ASN RSS https://amnat.org/ Latest press releases and announcements from the ASN en-us Mon, 29 Jun 2020 05:00:00 GMT 60 “Timing metabolic depression: predicting thermal stress in extreme intertidal environments” https://amnat.org/an/newpapers/Oct-Hui.html Tin Yan Hui, Yun-wei Dong, Guo-dong Han, Sarah L. Y. Lau, Martin C. F. Cheng, Chayanid Meepoka, Monthon Ganmanee, and Gray A. Williams (Oct 2020) Anticipatory metabolic depression aligns with temporal structure of rock temperature in a tropical intertidal oyster Read the Article (Just Accepted) Surviving on the highest tidal levels of tropical shores is extremely challenging given the long periods of extremely hot desiccating conditions when the tide is out. This is especially true if you are a sessile organism and yet the oyster, Isognomon nucleus, dominates this habitat on shores in central Thailand. Researchers from the Swire Institute of Marine Science, The University of Hong Kong and collaborators combined laboratory assays and field measurements to determine how this species manages to form dense beds at this extreme tidal level, where rock temperatures can reach 60&nbsp;°C, exceeding the oysters lethal limits, and rare tidal submergence restrains feeding opportunities. By measuring the heart rates of these animals over a thermal ramp Hui and colleagues found that the oyster undergoes extraordinary (by >50% and sometimes to flatline) metabolic depression when temperatures increase during low tides. The temperatures at which this depression occurs are related to the rock temperatures and Hui and colleagues demonstrated a strong coupling between physiology and predictability of the thermal environment. They hypothesized that temporal predictability in rock temperature can be exploited by the oyster as an early warning signal to initiate metabolic depression and prepare for severe thermal stress. This ‘early warning’ system allows preparative shifts in physiology to be achieved in a timely fashion following these cues in the environment and allows individual performance to be buffered against survival costs during unfavorable conditions, such as the high energetic costs required to maintain metabolism during severe thermal stress. Hui and colleagues argue this coupling between organismal physiology and temporal predictability of the environment plays a key role in determining species performance and survival in extreme thermal environments and, importantly, that the prevalence of metabolic depression in distantly-related high shore ectotherms suggests convergent evolution of this strategy as an underlying, key mechanism to survive in thermally extreme but energy-poor environments. Abstract Anticipatory changes in organismal responses, triggered by reliable environmental cues for future conditions, are key to species’ persistence in temporally variable environments. Such responses were tested by measuring the physiological performance of a tropical, high shore oyster in tandem with the temporal predictability of environmental temperature. Heart rate of the oyster increased with environmental temperatures until body temperature reached ~37&nbsp;°C, when a substantial depression occurred (~60%) before recovery between ~42–47&nbsp;°C, after which cardiac function collapsed. The sequential increase, depression and recovery in cardiac performance aligned with temporal patterns in rock surface temperatures, where the risk to reach temperatures close to the oysters’ lethal limit accelerates if the rock heats up beyond ~37&nbsp;°C, coinciding closely with the body temperature at which the oysters initiate metabolic depression. The increase in body temperature over a critical threshold serves as an early-warning cue to initiate anticipatory shifts in physiology and energy conservation before severe thermal stress occurs on the shore. Cross-correlating the onset of physiological mechanisms and temporal structures in environmental temperatures, therefore, reveals the potential role of reliable, real-time environmental cues for future conditions in driving the evolution of anticipatory responses. More forthcoming papers &raquo; <p>Tin Yan Hui, Yun-wei Dong, Guo-dong Han, Sarah L. Y. Lau, Martin C. F. Cheng, Chayanid Meepoka, Monthon Ganmanee, and Gray A. Williams (Oct 2020) </p> <p><b>Anticipatory metabolic depression aligns with temporal structure of rock temperature in a tropical intertidal oyster </b></p> <p><i><a href="https://dx.doi.org/10.1086/710339">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>urviving on the highest tidal levels of tropical shores is extremely challenging given the long periods of extremely hot desiccating conditions when the tide is out. This is especially true if you are a sessile organism and yet the oyster, <i>Isognomon nucleus</i>, dominates this habitat on shores in central Thailand. Researchers from the Swire Institute of Marine Science, The University of Hong Kong and collaborators combined laboratory assays and field measurements to determine how this species manages to form dense beds at this extreme tidal level, where rock temperatures can reach 60&nbsp;°C, exceeding the oysters lethal limits, and rare tidal submergence restrains feeding opportunities. </p><p>By measuring the heart rates of these animals over a thermal ramp Hui and colleagues found that the oyster undergoes extraordinary (by >50% and sometimes to flatline) metabolic depression when temperatures increase during low tides. The temperatures at which this depression occurs are related to the rock temperatures and Hui and colleagues demonstrated a strong coupling between physiology and predictability of the thermal environment. They hypothesized that temporal predictability in rock temperature can be exploited by the oyster as an early warning signal to initiate metabolic depression and prepare for severe thermal stress. This ‘early warning’ system allows preparative shifts in physiology to be achieved in a timely fashion following these cues in the environment and allows individual performance to be buffered against survival costs during unfavorable conditions, such as the high energetic costs required to maintain metabolism during severe thermal stress. </p><p>Hui and colleagues argue this coupling between organismal physiology and temporal predictability of the environment plays a key role in determining species performance and survival in extreme thermal environments and, importantly, that the prevalence of metabolic depression in distantly-related high shore ectotherms suggests convergent evolution of this strategy as an underlying, key mechanism to survive in thermally extreme but energy-poor environments. </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>nticipatory changes in organismal responses, triggered by reliable environmental cues for future conditions, are key to species’ persistence in temporally variable environments. Such responses were tested by measuring the physiological performance of a tropical, high shore oyster in tandem with the temporal predictability of environmental temperature. Heart rate of the oyster increased with environmental temperatures until body temperature reached ~37&nbsp;°C, when a substantial depression occurred (~60%) before recovery between ~42–47&nbsp;°C, after which cardiac function collapsed. The sequential increase, depression and recovery in cardiac performance aligned with temporal patterns in rock surface temperatures, where the risk to reach temperatures close to the oysters’ lethal limit accelerates if the rock heats up beyond ~37&nbsp;°C, coinciding closely with the body temperature at which the oysters initiate metabolic depression. The increase in body temperature over a critical threshold serves as an early-warning cue to initiate anticipatory shifts in physiology and energy conservation before severe thermal stress occurs on the shore. Cross-correlating the onset of physiological mechanisms and temporal structures in environmental temperatures, therefore, reveals the potential role of reliable, real-time environmental cues for future conditions in driving the evolution of anticipatory responses. </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, 25 Jun 2020 05:00:00 GMT “A comparative test for divergent adaptation: inferring speciation drivers from functional trait divergence” https://amnat.org/an/newpapers/Oct-Anderson.html Sean A. S. Anderson and Jason T. Weir (Oct 2020) A new framework to test for signatures of divergent selection between sister species and other paired lineages Read the Article (Just Accepted) Biologists have long been intrigued by the creative power of adaptation. More than 160 years ago, Darwin and Wallace suggested that populations adapting in different environments could evolve into distinct ‘varieties’, which may later become species of their own. Today we say that ‘ecological speciation’ occurs when populations adapt to exploit different resources such as habitat or diet, and the resulting changes cause a substantial reduction in their ability to successfully interbreed. The underlying process of divergent adaptation has received considerable study in recent decades – but much of this work has focused on just a handful of natural model systems, including benthic-vs-limnetic stickleback and red-vs-blue Pundamilia cichlids. These studies have yielded important insights into the early stages of lineage divergence, but crucial questions remain unanswered. In particular, we still don’t know if divergent adaptation is a generally important driver of speciation in nature or how it is influenced by changes in the ecological theatre. Anderson and Weir present a new tool to address these questions by modelling the evolution of differences in ecomorphology – specifically, continuous traits with known ecological function – between sister species and other lineage pairs. The authors show that divergent adaptation imparts a unique signature on the distribution of trait differences in datasets comprised of many paired lineages. Empiricists can test for this signature by providing a measure of trait differentiation and an estimate of the divergence time for each pair. Users can also test for changes in the strength of divergent selection across continuous variables like latitude and elevation or categorical variables like ‘sympatric’ versus ‘allopatric’. With this new tool, empiricists with a variety of research questions can begin to more generally characterize an adaptive process of long-hypothesized importance in evolutionary ecology. The tool is encoded as the R&nbsp;package diverge, now available on CRAN. Abstract Ecological differentiation between lineages is widely considered to be an important driver of speciation, but support for this hypothesis is mainly derived from the detailed study of a select set of model species pairs. Mounting evidence from non-model taxa, meanwhile, suggests that speciation often occurs with minimal differentiation in ecology or ecomorphology, calling into question the true contribution of divergent adaptation to species richness in nature. To better understand divergent ecological adaptation and its role in speciation generally, researchers require a comparative approach that can distinguish its signature from alternative processes such as drift and parallel selection in datasets containing many species pairs. Here we introduce the first statistical models of divergent adaptation in the continuous traits of paired lineages. In these models, ecomorphological characters diverge as two lineages adapt toward alternative phenotypic optima following their departure from a common ancestor. The absolute distance between optima measures the extent of divergent selection and provides a basis for interpretation. We encode the models in the new R&nbsp;package diverge and extend them to allow the distance between optima to vary across continuous and categorical variables. We test model performance using simulation and demonstrate model application using published datasets of trait divergence in birds and mammals. Our framework provides the first explicit test for signatures of divergent selection in trait divergence datasets, and it will enable empiricists from a wide range of fields to better understand the dynamics of divergent adaptation and its prevalence in nature beyond just our best-studied model systems. More forthcoming papers &raquo; <p>Sean A. S. Anderson and Jason T. Weir (Oct 2020) </p> <p><b>A new framework to test for signatures of divergent selection between sister species and other paired lineages </b></p> <p><i><a href="https://dx.doi.org/10.1086/710338">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;">B</span>iologists have long been intrigued by the creative power of adaptation. More than 160 years ago, Darwin and Wallace suggested that populations adapting in different environments could evolve into distinct ‘varieties’, which may later become species of their own. Today we say that ‘ecological speciation’ occurs when populations adapt to exploit different resources such as habitat or diet, and the resulting changes cause a substantial reduction in their ability to successfully interbreed. </p><p>The underlying process of divergent adaptation has received considerable study in recent decades – but much of this work has focused on just a handful of natural model systems, including benthic-vs-limnetic stickleback and red-vs-blue <i>Pundamilia</i> cichlids. These studies have yielded important insights into the early stages of lineage divergence, but crucial questions remain unanswered. In particular, we still don’t know if divergent adaptation is a generally important driver of speciation in nature or how it is influenced by changes in the ecological theatre. </p><p>Anderson and Weir present a new tool to address these questions by modelling the evolution of differences in ecomorphology – specifically, continuous traits with known ecological function – between sister species and other lineage pairs. The authors show that divergent adaptation imparts a unique signature on the distribution of trait differences in datasets comprised of many paired lineages. Empiricists can test for this signature by providing a measure of trait differentiation and an estimate of the divergence time for each pair. Users can also test for changes in the strength of divergent selection across continuous variables like latitude and elevation or categorical variables like ‘sympatric’ versus ‘allopatric’. With this new tool, empiricists with a variety of research questions can begin to more generally characterize an adaptive process of long-hypothesized importance in evolutionary ecology. The tool is encoded as the R&nbsp;package <i>diverge</i>, now available on CRAN. </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 differentiation between lineages is widely considered to be an important driver of speciation, but support for this hypothesis is mainly derived from the detailed study of a select set of model species pairs. Mounting evidence from non-model taxa, meanwhile, suggests that speciation often occurs with minimal differentiation in ecology or ecomorphology, calling into question the true contribution of divergent adaptation to species richness in nature. To better understand divergent ecological adaptation and its role in speciation generally, researchers require a comparative approach that can distinguish its signature from alternative processes such as drift and parallel selection in datasets containing many species pairs. Here we introduce the first statistical models of divergent adaptation in the continuous traits of paired lineages. In these models, ecomorphological characters diverge as two lineages adapt toward alternative phenotypic optima following their departure from a common ancestor. The absolute distance between optima measures the extent of divergent selection and provides a basis for interpretation. We encode the models in the new R&nbsp;package <i>diverge</i> and extend them to allow the distance between optima to vary across continuous and categorical variables. We test model performance using simulation and demonstrate model application using published datasets of trait divergence in birds and mammals. Our framework provides the first explicit test for signatures of divergent selection in trait divergence datasets, and it will enable empiricists from a wide range of fields to better understand the dynamics of divergent adaptation and its prevalence in nature beyond just our best-studied model systems. </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, 25 Jun 2020 05:00:00 GMT “Detecting the signature of body mass evolution in the broad-scale architecture of food webs” https://amnat.org/an/newpapers/Oct-DeLong.html John P. DeLong (Oct 2020) Resource-based optimization of predator body mass generates macro-scale patterns of predator-prey mass relationships Read the Article (Just Accepted) Ecological communities are connected by predator and prey. Those connections are influence by body size, with bigger predators eating bigger prey. Although the positive relationship between predator and prey size seems intuitive, the slope of that relationship varies across taxa, habitats, and temperature. This variation suggests that the structure of ecological communities depends on features of the environment that might also influence the evolution of body size itself, such as temperature and food availability. In this study, the author showed that the slope of the predator-prey body mass relationship could be predicted from a model of body size evolution. Moreover, variation in the body mass relationship could be linked to the time cost of handling prey, indicating that the size of predators is linked to what and how big their prey is in a predictable way. This finding suggests that the broad-scale pattern of who eats whom in a food web emerges from the small-scale processes that drive the evolution of predator body size. Abstract Aody mass-based links between predator and prey are fundamental to the architecture of food webs. These links determine who eats whom across trophic levels and strongly influence the population abundance, flow of energy, and stability properties of natural communities. Body mass links scale up to create predator-prey mass relationships across species, but the origin of these relationships is unclear. Here I show that predator-prey mass relationships are consistent with the idea that body mass evolves to maximize a dependable supply of resource uptake. I used a global databases of ~2,100 predator-prey links and a mechanistic optimization model to correctly predict the slope of the predator-prey mass scaling relationships across species generally and for nine taxonomic subsets. The model also predicted cross-group variation in the heights of the body mass relationships, providing an integrated explanation for mass relationships and their variation across taxa. The results suggest that natural selection on body mass at the local scale is detectable in ecological organization at the macro scale. More forthcoming papers &raquo; <p>John P. DeLong (Oct 2020) </p> <p><b>Resource-based optimization of predator body mass generates macro-scale patterns of predator-prey mass relationships </b></p> <p><i><a href="https://dx.doi.org/10.1086/710350">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;">E</span>cological communities are connected by predator and prey. Those connections are influence by body size, with bigger predators eating bigger prey. Although the positive relationship between predator and prey size seems intuitive, the slope of that relationship varies across taxa, habitats, and temperature. This variation suggests that the structure of ecological communities depends on features of the environment that might also influence the evolution of body size itself, such as temperature and food availability. In this study, the author showed that the slope of the predator-prey body mass relationship could be predicted from a model of body size evolution. Moreover, variation in the body mass relationship could be linked to the time cost of handling prey, indicating that the size of predators is linked to what and how big their prey is in a predictable way. This finding suggests that the broad-scale pattern of who eats whom in a food web emerges from the small-scale processes that drive the evolution of predator body size. </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>ody mass-based links between predator and prey are fundamental to the architecture of food webs. These links determine who eats whom across trophic levels and strongly influence the population abundance, flow of energy, and stability properties of natural communities. Body mass links scale up to create predator-prey mass relationships across species, but the origin of these relationships is unclear. Here I show that predator-prey mass relationships are consistent with the idea that body mass evolves to maximize a dependable supply of resource uptake. I used a global databases of ~2,100 predator-prey links and a mechanistic optimization model to correctly predict the slope of the predator-prey mass scaling relationships across species generally and for nine taxonomic subsets. The model also predicted cross-group variation in the heights of the body mass relationships, providing an integrated explanation for mass relationships and their variation across taxa. The results suggest that natural selection on body mass at the local scale is detectable in ecological organization at the macro scale. </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, 25 Jun 2020 05:00:00 GMT “Combinatorial signal processing in an insect” https://amnat.org/an/newpapers/Oct-Speck.html Bretta Speck, Sara Seidita, Samuel Belo, Samuel Johnson, Caley Conley, Camille Desjonquères, and Rafael L. Rodríguez (Oct 2020) A playback experiment shows that female Enchenopa treehoppers are capable of basic combinatorial signal processing Read the Article (Just Accepted) How much information can a tiny insect process? Animals with large brains are capable of processing complex, multi-component mating signals. Researchers at the University of Wisconsin-Milwaukee have found an insect with similar signal processing capabilities. Enchenopa binotata, a species of treehopper native to Wisconsin, communicate vibrationally through the branches of the Viburnum lentago trees they live on. Males seeking a mate will tap out a “whine-pulse” signal to attract females. Researchers presented female treehoppers with male signals that varied in signal composition. They found that the females were capable of discriminating between the signals and responding accordingly; thus helping to understand signal processing capabilities by animals with small brains. Abstract Human language is combinatorial: phonemes are grouped into syllables, syllables into words, and so on. The capacity for combinatorial processing is present to different degrees in some mammals and birds. We used a vibrational insect, Enchenopa treehoppers, to test the hypothesis of basic combinatorial processing against two competing hypotheses: beginning rule (where the early signal portions play a stronger role in acceptability); and no ordering rule (where the order of signal elements plays no role in signal acceptability). Enchenopa males use plant-borne vibrational signals that consist of a whine followed by pulses (WP). We tested the above hypotheses with vibrational playback experiments in which we presented Enchenopa females with stimuli varying in signal element combinations. We monitored female responses to these playbacks with laser vibrometry. We found strong support for combinatorial processing in Enchenopa: in brief, females preferred natural-combination signals regardless of the beginning element and discriminated against reverse-order signals or individual elements. Finding support for the combinatorial rule hypothesis in an insects suggests that this capability represents a common solution to the problems presented by complex communication. More forthcoming papers &raquo; <p>Bretta Speck, Sara Seidita, Samuel Belo, Samuel Johnson, Caley Conley, Camille Desjonquères, and Rafael L. Rodríguez (Oct 2020) </p> <p><b>A playback experiment shows that female Enchenopa treehoppers are capable of basic combinatorial signal processing </b></p> <p><i><a href="https://dx.doi.org/10.1086/710527">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 much information can a tiny insect process? Animals with large brains are capable of processing complex, multi-component mating signals. Researchers at the University of Wisconsin-Milwaukee have found an insect with similar signal processing capabilities. <i>Enchenopa binotata</i>, a species of treehopper native to Wisconsin, communicate vibrationally through the branches of the <i>Viburnum lentago</i> trees they live on. Males seeking a mate will tap out a “whine-pulse” signal to attract females. Researchers presented female treehoppers with male signals that varied in signal composition. They found that the females were capable of discriminating between the signals and responding accordingly; thus helping to understand signal processing capabilities by animals with small brains. </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>uman language is combinatorial: phonemes are grouped into syllables, syllables into words, and so on. The capacity for combinatorial processing is present to different degrees in some mammals and birds. We used a vibrational insect, <i>Enchenopa</i> treehoppers, to test the hypothesis of basic combinatorial processing against two competing hypotheses: beginning rule (where the early signal portions play a stronger role in acceptability); and no ordering rule (where the order of signal elements plays no role in signal acceptability). <i>Enchenopa</i> males use plant-borne vibrational signals that consist of a whine followed by pulses (WP). We tested the above hypotheses with vibrational playback experiments in which we presented <i>Enchenopa</i> females with stimuli varying in signal element combinations. We monitored female responses to these playbacks with laser vibrometry. We found strong support for combinatorial processing in <i>Enchenopa</i>: in brief, females preferred natural-combination signals regardless of the beginning element and discriminated against reverse-order signals or individual elements. Finding support for the combinatorial rule hypothesis in an insects suggests that this capability represents a common solution to the problems presented by complex communication. </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, 25 Jun 2020 05:00:00 GMT “Predicting multivariate responses of sexual dimorphism to direct and indirect selection” https://amnat.org/an/newpapers/Oct-Cheng.html Changde Cheng (成常德) and David Houle (Oct 2020) Sexual dimorphism evolves more when sex-averaged trait values are selected than when dimorphism itself is selected Read the Article (Just Accepted)Differences between male and female animals are a striking feature of many species, like the Flame Bowerbirds in the accompanying photo. Such sexual dimorphism can, for example, be explained if selection on males is dominated by females choosing to mate with males that have striking colors and behaviors, but selection on females favors individuals who avoid detection by predators. However, if you look closely, even traits with no obvious connection to mating often differ between the sexes. In a new paper in the American Naturalist, evolutionary biologists Changde Cheng and David Houle suggest that many of these differences between the sexes can be better explained by differences in the underlying inheritance of traits between the sexes, rather than by differences in natural selection. Using previously gathered data on the fruit fly, Cheng and Houle show that some traits may actually diverge faster when selection acts the same on both sexes than when selection favors differences between the sexes. Sexual dimorphism may often be better explained by differences in the way genes act in each sex, rather than by selection for the sexes to be different. 文章摘要 雌性和雄性为什么不一样?一种解释是不同的性别受不同的选择。比如说照片里的烈焰亭鸟,雄性的色彩为求偶而鲜艳夺目,雌性的色彩为生存而相对低调。但是进一步看,大多数性状在雄性和雌性间都会有差异,而这些差异不一定都是源自于性别间的选择差异。在最新一期的美国博物学家杂志上,演化生物学家成常德和David Houle在论文提出:遗传基础的差异比选择的差异能更好的解释广泛存在的性别二态性。即使选择在雌性和雄性中的作用完全一致,遗传基础上的差异也可以导致两性间的性状差异。根据果蝇中的研究数据,成常德和David Houle表明,当选择在雌性和雄性中发挥同样作用时,某些性状上在两性之间的分化速度甚至可以比在两性受差异选择时还要快。该文提供了一个新的性别二态性起源的解释:性二态性可能源于基因在不同性别中的不同作用,而不是选择的差异作用。 Abstract Sexual dimorphism is often assumed to result from balancing the strength of antagonistic selection in favor of dimorphism against the degree of constraint imposed by the shared genome of the sexes, reflected in the B matrix of genetic inter-sexual covariances. To investigate the totality of forces shaping dimorphism, we reparameterized the Lande equation to predict changes in trait averages and trait differences between the sexes. As genetic constraints on the evolution of dimorphism in response to antagonistic selection become larger, dimorphism will tend to respond more rapidly to concordant selection (which favors the same direction of change in male and female traits) than to antagonistic selection. When we apply this theory to four empirical estimates of B in Drosophila melanogaster, the indirect responses of dimorphism to concordant selection are of comparable or larger magnitude than the direct responses of dimorphism to antagonistic selection in two suites of traits with typical levels of inter-sex correlation. Antagonistic selection is more important in two suites of traits where the inter-sex correlations are unusually low. This suggests that the evolution of sexual dimorphism may sometimes be dominated by concordant selection, rather than antagonistic selection. 直接选择和间接选择对性二态演化的影响 性二态的演化通常被认为是两性冲突导致的反向选择,和彼此共有的基因组产生的遗传约束相平衡的结果;而在两性间作用一致的同向选择的影响是间接的,从而是次要的,甚至是无关的。但是我们通过Lande方程发现,当对反向选择的遗传约束增强时,同向选择变得更重要。这一结果得到果蝇中的实验数据支持。在具有典型的两性间遗传相关水平的两组性状中,性二态的演化对同向选择的间接响应不小于对反向选择的直接响应。其余两组的性间遗传相关极低,反向选择影响更大。结论是:性二态的演化有时会由两性一致的同向选择而非冲突导致的反向选择主导。 More forthcoming papers &raquo; <p>Changde Cheng (成常德) and David Houle (Oct 2020)</p> <p><b>Sexual dimorphism evolves more when sex-averaged trait values are selected than when dimorphism itself is selected </b></p> <p><i><a href="https://dx.doi.org/10.1086/710353">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;">D</span>ifferences between male and female animals are a striking feature of many species, like the Flame Bowerbirds in the accompanying photo. Such sexual dimorphism can, for example, be explained if selection on males is dominated by females choosing to mate with males that have striking colors and behaviors, but selection on females favors individuals who avoid detection by predators. However, if you look closely, even traits with no obvious connection to mating often differ between the sexes. In a new paper in the American Naturalist, evolutionary biologists Changde Cheng and David Houle suggest that many of these differences between the sexes can be better explained by differences in the underlying inheritance of traits between the sexes, rather than by differences in natural selection. Using previously gathered data on the fruit fly, Cheng and Houle show that some traits may actually diverge faster when selection acts the same on both sexes than when selection favors differences between the sexes. Sexual dimorphism may often be better explained by differences in the way genes act in each sex, rather than by selection for the sexes to be different.</p> <h4>文章摘要</h4> <p>雌性和雄性为什么不一样?一种解释是不同的性别受不同的选择。比如说照片里的烈焰亭鸟,雄性的色彩为求偶而鲜艳夺目,雌性的色彩为生存而相对低调。但是进一步看,大多数性状在雄性和雌性间都会有差异,而这些差异不一定都是源自于性别间的选择差异。在最新一期的美国博物学家杂志上,演化生物学家成常德和David Houle在论文提出:遗传基础的差异比选择的差异能更好的解释广泛存在的性别二态性。即使选择在雌性和雄性中的作用完全一致,遗传基础上的差异也可以导致两性间的性状差异。根据果蝇中的研究数据,成常德和David Houle表明,当选择在雌性和雄性中发挥同样作用时,某些性状上在两性之间的分化速度甚至可以比在两性受差异选择时还要快。该文提供了一个新的性别二态性起源的解释:性二态性可能源于基因在不同性别中的不同作用,而不是选择的差异作用。</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;">S</span>exual dimorphism is often assumed to result from balancing the strength of antagonistic selection in favor of dimorphism against the degree of constraint imposed by the shared genome of the sexes, reflected in the <b>B</b> matrix of genetic inter-sexual covariances. To investigate the totality of forces shaping dimorphism, we reparameterized the Lande equation to predict changes in trait averages and trait differences between the sexes. As genetic constraints on the evolution of dimorphism in response to antagonistic selection become larger, dimorphism will tend to respond more rapidly to concordant selection (which favors the same direction of change in male and female traits) than to antagonistic selection. When we apply this theory to four empirical estimates of <b>B</b> in <i>Drosophila melanogaster</i>, the indirect responses of dimorphism to concordant selection are of comparable or larger magnitude than the direct responses of dimorphism to antagonistic selection in two suites of traits with typical levels of inter-sex correlation. Antagonistic selection is more important in two suites of traits where the inter-sex correlations are unusually low. This suggests that the evolution of sexual dimorphism may sometimes be dominated by concordant selection, rather than antagonistic selection.</p> <h4>直接选择和间接选择对性二态演化的影响</h4> <p>性二态的演化通常被认为是两性冲突导致的反向选择,和彼此共有的基因组产生的遗传约束相平衡的结果;而在两性间作用一致的同向选择的影响是间接的,从而是次要的,甚至是无关的。但是我们通过Lande方程发现,当对反向选择的遗传约束增强时,同向选择变得更重要。这一结果得到果蝇中的实验数据支持。在具有典型的两性间遗传相关水平的两组性状中,性二态的演化对同向选择的间接响应不小于对反向选择的直接响应。其余两组的性间遗传相关极低,反向选择影响更大。结论是:性二态的演化有时会由两性一致的同向选择而非冲突导致的反向选择主导。</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, 25 Jun 2020 05:00:00 GMT “Propensity for risk in reproductive strategy affects susceptibility to anthropogenic disturbance” https://amnat.org/an/newpapers/Oct-Pirotta.html Enrico Pirotta, Vincent Hin, Marc Mangel, Leslie New, Daniel P. Costa, André M. de Roos, and John Harwood (Oct 2020) Risky reproductive strategies in pilot whales reduce the ability to cope with human disturbance Read the Article (Just Accepted) Human activities in the ocean are expanding at a fast pace. When disturbance from these activities causes animals to change their behavior (for example, interrupt feeding activity), the long-term consequences on populations are mediated by changes in the energy stores of individuals, which can affect their survival and, importantly, reproduction. When to reproduce, when to abandon an ongoing attempt, or how much energy to transfer to offspring are critical decisions for an animal, and the best strategy changes dynamically over the course of life. This is particularly true in long-lived organisms, like most cetaceans, where parents invest a lot of energy on their offspring. Researchers from Washington State University, the University of Amsterdam, University of California Santa Cruz, and the University of St Andrews developed a model to investigate how such reproductive strategies affect susceptibility to disturbance from human activities, using long-finned pilot whales in the North Atlantic as the model species. Results show that, in undisturbed conditions, females maximize the number of calves, but, when disturbance affects feeding activity, their finely tuned strategy leads to dramatic effects on both survival and reproduction. In contrast, females develop more cautious strategies in unpredictable environments, which improve their ability to cope with disturbed conditions. Because most animals live in variable environments, fragile reproductive strategies may be unlikely to evolve and persist. For example, the long-finned pilot whale population in the North Atlantic inhabits a seasonal environment, with large inter-annual variability in food resources. Therefore, pilot whales have likely evolved low propensity to risk, which would make them comparatively more able to cope with anthropogenic disturbance. More generally, this study shows how assumptions about risk propensity can drastically affect predictions of the population consequences of human disturbance. Abstract Animals initiate, interrupt or invest resources in reproduction in light of their physiology and the environment. The energetic risks entailed in an individual’s reproductive strategy can influence the ability to cope with additional stressors, such as anthropogenic climate change and disturbance. To explore the trade-offs between internal state, external resource availability and reproduction, we applied State-Dependent Life-History Theory (SDLHT) to a Dynamic Energy Budget (DEB) model for long-finned pilot whales (Globicephala melas). We investigated the reproductive strategies emerging from the interplay between fitness maximization and propensity to take energetic risks, and the resulting susceptibility of individual vital rates to disturbance. Without disturbance, facultative reproductive behavior from SDLHT and fixed rules in the DEB model led to comparable individual fitness. However, under disturbance, the reproductive strategies emerging from SDLHT increased vulnerability to energetic risks, resulting in lower fitness than fixed rules. These fragile strategies might therefore be unlikely to evolve in the first place. Heterogeneous resource availability favored more cautious, and thus more robust, strategies, particularly when knowledge of resource variation was accurate. Our results demonstrate that the assumptions regarding the dynamic trade-offs underlying an individual’s decision-making can have important consequences for predicting the effects of anthropogenic stressors on wildlife populations. More forthcoming papers &raquo; <p>Enrico Pirotta, Vincent Hin, Marc Mangel, Leslie New, Daniel P. Costa, André M. de Roos, and John Harwood (Oct 2020) </p> <p><b>Risky reproductive strategies in pilot whales reduce the ability to cope with human disturbance </b></p> <p><i><a href="https://dx.doi.org/10.1086/710150">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>uman activities in the ocean are expanding at a fast pace. When disturbance from these activities causes animals to change their behavior (for example, interrupt feeding activity), the long-term consequences on populations are mediated by changes in the energy stores of individuals, which can affect their survival and, importantly, reproduction. When to reproduce, when to abandon an ongoing attempt, or how much energy to transfer to offspring are critical decisions for an animal, and the best strategy changes dynamically over the course of life. This is particularly true in long-lived organisms, like most cetaceans, where parents invest a lot of energy on their offspring. </p><p>Researchers from Washington State University, the University of Amsterdam, University of California Santa Cruz, and the University of St Andrews developed a model to investigate how such reproductive strategies affect susceptibility to disturbance from human activities, using long-finned pilot whales in the North Atlantic as the model species. Results show that, in undisturbed conditions, females maximize the number of calves, but, when disturbance affects feeding activity, their finely tuned strategy leads to dramatic effects on both survival and reproduction. In contrast, females develop more cautious strategies in unpredictable environments, which improve their ability to cope with disturbed conditions. </p><p>Because most animals live in variable environments, fragile reproductive strategies may be unlikely to evolve and persist. For example, the long-finned pilot whale population in the North Atlantic inhabits a seasonal environment, with large inter-annual variability in food resources. Therefore, pilot whales have likely evolved low propensity to risk, which would make them comparatively more able to cope with anthropogenic disturbance. More generally, this study shows how assumptions about risk propensity can drastically affect predictions of the population consequences of human disturbance. </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 initiate, interrupt or invest resources in reproduction in light of their physiology and the environment. The energetic risks entailed in an individual’s reproductive strategy can influence the ability to cope with additional stressors, such as anthropogenic climate change and disturbance. To explore the trade-offs between internal state, external resource availability and reproduction, we applied State-Dependent Life-History Theory (SDLHT) to a Dynamic Energy Budget (DEB) model for long-finned pilot whales (<i>Globicephala melas</i>). We investigated the reproductive strategies emerging from the interplay between fitness maximization and propensity to take energetic risks, and the resulting susceptibility of individual vital rates to disturbance. Without disturbance, facultative reproductive behavior from SDLHT and fixed rules in the DEB model led to comparable individual fitness. However, under disturbance, the reproductive strategies emerging from SDLHT increased vulnerability to energetic risks, resulting in lower fitness than fixed rules. These fragile strategies might therefore be unlikely to evolve in the first place. Heterogeneous resource availability favored more cautious, and thus more robust, strategies, particularly when knowledge of resource variation was accurate. Our results demonstrate that the assumptions regarding the dynamic trade-offs underlying an individual’s decision-making can have important consequences for predicting the effects of anthropogenic stressors on wildlife 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, 24 Jun 2020 05:00:00 GMT “Experimental amelioration of harsh weather speeds growth and development in a tropical montane songbird” https://amnat.org/an/newpapers/Oct-Mitchell.html Adam E. Mitchell, Jordan Boersma, Anthonio Anthony, Kanehiro Kitayama, and Thomas E. Martin (Oct 2020) Slow growth and development of a montane songbird reflects developmental plasticity in response to abiotic conditions Read the Article (Just Accepted) Animals living at high elevations often have fewer offspring per breeding attempt, slower growth and development, and higher survival rates. These patterns have been shown in mammals, reptiles and amphibians, birds, and even insects. The Mountain Blackeye (Chlorocharis emiliae), a small songbird endemic to a few of the tallest mountains in Borneo, provides a clear example of these patterns. On Mt. Kinabalu in north Borneo, Mountain Blackeyes breeding at ~3200 meters elevation lay a single egg and their nestlings take 14-15 days to fledge, whereas the closely related Black-capped White-eye (Zosterops atricapilla) breeding at ~1500 meters lays two eggs and fledges in 11-12 days. The causes of slow growth and development at high elevations remains puzzling to scientists, but collaborative research led by scientists at the University of Montana has improved our understanding of these fascinating patterns.Previous studies have suggested that prolonged development at high elevations might reflect an evolved shift to enhance offspring quality in the face of harsh montane weather conditions. However, authors of this study test an alternative hypothesis. They posit that parents need to spend more time warming young in colder and wetter mountaintop environments, reducing time available to provide young with food, thereby causing slower growth and development. To test this hypothesis, the authors conducted an experiment where they simultaneously covered Mountain Blackeye nests from rain while adding supplemental heat to nests. Compared to unmanipulated nests, parents in heated and covered nests spent less time warming young while feeding them more often. Nestlings from heated and covered nests also fledged from their nests earlier as well as grew their wings and gained body mass faster. While slower growth at high elevations may also have an evolved component, results from this study emphasize the influence harsh montane weather can have on growth and development rates through time constraints on parental care. Abstract Organisms living at high elevations generally grow and develop slower than those at lower elevations. Slow montane ontogeny is thought to be an evolved adaptation to harsh environments that improve juvenile quality via physiological tradeoffs. However, slower montane ontogeny may also reflect proximate influences of harsh weather on parental care and offspring development. We experimentally heated and protected nests from rain to ameliorate harsh montane weather conditions for Mountain Blackeyes (Chlorocharis emiliae), a montane songbird living at ca. 3200&nbsp;m&nbsp;asl in Malaysian Borneo. This experiment was designed to test if cold and wet montane conditions contribute to parental care and post-natal growth and development rates at high elevations. We found that parents increased provisioning and reduced time spent warming offspring, which grew faster and departed the nest earlier compared to unmanipulated nests. Earlier departure reduces time-dependent predation risk, benefitting parents and offspring. These plastic responses highlight the importance of proximate weather contributions to broad patterns of montane ontogeny and parental care. More forthcoming papers &raquo; <p>Adam E. Mitchell, Jordan Boersma, Anthonio Anthony, Kanehiro Kitayama, and Thomas E. Martin (Oct 2020) </p> <p><b>Slow growth and development of a montane songbird reflects developmental plasticity in response to abiotic conditions </b></p> <p><i><a href="https://dx.doi.org/10.1086/710151">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 living at high elevations often have fewer offspring per breeding attempt, slower growth and development, and higher survival rates. These patterns have been shown in mammals, reptiles and amphibians, birds, and even insects. The Mountain Blackeye (<i>Chlorocharis emiliae</i>), a small songbird endemic to a few of the tallest mountains in Borneo, provides a clear example of these patterns. On Mt. Kinabalu in north Borneo, Mountain Blackeyes breeding at ~3200 meters elevation lay a single egg and their nestlings take 14-15 days to fledge, whereas the closely related Black-capped White-eye (<i>Zosterops atricapilla</i>) breeding at ~1500 meters lays two eggs and fledges in 11-12 days. The causes of slow growth and development at high elevations remains puzzling to scientists, but collaborative research led by scientists at the University of Montana has improved our understanding of these fascinating patterns.</p><p>Previous studies have suggested that prolonged development at high elevations might reflect an evolved shift to enhance offspring quality in the face of harsh montane weather conditions. However, authors of this study test an alternative hypothesis. They posit that parents need to spend more time warming young in colder and wetter mountaintop environments, reducing time available to provide young with food, thereby causing slower growth and development. To test this hypothesis, the authors conducted an experiment where they simultaneously covered Mountain Blackeye nests from rain while adding supplemental heat to nests. Compared to unmanipulated nests, parents in heated and covered nests spent less time warming young while feeding them more often. Nestlings from heated and covered nests also fledged from their nests earlier as well as grew their wings and gained body mass faster. While slower growth at high elevations may also have an evolved component, results from this study emphasize the influence harsh montane weather can have on growth and development rates through time constraints on parental care.</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;">O</span>rganisms living at high elevations generally grow and develop slower than those at lower elevations. Slow montane ontogeny is thought to be an evolved adaptation to harsh environments that improve juvenile quality via physiological tradeoffs. However, slower montane ontogeny may also reflect proximate influences of harsh weather on parental care and offspring development. We experimentally heated and protected nests from rain to ameliorate harsh montane weather conditions for Mountain Blackeyes (<i>Chlorocharis emiliae</i>), a montane songbird living at ca. 3200&nbsp;m&nbsp;asl in Malaysian Borneo. This experiment was designed to test if cold and wet montane conditions contribute to parental care and post-natal growth and development rates at high elevations. We found that parents increased provisioning and reduced time spent warming offspring, which grew faster and departed the nest earlier compared to unmanipulated nests. Earlier departure reduces time-dependent predation risk, benefitting parents and offspring. These plastic responses highlight the importance of proximate weather contributions to broad patterns of montane ontogeny and parental care. </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, 24 Jun 2020 05:00:00 GMT “Host-plant choices determined by reproductive interference between closely related butterflies” https://amnat.org/an/newpapers/Oct-Ohsaki.html Naota Ohsaki, Masaaki Ohata, Yoshibumi Sato, and Mark D. Rausher (Oct 2020) Read the Article (Just Accepted) A&nbsp; fundamental principle of ecology states that closely related organisms that use the same resources cannot coexist, and better competitors exclude lesser competitors. However, it has been claimed that competitive exclusion in phytophagous insects is uncommon. In Hokkaido, Japan, two Pierid butterflies use different host plants. Pieris napi uses a recently introduced host, whereas P.&nbsp;melete uses an ancestral host. When the novel host species was introduced around 1960, the two Pierid species exhibited little preference between the two species. By the 1970s they were shown to specialize on different hosts. Around the year 2000, Ohsaki and Sato showed that the ancestral host species was less suitable than the novel host for larval growth and survival for both butterfly species, which raised the question of why P.&nbsp;melete had shifted to prefer the inferior host. In 2018, Ohsaki and Ohata demonstrated that courtship by P.&nbsp;napi males concentrated on P.&nbsp;melete females, whereas P.&nbsp;melete males ignored P.&nbsp;napi females in outdoor cages of Kyoto University. P.&nbsp;melete is a larger species than P.&nbsp;napi. Because larger females lay more eggs, this size difference presumably makes P.&nbsp;melete females more attractive to P.&nbsp;napi males. This study demonstrates strong, asymmetric reproductive interference between the two butterfly species, with courtship by P.&nbsp;napi males substantially reducing the number of eggs laid by P.&nbsp;melete, but not the reverse. This sexual interference appears to be responsible for sexual exclusion of P.&nbsp;melete from using the introduced host. Evidence suggest this shift in host use is an evolutionary change, but other explanations, such as direct effects of interactions on female oviposition behavior cannot be ruled out definitively. Abstract A&nbsp;number of empirical studies have concluded that reproductive interference, RI, contributes to parapatric species distributions or sexual exclusion. However, the possibility that divergent host-plant use in phytophagous insects is due to sexual exclusion has seldom been considered. Here we present evidence that RI is responsible for different host-plant use by two Pierid butterfly species, Pieris napi and P.&nbsp;melete. When a novel host species was introduced about 50 years ago, two Pierid butterfly species at first used both the ancestral host species and the novel one. Subsequently, P.&nbsp;napi shifted to use only the novel host, while P.&nbsp;melete shifted to specialize on the ancestral host. To explain these patterns, we investigated whether the two host species differ in suitability for larval growth and survival. Additionally, we tested whether RI occurred between the two species using large outdoor field cages. Courtship of females by conspecific and heterospecific males reduces the number of eggs laid by approximately half. However, RI is asymmetric and would generate selection on P.&nbsp;melete females to evolve to avoid the more suitable host species preferred by P.&nbsp;napi. Thus, our study suggests that sexual exclusion can explain the shift in host use by these two butterfly species. More forthcoming papers &raquo; <p>Naota Ohsaki, Masaaki Ohata, Yoshibumi Sato, and Mark D. Rausher (Oct 2020) </p> <p><i><a href="https://dx.doi.org/10.1086/710211">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; fundamental principle of ecology states that closely related organisms that use the same resources cannot coexist, and better competitors exclude lesser competitors. However, it has been claimed that competitive exclusion in phytophagous insects is uncommon. In Hokkaido, Japan, two Pierid butterflies use different host plants. <i>Pieris napi</i> uses a recently introduced host, whereas <i>P.&nbsp;melete</i> uses an ancestral host. When the novel host species was introduced around 1960, the two Pierid species exhibited little preference between the two species. By the 1970s they were shown to specialize on different hosts. Around the year 2000, Ohsaki and Sato showed that the ancestral host species was less suitable than the novel host for larval growth and survival for both butterfly species, which raised the question of why <i>P.&nbsp;melete</i> had shifted to prefer the inferior host. In 2018, Ohsaki and Ohata demonstrated that courtship by <i>P.&nbsp;napi</i> males concentrated on <i>P.&nbsp;melete</i> females, whereas <i>P.&nbsp;melete</i> males ignored <i>P.&nbsp;napi</i> females in outdoor cages of Kyoto University. <i>P.&nbsp;melete</i> is a larger species than <i>P.&nbsp;napi</i>. Because larger females lay more eggs, this size difference presumably makes <i>P.&nbsp;melete</i> females more attractive to <i>P.&nbsp;napi</i> males. This study demonstrates strong, asymmetric reproductive interference between the two butterfly species, with courtship by <i>P.&nbsp;napi</i> males substantially reducing the number of eggs laid by <i>P.&nbsp;melete</i>, but not the reverse. This sexual interference appears to be responsible for sexual exclusion of <i>P.&nbsp;melete</i> from using the introduced host. Evidence suggest this shift in host use is an evolutionary change, but other explanations, such as direct effects of interactions on female oviposition behavior cannot be ruled out definitively. </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>&nbsp;number of empirical studies have concluded that reproductive interference, RI, contributes to parapatric species distributions or sexual exclusion. However, the possibility that divergent host-plant use in phytophagous insects is due to sexual exclusion has seldom been considered. Here we present evidence that RI is responsible for different host-plant use by two Pierid butterfly species, <i>Pieris napi</i> and <i>P.&nbsp;melete</i>. When a novel host species was introduced about 50 years ago, two Pierid butterfly species at first used both the ancestral host species and the novel one. Subsequently, <i>P.&nbsp;napi</i> shifted to use only the novel host, while <i>P.&nbsp;melete</i> shifted to specialize on the ancestral host. To explain these patterns, we investigated whether the two host species differ in suitability for larval growth and survival. Additionally, we tested whether RI occurred between the two species using large outdoor field cages. Courtship of females by conspecific and heterospecific males reduces the number of eggs laid by approximately half. However, RI is asymmetric and would generate selection on <i>P.&nbsp;melete</i> females to evolve to avoid the more suitable host species preferred by <i>P.&nbsp;napi</i>. Thus, our study suggests that sexual exclusion can explain the shift in host use by these two butterfly species. </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, 24 Jun 2020 05:00:00 GMT “High preservation potential of paleogeographic range size distributions in deep time” https://amnat.org/an/newpapers/Oct-Darroch.html Simon A. F. Darroch, Michelle M. Casey, Gwen S. Antell, Amy Sweeney, and Erin E. Saupe (Oct 2020) The paleogeographic ranges of fossil species may help us identify which species to protect in a future extinction event Read the Article (Just Accepted) The geographic ranges of species are fundamental units of biogeography, combining to form present-day spatial patterns in diversity on a vast range of scales. Reconstructing the geographic ranges of species from fossils allows us to study how the ranges of species may have expanded, contracted, and shifted through time in response to a wide variety of global change events. Not only do these approaches (‘paleo-range reconstruction’) thus offer a way to examine the deep time processes that have sculpted present-day patterns in biogeography, but also – by examining to what extent past mass extinction events have preferentially selected against small- or large-ranged species – may offer us a way to predict which species may be most vulnerable in the ongoing biodiversity crisis (the ‘6th mass extinction’). Despite this, the distribution of fossils and fossil-bearing sediments changes significantly through time, and so the extent to which fossils can be used to re-create the geographic ranges of species is unknown. This study takes the present-day distributions of mammal species across the United States, and performs a suite of experiments that simulate both fossil records and the shifting distribution of fossiliferous sediments, to test whether the distribution of range sizes can be reliably preserved in fossils. The results show for the first time that the distributions of paleogeographic range sizes can be reconstructed with surprisingly high fidelity in fossils, even when the sediments that host these fossils are extremely scarce. This in turn suggests that the fossil record preserves an invaluable archive of species distributions in deep time, and that by identifying patterns of range-selectivity across past extinction events, paleontologists may be able to help predict which species are most at-risk as global ecosystems continue to deteriorate. Abstract Reconstructing geographic range sizes from fossil data is a crucial tool in paleoecology, shedding light on macroecological and macroevolutionary processes. Studies examining links between range size and extinction risk may also offer a predictive tool for identifying species most vulnerable in the ‘6th mass extinction’. However, the extent to which paleogeographic ranges can be recorded reliably in the fossil record is unknown. We perform simulation-based extinction experiments to examine: 1) the fidelity of paleogeographic range size preservation in deep time, 2) the relative performance of different methods for reconstructing range size, and 3) the reliability of detecting patterns of extinction ‘selectivity’ on range size. Our results suggest both that relative paleogeographic range size can be consistently reconstructed, and that selectivity patterns on range size can be preserved under many extinction intensities, even when sedimentary rocks are scarce. By identifying patterns of selectivity across Earth history, paleontologists can thus augment neontological work that aims to predict and prevent extinctions of living species. Lastly, we find that introducing ‘false extinctions’ in the fossil record can produce spurious range-selectivity signals; errors in the temporal ranges of species may pose a larger barrier to reconstructing range size-extinction risk signals than the spatial distribution of fossiliferous sediments. More forthcoming papers &raquo; <p>Simon A. F. Darroch, Michelle M. Casey, Gwen S. Antell, Amy Sweeney, and Erin E. Saupe (Oct 2020) </p> <p><b>The paleogeographic ranges of fossil species may help us identify which species to protect in a future extinction event </b></p> <p><i><a href="https://dx.doi.org/10.1086/710176">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>he geographic ranges of species are fundamental units of biogeography, combining to form present-day spatial patterns in diversity on a vast range of scales. Reconstructing the geographic ranges of species from fossils allows us to study how the ranges of species may have expanded, contracted, and shifted through time in response to a wide variety of global change events. Not only do these approaches (‘paleo-range reconstruction’) thus offer a way to examine the deep time processes that have sculpted present-day patterns in biogeography, but also – by examining to what extent past mass extinction events have preferentially selected against small- or large-ranged species – may offer us a way to predict which species may be most vulnerable in the ongoing biodiversity crisis (the ‘6th mass extinction’). Despite this, the distribution of fossils and fossil-bearing sediments changes significantly through time, and so the extent to which fossils can be used to re-create the geographic ranges of species is unknown. This study takes the present-day distributions of mammal species across the United States, and performs a suite of experiments that simulate both fossil records and the shifting distribution of fossiliferous sediments, to test whether the distribution of range sizes can be reliably preserved in fossils. The results show for the first time that the distributions of paleogeographic range sizes can be reconstructed with surprisingly high fidelity in fossils, even when the sediments that host these fossils are extremely scarce. This in turn suggests that the fossil record preserves an invaluable archive of species distributions in deep time, and that by identifying patterns of range-selectivity across past extinction events, paleontologists may be able to help predict which species are most at-risk as global ecosystems continue to deteriorate. </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;">R</span>econstructing geographic range sizes from fossil data is a crucial tool in paleoecology, shedding light on macroecological and macroevolutionary processes. Studies examining links between range size and extinction risk may also offer a predictive tool for identifying species most vulnerable in the ‘6th mass extinction’. However, the extent to which paleogeographic ranges can be recorded reliably in the fossil record is unknown. We perform simulation-based extinction experiments to examine: 1) the fidelity of paleogeographic range size preservation in deep time, 2) the relative performance of different methods for reconstructing range size, and 3) the reliability of detecting patterns of extinction ‘selectivity’ on range size. Our results suggest both that relative paleogeographic range size can be consistently reconstructed, and that selectivity patterns on range size can be preserved under many extinction intensities, even when sedimentary rocks are scarce. By identifying patterns of selectivity across Earth history, paleontologists can thus augment neontological work that aims to predict and prevent extinctions of living species. Lastly, we find that introducing ‘false extinctions’ in the fossil record can produce spurious range-selectivity signals; errors in the temporal ranges of species may pose a larger barrier to reconstructing range size-extinction risk signals than the spatial distribution of fossiliferous sediments. </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, 24 Jun 2020 05:00:00 GMT “Mating preference for novel phenotypes can be explained by general neophilia in female guppies” https://amnat.org/an/newpapers/Oct-Daniel.html Mitchel J. Daniel, Laura Koffinas, and Kimberly A. Hughes (Oct 2020) Mating preference for novel phenotypes can be explained by general neophilia in female guppies Read the Article (Just Accepted) Why is it good to be different? In many species, individuals prefer mates that have novel or unusual features, such as unusual coloration. This preference has important evolutionary implications; if individuals with novel or unusual features have a mating advantage, this can prevent the loss of rare traits, thereby maintaining genetic diversity. However, the reason for this attraction to novelty is unclear. A new study by Mitchel Daniel, Laura Koffinas, and Kimberly Hughes at Florida State University shows that for female Trinidadian guppies, preference for mates with unusual color patterns is linked to preference for novelty in other parts of their lives. The authors put female guppies through an Olympiad of behavioral tests to determine whether they preferred novel features over familiar ones in a variety of different contexts. They find that, on average, female guppies prefer to mate with males that have novel color patterns over males that have familiar color patterns, prefer to eat novel foods over familiar foods, and prefer to explore novel environments over spending time in familiar locations. (Females show the reverse preference, however, when it comes to associating with other females, preferring familiar females to unfamiliar ones). The researchers also find evidence of consistent behavioral differences: the females who most prefer mates with unusual color patterns are also the ones who most prefer novel foods, environments, and even females. Females that prefer novel foods and environments may have an evolutionary advantage because they are more likely to discover new resources, habitats. If natural selection favored novelty-seeking behavioral type for these reasons, preference for mates with unusual traits might have become more common as an evolutionary side-effect. In this way, preference for mates with unusual color patterns could be a by-product of natural selection favoring novelty-seeking for reasons unrelated to mating. Abstract Understanding how genetic variation is maintained in ecologically-important traits is a fundamental question in evolutionary biology. Male Trinidadian guppies (Poecilia reticulata) exhibit extreme genetic diversity in color patterns within populations, which is believed to be promoted by a female mating preference for rare or novel patterns. However, the origins of this preference remain unclear. Here, we test the hypothesis that mating preference for novel phenotypes is a by-product of general neophilia that evolved in response to selection in non-mating contexts. We measured among-female variation in preference for eight different, novel stimuli that spanned four ecological contexts: mate choice, exploration, foraging, and social (but non-sexual) interactions. Females exhibited preference for novelty in 6 out of 8 tests. Individual variation in preference for novelty was positively correlated among all 8 types of stimuli. Furthermore, factor analysis revealed a single axis of general neophilia that accounts for 61% of individual variation in preference for novel color patterns. The single-factor structure of neophilia suggests that interest in novelty is governed primarily by shared processes that transcend context. Because neophilia likely has a sizable heritable component, our results provide evidence that mating preference for novel phenotypes may be a non-adaptive by-product of natural selection on neophilia. More forthcoming papers &raquo; <p>Mitchel J. Daniel, Laura Koffinas, and Kimberly A. Hughes (Oct 2020) </p> <p><b>Mating preference for novel phenotypes can be explained by general neophilia in female guppies </b></p> <p><i><a href="https://dx.doi.org/10.1086/710177">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 is it good to be different? In many species, individuals prefer mates that have novel or unusual features, such as unusual coloration. This preference has important evolutionary implications; if individuals with novel or unusual features have a mating advantage, this can prevent the loss of rare traits, thereby maintaining genetic diversity. However, the reason for this attraction to novelty is unclear. </p><p>A new study by Mitchel Daniel, Laura Koffinas, and Kimberly Hughes at Florida State University shows that for female Trinidadian guppies, preference for mates with unusual color patterns is linked to preference for novelty in other parts of their lives. The authors put female guppies through an Olympiad of behavioral tests to determine whether they preferred novel features over familiar ones in a variety of different contexts. They find that, on average, female guppies prefer to mate with males that have novel color patterns over males that have familiar color patterns, prefer to eat novel foods over familiar foods, and prefer to explore novel environments over spending time in familiar locations. (Females show the reverse preference, however, when it comes to associating with other females, preferring familiar females to unfamiliar ones). The researchers also find evidence of consistent behavioral differences: the females who most prefer mates with unusual color patterns are also the ones who most prefer novel foods, environments, and even females. </p><p>Females that prefer novel foods and environments may have an evolutionary advantage because they are more likely to discover new resources, habitats. If natural selection favored novelty-seeking behavioral type for these reasons, preference for mates with unusual traits might have become more common as an evolutionary side-effect. In this way, preference for mates with unusual color patterns could be a by-product of natural selection favoring novelty-seeking for reasons unrelated to mating. </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 genetic variation is maintained in ecologically-important traits is a fundamental question in evolutionary biology. Male Trinidadian guppies (<i>Poecilia reticulata</i>) exhibit extreme genetic diversity in color patterns within populations, which is believed to be promoted by a female mating preference for rare or novel patterns. However, the origins of this preference remain unclear. Here, we test the hypothesis that mating preference for novel phenotypes is a by-product of general neophilia that evolved in response to selection in non-mating contexts. We measured among-female variation in preference for eight different, novel stimuli that spanned four ecological contexts: mate choice, exploration, foraging, and social (but non-sexual) interactions. Females exhibited preference for novelty in 6 out of 8 tests. Individual variation in preference for novelty was positively correlated among all 8 types of stimuli. Furthermore, factor analysis revealed a single axis of general neophilia that accounts for 61% of individual variation in preference for novel color patterns. The single-factor structure of neophilia suggests that interest in novelty is governed primarily by shared processes that transcend context. Because neophilia likely has a sizable heritable component, our results provide evidence that mating preference for novel phenotypes may be a non-adaptive by-product of natural selection on neophilia. </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, 24 Jun 2020 05:00:00 GMT “Multiple environmental stressors induce an adaptive maternal effect” https://amnat.org/an/newpapers/Oct-Potticary-A.html Ahva L. Potticary and Renée A. Duckworth (Oct 2020) Multiple stressors in the maternal environment produce adaptive variation in offspring dispersal and aggression Read the Article (Just Accepted) Abstract Evolution of adaptation requires predictability and recurrence of functional contexts. Yet, organisms live in multi-faceted environments that are dynamic and ever-changing, making it difficult to understand how complex adaptations evolve. This problem is particularly apparent in the evolution of adaptive maternal effects, which are often assumed to require reliable and discrete cues that predict conditions in the offspring environment. One resolution to this problem is if adaptive maternal effects evolve through pre-existing, generalized maternal pathways that respond to many cues and also influence offspring development. Here, we assess whether an adaptive maternal effect in western bluebirds is influenced by maternal stress pathways across multiple challenging environments. Combining seventeen years of hormone sampling across diverse environmental contexts with an experimental manipulation of the competitive environment, we show that multiple environmental factors influenced maternal corticosterone levels which, in turn, influenced the maternal effect on aggression of sons in adulthood. Together, these results support the idea that multiple stressors can induce a known maternal effect in this system. More generally, it suggests that activation of general pathways, such as the HPA axis, may simplify and facilitate the evolution of adaptive maternal effects by integrating variable environmental conditions into pre-existing maternal physiological systems. More forthcoming papers &raquo; <p>Ahva L. Potticary and Renée A. Duckworth (Oct 2020) </p> <p><b>Multiple stressors in the maternal environment produce adaptive variation in offspring dispersal and aggression </b></p> <p><i><a href="https://dx.doi.org/10.1086/710210">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>volution of adaptation requires predictability and recurrence of functional contexts. Yet, organisms live in multi-faceted environments that are dynamic and ever-changing, making it difficult to understand how complex adaptations evolve. This problem is particularly apparent in the evolution of adaptive maternal effects, which are often assumed to require reliable and discrete cues that predict conditions in the offspring environment. One resolution to this problem is if adaptive maternal effects evolve through pre-existing, generalized maternal pathways that respond to many cues and also influence offspring development. Here, we assess whether an adaptive maternal effect in western bluebirds is influenced by maternal stress pathways across multiple challenging environments. Combining seventeen years of hormone sampling across diverse environmental contexts with an experimental manipulation of the competitive environment, we show that multiple environmental factors influenced maternal corticosterone levels which, in turn, influenced the maternal effect on aggression of sons in adulthood. Together, these results support the idea that multiple stressors can induce a known maternal effect in this system. More generally, it suggests that activation of general pathways, such as the HPA axis, may simplify and facilitate the evolution of adaptive maternal effects by integrating variable environmental conditions into pre-existing maternal physiological systems. </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, 24 Jun 2020 05:00:00 GMT ASN Statement Condemning Anti-Black Racism https://amnat.org/announcements/BLM.html The American Society of Naturalists strongly condemns any form of racism, harassment, or discrimination, and wishes to acknowledge the toll that societal and institutional racism has taken on our members of color. The recent killings of George Floyd in Minneapolis MN, Breonna Taylor in Louisville KY, and Ahmaud Arbery near Brunswick GA, highlight police brutality and racial profiling by members of the public, and serves to remind us why the phrase Black Lives Matter is both painfully relevant and important. We stand in solidarity with those engaging in peaceful protests of systemic racism, oppression, and brutality. As a society, we must do better to make sure all naturalists feel welcome, included, and appreciated — including Black Naturalists. At this time we must stay attuned to the pain and suffering that Black and Brown members of the community are feeling in the aftermath of these horrific murders. We must acknowledge the devastating effects that systemic racism, oppression, and violence have on the safety, security, and health of communities of color. We must do a better job of not simply confronting racism within our daily lives, but actively living as anti-racists. It is also our responsibility to constantly push ourselves, our institutions, and societies to enact anti-racist policies, because the status quo devalues Black lives. We cannot be silent. This work is hard, and requires changes in our institutions and society. It is essential that the burden of this work not fall primarily on early career naturalists and naturalists of color. Those of us who hold privilege must work to enact change. We at the American Society of Naturalists are dedicated to this change, and commit to the sustained effort it requires. We also want to hear from you. What can we as a Society do to reduce racism and its impacts? Please share your ideas and/or let us know if you want to be involved HERE. The ASN Diversity Committee can also be reached via email. Below are suggestions for specific actions that members can take, and resources for people who wish to learn more. Some actions and resources: What is privilege and how can it be used responsibly?, a comic by Robot Hugs Color of Change, the nation’s largest online racial justice organization Anti-racism resources for white people, a collection of resources compiled by Sarah Sophie Flicker and Alyssa Klein So You Want to Talk About Race, a YouTube talk by Ijeoma Oluo How to Be an Antiracist, a book by Ibram X. Kendi How Faculty Hiring Committees Reproduce Whiteness and Practical Suggestions for How They Can Change, an article by &Ouml;zlem Sensoy and Robin DiAngelo Homework for Those Seeking to Be Allies, a post by Sarah Ballard https://www.nytimes.com/2020/06/04/opinion/george-floyd-anti-blackness.html&nbsp; Why a statement on general racism isn&#39;t enough to address Anti-Blackism Dr. Susan Kalisz, President ASN, on behalf of the Executive Council and the Diversity Committee of the American Society of Naturalists &nbsp; <p>The American Society of Naturalists strongly condemns any form of racism, harassment, or discrimination, and wishes to acknowledge the toll that societal and institutional racism has taken on our members of color. The recent killings of George Floyd in Minneapolis MN, Breonna Taylor in Louisville KY, and Ahmaud Arbery near Brunswick GA, highlight police brutality and racial profiling by members of the public, and serves to remind us why the phrase Black Lives Matter is both painfully relevant and important. We stand in solidarity with those engaging in peaceful protests of systemic racism, oppression, and brutality. As a society, we must do better to make sure all naturalists feel welcome, included, and appreciated &mdash; including Black Naturalists.</p> <p>At this time we must stay attuned to the pain and suffering that Black and Brown members of the community are feeling in the aftermath of these horrific murders. We must acknowledge the devastating effects that systemic racism, oppression, and violence have on the safety, security, and health of communities of color. We must do a better job of not simply confronting racism within our daily lives, but actively living as anti-racists. It is also our responsibility to constantly push ourselves, our institutions, and societies to enact anti-racist policies, because the status quo devalues Black lives. We cannot be silent.</p> <p>This work is hard, and requires changes in our institutions and society. It is essential that the burden of this work not fall primarily on early career naturalists and naturalists of color. Those of us who hold privilege must work to enact change. We at the American Society of Naturalists are dedicated to this change, and commit to the sustained effort it requires.</p> <p>We also want to hear from you. What can we as a Society do to reduce racism and its impacts? Please share your ideas and/or let us know if you want to be involved <a href="https://docs.google.com/forms/d/e/1FAIpQLSfSdR19OOlkoEbJhijXI3VRpdQbmg8Hci6wKiKH6G_loVzLQg/viewform?usp=sf_link">HERE</a>. The ASN Diversity Committee can also be reached via <a href="mailto:asndiversity@gmail.com">email.</a></p> <p>Below are suggestions for specific actions that members can take, and resources for people who wish to learn more.</p> <p><strong>Some actions and resources:</strong></p> <ul> <li><a href="http://www.robot-hugs.com/privilege-clean-2/">What is privilege and how can it be used responsibly?</a>, a comic by Robot Hugs</li> <li><a href="https://colorofchange.org/">Color of Change</a>, the nation&rsquo;s largest online racial justice organization</li> <li><a href="https://docs.google.com/document/u/2/d/1BRlF2_zhNe86SGgHa6-VlBO-QgirITwCTugSfKie5Fs/mobilebasic?urp=gmail_link">Anti-racism resources for white people,</a> a collection of resources compiled by Sarah Sophie Flicker and Alyssa Klein</li> <li><a href="https://www.youtube.com/watch?time_continue=2&amp;v=TnybJZRWipg&amp;feature=emb_logo">So You Want to Talk About Race,</a> a YouTube talk by Ijeoma Oluo</li> <li><a href="https://www.penguinrandomhouse.com/books/564299/how-to-be-an-antiracist-by-ibram-x-kendi/">How to Be an Antiracist,</a> a book by Ibram X. Kendi</li> <li><a href="https://hepgjournals.org/doi/10.17763/1943-5045-87.4.557">How Faculty Hiring Committees Reproduce Whiteness and Practical Suggestions for How They Can Change,</a> an article by &Ouml;zlem Sensoy and Robin DiAngelo</li> <li><a href="http://mahalonottrash.blogspot.com/2015/05/homework-for-those-seeking-to-be-allies.html?m=1">Homework for Those Seeking to Be Allies</a>, a post by Sarah Ballard</li> <li><a href="https://www.nytimes.com/2020/06/04/opinion/george-floyd-anti-blackness.html">https://www.nytimes.com/2020/06/04/opinion/george-floyd-anti-blackness.html</a>&nbsp; Why a statement on general racism isn&#39;t enough to address Anti-Blackism</li> </ul> <p>Dr. Susan Kalisz, President ASN, on behalf of<br /> the <a href="https://www.amnat.org/about/governance/execcomm.html">Executive Council</a> and the <a href="https://www.amnat.org/about/governance/committees.html">Diversity Committee</a><br /> of the American Society of Naturalists</p> <p>&nbsp;</p> Tue, 02 Jun 2020 05:00:00 GMT “The origin and spread of locally adaptive seasonal camouflage in snowshoe hares” https://amnat.org/an/newpapers/Sep-Jones-A.html Matthew R. Jones, L. Scott Mills, Jeffrey D. Jensen, and Jeffrey M. Good (Sep 2020) Hybridization, selection, and genetic dominance interact to shape range edge adaptation in snowshoe hares Read the Article (Just Accepted) Abstract Adaptation is central to population persistence in the face of environmental change, yet we seldom precisely understand the origin and spread of adaptive variation in natural populations. Snowshoe hares (Lepus americanus) along the Pacific Northwest (PNW) coast have evolved brown winter camouflage through positive selection on recessive variation at the Agouti pigmentation gene introgressed from black-tailed jackrabbits (L.&nbsp;californicus). Here we combine new and published whole genome and exome sequences with targeted genotyping of Agouti in order to investigate the evolutionary history of local seasonal camouflage adaptation in the PNW. We find evidence of significantly elevated inbreeding and mutational load in coastal winter-brown hares, consistent with a recent range expansion into temperate coastal environments that incurred indirect fitness costs. The genome-wide distribution of introgression tract lengths supports a pulse of hybridization near the end of the last glacial maximum, which may have facilitated range expansion via introgression of winter-brown camouflage variation. However, signatures of a selective sweep at Agouti indicate a much more recent spread of winter-brown camouflage. Through simulations we show that the delay between the hybrid origin and subsequent selective sweep of the recessive winter-brown allele can be largely attributed to the limits of natural selection imposed by simple allelic dominance. We argue that while hybridization during periods of environmental change may provide a critical reservoir of adaptive variation at range edges, the probability and pace of local adaptation will strongly depend on population demography and the genetic architecture of introgressed variation. More forthcoming papers &raquo; <p>Matthew R. Jones, L. Scott Mills, Jeffrey D. Jensen, and Jeffrey M. Good (Sep 2020) </p> <p><b>Hybridization, selection, and genetic dominance interact to shape range edge adaptation in snowshoe hares </b></p> <p><i><a href="https://dx.doi.org/10.1086/710022">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;">A</span>daptation is central to population persistence in the face of environmental change, yet we seldom precisely understand the origin and spread of adaptive variation in natural populations. Snowshoe hares (<i>Lepus americanus</i>) along the Pacific Northwest (PNW) coast have evolved brown winter camouflage through positive selection on recessive variation at the<i> Agouti</i> pigmentation gene introgressed from black-tailed jackrabbits (<i>L.&nbsp;californicus</i>). Here we combine new and published whole genome and exome sequences with targeted genotyping of <i>Agouti</i> in order to investigate the evolutionary history of local seasonal camouflage adaptation in the PNW. We find evidence of significantly elevated inbreeding and mutational load in coastal winter-brown hares, consistent with a recent range expansion into temperate coastal environments that incurred indirect fitness costs. The genome-wide distribution of introgression tract lengths supports a pulse of hybridization near the end of the last glacial maximum, which may have facilitated range expansion via introgression of winter-brown camouflage variation. However, signatures of a selective sweep at <i>Agouti</i> indicate a much more recent spread of winter-brown camouflage. Through simulations we show that the delay between the hybrid origin and subsequent selective sweep of the recessive winter-brown allele can be largely attributed to the limits of natural selection imposed by simple allelic dominance. We argue that while hybridization during periods of environmental change may provide a critical reservoir of adaptive variation at range edges, the probability and pace of local adaptation will strongly depend on population demography and the genetic architecture of introgressed variation. </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, 29 May 2020 05:00:00 GMT “Consumer responses to experimental pulsed subsidies in isolated vs. connected habitats” https://amnat.org/an/newpapers/Sep-Wright-A.html Amber N. Wright, Louie H. Yang, Jonah Piovia-Scott, David A. Spiller, and Thomas W. Schoener (Sep 2020) Pulsed subsidies may facilitate establishment Read the Article (Just Accepted) Abstract Increases in consumer abundance following a resource pulse can be driven by diet shifts, aggregation, and reproductive responses, with combined responses expected to result in faster response times and larger numerical increases. Previous work in plots on large Bahamian islands has shown that lizards (Anolis sagrei) increased in abundance following pulses of seaweed deposition, which provide additional prey (i.e., seaweed detritivores). Numerical responses were associated with rapid diet shifts and aggregation, followed by increased reproduction. These dynamics are likely different on isolated small islands where lizards cannot readily immigrate or emigrate. To test this, we manipulated the frequency and magnitude of seaweed resource pulses on whole small islands and in plots within large islands, and monitored lizard diet and numerical responses over four years. We found that seaweed addition caused persistent increases in lizard abundance on small islands regardless of pulse frequency or magnitude. Increased abundance may have occurred because the initial pulse facilitated population establishment, possibly via enhanced overwinter survival. In contrast with a previous experiment, we did not detect numerical responses in plots on large islands, despite lizards consuming more marine resources in subsidized plots. This lack of a numerical response may be due to rapid aggregation followed by disaggregation, or stronger suppression of A.&nbsp;sagrei by their predators on large islands in this study. Our results highlight the importance of habitat connectivity in governing ecological responses to resource pulses and suggest that disaggregation and changes in survivorship may be underappreciated drivers of pulse-associated dynamics. More forthcoming papers &raquo; <p>Amber N. Wright, Louie H. Yang, Jonah Piovia-Scott, David A. Spiller, and Thomas W. Schoener (Sep 2020) </p> <p><b>Pulsed subsidies may facilitate establishment </b></p> <p><i><a href="https://dx.doi.org/10.1086/710040">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>ncreases in consumer abundance following a resource pulse can be driven by diet shifts, aggregation, and reproductive responses, with combined responses expected to result in faster response times and larger numerical increases. Previous work in plots on large Bahamian islands has shown that lizards (<i>Anolis sagrei</i>) increased in abundance following pulses of seaweed deposition, which provide additional prey (i.e., seaweed detritivores). Numerical responses were associated with rapid diet shifts and aggregation, followed by increased reproduction. These dynamics are likely different on isolated small islands where lizards cannot readily immigrate or emigrate. To test this, we manipulated the frequency and magnitude of seaweed resource pulses on whole small islands and in plots within large islands, and monitored lizard diet and numerical responses over four years. We found that seaweed addition caused persistent increases in lizard abundance on small islands regardless of pulse frequency or magnitude. Increased abundance may have occurred because the initial pulse facilitated population establishment, possibly via enhanced overwinter survival. In contrast with a previous experiment, we did not detect numerical responses in plots on large islands, despite lizards consuming more marine resources in subsidized plots. This lack of a numerical response may be due to rapid aggregation followed by disaggregation, or stronger suppression of <i>A.&nbsp;sagrei</i> by their predators on large islands in this study. Our results highlight the importance of habitat connectivity in governing ecological responses to resource pulses and suggest that disaggregation and changes in survivorship may be underappreciated drivers of pulse-associated 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> Fri, 29 May 2020 05:00:00 GMT “Deconstructing the impact of malaria vector diversity on disease risk” https://amnat.org/an/newpapers/Sep-Hoi.html Amber Gigi Hoi, Benjamin Gilbert, and Nicole Mideo (Sep 2020) Mosquitoes are not flying syringes—researchers at UofT dissects how mosquito diversity amplify malaria risk Read the Article (Just Accepted) A &nbsp;growing body of research explores how the structure of diverse host communities mediates the spread of infectious diseases; however, much less is known about the influence of vector communities despite their being major targets for disease control. In a new paper published in The&nbsp;American Naturalist, researchers at the University of Toronto, Amber Gigi Hoi, Benjamin Gilbert, and Nicole Mideo, present the first empirical evidence of mosquito diversity amplifying malaria prevalence. The parasites that cause malaria, one of the world’s deadliest vector-borne diseases, can be transmitted by more than 70 species of mosquitoes. Comparing mosquito communities around the globe, the precise number of species, and their relative abundances, vary considerably. These mosquito species also encompass substantial diversity in seasonal activity, habitat, and feeding preferences. Mosquitoes are not simply flying syringes (although it is sometimes convenient to think of them this way), and so nuances of their ecology and the structure of vector communities will influence disease risk. Amber and coauthors use publicly available mosquito and malaria survey data to tease apart the direct and indirect influences of total mosquito abundance, the number of species present, and the relative abundance of those species on malaria risk. They find that increasing the number of mosquito species directly increases malaria prevalence, though this effect is weakened slightly by more diverse mosquito communities harboring a lower relative abundance of the most ‘competent’ vector species. Total mosquito abundance is only indirectly associated with malaria prevalence through its relationship with these other measures of diversity. The researchers speculate that this is a consequence of species being active at different times of the year, prolonging the period over which disease transmission occurs. These results are consistent with previous theoretical work that predicts diverse vector communities will promote disease spread, and the study emphasizes the importance of understanding vector community ecology for designing sound vector management strategies. Abstract Recent years have seen significant progress in understanding the impact of host community assemblage on disease risk, yet diversity in disease vectors has rarely been investigated. Using published malaria and mosquito surveys from Kenya, we analyzed the relationship between malaria prevalence and multiple axes of mosquito diversity: abundance, species richness, and composition. We found a net amplification of malaria prevalence by vector species richness, a result of a strong direct positive association between richness and prevalence alongside a weak indirect negative association between the two, mediated through mosquito community composition. One plausible explanation of these patterns is species niche complementarity, whereby less competent vector species contribute to disease transmission by filling spatial or temporal gaps in transmission left by dominant vectors. A greater understanding of vector community assemblage and function, as well as any interactions between host and vector biodiversity, could offer insights to both fundamental and applied ecology. More forthcoming papers &raquo; <p>Amber Gigi Hoi, Benjamin Gilbert, and Nicole Mideo (Sep 2020) </p> <p><b>Mosquitoes are <i>not</i> flying syringes&mdash;researchers at UofT dissects how mosquito diversity amplify malaria risk </b></p> <p><i><a href="https://dx.doi.org/10.1086/710005">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;growing body of research explores how the structure of diverse host communities mediates the spread of infectious diseases; however, much less is known about the influence of vector communities despite their being major targets for disease control. In a new paper published in <i>The&nbsp;American Naturalist</i>, researchers at the University of Toronto, Amber Gigi Hoi, Benjamin Gilbert, and Nicole Mideo, present the first empirical evidence of mosquito diversity amplifying malaria prevalence. The parasites that cause malaria, one of the world’s deadliest vector-borne diseases, can be transmitted by more than 70 species of mosquitoes. Comparing mosquito communities around the globe, the precise number of species, and their relative abundances, vary considerably. These mosquito species also encompass substantial diversity in seasonal activity, habitat, and feeding preferences. Mosquitoes are not simply flying syringes (although it is sometimes convenient to think of them this way), and so nuances of their ecology and the structure of vector communities will influence disease risk. </p><p>Amber and coauthors use publicly available mosquito and malaria survey data to tease apart the direct and indirect influences of total mosquito abundance, the number of species present, and the relative abundance of those species on malaria risk. They find that increasing the number of mosquito species directly increases malaria prevalence, though this effect is weakened slightly by more diverse mosquito communities harboring a lower relative abundance of the most ‘competent’ vector species. Total mosquito abundance is only indirectly associated with malaria prevalence through its relationship with these other measures of diversity. The researchers speculate that this is a consequence of species being active at different times of the year, prolonging the period over which disease transmission occurs. These results are consistent with previous theoretical work that predicts diverse vector communities will promote disease spread, and the study emphasizes the importance of understanding vector community ecology for designing sound vector management strategies. </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;">R</span>ecent years have seen significant progress in understanding the impact of host community assemblage on disease risk, yet diversity in disease vectors has rarely been investigated. Using published malaria and mosquito surveys from Kenya, we analyzed the relationship between malaria prevalence and multiple axes of mosquito diversity: abundance, species richness, and composition. We found a net amplification of malaria prevalence by vector species richness, a result of a strong direct positive association between richness and prevalence alongside a weak indirect negative association between the two, mediated through mosquito community composition. One plausible explanation of these patterns is species niche complementarity, whereby less competent vector species contribute to disease transmission by filling spatial or temporal gaps in transmission left by dominant vectors. A greater understanding of vector community assemblage and function, as well as any interactions between host and vector biodiversity, could offer insights to both fundamental and applied ecology. </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, 29 May 2020 05:00:00 GMT “The Minimum Environmental Perturbation Principle: A New Perspective on Niche Theory” https://amnat.org/an/newpapers/Sep-Marsland-A.html Robert Marsland III, Wenping Cui, and Pankaj Mehta (Sep 2020) A new generalization of MacArthur&#39;s Minimization Principle produces an interpretable community-level objective function Read the Article (Just Accepted) Abstract Fifty years ago, Robert MacArthur showed that stable equilibria optimize quadratic functions of the population sizes in several important ecological models. Here, we generalize this finding to a broader class of systems within the framework of contemporary niche theory, and precisely state the conditions under which an optimization principle (not necessarily quadratic) can be obtained. We show that conducting the optimization in the space of environmental states instead of population sizes leads to a universal and transparent physical interpretation of the objective function. Specifically, the equilibrium state minimizes the perturbation of the environment induced by the presence of the competing species, subject to the constraint that no species has a positive net growth rate. We use this “minimum environmental perturbation principle” to make new predictions for evolution and community assembly, where the minimum perturbation increases monotonically under invasion by new species. We also describe a simple experimental setting where the conditions of validity for this optimization principle have been empirically tested. More forthcoming papers &raquo; <p>Robert Marsland III, Wenping Cui, and Pankaj Mehta (Sep 2020)</p> <p><b>A new generalization of MacArthur&#39;s Minimization Principle produces an interpretable community-level objective function </b></p> <p><i><a href="https://dx.doi.org/10.1086/710093">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;">F</span>ifty years ago, Robert MacArthur showed that stable equilibria optimize quadratic functions of the population sizes in several important ecological models. Here, we generalize this finding to a broader class of systems within the framework of contemporary niche theory, and precisely state the conditions under which an optimization principle (not necessarily quadratic) can be obtained. We show that conducting the optimization in the space of environmental states instead of population sizes leads to a universal and transparent physical interpretation of the objective function. Specifically, the equilibrium state minimizes the perturbation of the environment induced by the presence of the competing species, subject to the constraint that no species has a positive net growth rate. We use this &ldquo;minimum environmental perturbation principle&rdquo; to make new predictions for evolution and community assembly, where the minimum perturbation increases monotonically under invasion by new species. We also describe a simple experimental setting where the conditions of validity for this optimization principle have been empirically tested.</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, 29 May 2020 05:00:00 GMT “Defensive symbiosis and the evolution of virulence” https://amnat.org/an/newpapers/Sep-Nelson-A.html Paul Nelson and Georgiana May (Sep 2020) Symbiont defense of the host can protect against pathogens, but it may sometimes lead to the loss of mutualism Read the Article (Just Accepted) Abstract A&nbsp;microbiome rife with enemies of the host should cause selection for defensive traits in symbionts yet such complex environments are also predicted to select for greater symbiont virulence. Why then do we so often observe defensive mutualists that protect hosts while causing little to no damage? To address this question, we build a symbiont-centered model that incorporates the evolution of two independent symbiont traits: defense and virulence. Virulence is modeled as a continuous trait spanning parasitism (positive virulence) and mutualism (negative virulence), thus accounting for the entire range of direct effects that symbionts have on host mortality. Defense is modeled as a continuous trait that ameliorates the costs to the host associated with infection by a deleterious parasite. We show that the evolution of increased defense in one symbiont may lead to the evolution of lower virulence in both symbionts and even facilitate pathogens evolving to mutualism. However, results are context-dependent, and when defensive traits are costly, the evolution of greater defense may also lead to the evolution of greater virulence, breaking the common expectation that defensive symbionts are necessarily mutualists towards the host. More forthcoming papers &raquo; <p>Paul Nelson and Georgiana May (Sep 2020) </p> <p><b>Symbiont defense of the host can protect against pathogens, but it may sometimes lead to the loss of mutualism </b></p> <p><i><a href="https://dx.doi.org/10.1086/709962">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;">A</span>&nbsp;microbiome rife with enemies of the host should cause selection for defensive traits in symbionts yet such complex environments are also predicted to select for greater symbiont virulence. Why then do we so often observe defensive mutualists that protect hosts while causing little to no damage? To address this question, we build a symbiont-centered model that incorporates the evolution of two independent symbiont traits: defense and virulence. Virulence is modeled as a continuous trait spanning parasitism (positive virulence) and mutualism (negative virulence), thus accounting for the entire range of direct effects that symbionts have on host mortality. Defense is modeled as a continuous trait that ameliorates the costs to the host associated with infection by a deleterious parasite. We show that the evolution of increased defense in one symbiont may lead to the evolution of lower virulence in both symbionts and even facilitate pathogens evolving to mutualism. However, results are context-dependent, and when defensive traits are costly, the evolution of greater defense may also lead to the evolution of greater virulence, breaking the common expectation that defensive symbionts are necessarily mutualists towards the host. </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, 29 May 2020 05:00:00 GMT “Male-male competition causes parasite-mediated sexual selection for local adaptation” https://amnat.org/an/newpapers/Sep-Gomez-Llano.html Miguel Gómez-Llano, Aaditya Narasimhan, and Erik Svensson (Sep 2020) Read the Article (Just Accepted) Parasites can affect species in a myriad of ways, one of these is by reducing their reproductive success. In this study, the authors found that male mating success was reduced when they were infected with parasites, but interestingly female fecundity was not. Further experiments showed that males with parasites were less able to compete with healthy males for access to females. Because mating success of infected males was reduced, local adaptation to become more resistant to parasites evolved, as shown by a long-term monitoring program. While working in a system of ponds in Southern Sweden, the authors of this study noticed that in a population of the common blue tail damselfly (Ischnura elegans), particularly heavily infested with parasite mites, males with parasites were usually found as singles while males with no parasites were, seemingly, more likely to be found mating. With this idea in mind, the authors design a series of experiments to test if this idea. They not only show that this was true and parasitized males were less likely to reproduce, they also show that the main mechanism behind this was competition between males. Because parasites reduce male condition, infected males are less likely to succeed when competing with other males for access to females. This area of Sweden has been thoroughly studied and a database of the population exists from the last 15 years. This data allowed the authors to test if parasite resistance (individuals are less likely to be infected) and tolerance (individuals get less affected by parasites) has evolve as a response to the reduced reproductive success of parasitized males. Their results show evidence for adaptation due to a reduced reproductive success of parasitized males in a wild insect population. Abstract Sexual selection has been suggested to accelerate local adaptation and promote evolutionary rescue through several ecological and genetic mechanisms. Condition-dependent sexual selection has mainly been studied in laboratory settings while data from natural populations are lacking. One ecological factor that can cause condition-dependent sexual selection is parasitism. Here, we quantified ectoparasite load (Arrenurus water mites) in a natural population of the common bluetail damselfly (Ischnura elegans) over 15 years. We quantified the strength of sexual selection against parasite load in both sexes and experimentally investigated the mechanisms behind such selection. Then, we investigated how parasite resistance and tolerance changed over time to understand how they might influence population density. Parasites reduced mating success in both sexes, and sexual selection was stronger in males than in females. Experiments show that male-male competition is a strong force causing precopulatory sexual selection against parasite load. Although parasite resistance and male parasite tolerance increased over time, suggestive of increasing local adaptation against parasites, no signal of evolutionary rescue could be found. We suggest that condition-dependent sexual selection facilitates local adaptation against parasites and discuss its effects in evolutionary rescue. La competencia entre machos causa selecci&oacute;n sexual mediada por par&aacute;sitos, promoviendo la adaptaci&oacute;n Se ha sugerido que la selecci&oacute;n sexual puede acelerar la adaptaci&oacute;n y facilitar el rescate evolutivo a trav&eacute;s de diversos mecanismos ecol&oacute;gicos y gen&eacute;ticos. La selecci&oacute;n sexual sobre la condici&oacute;n ha sido estudiada principalmente en el laboratorio, mientras existe una escasez de datos de poblaciones silvestres. Un factor ecol&oacute;gico que puede causar selecci&oacute;n sexual sobre la condici&oacute;n es el parasitismo. En este estudio cuantificamos la carga de ectopar&aacute;sitos (&aacute;caros acu&aacute;ticos Arrenurus) en una poblaci&oacute;n silvestre de una especie de odonatos (Ischnura elegans) por 15 a&ntilde;os. Cuantificamos la fuerza de la selecci&oacute;n sexual en contra de individuos parasitados en ambos sexos e investigamos los mecanismos detr&aacute;s de dicha selecci&oacute;n. Posteriormente investigamos como la resistencia y tolerancia al par&aacute;sito ha cambiado a lo largo del tiempo y como puede influenciar la densidad poblacional. Los par&aacute;sitos redujeron el &eacute;xito reproductivo de ambos sexos, y la selecci&oacute;n sexual fue m&aacute;s fuerte en machos que en hembras. Los experimentos sugieren que la selecci&oacute;n sexual fue mediada principalmente por competencia entre machos, con poco o ning&uacute;n efecto de elecci&oacute;n de pareja. Aunque la resistencia y tolerancia al par&aacute;sito incrementaron con el tiempo, sugiriendo adaptaci&oacute;n al par&aacute;sito, no se encontraron se&ntilde;ales de rescate evolutivo. Sugerimos que la selecci&oacute;n sexual sobre la condici&oacute;n facilita la adaptaci&oacute;n al par&aacute;sito y discutimos sus efectos en el rescate evolutivo. More forthcoming papers &raquo; <p>Miguel Gómez-Llano, Aaditya Narasimhan, and Erik Svensson (Sep 2020) </p> <p><i><a href="https://dx.doi.org/10.1086/710039">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;">P</span>arasites can affect species in a myriad of ways, one of these is by reducing their reproductive success. In this study, the authors found that male mating success was reduced when they were infected with parasites, but interestingly female fecundity was not. Further experiments showed that males with parasites were less able to compete with healthy males for access to females. Because mating success of infected males was reduced, local adaptation to become more resistant to parasites evolved, as shown by a long-term monitoring program.</p> <p>While working in a system of ponds in Southern Sweden, the authors of this study noticed that in a population of the common blue tail damselfly (<i>Ischnura elegans</i>), particularly heavily infested with parasite mites, males with parasites were usually found as singles while males with no parasites were, seemingly, more likely to be found mating. With this idea in mind, the authors design a series of experiments to test if this idea. They not only show that this was true and parasitized males were less likely to reproduce, they also show that the main mechanism behind this was competition between males. Because parasites reduce male condition, infected males are less likely to succeed when competing with other males for access to females.</p> <p>This area of Sweden has been thoroughly studied and a database of the population exists from the last 15 years. This data allowed the authors to test if parasite resistance (individuals are less likely to be infected) and tolerance (individuals get less affected by parasites) has evolve as a response to the reduced reproductive success of parasitized males. Their results show evidence for adaptation due to a reduced reproductive success of parasitized males in a wild insect population.</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;">S</span>exual selection has been suggested to accelerate local adaptation and promote evolutionary rescue through several ecological and genetic mechanisms. Condition-dependent sexual selection has mainly been studied in laboratory settings while data from natural populations are lacking. One ecological factor that can cause condition-dependent sexual selection is parasitism. Here, we quantified ectoparasite load (<i>Arrenurus</i> water mites) in a natural population of the common bluetail damselfly (<i>Ischnura elegans</i>) over 15 years. We quantified the strength of sexual selection against parasite load in both sexes and experimentally investigated the mechanisms behind such selection. Then, we investigated how parasite resistance and tolerance changed over time to understand how they might influence population density. Parasites reduced mating success in both sexes, and sexual selection was stronger in males than in females. Experiments show that male-male competition is a strong force causing precopulatory sexual selection against parasite load. Although parasite resistance and male parasite tolerance increased over time, suggestive of increasing local adaptation against parasites, no signal of evolutionary rescue could be found. We suggest that condition-dependent sexual selection facilitates local adaptation against parasites and discuss its effects in evolutionary rescue.</p> <h4>La competencia entre machos causa selecci&oacute;n sexual mediada por par&aacute;sitos, promoviendo la adaptaci&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;">S</span>e ha sugerido que la selecci&oacute;n sexual puede acelerar la adaptaci&oacute;n y facilitar el rescate evolutivo a trav&eacute;s de diversos mecanismos ecol&oacute;gicos y gen&eacute;ticos. La selecci&oacute;n sexual sobre la condici&oacute;n ha sido estudiada principalmente en el laboratorio, mientras existe una escasez de datos de poblaciones silvestres. Un factor ecol&oacute;gico que puede causar selecci&oacute;n sexual sobre la condici&oacute;n es el parasitismo. En este estudio cuantificamos la carga de ectopar&aacute;sitos (&aacute;caros acu&aacute;ticos <i>Arrenurus</i>) en una poblaci&oacute;n silvestre de una especie de odonatos (<i>Ischnura elegans</i>) por 15 a&ntilde;os. Cuantificamos la fuerza de la selecci&oacute;n sexual en contra de individuos parasitados en ambos sexos e investigamos los mecanismos detr&aacute;s de dicha selecci&oacute;n. Posteriormente investigamos como la resistencia y tolerancia al par&aacute;sito ha cambiado a lo largo del tiempo y como puede influenciar la densidad poblacional. Los par&aacute;sitos redujeron el &eacute;xito reproductivo de ambos sexos, y la selecci&oacute;n sexual fue m&aacute;s fuerte en machos que en hembras. Los experimentos sugieren que la selecci&oacute;n sexual fue mediada principalmente por competencia entre machos, con poco o ning&uacute;n efecto de elecci&oacute;n de pareja. Aunque la resistencia y tolerancia al par&aacute;sito incrementaron con el tiempo, sugiriendo adaptaci&oacute;n al par&aacute;sito, no se encontraron se&ntilde;ales de rescate evolutivo. Sugerimos que la selecci&oacute;n sexual sobre la condici&oacute;n facilita la adaptaci&oacute;n al par&aacute;sito y discutimos sus efectos en el rescate evolutivo.</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, 28 May 2020 05:00:00 GMT “Phenotypic plasticity for desiccation resistance, climate change and future species distributions: will plasticity have much impact?” https://amnat.org/an/newpapers/Sep-Kellermann.html Vanessa Kellermann, Shane F. McEvey, Carla M. Sgrò, and Ary A. Hoffmann (Sep 2020) Phenotypic plasticity in desiccation resistance does not contribute much to climate change responses Read the Article (Just Accepted) Phenotypic plasticity, the ability of an organism to rapidly adjust traits, has been proposed as an important way organisms can buffer the impacts of climate change. This is because plasticity is a way of rapidly shifting traits (within a generation) in comparison to evolution (change in allele frequencies), which is likely slower. Despite the vital role plasticity could play in how species respond to climate change, our current methods for measuring the impact of climate change – distributional models that base future suitability of environments on current distributions – rarely take plasticity into account. Researchers from Monash University in Australia set out to test the relative importance of phenotypic plasticity in buffering species from climate change in Drosophila species. The researchers firstly determined how much species could increase their desiccation resistance (ability to tolerate dry environments a trait linked to climate change resilience) via plasticity. Then, using a semi-mechanistic distributional model (modeling species distributions from traits and distributional data), they examined whether the addition of plasticity could limit the impact of climate change. If plasticity is an important buffer, they expected species to retain more of their distribution under climate change than models without plasticity. While the researchers found species could shift their desiccation resistance considerably (i.e., these traits showed plasticity), adding plasticity to their models had only a small impact on the retention of species distributions under climate change. Although some of the largest shifts in plasticity were observed in tropically restricted species, reductions in the suitability of environments under climate change for this group of species were still observed. This suggests that plasticity for desiccation resistance is unlikely to buffer this vulnerable group of species from climate change. Abstract While species distribution models (SDMs) are widely used to predict the vulnerability of species to climate change, they do not explicitly indicate the extent to which plastic responses ameliorate climate change impacts. Here we use data on plastic responses of 32 species of Drosophila to desiccation stress to suggest that basal resistance rather than adult hardening is relatively more important in determining species differences in desiccation resistance and sensitivity to climate change. We go on to show, using the semi-mechanistic SDM CLIMEX, that the inclusion of plasticity has some impact on current species distributions and future vulnerability for widespread species, but has little impact on the distribution of arguably more vulnerable tropically-restricted species. More forthcoming papers &raquo; <p>Vanessa Kellermann, Shane F. McEvey, Carla M. Sgrò, and Ary A. Hoffmann (Sep 2020) </p> <p><b>Phenotypic plasticity in desiccation resistance does not contribute much to climate change responses </b></p> <p><i><a href="https://dx.doi.org/10.1086/710006">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;">P</span>henotypic plasticity, the ability of an organism to rapidly adjust traits, has been proposed as an important way organisms can buffer the impacts of climate change. This is because plasticity is a way of rapidly shifting traits (within a generation) in comparison to evolution (change in allele frequencies), which is likely slower. Despite the vital role plasticity could play in how species respond to climate change, our current methods for measuring the impact of climate change – distributional models that base future suitability of environments on current distributions – rarely take plasticity into account. Researchers from Monash University in Australia set out to test the relative importance of phenotypic plasticity in buffering species from climate change in <i>Drosophila</i> species. The researchers firstly determined how much species could increase their desiccation resistance (ability to tolerate dry environments a trait linked to climate change resilience) via plasticity. Then, using a semi-mechanistic distributional model (modeling species distributions from traits and distributional data), they examined whether the addition of plasticity could limit the impact of climate change. If plasticity is an important buffer, they expected species to retain more of their distribution under climate change than models without plasticity. While the researchers found species could shift their desiccation resistance considerably (i.e., these traits showed plasticity), adding plasticity to their models had only a small impact on the retention of species distributions under climate change. Although some of the largest shifts in plasticity were observed in tropically restricted species, reductions in the suitability of environments under climate change for this group of species were still observed. This suggests that plasticity for desiccation resistance is unlikely to buffer this vulnerable group of species from climate change. </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;">W</span>hile species distribution models (SDMs) are widely used to predict the vulnerability of species to climate change, they do not explicitly indicate the extent to which plastic responses ameliorate climate change impacts. Here we use data on plastic responses of 32 species of <i>Drosophila</i> to desiccation stress to suggest that basal resistance rather than adult hardening is relatively more important in determining species differences in desiccation resistance and sensitivity to climate change. We go on to show, using the semi-mechanistic SDM CLIMEX, that the inclusion of plasticity has some impact on current species distributions and future vulnerability for widespread species, but has little impact on the distribution of arguably more vulnerable tropically-restricted species. </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, 27 May 2020 05:00:00 GMT “Partner fidelity and asymmetric specialization in ecological networks” https://amnat.org/an/newpapers/Sep-Fortuna-A.html Miguel A. Fortuna, Arxhina Nagavci, Matthew A. Barbour, and Jordi Bascompte (Sep 2020) Asymmetric specialization leaves a pervasive signature on the biogeography of mutualistic interactions Read the Article (Just Accepted) Abstract Species are embedded in complex networks of interdependencies that may change across geographic locations. Yet, most approaches to investigate the architecture of this entangled web of life have considered exclusively local communities. In order to quantify to what extent species interactions change at a biogeographic scale, we need to shed light on how among-community variation affects the occurrence of species interactions. Here, we quantify the probability for two partners to interact wherever they co-occur (i.e., partner fidelity) by analyzing the most extensive database on species interaction networks worldwide. We found that mutualistic species show more fidelity in their interactions than antagonistic ones when there is asymmetric specialization (i.e., when specialist species interact with generalist partners). Moreover, resources (e.g., plants in plant-pollinator mutualisms or hosts in host-parasite interactions) show a higher partner fidelity in mutualistic than in antagonistic interactions, which can be explained neither by sampling effort, nor by phylogenetic constraints developed during their evolutionary histories. In spite of the general belief that mutualistic interactions among free-living species are labile, asymmetric specialization is very much conserved across large geographic areas. More forthcoming papers &raquo; <p>Miguel A. Fortuna, Arxhina Nagavci, Matthew A. Barbour, and Jordi Bascompte (Sep 2020) </p> <p><b>Asymmetric specialization leaves a pervasive signature on the biogeography of mutualistic interactions </b></p> <p><i><a href="https://dx.doi.org/10.1086/709961">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;">S</span>pecies are embedded in complex networks of interdependencies that may change across geographic locations. Yet, most approaches to investigate the architecture of this entangled web of life have considered exclusively local communities. In order to quantify to what extent species interactions change at a biogeographic scale, we need to shed light on how among-community variation affects the occurrence of species interactions. Here, we quantify the probability for two partners to interact wherever they co-occur (i.e., partner fidelity) by analyzing the most extensive database on species interaction networks worldwide. We found that mutualistic species show more fidelity in their interactions than antagonistic ones when there is asymmetric specialization (i.e., when specialist species interact with generalist partners). Moreover, resources (e.g., plants in plant-pollinator mutualisms or hosts in host-parasite interactions) show a higher partner fidelity in mutualistic than in antagonistic interactions, which can be explained neither by sampling effort, nor by phylogenetic constraints developed during their evolutionary histories. In spite of the general belief that mutualistic interactions among free-living species are labile, asymmetric specialization is very much conserved across large geographic areas. </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, 27 May 2020 05:00:00 GMT “What do ecology, evolution, and behavior have in common? The organism in the middle” https://amnat.org/an/newpapers/Aug-Ketterson.html Ellen D. Ketterson (Aug 2020) Read the Article (Just Accepted) Scientists at early stages in their careers can wonder how to go about shaping a research path. Major influences will include past experiences (undergrad research), people you know well as a graduate student (advisors, fellow lab members, faculty committee members), issues being addressed in the current literature, and chance encounters at meetings or workshops. Reading about the unfolding of careers of other biologists can be reassuring. In this account, the author looks back over nearly 50&nbsp;years of research to identify turning points in her research history. In her case, a persistent theme was the study organism and a curiosity about how mechanism and function work together. The research focused on the dark-eyed junco, a north-temperate passerine, and how its natural history could be used to address common themes in ecology, evolution, and animal behavior. The article describes research questions posed, including blind alleys, and those that proved more informative. The topics addressed include animal migrations (differential migration, site-fidelity, site recognition), hormone-mediated life history trade-offs (phenotypic engineering, hormonal pleiotropy, adaptation and constraint, phenotypic integration), and a return to migration as a contributing factor to population divergence (allochrony, heteropatry, photoperiodic thresholds, and mate choice). Unanswered questions are posed, including one of how reproductive timing will respond to environmental change and influence future species distributions. Very little of how Dr. Ketterson’s research turned out could have been foreseen, so the message to those starting out is to go bravely. Abstract Biologists who publish in The&nbsp;American Naturalist are drawn to its unifying mission of covering research in the fields of ecology, evolution, behavior, and integrative biology. Presented here is one scientist’s attempt to straddle these fields by focusing on a single organism. It is also an account of how time spent in the field stimulates a naturalist to wonder ‘why did that animal just do that?’ and how research is guided by chance and intention interacting with the scientific literature and the people one meets along the way. With respect to the science, the examples come from bird migration, hormones and their connection to phenotypic integration, sexual and natural selection, and urban ecology. They also come from research on the impact of environmental change on timing of reproduction and the potential for allochrony in migratory species to influence population divergence. More forthcoming papers &raquo; <p>Ellen D. Ketterson (Aug 2020) </p> <p><i><a href="https://dx.doi.org/10.1086/709699">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>cientists at early stages in their careers can wonder how to go about shaping a research path. Major influences will include past experiences (undergrad research), people you know well as a graduate student (advisors, fellow lab members, faculty committee members), issues being addressed in the current literature, and chance encounters at meetings or workshops. Reading about the unfolding of careers of other biologists can be reassuring. In this account, the author looks back over nearly 50&nbsp;years of research to identify turning points in her research history. In her case, a persistent theme was the study organism and a curiosity about how mechanism and function work together. The research focused on the dark-eyed junco, a north-temperate passerine, and how its natural history could be used to address common themes in ecology, evolution, and animal behavior. The article describes research questions posed, including blind alleys, and those that proved more informative. The topics addressed include animal migrations (differential migration, site-fidelity, site recognition), hormone-mediated life history trade-offs (phenotypic engineering, hormonal pleiotropy, adaptation and constraint, phenotypic integration), and a return to migration as a contributing factor to population divergence (allochrony, heteropatry, photoperiodic thresholds, and mate choice). Unanswered questions are posed, including one of how reproductive timing will respond to environmental change and influence future species distributions. Very little of how Dr. Ketterson’s research turned out could have been foreseen, so the message to those starting out is to go bravely. </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;">B</span>iologists who publish in <i>The&nbsp;American Naturalist</i> are drawn to its unifying mission of covering research in the fields of ecology, evolution, behavior, and integrative biology. Presented here is one scientist&rsquo;s attempt to straddle these fields by focusing on a single organism. It is also an account of how time spent in the field stimulates a naturalist to wonder &lsquo;why did that animal just do that?&rsquo; and how research is guided by chance and intention interacting with the scientific literature and the people one meets along the way. With respect to the science, the examples come from bird migration, hormones and their connection to phenotypic integration, sexual and natural selection, and urban ecology. They also come from research on the impact of environmental change on timing of reproduction and the potential for allochrony in migratory species to influence population divergence.</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, 15 May 2020 05:00:00 GMT “Shifts in reproductive investment in response to competitors lowers male reproductive success” https://amnat.org/an/newpapers/Sep-Spagopoulou.html Foteini Spagopoulou, Regina Vega-Trejo, Megan L. Head, and Michael D. Jennions (Sep 2020) The presence of sexual competition lowers male reproductive success in the G. holbrooki mosquitofish Read the Article (Just Accepted) Males of many species are exposed to highly variable social environments, where the presence and intensity of competition for access to females often change. In response, males can strategically adjust their investment in behavioral or morphological traits associated with higher mating or fertilization success. For instance, males can perceive an overabundance of other males as a signal for increased sexual competition and scale up investment in sexually selected traits. However, does such an increase in investment always lead to higher reproductive success? In a new study, Foteini Spagopoulou, Regina Vega-Trejo, Megan Head, and Michael Jennions from Uppsala University and the Australian National University, use the eastern mosquitofish (Gambusia holbrooki) to investigate whether a competitive environment drives males to increase their investment in sexually selected traits and ultimately maximize their reproductive success. Males are housed for a full spermatogenesis cycle in either a competitive treatment, by continually being exposed to cues that rivals are present, which mimics mating competition, or in a control treatment where such cues are absent. The authors first collect sperm measurements and then allow the males, following sperm replenishment, to compete freely with a similar-sized male (from the alternative treatment) for female access and copulations. Moreover, in contrast to previous studies, the authors specifically ask how male investment in sperm and mating traits ultimately translates in reproductive success using paternity testing. Contrary to theoretical expectations, the authors observe that males from the competitive treatment have slower swimming sperm, make fewer copulation attempts and courtship displays, and most importantly, sire fewer offspring. The unanticipated outcome of exposure to cues from rivals is, therefore, making males less, rather than more, reproductively successful. The authors discuss several possible explanations and highlight the importance of exposure duration to rivals. Moreover, these findings shed a critical perspective on experimental design and stress the need of testing whether observed changes in sexual traits elevate reproductive success. Abstract In many species, males exhibit phenotypic plasticity in sexually selected traits when exposed to social cues about the intensity of sexual competition. To date, however, few studies have tested how this plasticity affects male reproductive success. We initially tested whether male mosquitofish, Gambusia holbrooki (Poeciliidae), change their investment in traits under pre- and post- copulatory sexual selection depending on the social environment. Focal males were exposed, for a full spermatogenesis cycle, to visual and chemical cues of rivals that were either present (competitive treatment) or absent (control). Males from the competitive treatment had significantly slower swimming sperm, but did not differ in sperm count from control males. When two males competed for a female, competitive treatment males also made significantly fewer copulation attempts and courtship displays than control males. Further, paternity analysis of 708 offspring from 148 potential sires, testing whether these changes in reproductive traits affected male reproductive success, showed that males previously exposed to cues about the presence of rivals sired significantly fewer offspring when competing with a control male. We discuss several possible explanations for these unusual findings. More forthcoming papers &raquo; <p>Foteini Spagopoulou, Regina Vega-Trejo, Megan L. Head, and Michael D. Jennions (Sep 2020) </p> <p><b>The presence of sexual competition lowers male reproductive success in the <i>G. holbrooki</i> mosquitofish </b></p> <p><i><a href="https://dx.doi.org/10.1086/709821">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;">M</span>ales of many species are exposed to highly variable social environments, where the presence and intensity of competition for access to females often change. In response, males can strategically adjust their investment in behavioral or morphological traits associated with higher mating or fertilization success. For instance, males can perceive an overabundance of other males as a signal for increased sexual competition and scale up investment in sexually selected traits. However, does such an increase in investment always lead to higher reproductive success? </p><p>In a new study, Foteini Spagopoulou, Regina Vega-Trejo, Megan Head, and Michael Jennions from Uppsala University and the Australian National University, use the eastern mosquitofish (<i>Gambusia holbrooki</i>) to investigate whether a competitive environment drives males to increase their investment in sexually selected traits and ultimately maximize their reproductive success. Males are housed for a full spermatogenesis cycle in either a competitive treatment, by continually being exposed to cues that rivals are present, which mimics mating competition, or in a control treatment where such cues are absent. The authors first collect sperm measurements and then allow the males, following sperm replenishment, to compete freely with a similar-sized male (from the alternative treatment) for female access and copulations. Moreover, in contrast to previous studies, the authors specifically ask how male investment in sperm and mating traits ultimately translates in reproductive success using paternity testing. </p><p>Contrary to theoretical expectations, the authors observe that males from the competitive treatment have slower swimming sperm, make fewer copulation attempts and courtship displays, and most importantly, sire fewer offspring. The unanticipated outcome of exposure to cues from rivals is, therefore, making males less, rather than more, reproductively successful. The authors discuss several possible explanations and highlight the importance of exposure duration to rivals. Moreover, these findings shed a critical perspective on experimental design and stress the need of testing whether observed changes in sexual traits elevate reproductive success. </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 many species, males exhibit phenotypic plasticity in sexually selected traits when exposed to social cues about the intensity of sexual competition. To date, however, few studies have tested how this plasticity affects male reproductive success. We initially tested whether male mosquitofish, <i>Gambusia holbrooki</i> (Poeciliidae), change their investment in traits under pre- and post- copulatory sexual selection depending on the social environment. Focal males were exposed, for a full spermatogenesis cycle, to visual and chemical cues of rivals that were either present (competitive treatment) or absent (control). Males from the competitive treatment had significantly slower swimming sperm, but did not differ in sperm count from control males. When two males competed for a female, competitive treatment males also made significantly fewer copulation attempts and courtship displays than control males. Further, paternity analysis of 708 offspring from 148 potential sires, testing whether these changes in reproductive traits affected male reproductive success, showed that males previously exposed to cues about the presence of rivals sired significantly fewer offspring when competing with a control male. We discuss several possible explanations for these unusual findings. </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, 14 May 2020 05:00:00 GMT “Selection and constraints in the ecomorphological adaptive evolution of the skull of living Canidae (Carnivora, Mammalia)” https://amnat.org/an/newpapers/Aug-Machado-A.html Fabio Andrade Machado (Aug 2020) Evolution of cranial morphology was shaped by selection and constraints in Canidae (Carnivora) Read the ArticleAbstract The association between phenotype and ecology is essential for understanding the environmental drivers of morphological evolution. This is a particularly challenging task when dealing with complex traits such as the skull, where multiple selective pressures are at play and evolution might be constrained by ontogenetic and genetic factors. In the present contribution I integrate morphometric tools, comparative methods and quantitative genetics to investigate how ontogenetic constraints and selection might have interacted during the evolution of the skull in extant Canidae. The results confirm that the evolution of cranial morphology was largely adaptive and molded by changes in diet composition. While the investigation of the adaptive landscape reveals two main Selective Lines of Least Resistance (one associated with size and one associated with functional shape features), rates of evolution along size were higher than those found for shape dimensions, suggesting the influence of constraints on morphological evolution. Structural Modeling Analyses revealed that size, which is the line of most genetic/phenotypic variation, might have acted as a constraint, negatively impacting dietary evolution. Constraints might have been overcome in the case of selection for the consumption of large prey, by associating strong selection along both size and shape directions. The results obtained here show that microevolutionary constraints may have played a role in shaping macroevolutionary patterns of morphological evolution. More forthcoming papers &raquo; <p>Fabio Andrade Machado (Aug 2020)</p> <p><b>Evolution of cranial morphology was shaped by selection and constraints in Canidae (Carnivora) </b></p> <p><i><a href="https://dx.doi.org/10.1086/709610">Read the Article</a></i></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 association between phenotype and ecology is essential for understanding the environmental drivers of morphological evolution. This is a particularly challenging task when dealing with complex traits such as the skull, where multiple selective pressures are at play and evolution might be constrained by ontogenetic and genetic factors. In the present contribution I integrate morphometric tools, comparative methods and quantitative genetics to investigate how ontogenetic constraints and selection might have interacted during the evolution of the skull in extant Canidae. The results confirm that the evolution of cranial morphology was largely adaptive and molded by changes in diet composition. While the investigation of the adaptive landscape reveals two main Selective Lines of Least Resistance (one associated with size and one associated with functional shape features), rates of evolution along size were higher than those found for shape dimensions, suggesting the influence of constraints on morphological evolution. Structural Modeling Analyses revealed that size, which is the line of most genetic/phenotypic variation, might have acted as a constraint, negatively impacting dietary evolution. Constraints might have been overcome in the case of selection for the consumption of large prey, by associating strong selection along both size and shape directions. The results obtained here show that microevolutionary constraints may have played a role in shaping macroevolutionary patterns of morphological evolution. </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, 14 May 2020 05:00:00 GMT “Mammal community structure through the Paleocene-Eocene Thermal Maximum” https://amnat.org/an/newpapers/Sep-Fraser-A.html Danielle Fraser and S. Kathleen Lyons (Sep 2020) Despite increasing richness due to invasion and rapid climate change, PETM mammal community structure was unchanged Read the Article (Just Accepted) Abstract Human-mediated species invasion and climate change are leading to global extinctions and are predicted to result in the loss of important axes of phylogenetic and functional diversity. However, the long-term robustness of modern communities to invasion is unknown, given the limited timescales over which they can be studied. Using the fossil record of the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) in North America, we evaluate mammalian community-level response to a rapid global warming event (5° to 8°C) and invasion by three Eurasian mammalian orders and by species undergoing northward range shifts. We assembled a database of 144 species body sizes and created a time scaled composite phylogeny. We calculated the phylogenetic and functional diversity of all communities before, during, and after the PETM. Despite increases in the phylogenetic diversity of the regional species pool, phylogenetic diversity of mammalian communities remained relatively unchanged, a pattern that is invariant to the tree dating method, uncertainty in tree topology, and resolution. Similarly, body size dispersion and the degree of spatial taxonomic turnover of communities remained similar across the PETM. We suggest that invasion by new taxa had little impact on Paleocene-Eocene mammal communities because niches were not saturated. Our findings are consistent with the numerous studies of modern communities that record little change in community-scale richness despite turnover in taxonomic composition during invasion. What remains unknown is whether long-term robustness to biotic and abiotic perturbation are retained by modern communities given global anthropogenic landscape modification. More forthcoming papers &raquo; <p>Danielle Fraser and S. Kathleen Lyons (Sep 2020) </p> <p><b>Despite increasing richness due to invasion and rapid climate change, PETM mammal community structure was unchanged </b></p> <p><i><a href="https://dx.doi.org/10.1086/709819">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;">H</span>uman-mediated species invasion and climate change are leading to global extinctions and are predicted to result in the loss of important axes of phylogenetic and functional diversity. However, the long-term robustness of modern communities to invasion is unknown, given the limited timescales over which they can be studied. Using the fossil record of the Paleocene-Eocene Thermal Maximum (PETM; ~56 Ma) in North America, we evaluate mammalian community-level response to a rapid global warming event (5° to 8°C) and invasion by three Eurasian mammalian orders and by species undergoing northward range shifts. We assembled a database of 144 species body sizes and created a time scaled composite phylogeny. We calculated the phylogenetic and functional diversity of all communities before, during, and after the PETM. Despite increases in the phylogenetic diversity of the regional species pool, phylogenetic diversity of mammalian communities remained relatively unchanged, a pattern that is invariant to the tree dating method, uncertainty in tree topology, and resolution. Similarly, body size dispersion and the degree of spatial taxonomic turnover of communities remained similar across the PETM. We suggest that invasion by new taxa had little impact on Paleocene-Eocene mammal communities because niches were not saturated. Our findings are consistent with the numerous studies of modern communities that record little change in community-scale richness despite turnover in taxonomic composition during invasion. What remains unknown is whether long-term robustness to biotic and abiotic perturbation are retained by modern communities given global anthropogenic landscape modification. </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, 07 May 2020 05:00:00 GMT Results of the 2020 Election https://amnat.org/announcements/ANNelectionResults.html Election Statement 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.Election Statement 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. <p><strong>Election Statement</strong></p> <p>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.</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 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&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 Am Nat papers of the past. Melding my interests in diversity and Am Nat&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 Am Nat. 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><strong>Election Statement</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 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).</p> <p>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&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 American Naturalist.</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> Mon, 04 May 2020 05:00:00 GMT