10/19 species where the effect of helpers on breeder reproductive success has been estimated while controlling for the effects of breeder and territory quality, no benefits of help were detected. Here we use phylogenetic meta-analysis to show that the inconsistent evidence for helper benefits across species is explained by study design. After accounting for low sample sizes and the different study designs used to control for breeder and territory quality, we found that helpers consistently enhanced the reproductive success of breeders. Therefore, the assumption that helpers increase breeder reproductive success is supported by evidence across cooperatively breeding birds.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 12 Feb 2020 06:00:00 GMT “Within reach? Habitat availability as a function of individual mobility and spatial structuring” https://amnat.org/an/newpapers/June-Matthiopoulos-A.html Jason Matthiopoulos, John Fieberg, Geert Aarts, Frédéric Barraquand, and Bruce E. Kendall (June 2020) Habitat availability in terms of organism mobility and habitat structure. Geographical constraints in niche spaces Read the Article (Just Accepted) Abstract Organisms need access to particular habitats for their survival and reproduction. However, even if all necessary habitats are available within the broader environment, they may not all be easily reachable from the position of a single individual. Many Species Distribution Models (SDMs) consider populations in environmental (or niche) space, hence overlooking this fundamental aspect of geographical accessibility. Here, we develop a formal way of thinking about habitat availability in environmental spaces by describing how limitations in accessibility can cause animals to experience a more limited or, simply, different mixture of habitats than those more broadly available. We develop an analytical framework for characterizing constrained habitat availability based on the statistical properties of movement and environmental autocorrelation. Using simulation experiments, we show that our general statistical representation of constrained availability is a good approximation of habitat availability for particular realizations of landscape-organism interactions. We present two applications of our approach, one to the statistical analysis of habitat preference (using step-selection functions to analyze harbor seal telemetry data) and a second that derives theoretical insights about population viability from knowledge of the underlying environment. Analytical expressions for habitat availability, such as those we develop here, can yield gains in analytical speed, biological realism and conceptual generality by allowing us to formulate models that are habitat-sensitive, without needing to be spatially explicit. More forthcoming papers &raquo; <p>Jason Matthiopoulos, John Fieberg, Geert Aarts, Frédéric Barraquand, and Bruce E. Kendall (June 2020) </p> <p><b>Habitat availability in terms of organism mobility and habitat structure. Geographical constraints in niche spaces </b></p> <p><i><a href="https://dx.doi.org/10.1086/708519">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">O</span>rganisms need access to particular habitats for their survival and reproduction. However, even if all necessary habitats are available within the broader environment, they may not all be easily reachable from the position of a single individual. Many Species Distribution Models (SDMs) consider populations in environmental (or niche) space, hence overlooking this fundamental aspect of geographical accessibility. Here, we develop a formal way of thinking about habitat availability in environmental spaces by describing how limitations in accessibility can cause animals to experience a more limited or, simply, different mixture of habitats than those more broadly available. We develop an analytical framework for characterizing constrained habitat availability based on the statistical properties of movement and environmental autocorrelation. Using simulation experiments, we show that our general statistical representation of constrained availability is a good approximation of habitat availability for particular realizations of landscape-organism interactions. We present two applications of our approach, one to the statistical analysis of habitat preference (using step-selection functions to analyze harbor seal telemetry data) and a second that derives theoretical insights about population viability from knowledge of the underlying environment. Analytical expressions for habitat availability, such as those we develop here, can yield gains in analytical speed, biological realism and conceptual generality by allowing us to formulate models that are habitat-sensitive, without needing to be spatially explicit. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 12 Feb 2020 06:00:00 GMT “Assortative mating in hybrid zones is remarkably ineffective in promoting speciation” https://amnat.org/an/newpapers/June-Irwin.html Darren E. Irwin (June 2020) What happens when 2 pops meet with strong assortative mating & no hybrid problems? Simulations show they blend together! Read the Article (Just Accepted)Speciation, or the evolution of two species from one, is often said to start with the evolution of assortative mating, the tendency of individuals to choose mates similar to themselves. In this line of thinking, assortative mating between two populations is a form of “premating reproductive isolation” of two groups. This then allows the two groups to become more different over time, such that low hybrid fitness (“postzygotic reproductive isolation”) eventually develops between them. What happens if we use simulations to formally test these ideas? Professor Darren Irwin of the University of British Columbia built computer models of two populations coming into contact, with varying levels of assortative mating and hybrid fitness. To his initial surprise, even quite strong assortative mating (e.g. a 10 times greater mating preference for an individual’s own population) has little impact on limiting the formation of a broad hybrid zone. This is because rare hybrids can mate with each other, leading to growing numbers of hybrids and backcrosses, eventually forming a continuous genetic bridge between the populations. In contrast, a small (e.g. 5%) reduction in the fitness of hybrids has a large impact on limiting the width of the zone. These results call into question the concept of partial premating reproductive isolation, as it is ineffective if there is not also reduced fitness of hybrids. These findings also encourage speciation researchers to renew their interest in examining the fitness of hybrids, as that is the crucial determinant of whether two populations blend together or continue to evolve into two species. Abstract Partial prezygotic isolation is often viewed as more important than partial postzygotic isolation (low fitness of hybrids) early in the process of speciation. I simulate secondary contact between two populations (‘species’) to examine effects of assortative mating and low hybrid fitness in preventing blending. A small reduction in hybrid fitness (e.g., by 10%) produces a narrower hybrid zone than a strong but imperfect mating preference (e.g., 10x stronger preference for conspecific over heterospecific mates). In the latter case, rare F1 hybrids find each other attractive (due to assortative mating), leading to the buildup of a continuum of intermediates. The weakness of assortative mating compared to reduced fitness of hybrids in preventing blending is robust to varying genetic bases of these traits. Assortative mating is most powerful in limiting blending when it is encoded by a single locus, is essentially complete, or when there is a large mate search cost. In these cases assortative mating is likely to cause hybrids to have low fitness, due to frequency-dependent mating disadvantage of individuals of rare mating types. These results prompt a questioning of the concept of partial prezygotic isolation, since it is not very isolating unless there is also postzygotic isolation. More forthcoming papers &raquo; <p>Darren E. Irwin (June 2020)</p> <p><b>What happens when 2 pops meet with strong assortative mating & no hybrid problems? Simulations show they blend together!</b></p> <p><i><a href="https://dx.doi.org/10.1086/708529">Read the Article</a></i> (Just Accepted)</p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">S</span>peciation, or the evolution of two species from one, is often said to start with the evolution of assortative mating, the tendency of individuals to choose mates similar to themselves. In this line of thinking, assortative mating between two populations is a form of “premating reproductive isolation” of two groups. This then allows the two groups to become more different over time, such that low hybrid fitness (“postzygotic reproductive isolation”) eventually develops between them. What happens if we use simulations to formally test these ideas? Professor Darren Irwin of the University of British Columbia built computer models of two populations coming into contact, with varying levels of assortative mating and hybrid fitness. To his initial surprise, even quite strong assortative mating (e.g. a 10 times greater mating preference for an individual’s own population) has little impact on limiting the formation of a broad hybrid zone. This is because rare hybrids can mate with each other, leading to growing numbers of hybrids and backcrosses, eventually forming a continuous genetic bridge between the populations. In contrast, a small (e.g. 5%) reduction in the fitness of hybrids has a large impact on limiting the width of the zone. These results call into question the concept of partial premating reproductive isolation, as it is ineffective if there is not also reduced fitness of hybrids. These findings also encourage speciation researchers to renew their interest in examining the fitness of hybrids, as that is the crucial determinant of whether two populations blend together or continue to evolve into two species. </p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">P</span>artial prezygotic isolation is often viewed as more important than partial postzygotic isolation (low fitness of hybrids) early in the process of speciation. I simulate secondary contact between two populations (‘species’) to examine effects of assortative mating and low hybrid fitness in preventing blending. A small reduction in hybrid fitness (e.g., by 10%) produces a narrower hybrid zone than a strong but imperfect mating preference (e.g., 10x stronger preference for conspecific over heterospecific mates). In the latter case, rare F1 hybrids find each other attractive (due to assortative mating), leading to the buildup of a continuum of intermediates. The weakness of assortative mating compared to reduced fitness of hybrids in preventing blending is robust to varying genetic bases of these traits. Assortative mating is most powerful in limiting blending when it is encoded by a single locus, is essentially complete, or when there is a large mate search cost. In these cases assortative mating is likely to cause hybrids to have low fitness, due to frequency-dependent mating disadvantage of individuals of rare mating types. These results prompt a questioning of the concept of partial prezygotic isolation, since it is not very isolating unless there is also postzygotic isolation. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 12 Feb 2020 06:00:00 GMT George W. Gilchrist Student Support Fund https://amnat.org/announcements/Gilchrist.html The American Society of Naturalists and the Society for the Study of Evolution are deeply saddened to convey that George W. Gilchrist, a long-time member of our community, recently passed away.&nbsp; George earned his BS at Arizona State University working on butterflies with Ron Rutowski, his MS at Brown on damselflies with Jon Waage, and his PhD at the University of Washington with Joel Kingsolver working on the evolution of thermal sensitivity (1993). He then completed a postdoc with Ray Huey at the University of Washington on experimental evolution of thermal sensitivity in Drosophila. George extended his work on the evolutionary genetics of Drosophila while in faculty positions at Clarkson University and the College of William and Mary before becoming a long-time Program Director (Division of Environmental Biology) at the National Science Foundation. For 10 years, George was the liaison between the Education and Outreach Committees of ASN and SSE. His impact on our science and young scientists has been exceptional. George’s family has asked that a fund be created in his honor to support additional graduate student research and travel to the annual Evolution meetings. Donations in George’s honor can be made at this link “George W. Gilchrist Student Support Fund” on the ASN donations page or via this link&nbsp;https://payments.evolutionsociety.org/civicrm/contribute/transact?reset=1&id=4&nbsp; for the SSE donations page. &nbsp; &nbsp; <p>The American Society of Naturalists and the Society for the Study of Evolution are deeply saddened to convey that George W. Gilchrist, a long-time member of our community, recently passed away.&nbsp;</p> <p>George earned his BS at Arizona State University working on butterflies with Ron Rutowski, his MS at Brown on damselflies with Jon Waage, and his PhD at the University of Washington with Joel Kingsolver working on the evolution of thermal sensitivity (1993). He then completed a postdoc with Ray Huey at the University of Washington on experimental evolution of thermal sensitivity in Drosophila. George extended his work on the evolutionary genetics of Drosophila while in faculty positions at Clarkson University and the College of William and Mary before becoming a long-time Program Director (Division of Environmental Biology) at the National Science Foundation. For 10 years, George was the liaison between the Education and Outreach Committees of ASN and SSE. His impact on our science and young scientists has been exceptional.</p> <p>George&rsquo;s family has asked that a fund be created in his honor to support additional graduate student research and travel to the annual Evolution meetings.</p> <p>Donations in George&rsquo;s honor can be made at this link &ldquo;<a href="https://subfill.uchicago.edu/JournalPubs/Donation.aspx?webpub=ANX">George W. Gilchrist Student Support Fund</a>&rdquo; on the ASN donations page</p> <p>or via this link&nbsp;<a href="https://payments.evolutionsociety.org/civicrm/contribute/transact?reset=1&amp;id=4">https://payments.evolutionsociety.org/civicrm/contribute/transact?reset=1&amp;id=4</a>&nbsp; for the SSE donations page.</p> <p>&nbsp;</p> <p>&nbsp;</p> Mon, 10 Feb 2020 06:00:00 GMT 2020 Jasper Loftus-Hills Young Investigator Awards https://amnat.org/announcements/ANNwinYIA.html The American Society of Naturalist’s Young Investigator Award is in honor of Jasper Loftus-Hills, a young scientist who died tragically 3 years after receiving his PhD. This award goes to applicants who completed their PhD three years preceding the application deadline or are in their last year of a PhD program. We are pleased to announce that this year’s recipients of the ASN Young Investiagor Awards are: &bull;&nbsp;&nbsp; &nbsp;Stephen De Lisle: https://www.biology.lu.se/stephen-de-lisle &bull;&nbsp;&nbsp; &nbsp;Moises Exposito-Alonso: https://www.moisesexpositoalonso.org/ &bull;&nbsp;&nbsp; &nbsp;Mar&iacute;a Natalia Uma&ntilde;a Medina: https://lsa.umich.edu/eeb/people/faculty/maria-natalia-umana.html &bull;&nbsp;&nbsp;&nbsp; Diana Rennison:&nbsp;https://biology.ucsd.edu/research/faculty/drennison We are very much looking forward to their participation in the ASN YIA symposium at the annual meeting in Cleveland, Ohio, this June. For some background on the award, see the Jeremy Fox, former chair of the nominating committee, blog about the experience. As he says, "The strength and diversity of the winners reflect the strength and diversity of the applicant pool, both in terms of their research areas and demographics." <p>The American Society of Naturalist&rsquo;s Young Investigator Award is in honor of Jasper Loftus-Hills, a young scientist who died tragically 3 years after receiving his PhD. This award goes to applicants who completed their PhD three years preceding the application deadline or are in their last year of a PhD program.</p> <p>We are pleased to announce that this year&rsquo;s recipients of the ASN Young Investiagor Awards are:</p> <p>&bull;&nbsp;&nbsp; &nbsp;Stephen De Lisle: <a href="https://www.biology.lu.se/stephen-de-lisle">https://www.biology.lu.se/stephen-de-lisle</a><br /> &bull;&nbsp;&nbsp; &nbsp;Moises Exposito-Alonso: <a href="https://www.moisesexpositoalonso.org/">https://www.moisesexpositoalonso.org/</a><br /> &bull;&nbsp;&nbsp; &nbsp;Mar&iacute;a Natalia Uma&ntilde;a Medina: <a href="https://lsa.umich.edu/eeb/people/faculty/maria-natalia-umana.html">https://lsa.umich.edu/eeb/people/faculty/maria-natalia-umana.html </a><br /> &bull;&nbsp;&nbsp;&nbsp; Diana Rennison:&nbsp;<a href="https://biology.ucsd.edu/research/faculty/drennison">https://biology.ucsd.edu/research/faculty/drennison</a></p> <p>We are very much looking forward to their participation in the ASN YIA symposium at the annual meeting in Cleveland, Ohio, this June.</p> <p>For some background on the award, see the Jeremy Fox, former chair of the nominating committee, <a href="https://dynamicecology.wordpress.com/2018/02/19/the-winners-of-the-asn-jasper-loftus-hills-young-investigator-awards-have-been-announced/">blog</a> about the experience. As he says, &quot;The strength and diversity of the winners reflect the strength and diversity of the applicant pool, both in terms of their research areas and demographics.&quot;</p> Mon, 10 Feb 2020 06:00:00 GMT “Condition-dependent mutual mate preference and intersexual genetic correlations for mating activity” https://amnat.org/an/newpapers/June-Han-A.html Chang Seok Han, Robert C. Brooks, and Niels J. Dingemanse (June 2020) Mutual mate preference and intersexual genetic covariance for mating activity are weaker when environment is stressful Read the Article (Just Accepted) Abstract Despite mating representing a mutual interaction, the study of mate preferences has long focused on choice in one sex and on the preferred traits in the other. This has certainly been true in the study of the costs and condition-dependent expression of mating preferences, with the majority of studies concerning female preference. The condition-dependence and genetic architecture of mutual mate preferences remain largely unstudied, despite their likely relevance for the evolution of preferences and of mating behavior more generally. Here, we measured (i) male and female mate preferences and (ii) intersexual genetic correlations for the mating activity in pedigreed populations of southern field crickets (Gryllus bimaculatus) raised on a favorable (free-choice) or stressful (protein-deprived) diet. In the favorable dietary environment, mutual mate preferences were strong, and the intersexual genetic covariance for mating activity was not different from one. However, in the stressful dietary environment, mutual mate preferences were weak, and the intersexual genetic covariance for mating activity was significantly smaller than one. Altogether, our results show that diet environments affect the expression of genetic variation in mating behaviors: (i) the strength of mutual mate preference and (ii) intersexual genetic covariance for mating activity tend to be weaker when environment is stressful. This implies that mating dynamics strongly vary across environments. More forthcoming papers &raquo; <p>Chang Seok Han, Robert C. Brooks, and Niels J. Dingemanse (June 2020) </p> <p><b>Mutual mate preference and intersexual genetic covariance for mating activity are weaker when environment is stressful </b></p> <p><i><a href="https://dx.doi.org/10.1086/708497">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">D</span>espite mating representing a mutual interaction, the study of mate preferences has long focused on choice in one sex and on the preferred traits in the other. This has certainly been true in the study of the costs and condition-dependent expression of mating preferences, with the majority of studies concerning female preference. The condition-dependence and genetic architecture of mutual mate preferences remain largely unstudied, despite their likely relevance for the evolution of preferences and of mating behavior more generally. Here, we measured (i) male and female mate preferences and (ii) intersexual genetic correlations for the mating activity in pedigreed populations of southern field crickets (<i>Gryllus bimaculatus</i>) raised on a favorable (free-choice) or stressful (protein-deprived) diet. In the favorable dietary environment, mutual mate preferences were strong, and the intersexual genetic covariance for mating activity was not different from one. However, in the stressful dietary environment, mutual mate preferences were weak, and the intersexual genetic covariance for mating activity was significantly smaller than one. Altogether, our results show that diet environments affect the expression of genetic variation in mating behaviors: (i) the strength of mutual mate preference and (ii) intersexual genetic covariance for mating activity tend to be weaker when environment is stressful. This implies that mating dynamics strongly vary across environments. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 05 Feb 2020 06:00:00 GMT “Survival benefits of group living in a fluctuating environment” https://amnat.org/an/newpapers/June-Guindre-Parker.html Sarah Guindre-Parker and Dustin R. Rubenstein (June 2020) Group living does not buffer against harsh conditions in starlings, but living in larger groups does improve survival Read the Article (Just Accepted) Animals that live in large social groups can face increased competition for food or mates from other group members. Yet, group living persists in many species despite this increased competition—as a result, biologists expect that some advantage must exist to living in large groups at least under some contexts. One possibility for animals living in unpredictable environments is that group living is beneficial in order to overcome harsh environmental conditions where challenges cannot be anticipated.Guindre-Parker and Rubenstein studied a population of superb starlings in East Africa for over 15 years. These birds experience unpredictable variation in rainfall from year to year, and live in some of the largest social groups known for a cooperatively breeding bird (ranging from 7 to 57 individuals per group). The researchers monitored individual birds over their lifespan using unique combinations of colored leg bands and extensive field observations. The team tested whether survival was higher for individual birds belonging to the largest social group compared to small groups. They also examined whether living in the largest social group improved survival most under periods of harsh, low rainfall, compared to years with abundant rain. This study found that female superb starlings benefited from living in larger social groups, since female starlings had longer lifespans when they belonged to the largest groups. This result held true regardless of rainfall conditions, however, suggesting that female birds always benefit from living in large groups regardless of harsh conditions. A similar pattern was observed in males, where male starlings had the longest lifespan if they lived in larger social groups. However, living in larger social groups improved male survival most when rainfall was abundant. In other words, group living did not improve male survival under harsh conditions as previously expected, but instead improved male survival most under benign conditions. Overall, the authors conclude that group living provides important survival benefits to superb starlings, but group living does not appear to buffer group members against harsh periods of low rainfall and food availability. Abstract Group living is only predicted to arise when the fitness benefits outweigh the costs of sociality. Group-living species—including cooperatively breeding and family-living birds and mammals—occur most frequently in environments where climatic conditions fluctuate unpredictably from year-to-year. The fitness consequences of group living are thus expected to vary with changing environmental conditions, though few studies have examined this possibility. We examined whether living in large social groups improves adult survivorship in cooperatively breeding superb starlings (Lamprotornis superbus). We also tested the hypothesis that larger groups buffer against harsh conditions by increasing survivorship most under periods of low rainfall. We found that group size was positively correlated with adult survival, but in a sex-specific manner: female survival increased with group size across all environmental conditions, whereas male survival only increased with group size in wet years. Together with previous work in this system, our results suggest that larger groups confer survival benefits by reducing predation, rather than improving access to food or buffering against physiological stress. Although group living does not appear to buffer against harsh conditions in adult starlings living in a fluctuating environment, living in larger groups does confer a survival advantage. More forthcoming papers &raquo; <p>Sarah Guindre-Parker and Dustin R. Rubenstein (June 2020) </p> <p><b>Group living does not buffer against harsh conditions in starlings, but living in larger groups does improve survival </b></p> <p><i><a href="https://dx.doi.org/10.1086/708496">Read the Article</a></i> (Just Accepted) </p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>nimals that live in large social groups can face increased competition for food or mates from other group members. Yet, group living persists in many species despite this increased competition&mdash;as a result, biologists expect that some advantage must exist to living in large groups at least under some contexts. One possibility for animals living in unpredictable environments is that group living is beneficial in order to overcome harsh environmental conditions where challenges cannot be anticipated.</p><p>Guindre-Parker and Rubenstein studied a population of superb starlings in East Africa for over 15 years. These birds experience unpredictable variation in rainfall from year to year, and live in some of the largest social groups known for a cooperatively breeding bird (ranging from 7 to 57 individuals per group). The researchers monitored individual birds over their lifespan using unique combinations of colored leg bands and extensive field observations. The team tested whether survival was higher for individual birds belonging to the largest social group compared to small groups. They also examined whether living in the largest social group improved survival most under periods of harsh, low rainfall, compared to years with abundant rain. </p><p>This study found that female superb starlings benefited from living in larger social groups, since female starlings had longer lifespans when they belonged to the largest groups. This result held true regardless of rainfall conditions, however, suggesting that female birds always benefit from living in large groups regardless of harsh conditions. A similar pattern was observed in males, where male starlings had the longest lifespan if they lived in larger social groups. However, living in larger social groups improved male survival most when rainfall was abundant. In other words, group living did not improve male survival under harsh conditions as previously expected, but instead improved male survival most under benign conditions. Overall, the authors conclude that group living provides important survival benefits to superb starlings, but group living does not appear to buffer group members against harsh periods of low rainfall and food availability.</p> <hr /><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">G</span>roup living is only predicted to arise when the fitness benefits outweigh the costs of sociality. Group-living species&mdash;including cooperatively breeding and family-living birds and mammals&mdash;occur most frequently in environments where climatic conditions fluctuate unpredictably from year-to-year. The fitness consequences of group living are thus expected to vary with changing environmental conditions, though few studies have examined this possibility. We examined whether living in large social groups improves adult survivorship in cooperatively breeding superb starlings (<i>Lamprotornis superbus</i>). We also tested the hypothesis that larger groups buffer against harsh conditions by increasing survivorship most under periods of low rainfall. We found that group size was positively correlated with adult survival, but in a sex-specific manner: female survival increased with group size across all environmental conditions, whereas male survival only increased with group size in wet years. Together with previous work in this system, our results suggest that larger groups confer survival benefits by reducing predation, rather than improving access to food or buffering against physiological stress. Although group living does not appear to buffer against harsh conditions in adult starlings living in a fluctuating environment, living in larger groups does confer a survival advantage.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 05 Feb 2020 06:00:00 GMT “<i>The Adaptive Geometry of Trees</i> revisited” https://amnat.org/an/newpapers/June-Givnish-A.html Thomas J. Givnish (June 2020) Horn’s Adaptive Geometry of Trees had an important influence on plant ecology, but its central model must now be recast Read the Article (Just Accepted) Abstract The Adaptive Geometry of Trees had an important conceptual influence on plant ecology, and helped inspire many new approaches to understanding succession, plant adaptation, and plant competition. Its central model provided an elegant potential explanation for how optimal canopy form should shift with ecological conditions, change those conditions through time, and thus help drive succession and be a consequence of it. Yet, upon close examination, this deeply inspirational model does not lead to the predictions for which it is widely known. Here I show that the Horn model actually favors monolayer canopies over multilayers under all light conditions if relative growth rate (growth per unit investment) is maximized. Horn’s conclusion that multilayers would be favored over monolayers in brighter sites is an artifact. I propose that self-shading multilayers might gain an advantage in brightly lit sites by reducing water loss, reducing the costs of branch construction and maintenance, reducing photoinhibition, increasing light capture in side-lit microsites, and increasing water and nutrient supplies, or leaf longevity, when combined with one or more of the previous potential advantages. I conclude with a brief discussion connecting Horn’s model to other conceptual frameworks in plant ecology, and outlining possible future extensions. More forthcoming papers &raquo; <p>Thomas J. Givnish (June 2020) </p> <p><b>Horn’s <i>Adaptive Geometry of Trees</i> had an important influence on plant ecology, but its central model must now be recast </b></p> <p><i><a href="https://dx.doi.org/10.1086/708498">Read the Article</a></i> (Just Accepted) </p><h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">T</span><i>he Adaptive Geometry of Trees</i> had an important conceptual influence on plant ecology, and helped inspire many new approaches to understanding succession, plant adaptation, and plant competition. Its central model provided an elegant potential explanation for how optimal canopy form should shift with ecological conditions, change those conditions through time, and thus help drive succession and be a consequence of it. Yet, upon close examination, this deeply inspirational model does not lead to the predictions for which it is widely known. Here I show that the Horn model actually favors monolayer canopies over multilayers under all light conditions if relative growth rate (growth per unit investment) is maximized. Horn’s conclusion that multilayers would be favored over monolayers in brighter sites is an artifact. I propose that self-shading multilayers might gain an advantage in brightly lit sites by reducing water loss, reducing the costs of branch construction and maintenance, reducing photoinhibition, increasing light capture in side-lit microsites, and increasing water and nutrient supplies, or leaf longevity, when combined with one or more of the previous potential advantages. I conclude with a brief discussion connecting Horn’s model to other conceptual frameworks in plant ecology, and outlining possible future extensions. </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 05 Feb 2020 06:00:00 GMT “Prey exploits the auditory illusions of eavesdropping predators” https://amnat.org/an/newpapers/May-Legett.html Henry D. Legett, Claire T. Hemingway, and Ximena E. Bernal (May 2020) Read the Article&nbsp;Animals often use flashy signals to attract mates. The colorful plumage of birds or the night-time songs of frogs and crickets are examples of these so-called mating signals. Usually, more conspicuous mating signals, like brighter colors and louder songs, attract more mates. Conspicuousness, however, also attracts predators. This study investigates how pug-nosed treefrogs balance this tradeoff of attracting mates without also attracting predators. In this treefrog, groups of males simultaneously produce calls in near-perfect synchrony. These synchronized calls exploit an auditory illusion to reduce the call’s attractiveness to their predators, frog-eating bats and frog-biting midges. This auditory illusion results when two sounds are closely synchronized (a leading sound is produced closely followed by another sound), as both sounds are perceived as originating from the source of the leading sound. To examine how producing synchronized signals could create this illusion and obscure the location of the following mating signal from predators, field experiments were performed with two speakers playing pug-nosed frog calls mimicking a male producing a leading call closely followed by a call produced by a second male. These experiments revealed that both bats and midges are vulnerable to this auditory illusion, preferring to attack calls from the leading rather than following males. In contrast, female pug-nosed treefrogs have no preference, and choose either male at random. Male pug-nosed treefrogs, therefore, synchronize their calls to deceive predators with an illusion to avoid them but without reducing the attraction of mates. Abstract Mating signals have evolved to attract target receivers, even to the point of exploiting receivers through perceptual manipulation. Signals, however, can also expose signalers to non-target receivers, including predators and parasites, and thus have also evolved to decrease enemy attraction. Here we show that male treefrogs (Smilisca sila) reduce their attractiveness to eavesdropping enemies (bats and midges) by overlapping their calls at near-perfect synchrony with the calls of neighboring conspecifics. By producing calls that closely follow those of other males, synchronizing S.&nbsp;sila take advantage of an auditory illusion where enemies are more attracted to the leading call. Female S.&nbsp;sila, however, are not as susceptible to this illusion. Thus, synchronization among signaling males can result in acoustic crypsis from predators without affecting female attraction. Given the widespread use of conspicuous mating signals and eavesdropping enemies, perceptual exploitation of eavesdroppers is likely a common driver of signal evolution. Presa explota las ilusiones auditivas de los depredadores que usan su sistema de comunicaci&oacute;n Para atraer hembras, las se&ntilde;ales de apareamiento han evolucionado hasta el punto de explotar el mecanismo de percepci&oacute;n de los receptores de estas se&ntilde;ales. Sin embargo, estas se&ntilde;ales tambi&eacute;n exponen a sus emisores a ataques por depredadores y par&aacute;sitos, y por tanto, han evolucionado para disminuir su atracci&oacute;n a dichos enemigos. Demonstramos que los machos de ranas arbor&iacute;colas (Smilisca sila) sobreponen sus llamadas con llamadas de machos vecinos de la misma especie, produciendolas en sincron&iacute;a y reduciendo que tan atractivas son sus se&ntilde;ales para sus enemigos (murci&eacute;lagos y mosquitos). Al producir su llamada justo despu&eacute;s de la de otros machos, la sincronizaci&oacute;n de cantos en S.&nbsp;sila toma ventaja de una ilusi&oacute;n auditiva en la que los enemigos son atra&iacute;dos hacia la llamada del macho que canta primero. Las hembras de S.&nbsp;sila, sin embargo, no son susceptibles a esta ilusi&oacute;n. Por lo tanto, la sincronizaci&oacute;n de producci&oacute;n de se&ntilde;ales entre los machos puede dar lugar a cripsis ac&uacute;stica de los depredadores, sin afectar la atracci&oacute;n de las hembras. Dado el uso generalizado de las se&ntilde;ales de apareamiento exageradas y el uso de dichas se&ntilde;ales por enemigos, la explotaci&oacute;n de la percepci&oacute;n de se&ntilde;ales por enemigos es probablemente una fuerza com&uacute;n de selecci&oacute;n en la evoluci&oacute;n de se&ntilde;ales de comunicaci&oacute;n. More forthcoming papers &raquo; <p>Henry D. Legett, Claire T. Hemingway, and Ximena E. Bernal (May 2020)</p> <p><i><a href="https://dx.doi.org/10.1086/707719">Read the Article</a></i>&nbsp;</p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">A</span>nimals often use flashy signals to attract mates. The colorful plumage of birds or the night-time songs of frogs and crickets are examples of these so-called mating signals. Usually, more conspicuous mating signals, like brighter colors and louder songs, attract more mates. Conspicuousness, however, also attracts predators. This study investigates how pug-nosed treefrogs balance this tradeoff of attracting mates without also attracting predators. In this treefrog, groups of males simultaneously produce calls in near-perfect synchrony. These synchronized calls exploit an auditory illusion to reduce the call&rsquo;s attractiveness to their predators, frog-eating bats and frog-biting midges. This auditory illusion results when two sounds are closely synchronized (a leading sound is produced closely followed by another sound), as both sounds are perceived as originating from the source of the leading sound. To examine how producing synchronized signals could create this illusion and obscure the location of the following mating signal from predators, field experiments were performed with two speakers playing pug-nosed frog calls mimicking a male producing a leading call closely followed by a call produced by a second male. These experiments revealed that both bats and midges are vulnerable to this auditory illusion, preferring to attack calls from the leading rather than following males. In contrast, female pug-nosed treefrogs have no preference, and choose either male at random. Male pug-nosed treefrogs, therefore, synchronize their calls to deceive predators with an illusion to avoid them but without reducing the attraction of mates.</p> <hr /> <h3>Abstract</h3> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">M</span>ating signals have evolved to attract target receivers, even to the point of exploiting receivers through perceptual manipulation. Signals, however, can also expose signalers to non-target receivers, including predators and parasites, and thus have also evolved to decrease enemy attraction. Here we show that male treefrogs (<i>Smilisca sila</i>) reduce their attractiveness to eavesdropping enemies (bats and midges) by overlapping their calls at near-perfect synchrony with the calls of neighboring conspecifics. By producing calls that closely follow those of other males, synchronizing <i>S.&nbsp;sila</i> take advantage of an auditory illusion where enemies are more attracted to the leading call. Female <i>S.&nbsp;sila</i>, however, are not as susceptible to this illusion. Thus, synchronization among signaling males can result in acoustic crypsis from predators without affecting female attraction. Given the widespread use of conspicuous mating signals and eavesdropping enemies, perceptual exploitation of eavesdroppers is likely a common driver of signal evolution.</p> <h4>Presa explota las ilusiones auditivas de los depredadores que usan su sistema de comunicaci&oacute;n</h4> <p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">P</span>ara atraer hembras, las se&ntilde;ales de apareamiento han evolucionado hasta el punto de explotar el mecanismo de percepci&oacute;n de los receptores de estas se&ntilde;ales. Sin embargo, estas se&ntilde;ales tambi&eacute;n exponen a sus emisores a ataques por depredadores y par&aacute;sitos, y por tanto, han evolucionado para disminuir su atracci&oacute;n a dichos enemigos. Demonstramos que los machos de ranas arbor&iacute;colas (<i>Smilisca sila</i>) sobreponen sus llamadas con llamadas de machos vecinos de la misma especie, produciendolas en sincron&iacute;a y reduciendo que tan atractivas son sus se&ntilde;ales para sus enemigos (murci&eacute;lagos y mosquitos). Al producir su llamada justo despu&eacute;s de la de otros machos, la sincronizaci&oacute;n de cantos en <i>S.&nbsp;sila</i> toma ventaja de una ilusi&oacute;n auditiva en la que los enemigos son atra&iacute;dos hacia la llamada del macho que canta primero. Las hembras de <i>S.&nbsp;sila</i>, sin embargo, no son susceptibles a esta ilusi&oacute;n. Por lo tanto, la sincronizaci&oacute;n de producci&oacute;n de se&ntilde;ales entre los machos puede dar lugar a cripsis ac&uacute;stica de los depredadores, sin afectar la atracci&oacute;n de las hembras. Dado el uso generalizado de las se&ntilde;ales de apareamiento exageradas y el uso de dichas se&ntilde;ales por enemigos, la explotaci&oacute;n de la percepci&oacute;n de se&ntilde;ales por enemigos es probablemente una fuerza com&uacute;n de selecci&oacute;n en la evoluci&oacute;n de se&ntilde;ales de comunicaci&oacute;n.</p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 03 Feb 2020 06:00:00 GMT Command-Line Programming & Bioinformatics for Beginners https://amnat.org/announcements/ANNEvoWkshp.html The American Society of Naturalists Graduate Council will be hosting a pre-conference workshop, “Command-Line Programming and Bioinformatics for Beginners”, at Evolution 2020. This workshop is specifically aimed toward graduate students and post-docs that have minimal previous experience with these tools, and do not have access to learn these tools at their current institution. &nbsp; The workshop will be held from 9 AM to 5 PM on June 19, 2020 in Room 22 at the Huntington Convention Center, Cleveland, OH. Participants will need to bring their own laptop. Workshop amenities will include a packaged lunch and refreshment breaks throughout the day. Since this is a pre-conference workshop, we will also be offering a limited number of travel waivers to eligible applicants with financial needs to help reduce the additional costs associated with attending this workshop. If you are interested in applying for this workshop, please visit www.asngrads.com/events for more information and the application form. <p>The American Society of Naturalists Graduate Council will be hosting a pre-conference workshop, &ldquo;Command-Line Programming and Bioinformatics for Beginners&rdquo;, at Evolution 2020. This workshop is specifically aimed toward graduate students and post-docs that</p> <ol> <li>have minimal previous experience with these tools, and</li> <li>do not have access to learn these tools at their current institution. &nbsp;</li> </ol> <p>The workshop will be held from 9 AM to 5 PM on June 19, 2020 in Room 22 at the Huntington Convention Center, Cleveland, OH.</p> <p>Participants will need to bring their own laptop. Workshop amenities will include a packaged lunch and refreshment breaks throughout the day. Since this is a pre-conference workshop, we will also be offering a limited number of travel waivers to eligible applicants with financial needs to help reduce the additional costs associated with attending this workshop.</p> <p>If you are interested in applying for this workshop, please visit <a href="http://www.asngrads.com/events">www.asngrads.com/events</a> for more information and the application form.</p> Fri, 31 Jan 2020 06:00:00 GMT