ASN RSS http://amnat.org/ Latest press releases and announcements from the ASN en-us Mon, 22 May 2017 05:00:00 GMT 60 “Geographical variation in community divergence: insights from tropical forest monodominance by ectomycorrhizal trees” http://amnat.org/an/newpapers/VPFukami.html A new study suggests the answer to this question may lie in the fungi that grow in tree roots Tropical forests are the quintessence of biodiversity. Thousands of tree species are found in Borneo and the Amazon, for example. However, some of these forests contain distinct areas dominated by just one tree species. Ranging in size from one to several thousand hectares, these monodominant stands are puzzling because they occur within a vast tract of land that is otherwise co-dominated by many species of trees. How do monodominant stands arise, and what keeps them from being colonized by the many species that must be sending millions of seeds from adjacent areas? One possible answer is the fungi that colonize the roots of monodominant trees. These fungi help trees grow by making nutrients in the soil more readily available to the trees. It is thought that the trees that host one type of root-colonizing fungi, called ectomycorrhizal fungi, form monodominant stands if they happen to become established in a disturbed site earlier than other species because the soil is then made more favorable to the ectomycorrhizal trees than to other trees. However, monodominant stands arise only in some tropical regions, and not others. For example, we find them in Africa and South America, but not in Southeast Asia. Why is that? To answer this question, a group of researchers from Stanford University, the University of Nebraska, the University of California at Los Angeles and at Berkeley, and Florida International University used computer simulation models as a tool to develop a new hypothesis. The proposed hypothesis is that in regions with just a few tree species that host ectomycorrhizal fungi, such as Africa and South America, these trees evolve to acquire characteristics that closely match the environment. As a result, they can successfully compete against other species to form monodominant stands via their association with the fungi. By contrast, in regions with many tree species that host ectomycorrhizal fungi, such as Southeast Asia, these species maintain a variety of characteristics, with no species having the characteristics that enable them to form monodominance. This research provides a new idea to explain why biodiversity is distributed over space the way it is in tropical forests. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>A new study suggests the answer to this question may lie in the fungi that grow in tree roots </b></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>ropical forests are the quintessence of biodiversity. Thousands of tree species are found in Borneo and the Amazon, for example. However, some of these forests contain distinct areas dominated by just one tree species. Ranging in size from one to several thousand hectares, these monodominant stands are puzzling because they occur within a vast tract of land that is otherwise co-dominated by many species of trees. How do monodominant stands arise, and what keeps them from being colonized by the many species that must be sending millions of seeds from adjacent areas? </p><p>One possible answer is the fungi that colonize the roots of monodominant trees. These fungi help trees grow by making nutrients in the soil more readily available to the trees. It is thought that the trees that host one type of root-colonizing fungi, called ectomycorrhizal fungi, form monodominant stands if they happen to become established in a disturbed site earlier than other species because the soil is then made more favorable to the ectomycorrhizal trees than to other trees. </p><p>However, monodominant stands arise only in some tropical regions, and not others. For example, we find them in Africa and South America, but not in Southeast Asia. Why is that? To answer this question, a group of researchers from Stanford University, the University of Nebraska, the University of California at Los Angeles and at Berkeley, and Florida International University used computer simulation models as a tool to develop a new hypothesis. </p><p>The proposed hypothesis is that in regions with just a few tree species that host ectomycorrhizal fungi, such as Africa and South America, these trees evolve to acquire characteristics that closely match the environment. As a result, they can successfully compete against other species to form monodominant stands via their association with the fungi. By contrast, in regions with many tree species that host ectomycorrhizal fungi, such as Southeast Asia, these species maintain a variety of characteristics, with no species having the characteristics that enable them to form monodominance. This research provides a new idea to explain why biodiversity is distributed over space the way it is in tropical forests. <a href="http://dx.doi.org/10.1086/692439">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 22 May 2017 05:00:00 GMT “Natural history constrains the macroevolution of foot morphology in European plethodontid salamanders” http://amnat.org/an/newpapers/AugAdams.html Biomechanical constraints from climbing behavior limit morphological evolution At ecological timescales, it is well understood that alterations in environmental selection pressures can cause changes in phenotypic traits that enable organisms to survive in those habitats. However, how such changes affect the rate of evolution at larger scales across the tree of life is less well known. In a recent study, Adams and colleagues examined this question by quantifying rates of morphological evolution in a genus of European salamanders that display a unique natural history and behavior. Unlike most other plethodontid salamanders, European species of Hydromantes spend considerable time in caves, where they cling to the walls and ceilings. These animals also have considerable webbing on their hands and feet, which is thought to generate the suction required during climbing. Based on this unique natural history, the authors hypothesized that foot morphology is under strong selection due to the biomechanical constraints associated with climbing. If correct, this would result in a lower rate of evolution of foot traits when compared to other morphological traits not related to their climbing behavior. In addition, they posited that rates of evolution in foot morphology should be lower in Hydromantes than in other salamander lineages that do not climb extensively. To test these predictions, the authors measured several morphological traits on the feet of salamanders in two genera, Hydromantes and Plethodon, and measured several other morphological body traits in Hydromantes that were not related to climbing behavior. In accord with their predictions, they found that foot morphological traits evolved at significantly lower rates than did other phenotypic traits in Hydromantes. Additionally, Hydromantes displayed a lower rate of foot morphology evolution when compared to a non-climbing genus, Plethodon. Together, these findings suggest that macroevolutionary trends of phenotypic diversification can be mediated by the unique behavioral responses in taxa related to particular attributes of their natural history at ecological timescales. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Biomechanical constraints from climbing behavior limit morphological evolution </b></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>t ecological timescales, it is well understood that alterations in environmental selection pressures can cause changes in phenotypic traits that enable organisms to survive in those habitats. However, how such changes affect the rate of evolution at larger scales across the tree of life is less well known. In a recent study, Adams and colleagues examined this question by quantifying rates of morphological evolution in a genus of European salamanders that display a unique natural history and behavior. Unlike most other plethodontid salamanders, European species of <i>Hydromantes</i> spend considerable time in caves, where they cling to the walls and ceilings. These animals also have considerable webbing on their hands and feet, which is thought to generate the suction required during climbing. Based on this unique natural history, the authors hypothesized that foot morphology is under strong selection due to the biomechanical constraints associated with climbing. If correct, this would result in a lower rate of evolution of foot traits when compared to other morphological traits not related to their climbing behavior. In addition, they posited that rates of evolution in foot morphology should be lower in <i>Hydromantes</i> than in other salamander lineages that do not climb extensively. </p><p>To test these predictions, the authors measured several morphological traits on the feet of salamanders in two genera, <i>Hydromantes</i> and <i>Plethodon</i>, and measured several other morphological body traits in <i>Hydromantes</i> that were not related to climbing behavior. In accord with their predictions, they found that foot morphological traits evolved at significantly lower rates than did other phenotypic traits in <i>Hydromantes</i>. Additionally, <i>Hydromantes</i> displayed a lower rate of foot morphology evolution when compared to a non-climbing genus, <i>Plethodon</i>. Together, these findings suggest that macroevolutionary trends of phenotypic diversification can be mediated by the unique behavioral responses in taxa related to particular attributes of their natural history at ecological timescales. <a href="http://dx.doi.org/10.1086/692471">Read&nbsp;the&nbsp;Article</a> </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, 17 May 2017 05:00:00 GMT “Most colorful example of genetic assimilation? Exploring the evolutionary destiny of recurrent phenotypic accommodation” http://amnat.org/an/newpapers/AugBadyaev.html Evidence that carotenoid coloration may have evolved by genetic assimilation How can fully-grown multicellular organisms accommodate and retain novel inputs without losing functionality of already evolved structures? Framers of evolutionary theory envisioned a process – termed genetic assimilation – in which changes induced by the environment at peripheries of developmental trajectories get progressively stabilized by genetic controls of existing traits. Such a view of evolution as “the direction of ontogenetic accommodations of earlier generations” (Baldwin 1896, Am.&nbsp;Nat. 30:441–451) predicts developmental shifts in the determinants of a trait between ancestral and descendent forms. Yet we now know that such a shift is an inevitable consequence of the reshuffling of ancient genes for contemporary functions and thus an insufficient proof of any particular evolutionary mechanism. A new study by researchers from the University of Arizona overcomes this constraint by studying genetic assimilation as a recurrent process. Using one of the largest datasets ever assembled for such a study, they examined changes in feather structure caused by accommodation of carotenoid pigments with the same physical properties but distinct evolutionary histories, capitalizing on the fact that highly metabolically derived (i.e., internalized by an organism over a long evolutionary history) carotenoids in one species can be recent dietary additions in another species. The researchers applied a metabolic network view of carotenoid evolution to show that some derived carotenoids are biochemically redundant and thus co-evolve with feathers over longer time, despite having diverse dietary precursors in different environments. The researchers found that feathers repeatedly evolved the ability to integrate a diverse array of recurrent and metabolically internalized carotenoids into their growth, whereas inclusion of novel or dietary carotenoids of the same molecular weight induced significant aberrations in feather shape. Thus, the evolution of carotenoid-based ornamentation within avian lineages may be thought of as an arena for ongoing genetic assimilation – passing through stages of this process from phenotypic induction by external carotenoids to a progressively internalized metabolism of derived carotenoids and their integration with feather growth and restarting when the avian lineage switches to novel dietary precursors. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Evidence that carotenoid coloration may have evolved by genetic assimilation </b></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 can fully-grown multicellular organisms accommodate and retain novel inputs without losing functionality of already evolved structures? Framers of evolutionary theory envisioned a process – termed genetic assimilation – in which changes induced by the environment at peripheries of developmental trajectories get progressively stabilized by genetic controls of existing traits. Such a view of evolution as “the direction of ontogenetic accommodations of earlier generations” (Baldwin 1896, <i>Am.&nbsp;Nat.</i> 30:441&ndash;451) predicts developmental shifts in the determinants of a trait between ancestral and descendent forms. Yet we now know that such a shift is an inevitable consequence of the reshuffling of ancient genes for contemporary functions and thus an insufficient proof of any particular evolutionary mechanism. </p><p>A new study by researchers from the University of Arizona overcomes this constraint by studying genetic assimilation as a recurrent process. Using one of the largest datasets ever assembled for such a study, they examined changes in feather structure caused by accommodation of carotenoid pigments with the same physical properties but distinct evolutionary histories, capitalizing on the fact that highly metabolically derived (i.e., internalized by an organism over a long evolutionary history) carotenoids in one species can be recent dietary additions in another species. The researchers applied a metabolic network view of carotenoid evolution to show that some derived carotenoids are biochemically redundant and thus co-evolve with feathers over longer time, despite having diverse dietary precursors in different environments. </p><p>The researchers found that feathers repeatedly evolved the ability to integrate a diverse array of recurrent and metabolically internalized carotenoids into their growth, whereas inclusion of novel or dietary carotenoids of the same molecular weight induced significant aberrations in feather shape. Thus, the evolution of carotenoid-based ornamentation within avian lineages may be thought of as an arena for ongoing genetic assimilation – passing through stages of this process from phenotypic induction by external carotenoids to a progressively internalized metabolism of derived carotenoids and their integration with feather growth and restarting when the avian lineage switches to novel dietary precursors. <a href="http://dx.doi.org/10.1086/692327">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 16 May 2017 05:00:00 GMT “Towards a predictive framework for convergent evolution: integrating natural history, genetic mechanisms, and consequences for the diversity of life” http://amnat.org/an/newpapers/VPAgrawal.html In this article, the author attempts to develop a novel framework for studying repeated patterns in nature and why they occur. By synthesizing recent developments in evolutionary ecology and decades old classic theory, Agrawal provides a scheme for categorizing convergent evolution and advancing its study. This paper is also the introductory essay to a Special Issue of The&nbsp;American Naturalist, organized around the theme of Convergence, Natural History, and Some Big Questions in Biology. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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 this article, the author attempts to develop a novel framework for studying repeated patterns in nature and why they occur. By synthesizing recent developments in evolutionary ecology and decades old classic theory, Agrawal provides a scheme for categorizing convergent evolution and advancing its study. This paper is also the introductory essay to a Special Issue of <i>The&nbsp;American Naturalist</i>, organized around the theme of Convergence, Natural History, and Some Big Questions in Biology. <a href="http://dx.doi.org/10.1086/692111">Read&nbsp;the&nbsp;Article</a> </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, 11 May 2017 05:00:00 GMT “Microhabitat and climatic niche change explain patterns of diversification among frog families” http://amnat.org/an/newpapers/JulyMoen.html A new study of frogs shows that the fine-scale habitats where species live are the most important factors explaining patterns of evolution and biodiversity Different groups of animals and plants can have very different numbers of species. In frogs, for example, a family can contain anywhere from a single species (like the Mexican burrowing frog) to nearly a thousand (like treefrogs). The importance of different factors that explain this diversity has remained an unresolved mystery in many groups of organisms. In a new study appearing in The&nbsp;American Naturalist, researchers have now revealed these factors in frogs. Previous studies suggested that patterns of diversity among frog families were explained primarily by the rapid proliferation of species in the tropics, or by rapid proliferation in groups that occurred in many different environments. Surprisingly, the new study reveals that in frogs, the most important factor explaining their patterns of species proliferation and diversity is actually their fine-scale habitat. For example, they find that groups that live mostly in trees have higher rates of species proliferation than those that primarily live on the ground, underground, or in water. Although the effects of climates where species occurred were also significant, they were far less important than these fine-scale habitats. In fact, these fine-scale habitats were nearly three times as important for explaining biodiversity patterns as the large-scale climates where species lived. This study may be the first to directly compare the effects of fine-scale habitat and large-scale climate on patterns of biodiversity and species proliferation. The authors suggest that the pattern found in frogs may apply to many other organisms as well. The authors also find that the rate at which species adapt or adjust to different climates is also a key to explaining their patterns of species diversity and proliferation. Thus, groups that have been able to adapt to different climates more quickly have been more successful over tens of millions of years, in terms of having more species today. This may have important implications for how present climate change may influence long-term patterns of biodiversity in frogs and other organisms. The authors, Daniel Moen and John Wiens, are at Oklahoma State University and the University of Arizona, respectively. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>A new study of frogs shows that the fine-scale habitats where species live are the most important factors explaining patterns of evolution and biodiversity </b></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>ifferent groups of animals and plants can have very different numbers of species. In frogs, for example, a family can contain anywhere from a single species (like the Mexican burrowing frog) to nearly a thousand (like treefrogs). The importance of different factors that explain this diversity has remained an unresolved mystery in many groups of organisms. </p><p>In a new study appearing in <i>The&nbsp;American Naturalist</i>, researchers have now revealed these factors in frogs. Previous studies suggested that patterns of diversity among frog families were explained primarily by the rapid proliferation of species in the tropics, or by rapid proliferation in groups that occurred in many different environments. Surprisingly, the new study reveals that in frogs, the most important factor explaining their patterns of species proliferation and diversity is actually their fine-scale habitat. For example, they find that groups that live mostly in trees have higher rates of species proliferation than those that primarily live on the ground, underground, or in water. Although the effects of climates where species occurred were also significant, they were far less important than these fine-scale habitats. In fact, these fine-scale habitats were nearly three times as important for explaining biodiversity patterns as the large-scale climates where species lived. </p><p>This study may be the first to directly compare the effects of fine-scale habitat and large-scale climate on patterns of biodiversity and species proliferation. The authors suggest that the pattern found in frogs may apply to many other organisms as well. </p><p>The authors also find that the rate at which species adapt or adjust to different climates is also a key to explaining their patterns of species diversity and proliferation. Thus, groups that have been able to adapt to different climates more quickly have been more successful over tens of millions of years, in terms of having more species today. This may have important implications for how present climate change may influence long-term patterns of biodiversity in frogs and other organisms. </p><p>The authors, Daniel Moen and John Wiens, are at Oklahoma State University and the University of Arizona, respectively. <a href="http://dx.doi.org/10.1086/692065">Read&nbsp;the&nbsp;Article</a> </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, 11 May 2017 05:00:00 GMT “Convergence, consilience, and the evolution of temperate deciduous forests” http://amnat.org/an/newpapers/VPEdwards-A.html Abstract The deciduous habit of northern temperate trees and shrubs provides one of the most obvious examples of convergent evolution, but how did it evolve? Hypotheses based on the fossil record posit that deciduousness evolved first in response to drought or darkness, and pre-adapted certain lineages as cold climates spread. An alternative is that evergreens first established in freezing environments, and later evolved the deciduous habit. We monitored phenological patterns of 20 species of Viburnum spanning tropical, lucidophyllous (subtropical montane and warm-temperate), and cool-temperate Asian forests. In lucidophyllous forests, all viburnums were evergreen plants that exhibited coordinated leaf flushes with the onset of the rainy season, but varied greatly in the timing of leaf senescence. In contrast, deciduous species exhibited tight coordination of both flushing and senescence, and we found a perfect correlation between the deciduous habit and prolonged annual freezing. In contrast to previous “step-wise” hypotheses, a consilience of independent lines of evidence supports a “lock-step” model in which deciduousness evolved in situ, in parallel, and concurrent with a gradual cooling climate. A pervasive selective force combined with the elevated evolutionary accessibility of a particular response may explain the massive convergence of adaptive strategies that characterizes the world’s biomes. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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 deciduous habit of northern temperate trees and shrubs provides one of the most obvious examples of convergent evolution, but how did it evolve? Hypotheses based on the fossil record posit that deciduousness evolved first in response to drought or darkness, and pre-adapted certain lineages as cold climates spread. An alternative is that evergreens first established in freezing environments, and later evolved the deciduous habit. We monitored phenological patterns of 20 species of <i>Viburnum</i> spanning tropical, lucidophyllous (subtropical montane and warm-temperate), and cool-temperate Asian forests. In lucidophyllous forests, all viburnums were evergreen plants that exhibited coordinated leaf flushes with the onset of the rainy season, but varied greatly in the timing of leaf senescence. In contrast, deciduous species exhibited tight coordination of both flushing and senescence, and we found a perfect correlation between the deciduous habit and prolonged annual freezing. In contrast to previous “step-wise” hypotheses, a consilience of independent lines of evidence supports a “lock-step” model in which deciduousness evolved <i>in situ</i>, in parallel, and concurrent with a gradual cooling climate. A pervasive selective force combined with the elevated evolutionary accessibility of a particular response may explain the massive convergence of adaptive strategies that characterizes the world’s biomes. <a href="http://dx.doi.org/10.1086/692627">Read&nbsp;the&nbsp;Article</a> </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, 10 May 2017 05:00:00 GMT “The implications of eco-evolutionary processes for the emergence of marine plankton community biogeography” http://amnat.org/an/newpapers/JulySauterey.html Modeling the emergent plankton biogeography as a result of local eco-evolutionary processes and spatial dynamics Phytoplankton are oceans’ primary producers and thus play a critical role in the carbon cycle, forming the base of marine food webs and producing roughly half of the world’s oxygen. These ecological services rendered by marine plankton communities depend on their species composition and diversity, yet the processes underlying how plankton communities assemble remain poorly understood. Dr. Sauterey and his colleagues have developed a model of marine plankton metacommunity dynamics to examine how ecological, evolutionary, and spatial dynamics (i.e., resulting from ocean circulation) interact to influence the process of community assembly. Their results suggest that, while the predator-prey interactions tend to locally drive the emergence of diversity via an eco-evolutionary process, abiotic conditions (typically resource availability) act as a limiting factor for this diversification process. By modifying local competitive processes and abiotic conditions, ocean circulation can completely alter the outcome of the local process of community assembly. For instance, local plankton communities, when connected by water currents, might exhibit similarities in their size composition due to a shared eco-evolutionary history. Such sets of interacting communities then form coherent biogeographical units, referred to by Sauterey et al. as eco-evolutionary provinces. Sauterey et al. suggest that such biogeographical units might be key to better understanding both the past and future feedbacks between marine plankton communities and global environmental changes. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Modeling the emergent plankton biogeography as a result of local eco-evolutionary processes and spatial dynamics </b></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>hytoplankton are oceans’ primary producers and thus play a critical role in the carbon cycle, forming the base of marine food webs and producing roughly half of the world’s oxygen. These ecological services rendered by marine plankton communities depend on their species composition and diversity, yet the processes underlying how plankton communities assemble remain poorly understood. </p><p>Dr. Sauterey and his colleagues have developed a model of marine plankton metacommunity dynamics to examine how ecological, evolutionary, and spatial dynamics (i.e., resulting from ocean circulation) interact to influence the process of community assembly. Their results suggest that, while the predator-prey interactions tend to locally drive the emergence of diversity via an eco-evolutionary process, abiotic conditions (typically resource availability) act as a limiting factor for this diversification process. By modifying local competitive processes and abiotic conditions, ocean circulation can completely alter the outcome of the local process of community assembly. For instance, local plankton communities, when connected by water currents, might exhibit similarities in their size composition due to a shared eco-evolutionary history. Such sets of interacting communities then form coherent biogeographical units, referred to by Sauterey et al. as eco-evolutionary provinces. </p><p>Sauterey et al. suggest that such biogeographical units might be key to better understanding both the past and future feedbacks between marine plankton communities and global environmental changes. <a href="http://dx.doi.org/10.1086/692067">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 09 May 2017 05:00:00 GMT “Diversification of trait combinations in coevolving plants and insect lineages” http://amnat.org/an/newpapers/AugThompson.html Coevolution between plants and pollinators varies among ecosystems and among closely related species The ever-changing web of life is woven from the pattern of coevolving relationships among species. Even different populations of a species may coevolve with different numbers of other species. Woodland stars (Lithophragma spp.) have coevolved with highly specialized moths that simultaneously pollinate the same flowers in which they lay their eggs. Some woodland star populations rely on a single Greya moth species for pollination, whereas others rely on two Greya moth species that differ in how they pollinate the flowers. Plants and moths from ecosystems with only one woodland star species and one Greya moth species differ in floral and moth sizes and shapes from ecosystems in which two Greya moth species use the same woodland star plants. Similar effects of moth co-occurrence are found among ecosystems in multiple woodland star species. This study suggests that some of the complexity and, potentially, resilience of the web of life results from relentless evolutionary change in which natural selection reshapes the relationships among species in ecosystem after ecosystem. The results also suggest that, just as with the conservation of species, the conservation of coevolving interactions may be enhanced by conserving the multiple (co)evolutionary solutions that have arisen among populations of each species. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Coevolution between plants and pollinators varies among ecosystems and among closely related species </b></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 ever-changing web of life is woven from the pattern of coevolving relationships among species. Even different populations of a species may coevolve with different numbers of other species. Woodland stars (<i>Lithophragma</i> spp.) have coevolved with highly specialized moths that simultaneously pollinate the same flowers in which they lay their eggs. Some woodland star populations rely on a single <i>Greya</i> moth species for pollination, whereas others rely on two <i>Greya</i> moth species that differ in how they pollinate the flowers. Plants and moths from ecosystems with only one woodland star species and one <i>Greya</i> moth species differ in floral and moth sizes and shapes from ecosystems in which two <i>Greya</i> moth species use the same woodland star plants. Similar effects of moth co-occurrence are found among ecosystems in multiple woodland star species. This study suggests that some of the complexity and, potentially, resilience of the web of life results from relentless evolutionary change in which natural selection reshapes the relationships among species in ecosystem after ecosystem. The results also suggest that, just as with the conservation of species, the conservation of coevolving interactions may be enhanced by conserving the multiple (co)evolutionary solutions that have arisen among populations of each species. <a href="http://dx.doi.org/10.1086/692164">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 09 May 2017 05:00:00 GMT 2017 Presidential Award http://amnat.org/announcements/ANNPresAwa17.html The recipient of the 2017 Presidential Award for the best paper published in The American Naturalist during the preceding calendar year is Robin E. Snyder and Stephen P. Ellner, 2016. “We happy few: Using structured population models to identity the decisive events in the lives of exceptional individuals.” American Naturalist 188:E28-E45.&nbsp;--&nbsp;&nbsp;(lay summary here) What lucky events make individuals truly exceptional?&nbsp; That is the question posed by this engaging paper by Snyder and Ellner.&nbsp; They develop and apply novel demographic methods to identify the events and the moments in life during which luck produces exceptional individuals.&nbsp; They then apply those models to three contrasting plant systems.&nbsp; Using remarkably compelling and accessible language, the paper engages the phenomenon of chance and its contribution to individual differences.&nbsp; Extending existing analyses of which events in a life cycle, on average, contribute most to demographic output, the authors ask, for which of those events does its variance produce individuals that acquire exceptional fitness.&nbsp; They provide methods (and code) to identify “lucky” versus “unlucky” individuals, compare individual demographic parameters between those classes, and calculate the sensitivity and elasticity of the probability of becoming lucky with respect to individual demographic parameters across the life cycle.&nbsp; Their application of these methods to empirical data shows how these methods can provide specific information on how taxa differ in the stages at which luck matters.&nbsp; The authors also look forward and outline how their general approach can be developed to apply to evolutionary theory.&nbsp; First, the influence of stochastic variation creates reproductive skew among individuals, which influences effective populations size and genetic diversity. By identifying critical stages whose variance contributes most to such reproductive skew, moreover, the methods contribute to identifying potential targets of natural selection.&nbsp; Finally, the methods can be adapted to evaluate not only stochastic variance in demographic parameters, but also fixed differences between individuals, as caused by, for example, genetic differences.&nbsp; Future development of these methods has great potential to integrate demography and evolutionary theory to more fully understand what controls rates of adaptation and demographic performance.&nbsp; In uncertain environments, understanding the contribution of chance is critical. I thank all the authors who contributed to The American Naturalist in 2016, as reading their work was truly enjoyable.&nbsp; I congratulate all of you for your excellent contributions.&nbsp; Kathleen Donohue President, American Society of Naturalists <p>The recipient of the 2017 Presidential Award for the best paper published in <em>The American Naturalist</em> during the preceding calendar year is <a href="http://www.journals.uchicago.edu/doi/abs/10.1086/686996">Robin E. Snyder and Stephen P. Ellner, 2016. &ldquo;We happy few: Using structured population models to identity the decisive events in the lives of exceptional individuals.&rdquo; <em>American Naturalist</em> 188:E28-E45.</a>&nbsp;--&nbsp;&nbsp;(<a href="http://amnat.org/an/newpapers/AugSnyder.html">lay summary here</a>)</p> <p>What lucky events make individuals truly exceptional?&nbsp; That is the question posed by this engaging paper by Snyder and Ellner.&nbsp; They develop and apply novel demographic methods to identify the events and the moments in life during which luck produces exceptional individuals.&nbsp; They then apply those models to three contrasting plant systems.&nbsp;</p> <p>Using remarkably compelling and accessible language, the paper engages the phenomenon of chance and its contribution to individual differences.&nbsp; Extending existing analyses of which events in a life cycle, on average, contribute most to demographic output, the authors ask, for which of those events does its variance produce individuals that acquire exceptional fitness.&nbsp; They provide methods (and code) to identify &ldquo;lucky&rdquo; versus &ldquo;unlucky&rdquo; individuals, compare individual demographic parameters between those classes, and calculate the sensitivity and elasticity of the probability of becoming lucky with respect to individual demographic parameters across the life cycle.&nbsp; Their application of these methods to empirical data shows how these methods can provide specific information on how taxa differ in the stages at which luck matters.&nbsp;</p> <p>The authors also look forward and outline how their general approach can be developed to apply to evolutionary theory.&nbsp; First, the influence of stochastic variation creates reproductive skew among individuals, which influences effective populations size and genetic diversity. By identifying critical stages whose variance contributes most to such reproductive skew, moreover, the methods contribute to identifying potential targets of natural selection.&nbsp; Finally, the methods can be adapted to evaluate not only stochastic variance in demographic parameters, but also fixed differences between individuals, as caused by, for example, genetic differences.&nbsp; Future development of these methods has great potential to integrate demography and evolutionary theory to more fully understand what controls rates of adaptation and demographic performance.&nbsp; In uncertain environments, understanding the contribution of chance is critical.</p> <p>I thank all the authors who contributed to <em>The American Naturalist</em> in 2016, as reading their work was truly enjoyable.&nbsp; I congratulate all of you for your excellent contributions.&nbsp;</p> <p>Kathleen Donohue<br /> President, American Society of Naturalists</p> Mon, 08 May 2017 05:00:00 GMT ASN Attends Congressional Visits Day 2017 http://amnat.org/announcements/ReportAIBS.html On April 26, The American Institute for Biological Sciences organized “Congressional Visits Day.” &nbsp;Forty scientists at all levels assembled to meet with more than 70 congress people on Capitol Hill to advocate on behalf of funding for the National Science Foundation. &nbsp;ASN President Kathleen Donohue and Chair of the ASN Graduate Council Abigail Pastore attended and met with more than fifteen congressional offices. The purpose of the meetings was to request an increase in NSF funding to a level of $8 billion for fiscal year 2018. &nbsp;The goals during the meetings were a) to advocate for fundamental research as the essential upstream component of any translational or applied science; b) to educate congress people on how inadequate NSF funding impedes the progress of science because of costly interruptions to research programs and atrophy of the scientific workforce in the US (at the levels of students, postdocs, and young faculty); and c) to request that decisions on which programs to fund within NSF should be left to the NSF program officers rather than to a partisan congress. This is a good time to advocate for science. The American Institute for Biological Sciences &nbsp;(https://www.aibs.org/home/index.html) and the American Association for the Advancement of Science (https://www.aaas.org/) are excellent resources for learning more about science advocacy. &nbsp;The Ecological Society of America (http://www.esa.org/esablog/federal-agency-transition-tracker/) is very engaged in tracking science policy and in public and educational outreach. These organizations have fellowships and workshops for training in science communication and science advocacy. If you want to know more about this event and other opportunities for science advocacy, ATTEND THE ASN BUISINESS MEETING at the Evolution Meetings. &nbsp;We want to hear from ASN members about how ASN can help them to engage issues that are important to them. <p>On April 26, The American Institute for Biological Sciences organized &ldquo;Congressional Visits Day.&rdquo; &nbsp;Forty scientists at all levels assembled to meet with more than 70 congress people on Capitol Hill to advocate on behalf of funding for the National Science Foundation. &nbsp;ASN President Kathleen Donohue and Chair of the ASN Graduate Council Abigail Pastore attended and met with more than fifteen congressional offices.</p> <p> The purpose of the meetings was to request an increase in NSF funding to a level of $8 billion for fiscal year 2018. &nbsp;The goals during the meetings were a) to advocate for fundamental research as the essential upstream component of any translational or applied science; b) to educate congress people on how inadequate NSF funding impedes the progress of science because of costly interruptions to research programs and atrophy of the scientific workforce in the US (at the levels of students, postdocs, and young faculty); and c) to request that decisions on which programs to fund within NSF should be left to the NSF program officers rather than to a partisan congress.</p> <p> This is a good time to advocate for science. The American Institute for Biological Sciences &nbsp;(<a href="https://www.aibs.org/home/index.html">https://www.aibs.org/home/index.html</a>) and the American Association for the Advancement of Science <a href="https://www.aaas.org/">(https://www.aaas.org/</a>) are excellent resources for learning more about science advocacy. &nbsp;The Ecological Society of America (<a href="http://www.esa.org/esablog/federal-agency-transition-tracker/">http://www.esa.org/esablog/federal-agency-transition-tracker/</a>) is very engaged in tracking science policy and in public and educational outreach. These organizations have fellowships and workshops for training in science communication and science advocacy.</p> <p> If you want to know more about this event and other opportunities for science advocacy, <strong>ATTEND THE ASN BUISINESS MEETING</strong> at the Evolution Meetings. &nbsp;We want to hear from ASN members about how ASN can help them to engage issues that are important to them.</p> Thu, 04 May 2017 05:00:00 GMT “A parent-offspring trade-off limits the evolution of an ontogenetic niche shift” http://amnat.org/an/newpapers/JulyTenBrink.html Why do most animal species shift niche during life? Evolution is limited by a trade-off between juveniles and adults Almost all animal species, including fish, insects, amphibians and reptiles, change their diets as they grow larger. Even though these changes in diet are very common, it is not well understood why this strategy has evolved in the animal kingdom. Ten Brink and de Roos use computer simulations to study the evolution of diet shifting. They show that switching diets might induce the evolution of metamorphosis, where there is an abrupt change in morphology from the larval to the juvenile stage. While it can be advantageous for individuals to change their diet at one point, there is also a downside to this strategy. A morphology that allows the individual to feed on a certain food type is not necessarily useful when feeding on a different food type. Species that feed upon different food types over the course of their lives therefore face a trade-off. They can either specialize on the food they eat early in life or on the food they eat later in life. Ten Brink and de Roos show that it is beneficial for large individuals to change diet when this increases the food intake of the switching individuals. However, it is not possible to specialize on the food used later in life when this requires a morphology from birth which reduces the ability to eat the food used in the earlier life stages. There is therefore strong selection to decouple the different life-stages, for example by evolving a metamorphosis, such that juveniles and adults can evolve independently from each other. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Why do most animal species shift niche during life? Evolution is limited by a trade-off between juveniles and adults </b></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>lmost all animal species, including fish, insects, amphibians and reptiles, change their diets as they grow larger. Even though these changes in diet are very common, it is not well understood why this strategy has evolved in the animal kingdom. Ten Brink and de Roos use computer simulations to study the evolution of diet shifting. They show that switching diets might induce the evolution of metamorphosis, where there is an abrupt change in morphology from the larval to the juvenile stage. </p><p>While it can be advantageous for individuals to change their diet at one point, there is also a downside to this strategy. A morphology that allows the individual to feed on a certain food type is not necessarily useful when feeding on a different food type. Species that feed upon different food types over the course of their lives therefore face a trade-off. They can either specialize on the food they eat early in life or on the food they eat later in life. </p><p>Ten Brink and de Roos show that it is beneficial for large individuals to change diet when this increases the food intake of the switching individuals. However, it is not possible to specialize on the food used later in life when this requires a morphology from birth which reduces the ability to eat the food used in the earlier life stages. There is therefore strong selection to decouple the different life-stages, for example by evolving a metamorphosis, such that juveniles and adults can evolve independently from each other. <a href="http://dx.doi.org/10.1086/692066">Read&nbsp;the&nbsp;Article</a> </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, 04 May 2017 05:00:00 GMT “Dramatic fighting by male cuttlefish for a female mate” http://amnat.org/an/newpapers/JulyAllen.html Aggression is widespread among the animal kingdom yet its causation, function and theoretical underpinnings are not well understood. In a new paper in American Naturalist, authors Allen, Akkaynak, Schnell, and Hanlon present a fortuitous field observation of intense fighting between two male European cuttlefish (Sepia officinalis) for a female in a natural setting in the Turkish Aegean Sea. The imagery recorded during this encounter (watch their video at https://doi.org/10.7301/Z0PR7SX4) enabled the authors to describe the animals' aggression in the context of game theory, using models of fighting behavior. The males engaged in a series of aggressive bouts that escalated in intensity from skin pattern and posture displays to vicious physical fighting complete with dramatic grappling, biting, and rolling. The authors found that the male cuttlefish resolved conflict by progressing through successive phases of aggression while maintaining a similar rate of escalation. This suggests that the animals are monitoring the aggressive behavior of their opponent, rather than simply gauging their own fighting behavior. Although this conclusion is based on just one observation of wild animals, the authors cautiously suggest that this pattern of fighting behavior might follow some of the predictions of a mutual assessment strategy rather than a self-assessment strategy in this species. These findings encourage the investigation of the intricate details of competition to further our understanding of aggressive behaviors, which are fundamental to winning both short-term contests and long-term evolutionary success. Rare and exciting field observations like these complement and guide laboratory experiments by validating or refuting previous studies. Moreover, they inspire future lines of inquiry since the best way to build our understanding of the life history of a species is to study and analyze freely behaving animals in nature. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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>ggression is widespread among the animal kingdom yet its causation, function and theoretical underpinnings are not well understood. In a new paper in American Naturalist, authors Allen, Akkaynak, Schnell, and Hanlon present a fortuitous field observation of intense fighting between two male European cuttlefish (<i>Sepia officinalis</i>) for a female in a natural setting in the Turkish Aegean Sea. The imagery recorded during this encounter (watch their video at <a href="https://doi.org/10.7301/Z0PR7SX4">https://doi.org/10.7301/Z0PR7SX4</a>) enabled the authors to describe the animals' aggression in the context of game theory, using models of fighting behavior. The males engaged in a series of aggressive bouts that escalated in intensity from skin pattern and posture displays to vicious physical fighting complete with dramatic grappling, biting, and rolling. </p><p>The authors found that the male cuttlefish resolved conflict by progressing through successive phases of aggression while maintaining a similar rate of escalation. This suggests that the animals are monitoring the aggressive behavior of their opponent, rather than simply gauging their own fighting behavior. Although this conclusion is based on just one observation of wild animals, the authors cautiously suggest that this pattern of fighting behavior might follow some of the predictions of a mutual assessment strategy rather than a self-assessment strategy in this species. </p><p>These findings encourage the investigation of the intricate details of competition to further our understanding of aggressive behaviors, which are fundamental to winning both short-term contests and long-term evolutionary success. Rare and exciting field observations like these complement and guide laboratory experiments by validating or refuting previous studies. Moreover, they inspire future lines of inquiry since the best way to build our understanding of the life history of a species is to study and analyze freely behaving animals in nature. <a href="http://dx.doi.org/10.1086/692009">Read&nbsp;the&nbsp;Article</a> </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, 04 May 2017 05:00:00 GMT “A neutral model for the evolution of diet breadth” http://amnat.org/an/newpapers/AugForister-A.html A neutral model for ecological specialization challenges assumptions about the evolution of interactions Abstract Variation among organisms in diet breadth is a pervasive feature of the natural world that has resisted general explanation. In particular, trade-offs in the ability to use one resource at the expense of another have been expected but rarely detected. We explore a spatial model for the evolution of specialization, motivated by studies of plant-feeding insects. The model is neutral with respect to the causes and consequences of diet breadth: the number of hosts utilized is not constrained by trade-offs, nor does specialization or generalization confer a direct advantage with respect to the persistence of populations or the probability of diversification. We find that diet breadth evolves in ways that resemble reports from natural communities. Simulated communities are dominated by specialized species, with a predictable but less species-rich component of generalized taxa. These results raise the possibility that specialization might be a consequence of stochastic diversification dynamics acting on spatially segregated consumer-resource associations, rather than a trait either favored or constrained directly by natural selection. Finally, our model generates hypotheses for global patterns of herbivore diet breadth, including a positive effect of host richness and a negative effect of evenness in host plant abundance on the number of specialized taxa. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>A neutral model for ecological specialization challenges assumptions about the evolution of interactions </b></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;">V</span>ariation among organisms in diet breadth is a pervasive feature of the natural world that has resisted general explanation. In particular, trade-offs in the ability to use one resource at the expense of another have been expected but rarely detected. We explore a spatial model for the evolution of specialization, motivated by studies of plant-feeding insects. The model is neutral with respect to the causes and consequences of diet breadth: the number of hosts utilized is not constrained by trade-offs, nor does specialization or generalization confer a direct advantage with respect to the persistence of populations or the probability of diversification. We find that diet breadth evolves in ways that resemble reports from natural communities. Simulated communities are dominated by specialized species, with a predictable but less species-rich component of generalized taxa. These results raise the possibility that specialization might be a consequence of stochastic diversification dynamics acting on spatially segregated consumer-resource associations, rather than a trait either favored or constrained directly by natural selection. Finally, our model generates hypotheses for global patterns of herbivore diet breadth, including a positive effect of host richness and a negative effect of evenness in host plant abundance on the number of specialized taxa. <a href="http://dx.doi.org/10.1086/692325">Read&nbsp;the&nbsp;Article</a> </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, 04 May 2017 05:00:00 GMT “Plant size and competitive dynamics along nutrient gradients” http://amnat.org/an/newpapers/AugGoldberg-A.html Abstract Resource competition theory in plants has focused largely on resource-acquisition traits that are independent of size such as traits of individual leaves or roots or proportional allocation to different functions. However, plants also differ in maximum potential size, which could outweigh differences in module-level traits. We used a community-ecosystem model called MONDRIAN to investigate whether larger size inevitably increases competitive ability and how size interacts with nitrogen supply. Contrary to the conventional wisdom that bigger is better, we found that invader success and competitive ability are unimodal functions of maximum potential size, such that plants that are too large (or too small) are disproportionately suppressed by competition. Optimal size increases with nitrogen supply, even when plants compete only for nitrogen in a size-symmetric manner, although adding size-asymmetric competition for light does substantially increase the advantage of larger size at high nitrogen. These complex interactions of plant size and nitrogen supply lead to strong nonlinearities such that small differences in nitrogen can result in big differences in plant invasion success and the influence of competition along productivity gradients. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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>esource competition theory in plants has focused largely on resource-acquisition traits that are independent of size such as traits of individual leaves or roots or proportional allocation to different functions. However, plants also differ in maximum potential size, which could outweigh differences in module-level traits. We used a community-ecosystem model called M<span style="font-size: 75%">ONDRIAN</span> to investigate whether larger size inevitably increases competitive ability and how size interacts with nitrogen supply. Contrary to the conventional wisdom that bigger is better, we found that invader success and competitive ability are unimodal functions of maximum potential size, such that plants that are too large (or too small) are disproportionately suppressed by competition. Optimal size increases with nitrogen supply, even when plants compete only for nitrogen in a size-symmetric manner, although adding size-asymmetric competition for light does substantially increase the advantage of larger size at high nitrogen. These complex interactions of plant size and nitrogen supply lead to strong nonlinearities such that small differences in nitrogen can result in big differences in plant invasion success and the influence of competition along productivity gradients. <a href="http://dx.doi.org/10.1086/692438">Read&nbsp;the&nbsp;Article</a></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, 04 May 2017 05:00:00 GMT Call for Papers for the American Naturalist at 150 Symposium at ASN2018 http://amnat.org/announcements/CallAN150.html To celebrate the 150th Anniversary of the first publication of The American Naturalist, there will be a special symposium at the stand-alone meeting of the American Society of Naturalists (January 5 - 9, 2018, Asilomar CA, USA). The symposium is titled “On the shoulders of giants: the future of The American Naturalist”. The goal of the symposium will be to show how major advances published in the journal’s history have laid the foundation for exciting new directions in evolutionary ecology and related fields. There will be time for six 30-minute talks, each highlighting a different concept from a classic American Naturalist paper, and where those ideas are headed next. We want the talks to place the original paper into its historic context, trace the subsequent development of the idea, and (crucially) show how the classic ideas connect to today’s cutting-edge research. Potential speakers might wish to examine these special articles (listed here: http://www.amnat.org/announcements/Countdowns.html) both for inspiration and to minimize redundancy.We are requesting proposals for talks. Each proposal should be no more than 250 words. Proposals should: Identify what influential paper(s) from The American Naturalist’s past will be the starting point of the talk. Briefly explain how that past paper influenced the direction of the field generally and the speaker’s career in particular. Indicate how the speaker is using / developing / changing that classic paper’s ideas in their own current and future work. In addition to the 250 word limit, one figure and up to 5 references are allowed. Talk proposals should be sent to Daniel Bolnick&nbsp;&nbsp;by May 10. We expect to notify chosen speakers by June 1. We encourage junior researchers (post-docs, early-career faculty) to apply, and individuals from often under-represented groups. The society does not have the funds to pay for travel or lodging expenses of the chosen speakers. But in exceptional circumstances ASM may consider appeals to waive conference registration fees for junior presenters who lack other means to cover conference costs. In addition to this symposium, the American Society of Naturalists is separately seeking proposals for topics and speakers for two other organized symposia at the 2018 Asilomar meeting (see the details here.) <p>To celebrate the 150th Anniversary of the first publication of <em>The American Naturalist</em>, there will be a special symposium at the stand-alone meeting of the American Society of Naturalists (January 5 - 9, 2018, Asilomar CA, USA). The symposium is titled &ldquo;On the shoulders of giants: the future of <em>The American Naturalist</em>&rdquo;.</p> <p>The goal of the symposium will be to show how major advances published in the journal&rsquo;s history have laid the foundation for exciting new directions in evolutionary ecology and related fields. There will be time for six 30-minute talks, each highlighting a different concept from a classic <em>American Naturalist </em>paper, and where those ideas are headed next. We want the talks to place the original paper into its historic context, trace the subsequent development of the idea, and (crucially) show how the classic ideas connect to today&rsquo;s cutting-edge research.</p> <p>Potential speakers might wish to examine these special articles (listed here: <a href="http://www.amnat.org/announcements/Countdowns.html">http://www.amnat.org/announcements/Countdowns.html</a>) both for inspiration and to minimize redundancy.</p><p>We are requesting proposals for talks. Each proposal should be no more than 250 words. Proposals should:</p> <ol> <li>Identify what influential paper(s) from The American Naturalist&rsquo;s past will be the starting point of the talk.</li> <li>Briefly explain how that past paper influenced the direction of the field generally and the speaker&rsquo;s career in particular.</li> <li>Indicate how the speaker is using / developing / changing that classic paper&rsquo;s ideas in their own current and future work.</li> </ol> <p>In addition to the 250 word limit, one figure and up to 5 references are allowed.</p> <p><a href="mailto:danbolnick@austin.utexas.edu">Talk proposals should be sent to Daniel Bolnick&nbsp;</a>&nbsp;by May 10. We expect to notify chosen speakers by June 1.</p> <p>We encourage junior researchers (post-docs, early-career faculty) to apply, and individuals from often under-represented groups.</p> <p>The society does not have the funds to pay for travel or lodging expenses of the chosen speakers. But in exceptional circumstances ASM may consider appeals to waive conference registration fees for junior presenters who lack other means to cover conference costs.</p> <p>In addition to this symposium, the American Society of Naturalists is separately seeking proposals for topics and speakers for two other organized symposia at the 2018 Asilomar meeting (<a href="http://www.amnat.org/announcements/CallSympASN2018.html">see the details here.</a>)</p> Mon, 01 May 2017 05:00:00 GMT “How parallel is parallel evolution? A comparative analysis in fishes” http://amnat.org/an/newpapers/JulyOke.html How parallel is parallel evolution in fishes? Varies greatly, revealing importance of quantifying parallelism Parallel evolution is the repeated evolution of similar traits by independent populations colonizing similar environments. This parallelism is often taken as strong evidence that natural selection plays a deterministic (or “predictable” or “repeatable”) role in evolution, because, although similarities among populations could arise by chance, similarities that are repeatedly expressed in similar environments are more likely the result of selection typical of those environments. Despite many invocations of parallel evolution in the literature, differences are often evident among independent populations found in similar environments. That is, although independent populations in the same environment type are sometimes very similar, at other times they can be surprisingly different. In this study, researchers from McGill University leverage these differences to ask the basic question: just how parallel is parallel evolution? Analyzing results from 92 studies of putatively parallel evolution in fishes, the researchers find high variability in the extent to which ostensible parallel evolution is actually parallel in reality. The traits that they analyzed showed patterns ranging from highly parallel to hardly parallel at all, with everything in between. Moreover, the extent of parallelism did not differ between studies that explicitly described their findings as demonstrating parallel evolution versus studies that were not so explicit. These results highlight the importance of formally quantifying the extent of parallel evolution, rather than simply using binary parallel versus non-parallel categories. The various deviations from parallelism could be due to a number potential evolutionary nuances, including overlooked environmental variation, different genetic architectures or evolutionary histories, differences in gene flow, and others. Fortunately, the variation in the extent of parallel evolution described here reveals ample opportunities for researchers to identify the drivers of trait variation, thereby improving our understanding of the various forces shaping evolutionary trajectories in nature. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>How parallel is parallel evolution in fishes? Varies greatly, revealing importance of quantifying parallelism </b></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>arallel evolution is the repeated evolution of similar traits by independent populations colonizing similar environments. This parallelism is often taken as strong evidence that natural selection plays a deterministic (or “predictable” or “repeatable”) role in evolution, because, although similarities among populations could arise by chance, similarities that are repeatedly expressed in similar environments are more likely the result of selection typical of those environments. Despite many invocations of parallel evolution in the literature, differences are often evident among independent populations found in similar environments. That is, although independent populations in the same environment type are sometimes very similar, at other times they can be surprisingly different. In this study, researchers from McGill University leverage these differences to ask the basic question: just how parallel <i>is</i> parallel evolution? Analyzing results from 92 studies of putatively parallel evolution in fishes, the researchers find high variability in the extent to which ostensible parallel evolution is actually parallel in reality. The traits that they analyzed showed patterns ranging from highly parallel to hardly parallel at all, with everything in between. Moreover, the extent of parallelism did not differ between studies that explicitly described their findings as demonstrating parallel evolution versus studies that were not so explicit. These results highlight the importance of formally <i>quantifying</i> the extent of parallel evolution, rather than simply using binary parallel versus non-parallel categories. The various deviations from parallelism could be due to a number potential evolutionary nuances, including overlooked environmental variation, different genetic architectures or evolutionary histories, differences in gene flow, and others. Fortunately, the variation in the extent of parallel evolution described here reveals ample opportunities for researchers to identify the drivers of trait variation, thereby improving our understanding of the various forces shaping evolutionary trajectories in nature. <a href="http://dx.doi.org/10.1086/691989">Read&nbsp;the&nbsp;Article</a> </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, 27 Apr 2017 05:00:00 GMT “Extinction risk and lack of evolutionary rescue under resource depletion or area reduction” http://amnat.org/an/newpapers/JulyEngen.html We show that under r- and K-selection populations facing losses of habitats will not necessarily be rescued by evolution During the last century human impact on natural populations has increased dramatically, by fragmentation, harvesting, pollution, introduced species, and climate change, often with the consequence that species are faced with reduced amount of resources and increased risk of extinction. It is commonly, and correctly, argued that species may adapt to such changing environments and thereby produce a rescue effect counteracting the negative impact of human activities. In this paper Steinar&nbsp;Engen and Bernt‐Erik&nbsp;Sæther, at the Centre for Biodiversity Dynamics at The&nbsp;Norwegian University of Science and Technology, present a simple idea that force us to think differently about the possibility of rescue by Darwinian adaption to deteriorated environments. They apply their theory of continuously exchanging r‐ and K‐selection in fluctuating density dependent populations, previously worked out in collaboration with Russell&nbsp;Lande. At small population sizes the ability to grow quickly through large fecundity and short generation time is favored (r‐selection), while under large densities genes making individuals competitive for limited resources are selected for (K‐selection). Further, long‐term evolution must generate a genetic trade‐off between these properties, since otherwise evolution would lead to unlimited growth‐rates as well as competition ability. Engen and Sæther first show that the stationary fluctuations of mean phenotypes is the same before and after a given reduction of resources per individual. However, the interesting observation is what happens during a period of reduced resource availability. The number of individuals per resource unit will then increase, which according to the theory promotes K‐selection. The trade‐off between the growth rate r at small densities and the carrying capacity K then leads to evolution toward smaller r. Long‐lived species may often have a small growth rate and a long return time to equilibrium. Engen and Sæther show through examples that reduction of resources through time then may even produce negative values of r by natural selection. Although this is an adaption to the environmental conditions at the time because competitive ability is important, the long‐run consequence is that the extinction risk may be much larger than in the case of no adaption. Hence, there is no rescue effect by Darwinian adaption to the changing environments, but rather a reduction in sustainability, opposite of common belief. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>We show that under r- and K-selection populations facing losses of habitats will not necessarily be rescued by evolution </b></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>uring the last century human impact on natural populations has increased dramatically, by fragmentation, harvesting, pollution, introduced species, and climate change, often with the consequence that species are faced with reduced amount of resources and increased risk of extinction. It is commonly, and correctly, argued that species may adapt to such changing environments and thereby produce a rescue effect counteracting the negative impact of human activities.</p> <p>In this paper Steinar&nbsp;Engen and Bernt‐Erik&nbsp;Sæther, at the Centre for Biodiversity Dynamics at The&nbsp;Norwegian University of Science and Technology, present a simple idea that force us to think differently about the possibility of rescue by Darwinian adaption to deteriorated environments. They apply their theory of continuously exchanging <i>r</i>‐ and <i>K</i>‐selection in fluctuating density dependent populations, previously worked out in collaboration with Russell&nbsp;Lande. At small population sizes the ability to grow quickly through large fecundity and short generation time is favored (<i>r</i>‐selection), while under large densities genes making individuals competitive for limited resources are selected for (<i>K</i>‐selection). Further, long‐term evolution must generate a genetic trade‐off between these properties, since otherwise evolution would lead to unlimited growth‐rates as well as competition ability. Engen and Sæther first show that the stationary fluctuations of mean phenotypes is the same before and after a given reduction of resources per individual. However, the interesting observation is what happens during a period of reduced resource availability. The number of individuals per resource unit will then increase, which according to the theory promotes <i>K</i>‐selection. The trade‐off between the growth rate <i>r</i> at small densities and the carrying capacity <i>K</i> then leads to evolution toward smaller <i>r</i>.</p> <p>Long‐lived species may often have a small growth rate and a long return time to equilibrium. Engen and Sæther show through examples that reduction of resources through time then may even produce negative values of <i>r</i> by natural selection. Although this is an adaption to the environmental conditions at the time because competitive ability is important, the long‐run consequence is that the extinction risk may be much larger than in the case of no adaption. Hence, there is no rescue effect by Darwinian adaption to the changing environments, but rather a reduction in sustainability, opposite of common belief. <a href="http://dx.doi.org/10.1086/692011">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 26 Apr 2017 05:00:00 GMT “Decreasing stoichiometric resource quality drives compensatory feeding across trophic levels in tropical litter invertebrate communities” http://amnat.org/an/newpapers/JulyJochum.html Support for compensatory feeding being an important consumer response to low-quality resources across trophic levels When exposed to low-quality food resources, consumer communities have a limited number of options: They might alter the chemical composition of their own body tissue, avoid habitats with low-quality resources, or simply eat more (i.e., perform compensatory feeding). In a study appearing in The&nbsp;American Naturalist, a research team lead by Dr. Malte Jochum investigates how invertebrates living in the leaf litter of different semi-natural and agricultural sites on the island of Sumatra, Indonesia, cope with different-quality resources. In 2012, the researchers collected 7,472 animals across 32 field sites of the EFForTS project, a large German-Indonesian collaboration funded by the German Research Foundation (DFG) in tropical lowland rainforest, rubber, and oil palm plantations. Dr Jochum and colleagues find little evidence that consumer communities alter their chemical body composition or simply avoid habitats with low-quality resources. Instead, the study finds a strong indication that consumer communities across different trophic levels—namely predators and animals eating dead plant material—increase their feeding rates where resource quality is poor. Thus, while previous studies mostly document compensatory feeding for consumers feeding on plant resources, the new results from Sumatra indicate that this mechanism might be ubiquitous across trophic levels. These findings are of particular importance in light of global agricultural expansion and intensification and climate change, as they provide insights into how ecological communities might respond to changes in the chemical quality of the resources that are available in altered ecosystems. Small changes in basal resources could thus trigger changes that cascade upward to top predators, yielding more pervasive impacts than previously realized. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Support for compensatory feeding being an important consumer response to low-quality resources across trophic levels </b></p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">W</span>hen exposed to low-quality food resources, consumer communities have a limited number of options: They might alter the chemical composition of their own body tissue, avoid habitats with low-quality resources, or simply eat more (i.e., perform compensatory feeding). In a study appearing in <i>The&nbsp;American Naturalist</i>, a research team lead by Dr. Malte Jochum investigates how invertebrates living in the leaf litter of different semi-natural and agricultural sites on the island of Sumatra, Indonesia, cope with different-quality resources. In 2012, the researchers collected 7,472 animals across 32 field sites of the EFForTS project, a large German-Indonesian collaboration funded by the German Research Foundation (DFG) in tropical lowland rainforest, rubber, and oil palm plantations. Dr Jochum and colleagues find little evidence that consumer communities alter their chemical body composition or simply avoid habitats with low-quality resources. Instead, the study finds a strong indication that consumer communities across different trophic levels—namely predators and animals eating dead plant material—increase their feeding rates where resource quality is poor. Thus, while previous studies mostly document compensatory feeding for consumers feeding on plant resources, the new results from Sumatra indicate that this mechanism might be ubiquitous across trophic levels. These findings are of particular importance in light of global agricultural expansion and intensification and climate change, as they provide insights into how ecological communities might respond to changes in the chemical quality of the resources that are available in altered ecosystems. Small changes in basal resources could thus trigger changes that cascade upward to top predators, yielding more pervasive impacts than previously realized. <a href="http://dx.doi.org/10.1086/691790">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 24 Apr 2017 05:00:00 GMT “When predators help prey adapt and persist in a changing environment” http://amnat.org/an/newpapers/JulyOsmond.html Predators can help prey persist in a changing world by increasing selection or decreasing generation times According to the Oxford English Dictionary, a predator is “a ruthlessly exploitative or rapacious individual”. One would thus expect predators to hasten the demise of prey at risk of extinction. Indeed, many studies show that predators reduce prey numbers and it has also been shown that this can translate into prey extinction. But are predators always bad for prey? To address this question, researchers from the University of British Columbia and Michigan State University built and analyzed mathematical models describing prey population dynamics and trait evolution in the face of a changing environment, with and without an interacting predator. The authors find two circumstances under which predators actually help prey adapt and persist. The first mechanism occurs when predators kill more prey of a particular type, for example the sick and weak or the large and tasty, and this drives the prey to evolve in ways that are favoured in the new environment. That is, predators impose a “selective push” that helps the prey keep up with the environmental change. This makes sense, but the authors find another circumstance where predators help, which occurs even when predators do not directly induce selection on their prey but simply eat them. By eating prey, predators free-up resources that allow prey to give birth sooner, reducing generation times and hastening evolution. Metaphorically, the predator acts like Heracles beheading the Hydra, except the multitude of heads growing back tend to be better adapted to the current conditions. Matt Osmond, the lead author, points out that these findings “raise concerns for the conservation practice of removing predators for threatened populations, like Canada’s woodland caribou. While this practice may help prey survive in the short run, its unclear what effect this will have on their ability to adapt and persist in a changing world.” Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Predators can help prey persist in a changing world by increasing selection or decreasing generation times </b></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>ccording to the Oxford English Dictionary, a predator is &ldquo;a ruthlessly exploitative or rapacious individual&rdquo;. One would thus expect predators to hasten the demise of prey at risk of extinction. Indeed, many studies show that predators reduce prey numbers and it has also been shown that this can translate into prey extinction. </p><p>But are predators always bad for prey? To address this question, researchers from the University of British Columbia and Michigan State University built and analyzed mathematical models describing prey population dynamics and trait evolution in the face of a changing environment, with and without an interacting predator. The authors find two circumstances under which predators actually help prey adapt and persist. </p><p>The first mechanism occurs when predators kill more prey of a particular type, for example the sick and weak or the large and tasty, and this drives the prey to evolve in ways that are favoured in the new environment. That is, predators impose a “selective push” that helps the prey keep up with the environmental change. </p><p>This makes sense, but the authors find another circumstance where predators help, which occurs even when predators do not directly induce selection on their prey but simply eat them. By eating prey, predators free-up resources that allow prey to give birth sooner, reducing generation times and hastening evolution. Metaphorically, the predator acts like Heracles beheading the Hydra, except the multitude of heads growing back tend to be better adapted to the current conditions. </p><p>Matt Osmond, the lead author, points out that these findings “raise concerns for the conservation practice of removing predators for threatened populations, like Canada’s woodland caribou. While this practice may help prey survive in the short run, its unclear what effect this will have on their ability to adapt and persist in a changing world.” <a href="http://dx.doi.org/10.1086/691778">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 24 Apr 2017 05:00:00 GMT “Genetic correlations among developmental and contextual behavioral plasticity in Drosophila melanogaster” http://amnat.org/an/newpapers/JulySaltz.html Different types of behavioral plasticities are genetically correlated in flies Should “nature vs. nurture” really be “nature and nurture”? The old opposition between nature and nurture presents behaviors as either due to genes, or to learning—but not both. In contrast, genetic differences might influence the ways that individuals interact with, and learn from, their environments. To test how learning and other types of behavioral responses to the environment differ among genotypes, researchers have turned to larvae of the fruit fly, Drosophila melanogaster. Although tiny and with simple brains, larvae can learn to avoid odors that that have previously proved harmful. By measuring different fly genotypes from a single population—almost 50,000 flies in total—the researchers find heritable genetic variation in the flies’ ability to associate an odor with a harmful electric shock. Further, genotypes that are more adept at learning to avoid the odor also use environmental cues to fine-tune their decisions about where to pupate—more so than genotypes with lower learning scores. These results represent the first time these two seemingly different types of behavioral changes have been found to be genetically correlated. Identifying the relationships between learning and other types of behavioral flexibility is important for predicting how animals might change their behavior in response to environmental changes, such as invasive species, and for understanding how learning might evolve. More broadly, genetic variation in the ways that individuals interact with and respond to their environments highlights the complex ways that both genes and the environment—nature and nurture—together orchestrate behavior. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Different types of behavioral plasticities are genetically correlated in flies </b></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>hould “nature vs. nurture” really be “nature <i>and</i> nurture”? The old opposition between nature and nurture presents behaviors as either due to genes, or to learning—but not both. In contrast, genetic differences might influence the ways that individuals interact with, and learn from, their environments. To test how learning and other types of behavioral responses to the environment differ among genotypes, researchers have turned to larvae of the fruit fly, <i>Drosophila melanogaster</i>. Although tiny and with simple brains, larvae can learn to avoid odors that that have previously proved harmful. By measuring different fly genotypes from a single population—almost 50,000 flies in total—the researchers find heritable genetic variation in the flies’ ability to associate an odor with a harmful electric shock. Further, genotypes that are more adept at learning to avoid the odor also use environmental cues to fine-tune their decisions about where to pupate—more so than genotypes with lower learning scores. These results represent the first time these two seemingly different types of behavioral changes have been found to be genetically correlated. </p><p>Identifying the relationships between learning and other types of behavioral flexibility is important for predicting how animals might change their behavior in response to environmental changes, such as invasive species, and for understanding how learning might evolve. More broadly, genetic variation in the ways that individuals interact with and respond to their environments highlights the complex ways that both genes and the environment—nature <i>and</i> nurture—together orchestrate behavior. <a href="http://dx.doi.org/10.1086/692010">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 24 Apr 2017 05:00:00 GMT “65 million years of change in temperature and topography explain evolutionary history in eastern North American Plethodontid salamanders” http://amnat.org/an/newpapers/JulyBarnes.html 65 million years of temperature and topographic change explain phylogenetic and spatial patterns in salamanders What can salamanders tell us about how changes in climate and elevation might affect evolution? More than you might think, as it turns out. A new study suggests that models can be used to help disentangle how eroding mountains and changing temperatures act over millions of years to influence where and how salamanders live in the Appalachian Mountains. Co-authored by Richard Barnes, a PhD student at the University of California, Berkeley, and Adam Clark, a PhD student at the University of Minnesota, the study asks whether it is possible to separate the effects of the many processes that may have influenced the present day distribution and evolutionary history of Plethodontid salamanders in eastern North America. The salamanders have evolved and lived in the same region for up to 65 million years – a time period which includes several ice ages, the erosion of the Appalachians from a Himalayan-scale mountain range, and many chance events. For standard analytical tools, the complexity of these interactions makes the past too murky to reason about. However, in systems where changes have been particularly large and well-documented, there is hope that at least some of these relationships might be teased apart. To that end, Barnes and Clark developed a “general simulation model” based on historical records of temperature and elevation changes, and the impacts of these changes on species throughout their entire evolutionary histories. Building on existing examples of general simulation models, their findings present a possible path forward for researchers interested in combining models of ecology, evolution, and earth history to better explain the abundance and distribution of species over time. “Future studies may be able to adapt methods such as these to better understand species’ pasts, as well as their futures, as our planet’s climate and environment change,” says Clark. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>65 million years of temperature and topographic change explain phylogenetic and spatial patterns in salamanders </b></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>hat can salamanders tell us about how changes in climate and elevation might affect evolution? More than you might think, as it turns out. A new study suggests that models can be used to help disentangle how eroding mountains and changing temperatures act over millions of years to influence where and how salamanders live in the Appalachian Mountains. </p><p>Co-authored by Richard Barnes, a PhD student at the University of California, Berkeley, and Adam Clark, a PhD student at the University of Minnesota, the study asks whether it is possible to separate the effects of the many processes that may have influenced the present day distribution and evolutionary history of Plethodontid salamanders in eastern North America. </p><p>The salamanders have evolved and lived in the same region for up to 65 million years – a time period which includes several ice ages, the erosion of the Appalachians from a Himalayan-scale mountain range, and many chance events. For standard analytical tools, the complexity of these interactions makes the past too murky to reason about. </p><p>However, in systems where changes have been particularly large and well-documented, there is hope that at least some of these relationships might be teased apart. To that end, Barnes and Clark developed a “general simulation model” based on historical records of temperature and elevation changes, and the impacts of these changes on species throughout their entire evolutionary histories. </p><p>Building on existing examples of general simulation models, their findings present a possible path forward for researchers interested in combining models of ecology, evolution, and earth history to better explain the abundance and distribution of species over time. “Future studies may be able to adapt methods such as these to better understand species’ pasts, as well as their futures, as our planet’s climate and environment change,” says Clark. <a href="http://dx.doi.org/10.1086/691796">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 24 Apr 2017 05:00:00 GMT The ASN Student Research Awards http://amnat.org/announcements/ANNStuResearchAWA.html &nbsp;Name &nbsp;Institution &nbsp;Research Christopher K. Akcali UNC Chapel Hill The Evolution of Imprecise Coral Snake Mimicry&nbsp; Sara Berk University of Montana Testing the honesty of a sexually selected trait across conditions in the Mountain Bluebird, Siailia currucoides Rebecca Moss James Cook University Species interactions and the evolution of plasticity in mating signals&nbsp; Amanda Hund University of Colorado Boulder The role of early environment in the expression of a lifelong melanin-based sexual trait.&nbsp; Audrey Kelly UNC Chapel Hill Hybrid post-metamorphic survival across natural populations at the local and regional scale in spadefoot toads Phred Benham University of Montana Plasticity and genetic accommodation during adaptation to salt marshes in the Savannah Sparrow&nbsp; Jennifer Cocciardi James Cook University Can species interactions drive rapid niche evolution? James Stroud Florida International University Understanding the relationship between sociality and character displacement Therese Lamperty Rice University The genetic impacts of defaunation on a hyper-abundant palm species in the Peruvian Amazon Elizabeth Lange Florida State University Socially mediated plasticity and polymorphism: integrating theory and experiment to predict alternative life histories&nbsp; The ASN Student Research Awards support research by student members that advances the goals of the society: the conceptual unification of ecology, evolution, or behavior. Each award consists of a $2,000 check to the candidate. An applicant must be a member of the ASN (membership is international), must hold a bachelor’s degree or equivalent, must have passed to candidacy in a Ph.D. program or equivalent, and must be at least one year from completing the PhD. Projects in all types of research (i.e., laboratory, field, theory) are encouraged. Proposals are judged on originality, strength, and significance of the questions being addressed, prospects for significant results, and the match between the proposed research and the ASN mission. <table border="1" cellpadding="1" cellspacing="1" style="width:100%"> <tbody> <tr> <td>&nbsp;Name</td> <td>&nbsp;Institution</td> <td>&nbsp;Research</td> </tr> <tr> <td>Christopher K. Akcali</td> <td>UNC Chapel Hill</td> <td>The Evolution of Imprecise Coral Snake Mimicry&nbsp;</td> </tr> <tr> <td>Sara Berk</td> <td>University of Montana</td> <td>Testing the honesty of a sexually selected trait across conditions in the Mountain Bluebird, Siailia currucoides</td> </tr> <tr> <td>Rebecca Moss</td> <td>James Cook University</td> <td>Species interactions and the evolution of plasticity in mating signals&nbsp;</td> </tr> <tr> <td>Amanda Hund</td> <td>University of Colorado Boulder</td> <td>The role of early environment in the expression of a lifelong melanin-based sexual trait.&nbsp;</td> </tr> <tr> <td>Audrey Kelly</td> <td>UNC Chapel Hill</td> <td>Hybrid post-metamorphic survival across natural populations at the local and regional scale in spadefoot toads</td> </tr> <tr> <td>Phred Benham</td> <td>University of Montana</td> <td>Plasticity and genetic accommodation during adaptation to salt marshes in the Savannah Sparrow&nbsp;</td> </tr> <tr> <td>Jennifer Cocciardi</td> <td>James Cook University</td> <td>Can species interactions drive rapid niche evolution?</td> </tr> <tr> <td>James Stroud</td> <td>Florida International University</td> <td>Understanding the relationship between sociality and character displacement</td> </tr> <tr> <td>Therese Lamperty</td> <td>Rice University</td> <td>The genetic impacts of defaunation on a hyper-abundant palm species in the Peruvian Amazon</td> </tr> <tr> <td>Elizabeth Lange</td> <td>Florida State University</td> <td>Socially mediated plasticity and polymorphism: integrating theory and experiment to predict alternative life histories&nbsp;</td> </tr> </tbody> </table> <p>The ASN Student Research Awards support research by student members that advances the goals of the society: the conceptual unification of ecology, evolution, or behavior. Each award consists of a $2,000 check to the candidate. An applicant must be a member of the ASN (membership is international), must hold a bachelor&rsquo;s degree or equivalent, must have passed to candidacy in a Ph.D. program or equivalent, and must be at least one year from completing the PhD.</p> <p>Projects in all types of research (i.e., laboratory, field, theory) are encouraged. Proposals are judged on originality, strength, and significance of the questions being addressed, prospects for significant results, and the match between the proposed research and the ASN mission.</p> Thu, 20 Apr 2017 05:00:00 GMT “A sea scorpion’s strike: new evidence of extreme lateral flexibility in the opisthosoma of eurypterids” http://amnat.org/an/newpapers/JulyPersons.html Researchers report prehistoric sea-scorpions had slashing tail spines Four hundred thirty million years ago, long before the evolution of barracudas or sharks, the scariest predators lurking in the primordial seas were eurypterids—better known as “sea scorpions”. A group of arthropods related to modern terrestrial scorpions and horseshoe crabs, the eurypterids included some species that grew to over three meters long, had pinching claws like a modern spider crab, and could even crawl out of the water and hunt on land. Now, University of Alberta researchers Scott Persons and John Acorn have added a new weapon to the arsenals of these ancient sea creatures: a slashing tail spine! Sparked by a fossil of the eurypterid Slimonia acuminata, which preserves a serrated-spine-tipped tail fully articulated and curved strongly to one side, Persons and Acorn have made the biomechanical case for eurypterids dispatching their prey with sidelong tail strikes. Eurypterids had a flattened tail and body form. Unlike lobsters and shrimps, which can flip their broad tails up and down to help them swim, eurypterid tails were vertically inflexible but horizontally highly mobile. Their flattened weaponized tails could be aggressively slashed sideways, while meeting a minimum of hydraulic resistance and without propelling themselves away from an intended target. Among the likely prey of Slimonia acuminata and other eurypterids were our ancient early vertebrate ancestors. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Researchers report prehistoric sea-scorpions had slashing tail spines </b></p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">F</span>our hundred thirty million years ago, long before the evolution of barracudas or sharks, the scariest predators lurking in the primordial seas were eurypterids—better known as “sea scorpions”. A group of arthropods related to modern terrestrial scorpions and horseshoe crabs, the eurypterids included some species that grew to over three meters long, had pinching claws like a modern spider crab, and could even crawl out of the water and hunt on land. Now, University of Alberta researchers Scott Persons and John Acorn have added a new weapon to the arsenals of these ancient sea creatures: a slashing tail spine! Sparked by a fossil of the eurypterid <i>Slimonia acuminata</i>, which preserves a serrated-spine-tipped tail fully articulated and curved strongly to one side, Persons and Acorn have made the biomechanical case for eurypterids dispatching their prey with sidelong tail strikes. Eurypterids had a flattened tail and body form. Unlike lobsters and shrimps, which can flip their broad tails up and down to help them swim, eurypterid tails were vertically inflexible but horizontally highly mobile. Their flattened weaponized tails could be aggressively slashed sideways, while meeting a minimum of hydraulic resistance and without propelling themselves away from an intended target. Among the likely prey of Slimonia acuminata and other eurypterids were our ancient early vertebrate ancestors. <a href="http://dx.doi.org/10.1086/691967">Read&nbsp;the&nbsp;Article</a> </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, 19 Apr 2017 05:00:00 GMT “Unexpected non-genetic individual heterogeneity and trait covariance in Daphnia and its consequences for ecological and evolutionary dynamics” http://amnat.org/an/newpapers/JulyCressler.html If you look closely at any two animals of the same species, you will find differences. One may be larger than another, better at getting food, or better at finding mates. Many explanations exist for these differences. Two of the most common explanations are that the individuals differ because they have different genes or live in different environments. But what happens if those explanations vanish? Will there still be differences between individuals? If so, what does that mean for population dynamics and evolution? In research now appearing in The&nbsp;American Naturalist, Clay Cressler, Stefan Bengtson, and William Nelson tackle these questions. By restricting the environmental differences experienced by the clonal freshwater crustacean Daphnia, they observe what happens to individual differences when their usual sources were removed. “Because these organisms are clones of each other, it gives us a great opportunity to look at where differences come from and what that means for their ecology and evolution,” says Dr. Cressler. Under carefully controlled environments, they find that non-genetic sources of variation contribute more than genetic sources to individual differences. When these individual differences are scaled up to the population, they found that non-genetic sources of variation impacted population growth rates more than genetic sources. Surprisingly, independent of how traits co-varied among individuals, non-genetic sources of variation always slowed evolution in a way that is different from other evolutionary processes. Clonal animals often show an abundance of genetic diversity within a population. Counterintuitively, these results show that high levels of variation among genetically identical individuals are an important mechanism maintaining these high levels of genetic diversity. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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>f you look closely at any two animals of the same species, you will find differences. One may be larger than another, better at getting food, or better at finding mates. Many explanations exist for these differences. Two of the most common explanations are that the individuals differ because they have different genes or live in different environments. But what happens if those explanations vanish? Will there still be differences between individuals? If so, what does that mean for population dynamics and evolution? </p> <p>In research now appearing in <i>The&nbsp;American Naturalist</i>, Clay Cressler, Stefan Bengtson, and William Nelson tackle these questions. By restricting the environmental differences experienced by the clonal freshwater crustacean <i>Daphnia</i>, they observe what happens to individual differences when their usual sources were removed. “Because these organisms are clones of each other, it gives us a great opportunity to look at where differences come from and what that means for their ecology and evolution,” says Dr. Cressler. Under carefully controlled environments, they find that non-genetic sources of variation contribute more than genetic sources to individual differences. </p> <p>When these individual differences are scaled up to the population, they found that non-genetic sources of variation impacted population growth rates more than genetic sources. Surprisingly, independent of how traits co-varied among individuals, non-genetic sources of variation always slowed evolution in a way that is different from other evolutionary processes. </p> <p>Clonal animals often show an abundance of genetic diversity within a population. Counterintuitively, these results show that high levels of variation among genetically identical individuals are an important mechanism maintaining these high levels of genetic diversity. <a href="http://dx.doi.org/10.1086/691779">Read&nbsp;the&nbsp;Article</a> </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, 07 Apr 2017 05:00:00 GMT “Speciation and the latitudinal diversity gradient: insights from the global distribution of endemic fish” http://amnat.org/an/newpapers/JuneHanly.html Endemic fish show that speciation is faster at lower latitudes even after controlling for the effects of age and area The tropics are extraordinarily rich in species, but understanding the ecological and evolutionary causes of such diversity is challenging. Particularly controversial is whether tropical and temperate regions differ in how quickly new species arise. Analyses of DNA-based molecular phylogenies are increasing used to estimate latitudinal differences on speciation rates, but as yet there is little consensus in their conclusions (for example, see recent articles by Machac and Graham (2016) and Schluter (2016) in The American Naturalist). Here, three researchers from Michigan State University (Patrick Hanly, Gary Mittelbach, and Douglas Schemske) take a different approach to the question of whether latitude affects the process of speciation by examining the global distribution of endemism in freshwater fish. The world’s lakes and rivers contain tens of thousands of species fish – thousands of which are endemic (found in a single lake or in a single river basin). Because endemic species are unique evolutionary lineages confined to a single locale, they can be used to explore the conditions promoting the generation of new species. Using a new compilation on the distribution of 1,933 single-lake endemic fish in the world’s largest lakes, Hanly and colleagues show that fish diversification is linked to latitude, lake age, and lake surface area. As expected from previous studies, the generation of endemic species occurs more frequently in both older and larger lakes. However, Hanly et al.’s analysis shows that there is an additional positive effect of low (tropical) latitude on the generation of species and this latitudinal effect is similar in magnitude to the effects of age and area. These results suggest that the evolution of biodiversity is not a consistent process across the globe and that factors such as climatic stability, the importance of biotic interactions, and the exploitation of unique niches may contribute to the evolution of the richness of life in the tropics. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Endemic fish show that speciation is faster at lower latitudes even after controlling for the effects of age and area </b></p><p><span style="line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-size: 40px; font-weight: bold; float: left;">T</span>he tropics are extraordinarily rich in species, but understanding the ecological and evolutionary causes of such diversity is challenging. Particularly controversial is whether tropical and temperate regions differ in how quickly new species arise. Analyses of DNA-based molecular phylogenies are increasing used to estimate latitudinal differences on speciation rates, but as yet there is little consensus in their conclusions (for example, see recent articles by Machac and Graham (2016) and Schluter (2016) in <i>The American Naturalist</i>). Here, three researchers from Michigan State University (Patrick Hanly, Gary Mittelbach, and Douglas Schemske) take a different approach to the question of whether latitude affects the process of speciation by examining the global distribution of endemism in freshwater fish. The world&rsquo;s lakes and rivers contain tens of thousands of species fish &ndash; thousands of which are endemic (found in a single lake or in a single river basin). Because endemic species are unique evolutionary lineages confined to a single locale, they can be used to explore the conditions promoting the generation of new species.</p> <p>Using a new compilation on the distribution of 1,933 single-lake endemic fish in the world&rsquo;s largest lakes, Hanly and colleagues show that fish diversification is linked to latitude, lake age, and lake surface area. As expected from previous studies, the generation of endemic species occurs more frequently in both older and larger lakes. However, Hanly et al.&rsquo;s analysis shows that there is an additional positive effect of low (tropical) latitude on the generation of species and this latitudinal effect is similar in magnitude to the effects of age and area. These results suggest that the evolution of biodiversity is not a consistent process across the globe and that factors such as climatic stability, the importance of biotic interactions, and the exploitation of unique niches may contribute to the evolution of the richness of life in the tropics. <a href="http://dx.doi.org/10.1086/691535">Read&nbsp;the&nbsp;Article</a></p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"><span style="font-family: Georgia; font-size: large;"><i>More forthcoming papers</i> &raquo;</span></a></div> Fri, 07 Apr 2017 05:00:00 GMT “Eco-evolutionary theory and insect outbreaks” http://amnat.org/an/newpapers/JunePaez.html Evolutionary change helps drive ecological change in gypsy moth outbreaks Insect outbreaks devastate forests, killing trees and reducing the value of timber, but the destruction would be worse if outbreaks weren’t terminated by pathogen epidemics. Pathogens kill insects at very high rates, so if disease resistance is heritable, pathogen epidemics could lead to increased resistance through Darwinian evolution. This is important not just because resistance evolution could keep pathogens from controlling pests, but also because outbreaks occur over and over again in irregular but repeated cycles that might be partly due to evolution for increased resistance. One way to understand how evolution affects pests and population cycles is to construct mathematical models. Models are cheap, and therefore plentiful, but useful applications of the models require estimates of the heritability of disease resistance—and of the extent to which more resistant insects lay fewer eggs, a cost that can prevent the evolution of perfect resistance, in turn preventing forest destruction, but ensuring repeated outbreaks. Estimating these parameters requires field experiments, which are impossible for buffalo and brucellosis, or for fruit bats and Ebola, but which are easy for the gypsy moth and its baculovirus pathogen. David Páez and colleagues therefore used experiments to show that gypsy moths that are more resistant to the baculovirus have more resistant offspring but lay fewer eggs. When they added these effects to mathematical models, outbreaks kept happening, just as in nature, because evolution alternately favored higher resistance and higher eggs per insect, whereas non-evolutionary models show no outbreaks at all. Lately, a fungal pathogen has been keeping gypsy moths in check in eastern North America, but the sensitivity of the fungus to climate change means that the virus is likely to make a comeback. Tired of gypsy moth outbreaks? Darwinian evolution means that they are not going away. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Evolutionary change helps drive ecological change in gypsy moth outbreaks </b></p><p><span style="float: left; font-size: 40px; line-height: 25px; padding-top: 4px; padding-right: 2px; padding-left: 2px; font-family: Garamond; font-weight: bold;">I</span>nsect outbreaks devastate forests, killing trees and reducing the value of timber, but the destruction would be worse if outbreaks weren&rsquo;t terminated by pathogen epidemics. Pathogens kill insects at very high rates, so if disease resistance is heritable, pathogen epidemics could lead to increased resistance through Darwinian evolution. This is important not just because resistance evolution could keep pathogens from controlling pests, but also because outbreaks occur over and over again in irregular but repeated cycles that might be partly due to evolution for increased resistance. </p><p>One way to understand how evolution affects pests and population cycles is to construct mathematical models. Models are cheap, and therefore plentiful, but useful applications of the models require estimates of the heritability of disease resistance&mdash;and of the extent to which more resistant insects lay fewer eggs, a cost that can prevent the evolution of perfect resistance, in turn preventing forest destruction, but ensuring repeated outbreaks. Estimating these parameters requires field experiments, which are impossible for buffalo and brucellosis, or for fruit bats and Ebola, but which are easy for the gypsy moth and its baculovirus pathogen. </p> <p>David Páez and colleagues therefore used experiments to show that gypsy moths that are more resistant to the baculovirus have more resistant offspring but lay fewer eggs. When they added these effects to mathematical models, outbreaks kept happening, just as in nature, because evolution alternately favored higher resistance and higher eggs per insect, whereas non-evolutionary models show no outbreaks at all. </p><p>Lately, a fungal pathogen has been keeping gypsy moths in check in eastern North America, but the sensitivity of the fungus to climate change means that the virus is likely to make a comeback. </p><p>Tired of gypsy moth outbreaks? Darwinian evolution means that they are not going away. <a href="http://dx.doi.org/10.1086/691537">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 05 Apr 2017 05:00:00 GMT “Network structure and selection asymmetry drive coevolution in species-rich antagonistic interactions” http://amnat.org/an/newpapers/JulyAndreazzi.html The selective pressures imposed by ecological interactions are one of the forces shaping adaptation in populations. Coevolution, which is the reciprocal evolutionary change occurring in populations of species that interact, is one of the possible outcomes of the selective pressures imposed by interactions. A major challenge for evolutionary ecology is to understand if and how the coevolutionary process occurs when species interact with individuals of multiple species forming networks of interactions. In a study appearing in The&nbsp;American Naturalist, researchers from Brazil and the United States have used mathematical modeling and numerical simulations to explore how network organization affects and is affected by selection in antagonistic ecological interactions such as parasitism, predation, and herbivory. They find that the joint effects of selection imposed by interaction partners and network organization shape species evolutionary and coevolutionary dynamics in predictable ways, favoring arms races, coevolutionary alternation, or both. Arms races tend to occur when the intensity of selection is stronger on victims than on exploiters. If selection on exploiters is stronger than on victims, coevolutionary alternation is favored by nested network organization, creating asymmetry in specialization between exploiters and victims and generating a hierarchy of preferred victims among exploiters. Finally, their results highlight that coevolution not only is affected by network organization but also reshapes network organization: Higher modularity arises in antagonistic networks as an outcome of the coevolutionary process, emerging as a by-product of stronger selective pressures acting on exploiters. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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 selective pressures imposed by ecological interactions are one of the forces shaping adaptation in populations. Coevolution, which is the reciprocal evolutionary change occurring in populations of species that interact, is one of the possible outcomes of the selective pressures imposed by interactions. A major challenge for evolutionary ecology is to understand if and how the coevolutionary process occurs when species interact with individuals of multiple species forming networks of interactions. </p><p>In a study appearing in <i>The&nbsp;American Naturalist</i>, researchers from Brazil and the United States have used mathematical modeling and numerical simulations to explore how network organization affects and is affected by selection in antagonistic ecological interactions such as parasitism, predation, and herbivory. They find that the joint effects of selection imposed by interaction partners and network organization shape species evolutionary and coevolutionary dynamics in predictable ways, favoring arms races, coevolutionary alternation, or both. Arms races tend to occur when the intensity of selection is stronger on victims than on exploiters. If selection on exploiters is stronger than on victims, coevolutionary alternation is favored by nested network organization, creating asymmetry in specialization between exploiters and victims and generating a hierarchy of preferred victims among exploiters. </p><p>Finally, their results highlight that coevolution not only is affected by network organization but also reshapes network organization: Higher modularity arises in antagonistic networks as an outcome of the coevolutionary process, emerging as a by-product of stronger selective pressures acting on exploiters. <a href="http://dx.doi.org/10.1086/692110">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Wed, 05 Apr 2017 05:00:00 GMT “The evolution of cooperation: interacting phenotypes among social partners” http://amnat.org/an/newpapers/JunEdenbrow.html Many pathways to cooperation: Guppies adjust their antipredator behavior to their social partners Cooperation among non-related individuals is widespread in both human and non-human animals. However, understanding how cooperation is maintained (i.e. why one individual should pay a cost so another can receive a benefit) has puzzled scientists for generations. One of the key requirements for cooperation to evolve is that individuals have a way to find and associate with social partners that behave similarly to themselves. Few studies, however, have demonstrated how animals do this in the wild. Guppies live in rivers in northern Trinidad that vary widely in composition and number of predators, and wherever there are large predatory fish, guppies cooperate to share the risk to investigate potential threats. A group of researchers from the University of Exeter (UK), Stonehill College (USA), and the University of the West Indies (Trinidad) found that guppies change their antipredator behavior depending on the cooperativeness of their social partners. Such behavioral flexibility provides a mechanism for fish to match social partners’ cooperativeness. In the experiments they paired fish with two different social partners across four interactions and measured how much fish changed their behavior based on both their current social partner and previous partners during past interactions.While a fish’s current social partner has the strongest influence on its behavior, longer-lasting effects of interacting with previous partners can be measured in subsequent interactions with other fish. Just how influential social partners are on a fish’s behavior depends on the sex of the fish (males change their behavior more than females) and whether the fish had evolved with predators (fish from low predation populations are more influenced by social partners than fish from high predation populations). The degree to which guppies change their behavior in response to social partners, rather than behaving a particular way, is likely to contribute to whether cooperation evolves in a population. Most importantly, there wasn’t just one route to getting effective cooperation between social partners; different combinations of individuals can lead to successful cooperation. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Many pathways to cooperation: Guppies adjust their antipredator behavior to their social partners </b></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;">C</span>ooperation among non-related individuals is widespread in both human and non-human animals. However, understanding how cooperation is maintained (i.e. why one individual should pay a cost so another can receive a benefit) has puzzled scientists for generations. One of the key requirements for cooperation to evolve is that individuals have a way to find and associate with social partners that behave similarly to themselves. Few studies, however, have demonstrated how animals do this in the wild. Guppies live in rivers in northern Trinidad that vary widely in composition and number of predators, and wherever there are large predatory fish, guppies cooperate to share the risk to investigate potential threats. A group of researchers from the University of Exeter (UK), Stonehill College (USA), and the University of the West Indies (Trinidad) found that guppies change their antipredator behavior depending on the cooperativeness of their social partners. Such behavioral flexibility provides a mechanism for fish to match social partners’ cooperativeness. In the experiments they paired fish with two different social partners across four interactions and measured how much fish changed their behavior based on both their current social partner and previous partners during past interactions.</p><p>While a fish’s current social partner has the strongest influence on its behavior, longer-lasting effects of interacting with previous partners can be measured in subsequent interactions with other fish. Just how influential social partners are on a fish’s behavior depends on the sex of the fish (males change their behavior more than females) and whether the fish had evolved with predators (fish from low predation populations are more influenced by social partners than fish from high predation populations). The degree to which guppies change their behavior in response to social partners, rather than behaving a particular way, is likely to contribute to whether cooperation evolves in a population. Most importantly, there wasn’t just one route to getting effective cooperation between social partners; different combinations of individuals can lead to successful cooperation. <a href="http://dx.doi.org/10.1086/691386">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 04 Apr 2017 05:00:00 GMT “What kind of maternal effects can be selected for in fluctuating environments?” http://amnat.org/an/newpapers/JuneProulx.html Should mothers play dice with their babies’ future? Only when the stakes are really high! How should parents act to improve the fitness of their offspring in an uncertain world? While much attention has been paid to “diversifying bet-hedging” (where offspring phenotypes are randomized), Proulx and Teotónio find that bet-hedging is unlikely to evolve de novo. Rather, most ecological conditions lead to the initial evolution of maternal strategies that base offspring phenotype on the maternal environment itself. This is because parents almost always have some direct probabilistic information about their offspring’s environment simply because environments are correlated in time (positively or negatively). To study the evolution of maternal effects, the researchers considered scenarios where offspring phenotype determines fitness in an environmentally dependent way and where total maternal fecundity depends on the suite of offspring phenotypes, owing to the costs of offspring production. This allows an “apples to apples” comparison between bet-hedging strategies and informed maternal effect strategies with the same phenotypic capabilities. The authors found a simple relationship between the fitness parameters and the frequency of environmental change that shows that informed maternal effects are favored when there is more information available. But fitness comparisons of alternative strategies do not get at the question of the evolutionary dynamics governing the origin of novel strategies. After modeling the micro-evolution of maternal effect strategies, Proulx and Teotónio found that even when the environment contains little information, informed maternal effect strategies are much more likely to evolve than bet-hedging type strategies. However, once phenotypes with extreme differences in environment-dependent fitness evolve, bet-hedging strategies may evolve and come to dominate the population. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Should mothers play dice with their babies&rsquo; future? Only when the stakes are really high! </b></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 should parents act to improve the fitness of their offspring in an uncertain world? While much attention has been paid to “diversifying bet-hedging” (where offspring phenotypes are randomized), Proulx and Teotónio find that bet-hedging is unlikely to evolve de novo. Rather, most ecological conditions lead to the initial evolution of maternal strategies that base offspring phenotype on the maternal environment itself. This is because parents almost always have some direct probabilistic information about their offspring’s environment simply because environments are correlated in time (positively or negatively). </p><p>To study the evolution of maternal effects, the researchers considered scenarios where offspring phenotype determines fitness in an environmentally dependent way and where total maternal fecundity depends on the suite of offspring phenotypes, owing to the costs of offspring production. This allows an “apples to apples” comparison between bet-hedging strategies and informed maternal effect strategies with the same phenotypic capabilities. The authors found a simple relationship between the fitness parameters and the frequency of environmental change that shows that informed maternal effects are favored when there is more information available. But fitness comparisons of alternative strategies do not get at the question of the evolutionary dynamics governing the origin of novel strategies. </p><p>After modeling the micro-evolution of maternal effect strategies, Proulx and Teotónio found that even when the environment contains little information, informed maternal effect strategies are much more likely to evolve than bet-hedging type strategies. However, once phenotypes with extreme differences in environment-dependent fitness evolve, bet-hedging strategies may evolve and come to dominate the population. <a href="http://dx.doi.org/10.1086/691423">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 04 Apr 2017 05:00:00 GMT “Specialization to extremely low-nutrient soils limits the nutritional adaptability of plant lineages” http://amnat.org/an/newpapers/JuneVerboom.html Foliar stoichiometry indicates that specialization to extremely poor soils limits the nutritional adaptability of plants Specialization offers clear benefits in a competitive world but it also has its downsides, especially a loss of versatility. This is as true evolutionarily as it is in the professional world. In a paper appearing in The&nbsp;American Naturalist, Verboom et al. use data for a range of plants sampled from the Cape flora of South Africa to show that the leaf concentrations of physiologically important nutrients such as phosphorus and potassium have a strong genetic basis and are highly regulated, with variation between plant lineages reflecting adaptation to the environments in which they occur. They also show that the rate at which leaf nutrient concentrations evolve differs between lineages, these attributes being least “flexible” in lineages (e.g. Ericaceae, Proteaceae, Restionaceae) which associate almost exclusively with the highly infertile fynbos heathlands of the Cape region. Conservatism in the nutritional attributes of low-nutrient, fynbos-specialist lineages probably explains why the fynbos flora is so different taxonomically from that of the surrounding vegetation, which for the most part associates with more fertile soils. It also suggests that fynbos-specialist lineages should be less predisposed to speciation via adaptation to soils of contrasting fertility than are non-specialist lineages. This is important for our understanding of why the Cape flora is so rich, particularly given the considerable importance accorded to geological and soil heterogeneity as a driver of plant speciation in the Cape. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Foliar stoichiometry indicates that specialization to extremely poor soils limits the nutritional adaptability of plants </b></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>pecialization offers clear benefits in a competitive world but it also has its downsides, especially a loss of versatility. This is as true evolutionarily as it is in the professional world. In a paper appearing in <i>The&nbsp;American Naturalist</i>, Verboom et al. use data for a range of plants sampled from the Cape flora of South Africa to show that the leaf concentrations of physiologically important nutrients such as phosphorus and potassium have a strong genetic basis and are highly regulated, with variation between plant lineages reflecting adaptation to the environments in which they occur. They also show that the rate at which leaf nutrient concentrations evolve differs between lineages, these attributes being least “flexible” in lineages (e.g. Ericaceae, Proteaceae, Restionaceae) which associate almost exclusively with the highly infertile fynbos heathlands of the Cape region. Conservatism in the nutritional attributes of low-nutrient, fynbos-specialist lineages probably explains why the fynbos flora is so different taxonomically from that of the surrounding vegetation, which for the most part associates with more fertile soils. It also suggests that fynbos-specialist lineages should be less predisposed to speciation via adaptation to soils of contrasting fertility than are non-specialist lineages. This is important for our understanding of why the Cape flora is so rich, particularly given the considerable importance accorded to geological and soil heterogeneity as a driver of plant speciation in the Cape. <a href="http://dx.doi.org/10.1086/691449">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Tue, 04 Apr 2017 05:00:00 GMT “Re-examining the causes and meaning of the risk allocation hypothesis” http://amnat.org/an/newpapers/JuneLuttbeg.html Prey have to balance avoiding predators and finding food. Periods of lower predation risk can provide prey with the opportunity to forage intensely while risk is relatively low. Lima and Bednekoff in 1999 presented their risk allocation model and showed that as the frequency of high-risk periods increases prey are expected to increase their foraging efforts during both low- and high-risk periods. In a new article appearing in The&nbsp;American Naturalist, Barney Luttbeg of Oklahoma State University presents a model that explores how the predicted behavior of prey is affected by receiving imperfect information about the current state of their environment. Imperfect information has two main effects. It causes mistakes in prey behavior because individuals incorrectly assess the current state of their environment, and this weakens the risk allocation prediction. Long-term evolutionary exposure to imperfect information also changes how much individuals should rely on information they receive. The researcher finds that prey that have evolved in the presence of imperfect information can show a decrease in foraging efforts as the frequency of high-risk periods increases, which is a reversal of the risk allocation prediction. As environments continue to be quickly altered by human activities, a critical question is how individuals will behave and perform in altered environments. Luttbeg’s work highlights that the answer to this question will depend on how past environments have shaped the expectations and cognitive rules of individuals. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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>rey have to balance avoiding predators and finding food. Periods of lower predation risk can provide prey with the opportunity to forage intensely while risk is relatively low. Lima and Bednekoff in 1999 presented their risk allocation model and showed that as the frequency of high-risk periods increases prey are expected to increase their foraging efforts during both low- and high-risk periods. In a new article appearing in <i>The&nbsp;American Naturalist</i>, Barney Luttbeg of Oklahoma State University presents a model that explores how the predicted behavior of prey is affected by receiving imperfect information about the current state of their environment. Imperfect information has two main effects. It causes mistakes in prey behavior because individuals incorrectly assess the current state of their environment, and this weakens the risk allocation prediction. Long-term evolutionary exposure to imperfect information also changes how much individuals should rely on information they receive. The researcher finds that prey that have evolved in the presence of imperfect information can show a decrease in foraging efforts as the frequency of high-risk periods increases, which is a reversal of the risk allocation prediction. As environments continue to be quickly altered by human activities, a critical question is how individuals will behave and perform in altered environments. Luttbeg’s work highlights that the answer to this question will depend on how past environments have shaped the expectations and cognitive rules of individuals. <a href="http://dx.doi.org/10.1086/691470">Read&nbsp;the&nbsp;Article</a> </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, 29 Mar 2017 05:00:00 GMT “Why have multiple plastic responses? Interactions between color change and heat avoidance behavior in Battus philenor larvae” http://amnat.org/an/newpapers/JuneNielsen.html Color change and heat avoidance behavior complement each other, helping caterpillars stay cool on different timescales Pipevine swallowtail caterpillars cool themselves off in the summer by changing color when they molt from a light-absorbing black to a brighter, cooler red, but they can also cool off by leaving their short host plant to seek a refuge further above the hot ground. However, do these two responses to high temperatures work well together, or is one simply better? As part of his dissertation research, Matthew Nielsen along with his advisor Daniel Papaj at the University of Arizona addressed this question using experiments with both live caterpillars and painted models of them at the Santa Rita Experimental Range in southern Arizona. They found that not only can behavior cool caterpillars much more than color change, but once caterpillars leave their host for a refuge, color hardly affects their temperature or survival at all.Nevertheless, color change reduces the amount of time caterpillars need to spend on refuges, which gives them more time on their host plant to eat. Thus, color change and refuge-seeking each work best on different timescales; refuge-seeking provides a strong, rapid response to daily temperature variation while color change provides a less costly response to temperature changes that persist for multiple days. Interactions between different responses to temperature have received little attention, but similar interactions to these likely occur between behavior and other temperature responses in many other animals. This research improves our understanding of how animals can combine changes in multiple traits when responding to temperature change in their environment, including climate change, and provides a new framework which can be applied to the study of responses to many different environmental changes. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Color change and heat avoidance behavior complement each other, helping caterpillars stay cool on different timescales </b></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>ipevine swallowtail caterpillars cool themselves off in the summer by changing color when they molt from a light-absorbing black to a brighter, cooler red, but they can also cool off by leaving their short host plant to seek a refuge further above the hot ground. However, do these two responses to high temperatures work well together, or is one simply better? As part of his dissertation research, Matthew Nielsen along with his advisor Daniel Papaj at the University of Arizona addressed this question using experiments with both live caterpillars and painted models of them at the Santa Rita Experimental Range in southern Arizona. They found that not only can behavior cool caterpillars much more than color change, but once caterpillars leave their host for a refuge, color hardly affects their temperature or survival at all.</p><p>Nevertheless, color change reduces the amount of time caterpillars need to spend on refuges, which gives them more time on their host plant to eat. Thus, color change and refuge-seeking each work best on different timescales; refuge-seeking provides a strong, rapid response to daily temperature variation while color change provides a less costly response to temperature changes that persist for multiple days. Interactions between different responses to temperature have received little attention, but similar interactions to these likely occur between behavior and other temperature responses in many other animals. This research improves our understanding of how animals can combine changes in multiple traits when responding to temperature change in their environment, including climate change, and provides a new framework which can be applied to the study of responses to many different environmental changes. <a href="http://dx.doi.org/10.1086/691536">Read&nbsp;the&nbsp;Article</a> </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, 29 Mar 2017 05:00:00 GMT “A water-borne pursuit-deterrent signal deployed by a sea urchin” http://amnat.org/an/newpapers/JunShepBren-A.html Unusual defense deployed by a sea urchin Abstract Selection by consumers has led to the evolution of a vast array of defenses in animals and plants. These defenses include physical structures, behaviors, and chemical signals that mediate interactions with predators. Some of the strangest defensive structures in nature are the globiferous pedicellariae of the echinoderms. These are small venomous appendages with jaws and teeth that cover the test of many sea urchins and sea stars. In this study, we report a unique use of these defensive structures by the collector sea urchin Tripneustes gratilla. In both the laboratory and the field, globiferous pedicellariae were unpalatable to fish consumers. When subject to simulated predator attack, sea urchins released a cloud of pedicellaria heads into the water column. Flume experiments established the presence of a water-borne cue associated with this release of pedicellariae that is deterrent to predatory fish. These novel results add to our understanding of how the ecosystem-shaping sea urchin T.&nbsp;gratilla is able to reach high densities in many reef habitats with subsequent impacts on algal cover. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Unusual defense deployed by a sea urchin </b></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>election by consumers has led to the evolution of a vast array of defenses in animals and plants. These defenses include physical structures, behaviors, and chemical signals that mediate interactions with predators. Some of the strangest defensive structures in nature are the globiferous pedicellariae of the echinoderms. These are small venomous appendages with jaws and teeth that cover the test of many sea urchins and sea stars. In this study, we report a unique use of these defensive structures by the collector sea urchin <i>Tripneustes gratilla</i>. In both the laboratory and the field, globiferous pedicellariae were unpalatable to fish consumers. When subject to simulated predator attack, sea urchins released a cloud of pedicellaria heads into the water column. Flume experiments established the presence of a water-borne cue associated with this release of pedicellariae that is deterrent to predatory fish. These novel results add to our understanding of how the ecosystem-shaping sea urchin <i>T.&nbsp;gratilla</i> is able to reach high densities in many reef habitats with subsequent impacts on algal cover. <a href="http://dx.doi.org/10.1086/691437">Read&nbsp;the&nbsp;Article</a> </p> <div style="float: right;"><a href="http://www.amnat.org/an/newpapers.html"> <span style="font-size: large; font-family: Georgia;"><i>More forthcoming papers</i> &raquo;</span></a></div> Mon, 27 Mar 2017 05:00:00 GMT “Timing of breeding in an ecologically trapped bird” http://amnat.org/an/newpapers/MayHollander.html Human-induced environmental change has the capacity to confuse the way organisms perceive their environment and ultimately respond to it. For instance, organisms may prefer to settle and reproduce in anthropogenic habitats of low quality even when higher-quality habitat is available. Such ecological traps lead to fitness loss and are of growing conservation concern worldwide. While the underlying mechanisms are still poorly understood, a recent study shows a functional explanation for ecological traps in seasonally changing environments. Researchers from the Université Catholique de Louvain in Belgium studied the relationship between timing of breeding, reproductive performance, and food resources to explain the observed ecological trap in the red-backed shrike (Lanius collurio), a long-distant migratory bird breeding in seasonally changing habitats. Their previous work showed that this bird prefers to breed in newly colonized forest clearings, where its reproductive performance is significantly lower than in farmland, which is its original longtime breeding habitat. For three successive years, they sampled data in these two human-modified habitats. The team found a stronger seasonal decrease in the food resources available for rearing nestlings in forest clearings compared to farmland habitat. This provides a functional explanation for why brood size and quality also gradually decreased more strongly in the preferred forest habitat over the course of the season. This is the first time that maladaptive timing of breeding has been found to explain fitness loss in an ecological trap. The same mechanism possibly creates ecological traps for a wide range of organisms breeding in seasonal environments. There is now a need to study how trapped organisms will further cope with their situation and with further environmental change that might arise. The results of this study are also relevant for conservation strategies: Plantation forests may provide less valuable conservation opportunities than previously thought. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <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-induced environmental change has the capacity to confuse the way organisms perceive their environment and ultimately respond to it. For instance, organisms may prefer to settle and reproduce in anthropogenic habitats of low quality even when higher-quality habitat is available. Such ecological traps lead to fitness loss and are of growing conservation concern worldwide. While the underlying mechanisms are still poorly understood, a recent study shows a functional explanation for ecological traps in seasonally changing environments. </p> <p>Researchers from the Université Catholique de Louvain in Belgium studied the relationship between timing of breeding, reproductive performance, and food resources to explain the observed ecological trap in the red-backed shrike (<i>Lanius collurio</i>), a long-distant migratory bird breeding in seasonally changing habitats. Their previous work showed that this bird prefers to breed in newly colonized forest clearings, where its reproductive performance is significantly lower than in farmland, which is its original longtime breeding habitat. For three successive years, they sampled data in these two human-modified habitats. </p> <p>The team found a stronger seasonal decrease in the food resources available for rearing nestlings in forest clearings compared to farmland habitat. This provides a functional explanation for why brood size and quality also gradually decreased more strongly in the preferred forest habitat over the course of the season. This is the first time that maladaptive timing of breeding has been found to explain fitness loss in an ecological trap. </p> <p>The same mechanism possibly creates ecological traps for a wide range of organisms breeding in seasonal environments. There is now a need to study how trapped organisms will further cope with their situation and with further environmental change that might arise. The results of this study are also relevant for conservation strategies: Plantation forests may provide less valuable conservation opportunities than previously thought. <a href="http://dx.doi.org/10.1086/691329">Read&nbsp;the&nbsp;Article</a> </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, 23 Mar 2017 05:00:00 GMT