ASN RSS http://amnat.org/ Latest press releases and announcements from the ASN en-us Mon, 18 Sep 2017 05:00:00 GMT 60 “Artificial selection to increase the phenotypic variance in gmax fails” http://amnat.org/an/newpapers/NovSztepanacz.html Many traits are subject to stabilizing selection that acts to reduce or maintain levels of genetic variance and the status quo. Each generation genetic variation is increased by mutation and removed by selection, such that the resulting genetic variation, known as the standing genetic variance, should reflect the outcome of these two competing processes. As a consequence, some theories predict that the magnitude of standing genetic variance in traits may reflect the strength of stabilizing selection that acts on them. Traits with high standing genetic variance may be subject to weaker stabilizing selection than traits with low standing genetic variance. This pattern is, of course, correlative. More direct evidence for the strength of stabilizing selection may be gained by manipulating traits to increase their variance, where the extent to which a trait increases in variance indicates the strength of stabilizing selection acting on it. Working with a population of the Australian fruit-fly Drosophila serrata, Sztepanacz and Blows applied artificial selection to increase the variance in two traits, where the strength of stabilizing selection acting on each was predicted to differ by an order of magnitude. Contrary to their expectations the trait predicted to be under strong stabilizing selection increased in phenotypic variance to a large extent, by more than a third of a phenotypic standard deviation. In contrast, the trait predicted to be under weak stabilizing selection showed a completely unexpected response, decreasing in variance. While their results overall provided evidence for stabilizing selection acting in this population, the pattern was not consistent with predictions based on the levels of estimated mutational variance and standing genetic variance in these traits. The reasons why remain unresolved, but the authors explore several possibilities in the paper. 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;">M</span>any traits are subject to stabilizing selection that acts to reduce or maintain levels of genetic variance and the status quo. Each generation genetic variation is increased by mutation and removed by selection, such that the resulting genetic variation, known as the standing genetic variance, should reflect the outcome of these two competing processes. As a consequence, some theories predict that the magnitude of standing genetic variance in traits may reflect the strength of stabilizing selection that acts on them. Traits with high standing genetic variance may be subject to weaker stabilizing selection than traits with low standing genetic variance. This pattern is, of course, correlative. More direct evidence for the strength of stabilizing selection may be gained by manipulating traits to increase their variance, where the extent to which a trait increases in variance indicates the strength of stabilizing selection acting on it. </p><p>Working with a population of the Australian fruit-fly <i>Drosophila serrata</i>, Sztepanacz and Blows applied artificial selection to increase the variance in two traits, where the strength of stabilizing selection acting on each was predicted to differ by an order of magnitude. Contrary to their expectations the trait predicted to be under strong stabilizing selection increased in phenotypic variance to a large extent, by more than a third of a phenotypic standard deviation. In contrast, the trait predicted to be under weak stabilizing selection showed a completely unexpected response, decreasing in variance. While their results overall provided evidence for stabilizing selection acting in this population, the pattern was not consistent with predictions based on the levels of estimated mutational variance and standing genetic variance in these traits. The reasons why remain unresolved, but the authors explore several possibilities in the paper. <a href="http://dx.doi.org/10.1086/693959">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, 15 Sep 2017 05:00:00 GMT Nominate ASN President, Vice President, & Secretary http://amnat.org/announcements/NomASNOfficersANN.html Members of the American Society of Naturalists are encouraged to submit nominations for the Executive Committee (EC). Elections will be held in 2018 for President, Vice President, and Secretary President serves on the EC from 2019-2023, acting as President in 2020 Vice President serves on the EC from 2019-2021, acting as VP in 2020. The VP organizes a symposium to be presented at the meetings in 2020 and edits the papers for The American Naturalist.. Secretary serves on the EC from 2019-2021 and then as past-Secretaru from 2022-2024. Names of nominees for specific offices should be submitted by October 15, 2017, to Suzanne Alonzo shalonzo@ucsc.edu Please indicate “ASN Nomination” in the subject line. As you contemplate nominations, you may want to check the current (http://www.amnat.org/about/governance/execcomm.html) and past officers (http://www.amnat.org/about/history/past-ec.html) for reference. &nbsp;The PRESIDENT leads the ASN Executive Council and selects the membership of the award and officer nomination committees. The President selects the President’s Award for the “best” paper in The American Naturalist in the past year, gives the ASN Presidential Address and presents the Society’s awards at the annual meeting, and represents the ASN in multiple other ways through the year. The President serves on the Executive Council for five years, including one year as President-Elect and three years as a Past-President. The VICE PRESIDENT organizes the Vice-President’s Symposium for the annual meeting and edits the special supplement to The American Naturalist that contains the papers derived from the VP Symposium. The Vice-President is also the Society’s liaison for the organizers of the annual meeting. The Vice-President serves as a member of the Executive Council for three years, two as a regular member and one as ex officio member. The TREASURER manages the accounts of the ASN, tracks all revenues and expenses, arranges for official annual financial reviews and tax return preparation, files tax returns, makes payments for all annual awards and travel reimbursements related to the annual meeting, keeps track of revisions to the award amounts and reimbursement policies, and prepares the annual Treasurer’s Report. The Treasurer also convenes a Finance Committee comprised of two other members of the Executive Council, for making investment decisions as needed. The Treasurer serves on the Executive Council for six years, three as a regular member and three as Past Treasurer. <p>Members of the American Society of Naturalists are encouraged to submit nominations for the Executive Committee (EC). Elections will be held in 2018 for President, Vice President, and Secretary</p> <ul> <li>President serves on the EC from 2019-2023, acting as President in 2020</li> <li>Vice President serves on the EC from 2019-2021, acting as VP in 2020. The VP organizes a symposium to be presented at the meetings in 2020 and edits the papers for <em>The American Naturalist</em>..</li> <li>Secretary serves on the EC from 2019-2021 and then as past-Secretaru from 2022-2024.</li> </ul> <p>Names of nominees for specific offices should be submitted by October 15, 2017, to Suzanne Alonzo <a href="mailto:shalonzo@ucsc.edu">shalonzo@ucsc.edu</a></p> <p>Please indicate &ldquo;ASN Nomination&rdquo; in the subject line.</p> <p>As you contemplate nominations, you may want to check the current (<a href="http://www.amnat.org/about/governance/execcomm.html">http://www.amnat.org/about/governance/execcomm.html</a>) and past officers (<a href="http://www.amnat.org/about/history/past-ec.html)">http://www.amnat.org/about/history/past-ec.html)</a> for reference.</p> <p>&nbsp;</p><p>The <strong>PRESIDENT </strong>leads the ASN Executive Council and selects the membership of the award and officer nomination committees. The President selects the President&rsquo;s Award for the &ldquo;best&rdquo; paper in <em>The American Naturalist </em>in the past year, gives the ASN Presidential Address and presents the Society&rsquo;s awards at the annual meeting, and represents the ASN in multiple other ways through the year. The President serves on the Executive Council for five years, including one year as President-Elect and three years as a Past-President.</p> <p>The <strong>VICE PRESIDENT </strong>organizes the Vice-President&rsquo;s Symposium for the annual meeting and edits the special supplement to <em>The American Naturalist </em>that contains the papers derived from the VP Symposium. The Vice-President is also the Society&rsquo;s liaison for the organizers of the annual meeting. The Vice-President serves as a member of the Executive Council for three years, two as a regular member and one as ex officio member.</p> <p>The <strong>TREASURER</strong> manages the accounts of the ASN, tracks all revenues and expenses, arranges for official annual financial reviews and tax return preparation, files tax returns, makes payments for all annual awards and travel reimbursements related to the annual meeting, keeps track of revisions to the award amounts and reimbursement policies, and prepares the annual Treasurer&rsquo;s Report. The Treasurer also convenes a Finance Committee comprised of two other members of the Executive Council, for making investment decisions as needed. The Treasurer serves on the Executive Council for six years, three as a regular member and three as Past Treasurer.</p> Thu, 14 Sep 2017 05:00:00 GMT “Habitat association predicts genetic diversity and population divergence in Amazonian birds” http://amnat.org/an/newpapers/NovHarvey.html The habitat in which Amazonian birds occur predicts their patterns of genetic diversity and evolutionary processes Organisms differ dramatically in ecology and behavior, but do these traits have any implications for their evolution? In a new paper, Harvey et al. use Amazonian birds to examine whether one ecological trait, the habitat in which a species occurs, predicts levels and patterns of genetic diversity. They examine genetic data sampled from across the genomes of over four hundred birds sampled during decades of field work in the Amazon Basin. Their results indicate that birds residing in open floodplain forest and edge habitats have less genetic diversity and divergence than those of the interior of upland forest, and that differences may reflect differences in the evolutionary processes at work in the two habitats. The study suggests that habitat association is an organismal trait that impacts evolutionary processes, and that knowledge of organismal traits therefore may be fundamental to understanding the formation of biological diversity and to tailoring conservation efforts to different species. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>The habitat in which Amazonian birds occur predicts their patterns of genetic diversity and evolutionary processes </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;">O</span>rganisms differ dramatically in ecology and behavior, but do these traits have any implications for their evolution? In a new paper, Harvey et al. use Amazonian birds to examine whether one ecological trait, the habitat in which a species occurs, predicts levels and patterns of genetic diversity. They examine genetic data sampled from across the genomes of over four hundred birds sampled during decades of field work in the Amazon Basin. Their results indicate that birds residing in open floodplain forest and edge habitats have less genetic diversity and divergence than those of the interior of upland forest, and that differences may reflect differences in the evolutionary processes at work in the two habitats. The study suggests that habitat association is an organismal trait that impacts evolutionary processes, and that knowledge of organismal traits therefore may be fundamental to understanding the formation of biological diversity and to tailoring conservation efforts to different species. <a href="http://dx.doi.org/10.1086/693856">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, 14 Sep 2017 05:00:00 GMT “Cannibalism and intraguild predation community dynamics: coexistence, competitive exclusion and the loss of alternative stable states” http://amnat.org/an/newpapers/NovToscano.html Cannibalism leads to predator population collapse within stage-structured intraguild predation systems As predators grow in size, their role within ecological communities often changes. A common scenario is that while adult predators consume prey, juvenile predators engage in competition with prey for a shared food resource. In a new article in The&nbsp;American Naturalist, Benjamin Toscano, Vincent Hin, and Volker Rudolf provide evidence that such size-dependent predators are often preferentially cannibalistic, and further use theory to explore how such cannibalism alters the structure of ecological communities that predators inhabit. These authors, from the United States and the Netherlands, demonstrate that cannibalism causes the predator population to shift, counterintuitively, from a preponderance of adult predators to a preponderance of juvenile predators. This simple mechanism has cascading effects induced by a reduction in predation, a function unique to adult predators. For example, Toscano et al. show that cannibalism facilitates coexistence in the community, but can also drive predator extinction depending on system details. Considering the prevalence of size-dependent interactions in nature and that predators face a higher risk of extinction than other trophic levels, this work has broad implications for understanding the potential consequences of predator loss across the globe. Their work shows that even changes to the size structure of predator populations, for example due to fishing practices that target adults, have the capacity to dramatically shift the structure of entire ecological communities to new and potentially irreversible states. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Cannibalism leads to predator population collapse within stage-structured intraguild predation systems </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>s predators grow in size, their role within ecological communities often changes. A common scenario is that while adult predators consume prey, juvenile predators engage in competition with prey for a shared food resource. In a new article in <i>The&nbsp;American Naturalist</i>, Benjamin Toscano, Vincent Hin, and Volker Rudolf provide evidence that such size-dependent predators are often preferentially cannibalistic, and further use theory to explore how such cannibalism alters the structure of ecological communities that predators inhabit. These authors, from the United States and the Netherlands, demonstrate that cannibalism causes the predator population to shift, counterintuitively, from a preponderance of adult predators to a preponderance of juvenile predators. This simple mechanism has cascading effects induced by a reduction in predation, a function unique to adult predators. For example, Toscano et al. show that cannibalism facilitates coexistence in the community, but can also drive predator extinction depending on system details. Considering the prevalence of size-dependent interactions in nature and that predators face a higher risk of extinction than other trophic levels, this work has broad implications for understanding the potential consequences of predator loss across the globe. Their work shows that even changes to the size structure of predator populations, for example due to fishing practices that target adults, have the capacity to dramatically shift the structure of entire ecological communities to new and potentially irreversible states. <a href="http://dx.doi.org/10.1086/693997">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, 14 Sep 2017 05:00:00 GMT Applications invited for the ASN Jasper Loftus-Hills Young Investigator’s Awards! http://amnat.org/announcements/NomYIA.html The American Society of Naturalists invites applications for the Jasper Loftus-Hills Young Investigators Award. This year I have the honor of chairing the ASN YIA committee, along with Luke Harmon, Janneke Hille Ris Lambers, and Renee Duckworth. I think it’s great that ASN honors not just one but four outstanding young investigators from across ecology, evolution, behavior, and genetics. The official announcement for award nominations is copied below, but I wanted to start out with some personal reflections on the recent applicant pool and award winners, along with a specific plea to encourage more topical diversity in our applicants. Every year’s applicant pool is truly outstanding, and in many respects it’s an admirably diverse pool. I’m particularly glad about the high gender diversity of both the applicant pool and the award winners in recent years. But recent applicant pools have featured a predominance of evolutionary work (particularly on sexual selection and sexual conflict), and a relative paucity of ecology. Ideally, we’d like the applicant pool to include people working on the full range of topics of interest to ASN members. So without wanting to discourage applications from those working in areas traditionally well-represented in the applicant pool, let me emphasize that we welcome and encourage applicants working in any area of ecology, evolution, behavioral ecology, or genetics. The YIA committee is a broad-minded group that includes significant ecological expertise. All applicants from every field will be given full consideration. Let me emphasize as well that the committee doesn’t favor applicants at a particular career stage, we don’t disfavor applicants who’ve applied before, and we don’t base our decisions on quantitative metrics. You can apply as soon as you are eligible and for as long as you are eligible, and we encourage you to do so. You’ll be considered fully even if you’re still in graduate school or only recently finished your Ph.D. Not all past awardees were in their final year of eligibility. And the committee will evaluate your application holistically and consider your scientific work on its merits, rather than by just counting your publications, or looking at your h-index, or etc. Looking forward to receiving your applications. If you have any questions, please feel free to email me (jefox@ucalgary.ca). Below is the official call for applications. The Jasper Loftus-Hill Young Investigator’s Award of the American Society of Naturalists honors outstanding promise and accomplishments of young investigators who conduct integrative work in the fields of Ecology, Evolutionary Biology, Behavioral Ecology and Genetics. Applicants working in any of these fields are encouraged to apply. The award honors outstanding promise and accomplishments of young investigators (3 years post-Ph.D., or in the final year of their Ph.D.) who conduct integrative work in ecology, evolution, behavioral ecology, and genetics. The award was established in 1984 to recognize exceptional work by investigators who received their doctorates in the three years preceding the application deadline, or who are in their final year of graduate school. The award commemorates Jasper Loftus-Hills (1946-1974), an Australian biologist of exceptional promise who was killed during the course of fieldwork three years after receiving his degree. Winners of this award will present a research paper in the Young Investigator’s Symposium at the ASN annual meeting and receive a $500 prize, a travel allowance of $700, cost of registration for the meetings, and a supplement of $500 in case of intercontinental travel. Four awards are made annually. Recipients need not be members of the Society. The prize committee encourages direct applications and welcomes suggestions of people who should be encouraged to apply. Applications should consist of no more than three pages that summarize the applicant’s work (excluding tables, figures, and references), no more than four appropriate reprints, and a CV combined as a single pdf. Two letters from individuals familiar with the applicant’s work should be sent separately. All application materials should be sent via e-mail by January 1, 2018, to Jeremy Fox (jefox@ucalgary.ca). Please indicate “Young Investigators’ Award” in the subject line, and for reference letters, the name of the applicant. Jasper Loftus-Hills (1946-1974) was an Australian biologist of exceptional promise who lost his life doing fieldwork recording frog calls in Texas, three years after receiving his degree from the University of Melbourne. An obituary appeared in Copeia:&nbsp;in 1974 (Alexander, Richard D. "Jasper Loftus-Hills." Copeia 1974:812-13).&nbsp; The Golden Coqui (in the photo above) was discovered on Puerto Rico by George E. Drewry, Kirkland L. Jones, Julia R. Clark, and Jasper J. Loftus-Hills. They had planned to name the species for its color, but when Loftus-Hills was killed in 1974, his colleagues chose instead to name it in his honor:&nbsp; A further description of Jasper Loftus-Hills appeared in&nbsp;Copeia 2015 (103:467-475), which is a retrospective on his mentor, Murray John Littlejohn (doi:&nbsp;http://dx.doi.org/10.1643/OT-15-274) The most gifted graduate student Murray ever worked with (in his own estimation) was Jasper Loftus-Hills, whose Ph.D. thesis “Auditory function and acoustic communication in anuran amphibians” was completed in 1971. Jasper followed in Murray’s footsteps to Austin and then went on to Cornell University and the University of Michigan. He was tragically killed by a hit-and-run driver while doing night fieldwork on Gastrophryne in Texas in 1974. The 1992 Gastrophryne paper coauthored by Jasper and Murray is a lucid analysis of the state of the art in character displacement and reinforcement, two terms burdened with a long history of confusion. &nbsp;(Loftus-Hills, J. J., and M. J. Littlejohn.&nbsp;1992.&nbsp;Reinforcement and reproductive character displacement inGastrophryne carolinensis&nbsp;and&nbsp;G. olivacea&nbsp;(Anura: Microhylidae): a re-evaluation.&nbsp;Evolution 46:896–906. &nbsp; <p>The American Society of Naturalists invites applications for the Jasper Loftus-Hills Young Investigators Award. This year I have the honor of chairing the ASN YIA committee, along with Luke Harmon, Janneke Hille Ris Lambers, and Renee Duckworth. I think it&rsquo;s great that ASN honors not just one but four outstanding young investigators from across ecology, evolution, behavior, and genetics.</p> <p>The official announcement for award nominations is copied below, but I wanted to start out with some personal reflections on the recent applicant pool and award winners, along with a specific plea to encourage more topical diversity in our applicants.</p> <p>Every year&rsquo;s applicant pool is truly outstanding, and in many respects it&rsquo;s an admirably diverse pool. I&rsquo;m particularly glad about the high gender diversity of both the applicant pool and the award winners in recent years. But recent applicant pools have featured a predominance of evolutionary work (particularly on sexual selection and sexual conflict), and a relative paucity of ecology. Ideally, we&rsquo;d like the applicant pool to include people working on the full range of topics of interest to ASN members. So without wanting to discourage applications from those working in areas traditionally well-represented in the applicant pool, let me emphasize that we welcome and encourage applicants working in any area of ecology, evolution, behavioral ecology, or genetics. The YIA committee is a broad-minded group that includes significant ecological expertise. All applicants from every field will be given full consideration.</p> <p>Let me emphasize as well that the committee doesn&rsquo;t favor applicants at a particular career stage, we don&rsquo;t disfavor applicants who&rsquo;ve applied before, and we don&rsquo;t base our decisions on quantitative metrics. You can apply as soon as you are eligible and for as long as you are eligible, and we encourage you to do so. You&rsquo;ll be considered fully even if you&rsquo;re still in graduate school or only recently finished your Ph.D. Not all past awardees were in their final year of eligibility. And the committee will evaluate your application holistically and consider your scientific work on its merits, rather than by just counting your publications, or looking at your h-index, or etc.</p> <p>Looking forward to receiving your applications. If you have any questions, please feel free to email me (<a href="mailto:jefox@ucalgary.ca">jefox@ucalgary.ca</a>). Below is the official call for applications.</p> <hr><p>The Jasper Loftus-Hill Young Investigator&rsquo;s Award of the American Society of Naturalists honors outstanding promise and accomplishments of young investigators who conduct integrative work in the fields of Ecology, Evolutionary Biology, Behavioral Ecology and Genetics. Applicants working in any of these fields are encouraged to apply.</p> <p>The award honors outstanding promise and accomplishments of young investigators (3 years post-Ph.D., or in the final year of their Ph.D.) who conduct integrative work in ecology, evolution, behavioral ecology, and genetics. The award was established in 1984 to recognize exceptional work by investigators who received their doctorates in the three years preceding the application deadline, or who are in their final year of graduate school. The award commemorates Jasper Loftus-Hills (1946-1974), an Australian biologist of exceptional promise who was killed during the course of fieldwork three years after receiving his degree.</p> <p>Winners of this award will present a research paper in the Young Investigator&rsquo;s Symposium at the ASN annual meeting and receive a $500 prize, a travel allowance of $700, cost of registration for the meetings, and a supplement of $500 in case of intercontinental travel. Four awards are made annually. Recipients need not be members of the Society.</p> <p>The prize committee encourages direct applications and welcomes suggestions of people who should be encouraged to apply. Applications should consist of no more than three pages that summarize the applicant&rsquo;s work (excluding tables, figures, and references), no more than four appropriate reprints, and a CV combined as a single pdf. Two letters from individuals familiar with the applicant&rsquo;s work should be sent separately. All application materials should be sent via e-mail by January 1, 2018, to Jeremy Fox (<a href="mailto:jefox@ucalgary.ca">jefox@ucalgary.ca</a>). Please indicate &ldquo;Young Investigators&rsquo; Award&rdquo; in the subject line, and for reference letters, the name of the applicant.</p> <hr><p>Jasper Loftus-Hills (1946-1974) was an Australian biologist of exceptional promise who lost his life doing fieldwork recording frog calls in Texas, three years after receiving his degree from the University of Melbourne.</p> <p><a href="/dam/jcr:50a091cd-227f-4bff-9f60-687a6679b1d8/JLH%20obituary.pdf">An obituary appeared in Copeia:</a>&nbsp;in 1974 (Alexander, Richard D. &quot;Jasper Loftus-Hills.&quot; <em>Copeia </em>1974:812-13).&nbsp;</p> <p>The Golden Coqui (in the photo above) was discovered on Puerto Rico by George E. Drewry, Kirkland L. Jones, Julia R. Clark, and Jasper J. Loftus-Hills. They had planned to name the species for its color, but when Loftus-Hills was killed in 1974, his colleagues chose instead to name it in his honor:&nbsp;</p> <p>A further description of Jasper Loftus-Hills appeared in&nbsp;<span style="color: rgb(88, 89, 91); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">Copeia 2015 (103:467-475), which is a retrospective on his mentor, Murray John Littlejohn (</span><span style="color: rgb(88, 89, 91); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">doi:&nbsp;</span><a href="http://dx.doi.org/10.1643/OT-15-274" style="color: rgb(57, 71, 141); text-decoration: none; font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">http://dx.doi.org/10.1643/OT-15-274</a>)</p> <blockquote>The most gifted graduate student Murray ever worked with (in his own estimation) was Jasper Loftus-Hills, whose Ph.D. thesis &ldquo;Auditory function and acoustic communication in anuran amphibians&rdquo; was completed in 1971. Jasper followed in Murray&rsquo;s footsteps to Austin and then went on to Cornell University and the University of Michigan. He was tragically killed by a hit-and-run driver while doing night fieldwork on Gastrophryne in Texas in 1974. The 1992 Gastrophryne paper coauthored by Jasper and Murray is a lucid analysis of the state of the art in character displacement and reinforcement, two terms burdened with a long history of confusion. &nbsp;(<span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">Loftus-Hills, J. J., and M. J. Littlejohn.&nbsp;</span><span class="NLM_year" style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">1992</span><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">.&nbsp;</span><span class="NLM_article-title" style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">Reinforcement and reproductive character displacement in<i>Gastrophryne carolinensis</i>&nbsp;and&nbsp;<i>G. olivacea</i>&nbsp;(Anura: Microhylidae): a re-evaluation</span><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">.&nbsp;</span><span class="citation_source-journal" style="font-style: italic; color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">Evolution </span><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">46:</span><span class="NLM_fpage" style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">896</span><span style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">&ndash;</span><span class="NLM_lpage" style="color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">906</span><span class="citation_source-journal" style="font-style: italic; color: rgb(0, 0, 0); font-family: Verdana, Arial, Helvetica, sans-serif; font-size: 12.512px;">. </span></blockquote> <p>&nbsp;</p> Thu, 14 Sep 2017 05:00:00 GMT “The evolution of clutch size in hosts of avian brood parasites” http://amnat.org/an/newpapers/NovMedina.html Avian brood parasites, like cuckoos, could be selecting for larger clutches in their hosts Clutch size is a very important and variable trait in birds. Some birds, such as albatrosses and petrels, lay only one egg per breeding season, while pheasants usually lay around ten. Researchers have found that latitude and nest type are important predictors of avian clutch size, and species at higher latitudes and with cavity nests have larger clutches. In a recent article, Medina et al. explore whether the interaction between brood parasites and hosts could also affect the evolution of clutch size. Avian brood parasites lay their eggs in the nests of other species, their hosts. There are ~100 species of brood parasites and more than 500 species of hosts. The most famous brood parasites are cuckoos, and cuckoo chicks evict all the other host eggs from the nest, being left to receive all the parental care of their foster parents. By using a mathematical model, Medina et al. found that selection can potentially favor the evolution of larger clutches, in hosts of brood parasites. This result was further complemented by current information on clutch size in over 800 species, which revealed that species that suffer larger costs from parasitism (e.g. smaller species exploited by large cuckoos) tend to have larger clutches. These results suggest that brood parasitism could be an important force in driving the evolution of clutch size in species that are hosts of brood parasites. This interesting possibility should be further explored with field and experimental data in different species. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Avian brood parasites, like cuckoos, could be selecting for larger clutches in their hosts </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>lutch size is a very important and variable trait in birds. Some birds, such as albatrosses and petrels, lay only one egg per breeding season, while pheasants usually lay around ten. Researchers have found that latitude and nest type are important predictors of avian clutch size, and species at higher latitudes and with cavity nests have larger clutches. In a recent article, Medina et al. explore whether the interaction between brood parasites and hosts could also affect the evolution of clutch size. </p><p>Avian brood parasites lay their eggs in the nests of other species, their hosts. There are ~100 species of brood parasites and more than 500 species of hosts. The most famous brood parasites are cuckoos, and cuckoo chicks evict all the other host eggs from the nest, being left to receive all the parental care of their foster parents. By using a mathematical model, Medina et al. found that selection can potentially favor the evolution of larger clutches, in hosts of brood parasites. This result was further complemented by current information on clutch size in over 800 species, which revealed that species that suffer larger costs from parasitism (e.g. smaller species exploited by large cuckoos) tend to have larger clutches. </p><p>These results suggest that brood parasitism could be an important force in driving the evolution of clutch size in species that are hosts of brood parasites. This interesting possibility should be further explored with field and experimental data in different species. <a href="http://dx.doi.org/10.1086/693778">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, 05 Sep 2017 05:00:00 GMT “Bioinvasion triggers rapid evolution of life-histories in freshwater snails” http://amnat.org/an/newpapers/NovChapuis.html For the first time, a study tries to measure rapid evolution in coexisting, close invasive, and native species at the same time Biological invasions are a major threat to biodiversity, but at the same time they have been recognized as unique field settings to observe evolutionary and ecological processes. A major issue is to evaluate how invasive species and native species evolve in the course of an invasion. Invaders and natives face different evolutionary challenges, since introduced species may not invade if they do not tolerate well interactions with natives, while the reverse is not necessarily true. Therefore, traits in natives should be selected to minimize negative impacts of invaders, while trait evolution in invasives should rather be constrained by colonization dynamics, reflecting selection for colonizing ability and/or transient mutation accumulation at the colonization front (the so-called expansion load). These ideas are tested by Chapuis and colleagues in a collaborative work between researchers from IRD Montpellier and La Réunion and from the CNRS-CEFE in Montpellier, by comparing populations invaded at different times in two competing related species, one invasive and one native. The authors apply this approach through a common-garden experiment in two freshwater snails competing in the pond network of a tropical island. In agreement with their hypothesis, they find evidence of rapid evolution of life-history traits in the native species in a way that favours coexistence with the invasive, while trait changes in the invasive species reflect slightly decreased performances at the invasion front as predicted by the expansion load hypothesis. This study not only adds to a growing number of examples of well-documented rapid evolution, but is also the first to measure evolution in coexisting, related invasive and native species at the same time. It also illustrates how the evolution of life history traits may play a role in promoting species coexistence in a guild, as suggested by recent ecological theory. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>For the first time, a study tries to measure rapid evolution in coexisting, close invasive, and native species at the same time </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;">B</span>iological invasions are a major threat to biodiversity, but at the same time they have been recognized as unique field settings to observe evolutionary and ecological processes. A major issue is to evaluate how invasive species and native species evolve in the course of an invasion. Invaders and natives face different evolutionary challenges, since introduced species may not invade if they do not tolerate well interactions with natives, while the reverse is not necessarily true. Therefore, traits in natives should be selected to minimize negative impacts of invaders, while trait evolution in invasives should rather be constrained by colonization dynamics, reflecting selection for colonizing ability and/or transient mutation accumulation at the colonization front (the so-called expansion load). </p><p>These ideas are tested by Chapuis and colleagues in a collaborative work between researchers from IRD Montpellier and La Réunion and from the CNRS-CEFE in Montpellier, by comparing populations invaded at different times in two competing related species, one invasive and one native. The authors apply this approach through a common-garden experiment in two freshwater snails competing in the pond network of a tropical island. In agreement with their hypothesis, they find evidence of rapid evolution of life-history traits in the native species in a way that favours coexistence with the invasive, while trait changes in the invasive species reflect slightly decreased performances at the invasion front as predicted by the expansion load hypothesis. </p><p>This study not only adds to a growing number of examples of well-documented rapid evolution, but is also the first to measure evolution in coexisting, related invasive and native species at the same time. It also illustrates how the evolution of life history traits may play a role in promoting species coexistence in a guild, as suggested by recent ecological theory. <a href="http://dx.doi.org/10.1086/693854">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, 05 Sep 2017 05:00:00 GMT “The roles of sexual and viability selection in the evolution of incomplete reproductive isolation: From allopatry to sympatry” http://amnat.org/an/newpapers/NovCotto.html Contrasting forces on choosiness evolution often lead to the evolution of incomplete reproductive isolation What are the mechanisms leading to reproduction between individuals from different species? Hybrids are commonly observed in the wild and result from incomplete reproductive preferences of individuals in well-characterized species. We know from previous research that imperfect reproductive preferences can be an evolutionary optimum when the encounter rate between incipient species is low. However, breeding often occurs in mating areas that are shared by closely related species, even though they spend most of their foraging time in different places. Olivier Cotto and Maria Servedio of the Biology Department at the University of North Carolina at Chapel Hill recently investigated how the geographical context of sister species can affect the evolution of reproductive isolation when mating choice is based on trait similarity between mating partners. They find that incomplete reproductive isolation can be a selected optimum in a wider range of scenarios than previously known, especially when hybrids have low fitness. When the encounter rate between incipient species varies within their range, incomplete reproductive preference tends to be favored where the encounter rate is low whereas complete reproductive isolation is favored when the encounter rate is high. The overall strength of reproductive preference results from the interaction between processes occurring in each locality. With this new research, Olivier Cotto and Maria Servedio propose a new avenue to understand apparent persistent hybridization between species and its variation across space and taxa. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Contrasting forces on choosiness evolution often lead to the evolution of incomplete reproductive isolation </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 are the mechanisms leading to reproduction between individuals from different species? Hybrids are commonly observed in the wild and result from incomplete reproductive preferences of individuals in well-characterized species. We know from previous research that imperfect reproductive preferences can be an evolutionary optimum when the encounter rate between incipient species is low. However, breeding often occurs in mating areas that are shared by closely related species, even though they spend most of their foraging time in different places. Olivier Cotto and Maria Servedio of the Biology Department at the University of North Carolina at Chapel Hill recently investigated how the geographical context of sister species can affect the evolution of reproductive isolation when mating choice is based on trait similarity between mating partners. They find that incomplete reproductive isolation can be a selected optimum in a wider range of scenarios than previously known, especially when hybrids have low fitness. When the encounter rate between incipient species varies within their range, incomplete reproductive preference tends to be favored where the encounter rate is low whereas complete reproductive isolation is favored when the encounter rate is high. The overall strength of reproductive preference results from the interaction between processes occurring in each locality. With this new research, Olivier Cotto and Maria Servedio propose a new avenue to understand apparent persistent hybridization between species and its variation across space and taxa. <a href="http://dx.doi.org/10.1086/693855">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, 05 Sep 2017 05:00:00 GMT “Predator persistence through variability of resource productivity in tritrophic systems” http://amnat.org/an/newpapers/DecSoudijn-A.html Resource variability promotes species persistence at higher trophic levels Abstract The trophic structure of species communities depends on the energy transfer between trophic levels. Primary productivity varies strongly through time, challenging the persistence of species at higher trophic levels. Yet, resource variability has mostly been studied in systems with only one or two trophic levels. We test the effect of variability in resource productivity in a tritrophic model system, including a resource, size-structured consumer and size-specific predator. The model complies with fundamental principles of mass conservation and, the body-size dependence of individual-level energetics and predator-prey interactions. Surprisingly, we find that resource variability may promote predator persistence. The positive effect of variability on the predator arises through periods with starvation mortality of juvenile prey, which reduces the intraspecific competition in the prey population. With increasing variability in productivity and starvation mortality in the juvenile prey, the prey availability increases in the size range preferred by the predator. The positive effect of prey mortality on the trophic transfer efficiency depends on the biologically realistic consideration of body-size- and food-dependent functions for growth and reproduction in our model. Our findings show that variability may promote the trophic transfer efficiency, indicating that environmental variability may sustain species at higher trophic levels in natural ecosystems. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Resource variability promotes species persistence at higher trophic levels </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;">T</span>he trophic structure of species communities depends on the energy transfer between trophic levels. Primary productivity varies strongly through time, challenging the persistence of species at higher trophic levels. Yet, resource variability has mostly been studied in systems with only one or two trophic levels. We test the effect of variability in resource productivity in a tritrophic model system, including a resource, size-structured consumer and size-specific predator. The model complies with fundamental principles of mass conservation and, the body-size dependence of individual-level energetics and predator-prey interactions. Surprisingly, we find that resource variability may promote predator persistence. The positive effect of variability on the predator arises through periods with starvation mortality of juvenile prey, which reduces the intraspecific competition in the prey population. With increasing variability in productivity and starvation mortality in the juvenile prey, the prey availability increases in the size range preferred by the predator. The positive effect of prey mortality on the trophic transfer efficiency depends on the biologically realistic consideration of body-size- and food-dependent functions for growth and reproduction in our model. Our findings show that variability may promote the trophic transfer efficiency, indicating that environmental variability may sustain species at higher trophic levels in natural ecosystems. <a href="http://dx.doi.org/10.1086/694119">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, 01 Sep 2017 05:00:00 GMT “Climate effects on growth, body condition and survival depend on the genetic characteristics of the population” http://amnat.org/an/newpapers/NovRomeroD.html Climate effects on populations are context dependent; Age and sex structures and genetic characteristics matter Predicting how changes in the environmental conditions will affect the size and structure (e.g. age composition, sex ratio) of natural populations over time, and thus their chances of persistence/extinction, may prove to be more complicated than we thought. Why? The reason behind this complexity is a process known as eco-evolutionary dynamics; that is, the ongoing feedbacks between ecological change and evolutionary change. Experimental support for this idea comes from a new population study with lizards, carried out by researchers from the National Museum of Natural Sciences in Madrid, Spain (MNCN-CSIC), showing that trait responses to environmental conditions depend on the genetic characteristics of the population. Eco-evolutionary feedbacks can occur between natural selection and population dynamics, when a demographic trait (e.g. survival, reproductive success) responds to ecological selective pressures determined by the environmental conditions, and the resulting change in population density and/or composition modifies the environment, thereby changing the nature of selection. Understanding the role of population dynamics in shaping selection pressures is thus key in order to predict population responses under novel climates. The researchers at the MNCN have been studying population dynamics of the color polymorphic common lizard (Zootoca vivipara) in the Spanish Pyrenees for years. In this year-long experiment with semi-natural populations, focusing on the interactive effects of abiotic conditions and genetic characteristics of the population, they reveal that individual responses in growth, body condition, survival, and reproduction to habitat humidity depend on the (genetic) color morph frequencies of the population. Moreover, individual responses are age-class- and sex-dependent, suggesting different susceptibilities to environmental conditions among juveniles, yearlings and adults, and between males and females. Taken together, their results suggest that changes in the demographic characteristics of populations, genetic or otherwise, alter the level of intra- and inter-age class competition experienced by their individuals and thus the ecological selective pressures shaping fitness-related traits. This study is one of the few empirical evidences to date supporting the idea that ecology can influence evolution, and vice versa, on short/ecological time-scales. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Climate effects on populations are context dependent; Age and sex structures and genetic characteristics matter </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;">P</span>redicting how changes in the environmental conditions will affect the size and structure (e.g. age composition, sex ratio) of natural populations over time, and thus their chances of persistence/extinction, may prove to be more complicated than we thought. Why? The reason behind this complexity is a process known as eco-evolutionary dynamics; that is, the ongoing feedbacks between ecological change and evolutionary change. Experimental support for this idea comes from a new population study with lizards, carried out by researchers from the National Museum of Natural Sciences in Madrid, Spain (MNCN-CSIC), showing that trait responses to environmental conditions depend on the genetic characteristics of the population.</p> <p>Eco-evolutionary feedbacks can occur between natural selection and population dynamics, when a demographic trait (e.g. survival, reproductive success) responds to ecological selective pressures determined by the environmental conditions, and the resulting change in population density and/or composition modifies the environment, thereby changing the nature of selection. Understanding the role of population dynamics in shaping selection pressures is thus key in order to predict population responses under novel climates. </p><p>The researchers at the MNCN have been studying population dynamics of the color polymorphic common lizard (<i>Zootoca vivipara</i>) in the Spanish Pyrenees for years. In this year-long experiment with semi-natural populations, focusing on the interactive effects of abiotic conditions and genetic characteristics of the population, they reveal that individual responses in growth, body condition, survival, and reproduction to habitat humidity depend on the (genetic) color morph frequencies of the population. Moreover, individual responses are age-class- and sex-dependent, suggesting different susceptibilities to environmental conditions among juveniles, yearlings and adults, and between males and females. Taken together, their results suggest that changes in the demographic characteristics of populations, genetic or otherwise, alter the level of intra- and inter-age class competition experienced by their individuals and thus the ecological selective pressures shaping fitness-related traits. </p><p>This study is one of the few empirical evidences to date supporting the idea that ecology can influence evolution, and vice versa, on short/ecological time-scales. <a href="http://dx.doi.org/10.1086/693780">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, 30 Aug 2017 05:00:00 GMT “Divorce in an island bird population: causes, consequences, and lack of inheritance” http://amnat.org/an/newpapers/OctWhlwrght.html In birds that form pair bonds, divorce occurs when both members of a pair survive to breed again but no longer remain social mates. What drives mate-switching? Does rejecting one’s partner in favor of another improve a bird’s lifetime reproductive success? Is divorce a heritable trait whose transmission is influenced by genes or culture? Nat Wheelwright (Bowdoin College, Brunswick, ME, USA) teamed up with Céline Teplitsky (Centre d’Écologie Fonctionnelle et Évolutive, Montpellier, France) to try to answer these questions in a wild bird population, taking advantage of a long-term study of Savannah sparrows (Passerculus sandwichensis) breeding on Kent Island, New Brunswick, Canada. Divorce is commonplace among Savannah sparrows: Over an 18-year period, nearly half of all pairs split. One female sparrow accumulated five divorces over her lifetime (only two fewer than the legendary American film actress Elizabeth Taylor). Females who had received relatively little parental assistance from their mates were more likely to divorce if they had had a poor breeding season or been paired with a small male. Divorce did not necessarily result in improved reproductive success for young females, although it did for older females. Young males (but not older males) suffered lower reproductive success following a divorce. Overall, the researchers found that natural selection for divorce was weak or non-existent. Although divorce was repeatable in females, a quantitative genetic analysis found no additive genetic variance underlying the trait or evidence of maternal or paternal effects. Divorce in Savannah sparrows appears to be a non-heritable, flexible behavior whose expression and consequences depend upon an individual’s sex, mating status, size, and age. 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 birds that form pair bonds, divorce occurs when both members of a pair survive to breed again but no longer remain social mates. What drives mate-switching? Does rejecting one’s partner in favor of another improve a bird’s lifetime reproductive success? Is divorce a heritable trait whose transmission is influenced by genes or culture? Nat Wheelwright (Bowdoin College, Brunswick, ME, USA) teamed up with Céline Teplitsky (Centre d’Écologie Fonctionnelle et Évolutive, Montpellier, France) to try to answer these questions in a wild bird population, taking advantage of a long-term study of Savannah sparrows (<i>Passerculus sandwichensis</i>) breeding on Kent Island, New Brunswick, Canada. </p><p>Divorce is commonplace among Savannah sparrows: Over an 18-year period, nearly half of all pairs split. One female sparrow accumulated five divorces over her lifetime (only two fewer than the legendary American film actress Elizabeth Taylor). Females who had received relatively little parental assistance from their mates were more likely to divorce if they had had a poor breeding season or been paired with a small male. Divorce did not necessarily result in improved reproductive success for young females, although it did for older females. Young males (but not older males) suffered lower reproductive success following a divorce. Overall, the researchers found that natural selection for divorce was weak or non-existent. Although divorce was repeatable in females, a quantitative genetic analysis found no additive genetic variance underlying the trait or evidence of maternal or paternal effects. Divorce in Savannah sparrows appears to be a non-heritable, flexible behavior whose expression and consequences depend upon an individual’s sex, mating status, size, and age. <a href="http://dx.doi.org/10.1086/693387">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, 30 Aug 2017 05:00:00 GMT “Towards a periodic table of niches or exploring the lizard niche hypervolume” http://amnat.org/an/newpapers/NovPianka.html Ecologists begin to construct a Periodic Table of Niches Five prominent ecologists present new insights into a concept first suggested by the late Robert H. MacArthur over half a century ago. MacArthur suggested a Periodic Table of ecological niches could be constructed similar to the chemist’s Periodic Table of Elements, which are ordered by a combination of their atomic number (protons), configuration of electrons, and certain chemical properties. Throughout, the paper features a back-and-forth interplay among outright natural history, niche theory, state-of-the-art multivariate statistical analyses, and downloadable rotatable 3D plots. Ecological niches are so complex that the notion they could somehow be ordered in a predictable way has eluded ecologists. The niche defines how species live, reproduce, and interact with other organisms and their environments. Consequently, niches are multidimensional. Visualizing and understanding such complex systems is difficult because humans perceive only three dimensions. In a major synthesis appearing in The&nbsp;American Naturalist, a niche ordination and classification framework is presented based on extensive ecological data gathered by the first two authors during the course of two lifetimes of fieldwork conducted in diverse habitats on four continents over the last half-century. A key prediction of this theory is that distantly related species on different continents should evolve to fill identifiably similar niches, and should exhibit similar sets of ecological traits, referred to as evolutionarily convergence by ecologists. To test this prediction, data were assembled on five major niche dimensions (habitat, diet, life history, metabolism, and defense, each with 7-15 variables) for 134 species representing 24 of the 38 extant lizard families. Lizard niche dimensions have evolved in concert; transitions in life history and trophic traits occur in synchrony. Natural dichotomies include activity time, foraging mode, parity mode (egg laying/live bearing), and habitat. Patterns are repeated: Australian desert lizards solve problems in the same ways that African and American lizards do, even when they are not evolutionarily related.Convergent evolution among lizards around the world is one of the pillars for the idea of a Periodic Table. Based on multivariate analyses of 50+ lizard niche dimensions, just three capture 61.7 % of the total variation indicating that lizard niches are tightly constrained. To more easily visualize their results, the authors produced rotating 3-dimensional graphics (link to 3-dimensional graphics) that allow exploration of constraints and tradeoffs in the evolution of lizard niches. These reveal the manner in which species overlap or separate out based on habitat, body size, foraging mode, diet, life history, metabolism, defensive tactics, and/or time and place of activity. One hundred distantly-related convergent species pairs from different geographic regions stay close to each other as niche space is rotated (link to 3D plot showing some convergent pairs), thus confirming periodicity in lizard niche dimensions, and strongly supporting the utility of a Periodic Table. Extending this approach to other taxa should lead to a wider understanding of niche evolution. Lead author Eric Pianka points out, “Summarizing major ecological traits in such simple schemes will allow ecologists to predict how species might react to new environmental conditions, the invasive potential of species, and even inform us about how niches have evolved in the past and will evolve in the future, all of which have direct bearing on impacts of climate change.” Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Ecologists begin to construct a Periodic Table of Niches </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>ive prominent ecologists present new insights into a concept first suggested by the late Robert H. MacArthur over half a century ago. MacArthur suggested a Periodic Table of ecological niches could be constructed similar to the chemist&rsquo;s Periodic Table of Elements, which are ordered by a combination of their atomic number (protons), configuration of electrons, and certain chemical properties.</p> <p>Throughout, the paper features a back-and-forth interplay among outright natural history, niche theory, state-of-the-art multivariate statistical analyses, and downloadable rotatable 3D plots.</p> <p>Ecological niches are so complex that the notion they could somehow be ordered in a predictable way has eluded ecologists. The niche defines how species live, reproduce, and interact with other organisms and their environments. Consequently, niches are multidimensional. Visualizing and understanding such complex systems is difficult because humans perceive only three dimensions.</p> <p>In a major synthesis appearing in <i>The&nbsp;American Naturalist</i>, a niche ordination and classification framework is presented based on extensive ecological data gathered by the first two authors during the course of two lifetimes of fieldwork conducted in diverse habitats on four continents over the last half-century. A key prediction of this theory is that distantly related species on different continents should evolve to fill identifiably similar niches, and should exhibit similar sets of ecological traits, referred to as evolutionarily convergence by ecologists. To test this prediction, data were assembled on five major niche dimensions (habitat, diet, life history, metabolism, and defense, each with 7-15 variables) for 134 species representing 24 of the 38 extant lizard families.</p> <p>Lizard niche dimensions have evolved in concert; transitions in life history and trophic traits occur in synchrony. Natural dichotomies include activity time, foraging mode, parity mode (egg laying/live bearing), and habitat. Patterns are repeated: Australian desert lizards solve problems in the same ways that African and American lizards do, even when they are not evolutionarily related.</p><p>Convergent evolution among lizards around the world is one of the pillars for the idea of a Periodic Table. Based on multivariate analyses of 50+ lizard niche dimensions, just three capture 61.7 % of the total variation indicating that lizard niches are tightly constrained. To more easily visualize their results, the authors produced rotating 3-dimensional graphics <a href=http://www.zo.utexas.edu/faculty/pianka/ModelsMK/>(link to 3-dimensional graphics)</a> that allow exploration of constraints and tradeoffs in the evolution of lizard niches. These reveal the manner in which species overlap or separate out based on habitat, body size, foraging mode, diet, life history, metabolism, defensive tactics, and/or time and place of activity. One hundred distantly-related convergent species pairs from different geographic regions stay close to each other as niche space is rotated <a href=http://www.zo.utexas.edu/faculty/pianka/ModelsMK/convergent.html>(link to 3D plot showing some convergent pairs)</a>, thus confirming periodicity in lizard niche dimensions, and strongly supporting the utility of a Periodic Table. Extending this approach to other taxa should lead to a wider understanding of niche evolution. </p> <p>Lead author Eric Pianka points out, “Summarizing major ecological traits in such simple schemes will allow ecologists to predict how species might react to new environmental conditions, the invasive potential of species, and even inform us about how niches have evolved in the past and will evolve in the future, all of which have direct bearing on impacts of climate change.” <a href="http://dx.doi.org/10.1086/693781">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, 29 Aug 2017 05:00:00 GMT “Differential allocation revisited: When should mate quality affect parental investment?” http://amnat.org/an/newpapers/OctHaaland.html When should parental investment depend on mate quality? Models shed new light on the differential allocation hypothesis Thomas Haaland and colleagues at the Norwegian University of Science and Technology and the University of Exeter have combined several different modelling approaches to investigate the phenomenon known as differential allocation: adjusting parental investment according to the quality or attractiveness of the current mate. Since its discovery in the late ’80’s, this surprising finding has attracted a lot of research attention in animal behavior circles. Experiments on organisms as diverse as penguins, peacocks, antelopes, frogs, and beetles have shown how egg size, clutch size, feeding rates, and other reproductive decisions vary with mate quality. However, results from different studies have often shown confusing and contradictory results, and a lack of theory underlying the differential allocation hypothesis makes interpretations difficult. For example, females in some species show increased investment in offspring when paired with good-quality males, while in a closely related species it is the young of poor-quality males who receive extra investment. In other studies, no relationship is seen at all. In order to understand which mechanisms drive this variation, a theoretical explanation of the logic is necessary. Haaland and colleagues show how female investment should differ when male quality affects either the offspring fitness or the female’s reproductive costs in various ways. The benefits of mating with a good-quality male will therefore depend on the details of the species’ mating system and biology, and using these new models, researchers will be able to generate predictions for their experiments and interpret their results to better understand why the animals behave the way they do. In a wider context, this better understanding of differential allocation will also aid research concerning sexual selection and the evolution of parental care. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>When should parental investment depend on mate quality? Models shed new light on the differential allocation hypothesis </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>homas Haaland and colleagues at the Norwegian University of Science and Technology and the University of Exeter have combined several different modelling approaches to investigate the phenomenon known as differential allocation: adjusting parental investment according to the quality or attractiveness of the current mate. </p><p>Since its discovery in the late ’80’s, this surprising finding has attracted a lot of research attention in animal behavior circles. Experiments on organisms as diverse as penguins, peacocks, antelopes, frogs, and beetles have shown how egg size, clutch size, feeding rates, and other reproductive decisions vary with mate quality. However, results from different studies have often shown confusing and contradictory results, and a lack of theory underlying the differential allocation hypothesis makes interpretations difficult. For example, females in some species show increased investment in offspring when paired with good-quality males, while in a closely related species it is the young of poor-quality males who receive extra investment. In other studies, no relationship is seen at all. In order to understand which mechanisms drive this variation, a theoretical explanation of the logic is necessary. </p><p>Haaland and colleagues show how female investment should differ when male quality affects either the offspring fitness or the female’s reproductive costs in various ways. The benefits of mating with a good-quality male will therefore depend on the details of the species’ mating system and biology, and using these new models, researchers will be able to generate predictions for their experiments and interpret their results to better understand why the animals behave the way they do. In a wider context, this better understanding of differential allocation will also aid research concerning sexual selection and the evolution of parental care. <a href="http://dx.doi.org/10.1086/693484">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, 23 Aug 2017 05:00:00 GMT “Sanctions, partner recognition, and variation in mutualism” http://amnat.org/an/newpapers/OctYoder.html Coevolving communication between mutualists can explain why they aren’t always cooperative Mutually beneficial relationships between species, or mutualisms, are ubiquitous in the living world, with examples ranging from flowering plants that rely on animal pollinators to fish that clean the teeth and scales of other fish. Mutualisms are often imperfect—one partner or the other varies in the quality of the help it provides. Evolutionary theory predicts that this should break up the relationship, but most mutualisms hold together in spite of partners that take the benefits of mutualism without properly paying them back. This paradox may be explained by the fact that there’s more to mutualism than trading goods or services. This is a key result of mathematical evolutionary models published in The&nbsp;American Naturalist by Jeremy Yoder and Peter Tiffin, biologists at the University of British Columbia and the University of Minnesota. Yoder and Tiffin built a mathematical evolutionary model of mutualists that communicate before trading resources, and compared it to simpler models with only resource-trading or only communication. In the model with communication and resource-trading, host could “sanction” by cutting off resources to prevent poor quality partners from taking over, but evolution of the signals sent by partners and the hosts’ response to those signals maintained variation over time. Neither of the simpler models could do this. With only resource-trading, sanctions eliminated all poor-quality partners, and all variation; with only communication, poor-quality partners took over the mutualism. These results from mathematical models confirm what biologists see in studying real-world mutualists, that the relationship is both imperfect and persistent. Communication plays a role in many interactions between species, and this project may spur other biologists to consider its role in the co-evolution of mutualists and the aid they provide each other. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Coevolving communication between mutualists can explain why they aren’t always cooperative </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;">M</span>utually beneficial relationships between species, or mutualisms, are ubiquitous in the living world, with examples ranging from flowering plants that rely on animal pollinators to fish that clean the teeth and scales of other fish. Mutualisms are often imperfect—one partner or the other varies in the quality of the help it provides. Evolutionary theory predicts that this should break up the relationship, but most mutualisms hold together in spite of partners that take the benefits of mutualism without properly paying them back. </p><p>This paradox may be explained by the fact that there’s more to mutualism than trading goods or services. This is a key result of mathematical evolutionary models published in <i>The&nbsp;American Naturalist</i> by Jeremy Yoder and Peter Tiffin, biologists at the University of British Columbia and the University of Minnesota. Yoder and Tiffin built a mathematical evolutionary model of mutualists that communicate before trading resources, and compared it to simpler models with only resource-trading or only communication. In the model with communication and resource-trading, host could “sanction” by cutting off resources to prevent poor quality partners from taking over, but evolution of the signals sent by partners and the hosts’ response to those signals maintained variation over time. Neither of the simpler models could do this. With only resource-trading, sanctions eliminated all poor-quality partners, and all variation; with only communication, poor-quality partners took over the mutualism. </p><p>These results from mathematical models confirm what biologists see in studying real-world mutualists, that the relationship is both imperfect and persistent. Communication plays a role in many interactions between species, and this project may spur other biologists to consider its role in the co-evolution of mutualists and the aid they provide each other. <a href="http://dx.doi.org/10.1086/693472">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, 23 Aug 2017 05:00:00 GMT “Comparative analyses of phenotypic trait covariation within and among populations” http://amnat.org/an/newpapers/OctPeiman.html Reconsidering phenotypic covariation and evolution through the lens of different trait relationships Many organismal features provide specific performance benefits, but Darwin was one of the first to suggest that combinations of different traits may do this as well. Trait co-occurrence is common and arises at different biological scales, such as among the average types of different species and even among individuals within a population, although the two levels do not have to correspond. This raises interesting questions about how traits evolve. Why are there strong relationships between certain traits, yet none between others? Why may this change from one population to the next, or across different biological scales? It is well known that evolution is influenced by trait relationships and different trait relationships have recently been identified. But little effort has addressed whether the type of relationship between traits should influence how traits co-occur. The authors combine three conventional methods to consider the effects of different trait relationships on trait co-occurrence. The performance paradigm – which separates how traits affect performance, and how performance affects fitness – is used to identify three fundamental categories of trait relationships. Considering the genetic control of these different relationships reveals more complex genetic effects on trait co-occurrence then is usually considered. The authors then evaluate how trait co-occurrence evolves under selection using fitness landscapes. This clarifies the distinct roles of selection in generating adaptive trait co-occurrence (within a population) and adaptive diversity (among populations and species). Finally, they consider the opportunities and limitations of comparative approaches to evaluate the evolutionary causes and consequences of trait co-occurrence. This highlights the value of evaluating trait co-occurrence within populations replicated in the same and in different selective environments. This synthesis provides a new way to consider explicit hypotheses about trait relationships that will allow researchers to generate more effective predictions about trait evolution. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Reconsidering phenotypic covariation and evolution through the lens of different trait relationships </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;">M</span>any organismal features provide specific performance benefits, but Darwin was one of the first to suggest that combinations of different traits may do this as well. Trait co-occurrence is common and arises at different biological scales, such as among the average types of different species and even among individuals within a population, although the two levels do not have to correspond. This raises interesting questions about how traits evolve. Why are there strong relationships between certain traits, yet none between others? Why may this change from one population to the next, or across different biological scales? It is well known that evolution is influenced by trait relationships and different trait relationships have recently been identified. But little effort has addressed whether the type of relationship between traits should influence how traits co-occur. </p><p>The authors combine three conventional methods to consider the effects of different trait relationships on trait co-occurrence. The performance paradigm – which separates how traits affect performance, and how performance affects fitness – is used to identify three fundamental categories of trait relationships. Considering the genetic control of these different relationships reveals more complex genetic effects on trait co-occurrence then is usually considered. The authors then evaluate how trait co-occurrence evolves under selection using fitness landscapes. This clarifies the distinct roles of selection in generating adaptive trait co-occurrence (within a population) and adaptive diversity (among populations and species). Finally, they consider the opportunities and limitations of comparative approaches to evaluate the evolutionary causes and consequences of trait co-occurrence. This highlights the value of evaluating trait co-occurrence within populations replicated in the same and in different selective environments. This synthesis provides a new way to consider explicit hypotheses about trait relationships that will allow researchers to generate more effective predictions about trait evolution. <a href="http://dx.doi.org/10.1086/693482">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, 18 Aug 2017 05:00:00 GMT “Should I change or should I go? Phenotypic plasticity and matching habitat choice in the adaptation to environmental heterogeneity” http://amnat.org/an/newpapers/OctEdelaar.html A new model explains when to expect matching habitat choice and when phenotypic plasticity given environmental variation Wouldn’t it be nice if the environment was just perfect wherever you are? Unfortunately this is not the case, so all organisms have to somehow cope with environmental variation, or suffer the consequences. For example, when grasshoppers resemble the color of their environment, they are harder to find by predators. How then do grasshoppers that live in environments of different colors improve their camouflage? Perhaps via genetic divergence in color among grasshopper populations living in distinct environments? Or do individual grasshoppers change their color (phenotypic plasticity)? Or do they move to color matching environments (matching habitat choice)? Or all of the above? Surprisingly few studies consider so many possible solutions at the same time. In their simulation study, Pim Edelaar, Roger Jovani, and Ivan Gomez-Mestre investigate which solutions might evolve, and what this may depend on. When phenotypic plasticity and matching habitat choice are not allowed, populations evolve through differential survival of individuals, resulting in adaptive genetic divergence. However, if environments change too fast, natural selection is too strong and genetic variation insufficient, and populations go extinct. Phenotypic plasticity that allows organisms to improve their match with the environment can avoid this extinction, and in fact evolves under most circumstances. The ability of individuals to purposefully move to a matching environment can similarly prevent extinction, but provides a less perfect solution when the set of environments available is limiting. Hence, only when phenotypic plasticity does not evolve (e.g. because it is too costly) does habitat choice evolve. Overall, this study shows the diverse ways in which organisms cope with variation among environments. It also predicts when we should expect different solutions to occur in nature. At the same time, it promotes the simultaneous study of multiple solutions to this key challenge to all living organisms. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>A new model explains when to expect matching habitat choice and when phenotypic plasticity given environmental variation </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>ouldn’t it be nice if the environment was just perfect wherever you are? Unfortunately this is not the case, so all organisms have to somehow cope with environmental variation, or suffer the consequences. For example, when grasshoppers resemble the color of their environment, they are harder to find by predators. How then do grasshoppers that live in environments of different colors improve their camouflage? Perhaps via genetic divergence in color among grasshopper populations living in distinct environments? Or do individual grasshoppers change their color (phenotypic plasticity)? Or do they move to color matching environments (matching habitat choice)? Or all of the above? Surprisingly few studies consider so many possible solutions at the same time. In their simulation study, Pim Edelaar, Roger Jovani, and Ivan Gomez-Mestre investigate which solutions might evolve, and what this may depend on. When phenotypic plasticity and matching habitat choice are not allowed, populations evolve through differential survival of individuals, resulting in adaptive genetic divergence. However, if environments change too fast, natural selection is too strong and genetic variation insufficient, and populations go extinct. Phenotypic plasticity that allows organisms to improve their match with the environment can avoid this extinction, and in fact evolves under most circumstances. The ability of individuals to purposefully move to a matching environment can similarly prevent extinction, but provides a less perfect solution when the set of environments available is limiting. Hence, only when phenotypic plasticity does not evolve (e.g. because it is too costly) does habitat choice evolve. Overall, this study shows the diverse ways in which organisms cope with variation among environments. It also predicts when we should expect different solutions to occur in nature. At the same time, it promotes the simultaneous study of multiple solutions to this key challenge to all living organisms. <a href="http://dx.doi.org/10.1086/693345">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, 18 Aug 2017 05:00:00 GMT “Hybridization associated with cycles of ecological succession in a passerine bird” http://amnat.org/an/newpapers/OctDuckworth.html Interbreeding between species has the potential to be an important force in evolution; however, its importance depends on its prevalence. Historically viewed as rare and unnatural, there is still debate about how commonly hybridization occurs across taxa. To assess the prevalence and evolutionary importance of hybridization it is important to identify ecological contexts which increase the chances of species interbreeding. Mixed-species mating is most likely to occur when one species is rarer than the other. Ecological succession, where there is a predictable change in the abundance of different species over time, often produces a disparity in population sizes of closely related species and so has the potential to be an important context for hybridization. In this study, Duckworth and Semenov from the University of Arizona test this idea in two passerine birds, mountain and western bluebirds, which are locked into successional cycles of colonization and replacement due to their differences in dispersal and competitive ability. The researchers surveyed nearly 1300 breeding pairs across ten populations that varied in successional stage and found that western and mountain bluebirds only form mixed-species pairs in the earliest stages of ecological succession when western bluebirds have recently colonized and are rare relative to mountain bluebirds. Using genetic markers, the researchers found that hybrids were present at all successional stages and showed novel patterns of variation in morphology and behavior, emphasizing that even short-lived periods of species interbreeding can have important evolutionary consequences. Most importantly, the authors suggest that ecological succession, which is widespread in nature, may be a frequently overlooked, but potentially important context for hybridization. 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>nterbreeding between species has the potential to be an important force in evolution; however, its importance depends on its prevalence. Historically viewed as rare and unnatural, there is still debate about how commonly hybridization occurs across taxa. To assess the prevalence and evolutionary importance of hybridization it is important to identify ecological contexts which increase the chances of species interbreeding. </p><p>Mixed-species mating is most likely to occur when one species is rarer than the other. Ecological succession, where there is a predictable change in the abundance of different species over time, often produces a disparity in population sizes of closely related species and so has the potential to be an important context for hybridization. </p><p>In this study, Duckworth and Semenov from the University of Arizona test this idea in two passerine birds, mountain and western bluebirds, which are locked into successional cycles of colonization and replacement due to their differences in dispersal and competitive ability. The researchers surveyed nearly 1300 breeding pairs across ten populations that varied in successional stage and found that western and mountain bluebirds only form mixed-species pairs in the earliest stages of ecological succession when western bluebirds have recently colonized and are rare relative to mountain bluebirds. Using genetic markers, the researchers found that hybrids were present at all successional stages and showed novel patterns of variation in morphology and behavior, emphasizing that even short-lived periods of species interbreeding can have important evolutionary consequences. Most importantly, the authors suggest that ecological succession, which is widespread in nature, may be a frequently overlooked, but potentially important context for hybridization. <a href="http://dx.doi.org/10.1086/693160">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, 16 Aug 2017 05:00:00 GMT “Hollow internodes permit a Neotropical understory plant to shelter multiple mutualistic ant species, obtaining protection and nutrient provisioning (myrmecotrophy)” http://amnat.org/an/newpapers/NovDejean-A.html Biotic protection and nutrient provisioning by sheltered ants in a Neotropical gentian: a non-specialized myrmecophyte Abstract The Neotropical understory plant Tachia guianensis (Gentianaceae), known to shelter the colonies of several ant species in its hollow trunks and branches, does not provide them with food rewards (e.g., extrafloral nectar). We tested if these ants are opportunistic nesters or if mutualistic relationships exist as for myrmecophytes or plants sheltering ant colonies in specialized hollow structures in exchange for protection from enemies and/or nutrient provisioning (myrmecotrophy). We noted 37 ant species sheltering inside T.&nbsp;guianensis internodes, three of them accounting for 43.5% of the cases. They protect their host plants from leaf-cutting ant defoliation and termite damage since individuals devoid of associated ants suffered significantly more attacks. Using the stable isotope nitrogen-15, we experimentally showed that the tested ant species furnish their host plants with nutrients. Therefore, a mutualism exists. However, because it is associated with numerous ant species, T.&nbsp;guianensis can be considered a “non-specialized myrmecophyte.” Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Biotic protection and nutrient provisioning by sheltered ants in a Neotropical gentian: a non-specialized myrmecophyte </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;">T</span>he Neotropical understory plant <i>Tachia guianensis</i> (Gentianaceae), known to shelter the colonies of several ant species in its hollow trunks and branches, does not provide them with food rewards (e.g., extrafloral nectar). We tested if these ants are opportunistic nesters or if mutualistic relationships exist as for myrmecophytes or plants sheltering ant colonies in specialized hollow structures in exchange for protection from enemies and/or nutrient provisioning (myrmecotrophy). We noted 37 ant species sheltering inside <i>T.&nbsp;guianensis</i> internodes, three of them accounting for 43.5% of the cases. They protect their host plants from leaf-cutting ant defoliation and termite damage since individuals devoid of associated ants suffered significantly more attacks. Using the stable isotope nitrogen-15, we experimentally showed that the tested ant species furnish their host plants with nutrients. Therefore, a mutualism exists. However, because it is associated with numerous ant species, <i>T.&nbsp;guianensis</i> can be considered a “non-specialized myrmecophyte.” <a href="http://dx.doi.org/10.1086/693782">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, 16 Aug 2017 05:00:00 GMT “Predator perspective drives geographic variation in frequency-dependent polymorphism” http://amnat.org/an/newpapers/OctHolmes-A.html Size of predator vs prey home range can drive mosaics in color polymorphism even without spatially varying selection Abstract Color polymorphism in natural populations can manifest as a striking patchwork of phenotypes in space, with neighboring populations characterized by dramatic differences in morph composition. These “geographic mosaics” can be challenging to explain in the absence of localized selection because they are unlikely to result from simple isolation-by-distance or clinal variation in selective regimes. To identify processes that can lead to the formation of geographic mosaics, we developed a simulation-based model to explore the influence of predator perspective, selection, migration, and genetic linkage of color loci on allele frequencies in polymorphic populations over space and time. Using simulated populations inspired by the biology of Heliconius longwing butterflies, Cepaea land snails, Oophaga poison frogs, and Sonora ground snakes, we found that the relative sizes of predator and prey home ranges can produce large differences in morph composition between neighboring populations under both positive and negative frequency-dependent selection. We also demonstrated the importance of the interaction of predator perspective with the type of frequency-dependence and localized directional selection across migration and selection intensities. Our results show that regional-scale predation can promote the formation of phenotypic mosaics in prey species, without the need to invoke spatial variation in selective regimes. We suggest that predator behavior can play an important and underappreciated role in the formation and maintenance of geographic mosaics in polymorphic species. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Size of predator vs prey home range can drive mosaics in color polymorphism even without spatially varying selection </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;">C</span>olor polymorphism in natural populations can manifest as a striking patchwork of phenotypes in space, with neighboring populations characterized by dramatic differences in morph composition. These “geographic mosaics” can be challenging to explain in the absence of localized selection because they are unlikely to result from simple isolation-by-distance or clinal variation in selective regimes. To identify processes that can lead to the formation of geographic mosaics, we developed a simulation-based model to explore the influence of predator perspective, selection, migration, and genetic linkage of color loci on allele frequencies in polymorphic populations over space and time. Using simulated populations inspired by the biology of <i>Heliconius</i> longwing butterflies, <i> Cepaea</i> land snails, <i>Oophaga</i> poison frogs, and <i>Sonora</i> ground snakes, we found that the relative sizes of predator and prey home ranges can produce large differences in morph composition between neighboring populations under both positive and negative frequency-dependent selection. We also demonstrated the importance of the interaction of predator perspective with the type of frequency-dependence and localized directional selection across migration and selection intensities. Our results show that regional-scale predation can promote the formation of phenotypic mosaics in prey species, without the need to invoke spatial variation in selective regimes. We suggest that predator behavior can play an important and underappreciated role in the formation and maintenance of geographic mosaics in polymorphic species. <a href="http://dx.doi.org/10.1086/693159">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, 15 Aug 2017 05:00:00 GMT “Effects of clonal reproduction on evolutionary lag and evolutionary rescue” http://amnat.org/an/newpapers/OctOrive.html Clonality and stage structure help or hinder evolutionary rescue depending on temporal texture of environmental change In rapidly changing environments, organisms must constantly evolve in order to maintain the ability to survive and reproduce. Rapid change may take many forms, such as coevolving pathogens and diseases, other competing species, or changes in temperature or other climatic conditions. But evolution takes time, and a population experiencing a changing environment may not be able to evolve quickly enough to track that change. The relative difference between the average value of a trait that affects the ability to survive and reproduce of a population, and the optimum for that trait is termed “evolutionary lag”. Many ecologically important organisms, such as reef-building corals and perennial grasses in prairies and savannahs, have life histories that include indeterminate growth and the existence of both asexual reproduction (via budding, fragmentation, or other types of clonal reproduction) and sexual reproduction (via the production of sperm and eggs). Yet how this type of life history structure and clonality interplay to govern a population’s rate of evolution and evolutionary lag is unknown. Orive and her colleagues developed a general mathematical model to consider how traits evolve under both sexual and clonal reproduction. They found that the effect of clonal reproduction on the mean of a trait partitions into two portions: one that is dependent on the value of the trait itself (phenotype-dependent) and one that depends on the genetics underlying the trait (genotype-dependent). This partitioning is governed by the amount of “extra similarity” in the trait seen between parents and their clonal offspring, compared to that seen between parents and their sexual offspring. Are clonally reproducing organisms at a disadvantage under changing environmental conditions? Not always. Clonality was seen to increase population persistence after a single, step-change in the environment, while it decreased population persistence under continuous, linear change requiring de novo variation. Thus, the impact of clonality on the probability of persistence for species in a changing world depends strongly on the temporal texture of the change they experience. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Clonality and stage structure help or hinder evolutionary rescue depending on temporal texture of environmental change </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>n rapidly changing environments, organisms must constantly evolve in order to maintain the ability to survive and reproduce. Rapid change may take many forms, such as coevolving pathogens and diseases, other competing species, or changes in temperature or other climatic conditions. But evolution takes time, and a population experiencing a changing environment may not be able to evolve quickly enough to track that change. </p><p>The relative difference between the average value of a trait that affects the ability to survive and reproduce of a population, and the optimum for that trait is termed “evolutionary lag”. Many ecologically important organisms, such as reef-building corals and perennial grasses in prairies and savannahs, have life histories that include indeterminate growth and the existence of both asexual reproduction (via budding, fragmentation, or other types of clonal reproduction) and sexual reproduction (via the production of sperm and eggs). Yet how this type of life history structure and clonality interplay to govern a population’s rate of evolution and evolutionary lag is unknown. </p><p>Orive and her colleagues developed a general mathematical model to consider how traits evolve under both sexual and clonal reproduction. They found that the effect of clonal reproduction on the mean of a trait partitions into two portions: one that is dependent on the value of the trait itself (phenotype-dependent) and one that depends on the genetics underlying the trait (genotype-dependent). This partitioning is governed by the amount of “extra similarity” in the trait seen between parents and their clonal offspring, compared to that seen between parents and their sexual offspring. </p><p>Are clonally reproducing organisms at a disadvantage under changing environmental conditions? Not always. Clonality was seen to increase population persistence after a single, step-change in the environment, while it decreased population persistence under continuous, linear change requiring de novo variation. Thus, the impact of clonality on the probability of persistence for species in a changing world depends strongly on the temporal texture of the change they experience. <a href="http://dx.doi.org/10.1086/693006">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, 14 Aug 2017 05:00:00 GMT “Historical biogeography and extinction in the Hawaiian honeycreepers” http://amnat.org/an/newpapers/OctRicklefs.html Hawaiian honeycreepers exhibit commonality in vulnerability to extinction from anthropogenic and natural causes Populations may decline and go extinct in response to a variety of causes, including direct exploitation by humans, introduction of pathogens, and destruction of suitable habitats. The Hawaiian honeycreepers, which are a large evolutionary radiation of small landbirds endemic to the Hawaiian Islands, have suffered from all these causes. Of 50 recognized species, 30 are extinct and 9 more are critically endangered according to the IUCN Red List. A new analysis of honeycreeper distributions appearing in The&nbsp;American Naturalist suggests that species vary in their vulnerability to external threats, regardless of the causes. Using available fossil information and historical records, Bob Ricklefs, Professor of Biology at the University of Missouri–St. Louis, was able to reconstruct the distributions of honeycreeper species at the times of the Polynesian and European colonization of the islands. When populations undergo expansion within archipelagoes, they generally colonize all islands and leave no gaps in their distributions. Accordingly, gaps indicate extinction of individual island populations over time. Ricklefs found that species that had lost island populations during the period of Polynesian colonization, as indicated by the fossil record and by gaps in distributions at the beginning of European scientific exploration, were more likely to suffer extinction of island populations during the past century. Earlier population declines were primarily the result of direct exploitation and habitat destruction. More recently, introduced diseases, including avian pox and avian malaria, have taken a terrible toll on native Hawaiian birds. Because the most severely affected populations belong to species that had also suffered from human impacts before the arrival of these diseases, Ricklefs inferred that populations of some species have a general vulnerability to diverse threats. It is likely that this vulnerability is related to intrinsically low reproductive rates, which are unable to replace elevated losses regardless of the cause. Although Ricklefs’s study underscores the general challenges of conserving island populations, it also suggests an approach to identifying the most vulnerable species based on the geographic distribution and differentiation of island populations. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Hawaiian honeycreepers exhibit commonality in vulnerability to extinction from anthropogenic and natural causes </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>opulations may decline and go extinct in response to a variety of causes, including direct exploitation by humans, introduction of pathogens, and destruction of suitable habitats. The Hawaiian honeycreepers, which are a large evolutionary radiation of small landbirds endemic to the Hawaiian Islands, have suffered from all these causes. Of 50 recognized species, 30 are extinct and 9 more are critically endangered according to the IUCN Red List. A new analysis of honeycreeper distributions appearing in <i>The&nbsp;American Naturalist</i> suggests that species vary in their vulnerability to external threats, regardless of the causes. Using available fossil information and historical records, Bob Ricklefs, Professor of Biology at the University of Missouri–St. Louis, was able to reconstruct the distributions of honeycreeper species at the times of the Polynesian and European colonization of the islands. When populations undergo expansion within archipelagoes, they generally colonize all islands and leave no gaps in their distributions. Accordingly, gaps indicate extinction of individual island populations over time. </p><p>Ricklefs found that species that had lost island populations during the period of Polynesian colonization, as indicated by the fossil record and by gaps in distributions at the beginning of European scientific exploration, were more likely to suffer extinction of island populations during the past century. Earlier population declines were primarily the result of direct exploitation and habitat destruction. More recently, introduced diseases, including avian pox and avian malaria, have taken a terrible toll on native Hawaiian birds. Because the most severely affected populations belong to species that had also suffered from human impacts before the arrival of these diseases, Ricklefs inferred that populations of some species have a general vulnerability to diverse threats. It is likely that this vulnerability is related to intrinsically low reproductive rates, which are unable to replace elevated losses regardless of the cause. Although Ricklefs’s study underscores the general challenges of conserving island populations, it also suggests an approach to identifying the most vulnerable species based on the geographic distribution and differentiation of island populations. <a href="http://dx.doi.org/10.1086/693346">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, 14 Aug 2017 05:00:00 GMT “Resemblance to the enemy’s eyes underlies the intimidating effect of eyespots” http://amnat.org/an/newpapers/OctKjernsmo.html 3-trophic deception: Predators associate the eyelike appearance of prey eyespots with the threat posed by own enemies The widespread occurrence of eyespots, from butterflies to fishes, has intrigued biologists for years, but the mechanism behind their function has, until now, remained unclear. New evidence published in The&nbsp;American Naturalist shows that prey eyespots intimidate predators because they associate the eyelike appearance of eyespots with the threat posed by their own enemies. Eyespots are enigmatic marks that are often found on prey species. To humans at least, these concentric circle markings often bear a resemblance to the vertebrate eye, such as those of an owl. One enduring theory of their function has been that they mimic the eyes of a predator’s own predator and thus produce an intimidating effect. However, even though we may think that eyespots resemble staring eyes, evidence has been lacking as to whether other creatures make the same association. Researchers at Åbo Akademi University conducted an experiment in which artificial prey with different marks were presented to three-spined sticklebacks, a small species of fish, half of which had been exposed to the presence of their natural enemy, a larger fish. “The challenge has been to find a way to tell what comes to the mind of an attacking predator when it sees an eyespot,” says Dr. Sami Merilaita, one of the two researchers involved in the project. “The problem has been that it is difficult to tell whether predators react to eye-likeness or some other property of the mark. The solution came with the realization that even though eyespots may resemble eyes, not all views of animal eyes always resemble eyespots.” Most of the previous research on eyespots has been conducted on small birds and their prey, typically butterflies or moths that have eyespots. “By conducting the study in an aquatic environment, we were able to decouple the eyespot-like appearance from the eyelike appearance,” adds Dr. Karin Kjernsmo. “If you consider the stare of a fish that has its eyes on the sides of its head, from the front it looks quite different from eyespots, while still being eyelike. At the same time when viewed from the side, a fish eye does resemble the normal round and concentric eyespot pattern. Therefore, we presented fish with artificial prey that displayed an image of their predators’ eyes from different angles making them eyespot-like or not (but always eye-like). We found that compared to the predator-unexperienced fish, the fish that had experienced predation threat were more hesitant to attack the prey with the eye-like marks, even when they were not eyespot-like. This is strong evidence that the fish associated the eyelike appearance of the mark with the threat imposed by its own enemy.” Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>3-trophic deception: Predators associate the eyelike appearance of prey eyespots with the threat posed by own enemies </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 widespread occurrence of eyespots, from butterflies to fishes, has intrigued biologists for years, but the mechanism behind their function has, until now, remained unclear. New evidence published in <i>The&nbsp;American Naturalist</i> shows that prey eyespots intimidate predators because they associate the eyelike appearance of eyespots with the threat posed by their own enemies. </p><p>Eyespots are enigmatic marks that are often found on prey species. To humans at least, these concentric circle markings often bear a resemblance to the vertebrate eye, such as those of an owl. One enduring theory of their function has been that they mimic the eyes of a predator’s own predator and thus produce an intimidating effect. However, even though we may think that eyespots resemble staring eyes, evidence has been lacking as to whether other creatures make the same association. </p><p>Researchers at Åbo Akademi University conducted an experiment in which artificial prey with different marks were presented to three-spined sticklebacks, a small species of fish, half of which had been exposed to the presence of their natural enemy, a larger fish. “The challenge has been to find a way to tell what comes to the mind of an attacking predator when it sees an eyespot,” says Dr. Sami Merilaita, one of the two researchers involved in the project. “The problem has been that it is difficult to tell whether predators react to eye-likeness or some other property of the mark. The solution came with the realization that even though eyespots may resemble eyes, not all views of animal eyes always resemble eyespots.” </p><p>Most of the previous research on eyespots has been conducted on small birds and their prey, typically butterflies or moths that have eyespots. “By conducting the study in an aquatic environment, we were able to decouple the eyespot-like appearance from the eyelike appearance,” adds Dr. Karin Kjernsmo. “If you consider the stare of a fish that has its eyes on the sides of its head, from the front it looks quite different from eyespots, while still being eyelike. At the same time when viewed from the side, a fish eye does resemble the normal round and concentric eyespot pattern. Therefore, we presented fish with artificial prey that displayed an image of their predators’ eyes from different angles making them eyespot-like or not (but always eye-like). We found that compared to the predator-unexperienced fish, the fish that had experienced predation threat were more hesitant to attack the prey with the eye-like marks, even when they were not eyespot-like. This is strong evidence that the fish associated the eyelike appearance of the mark with the threat imposed by its own enemy.” <a href="http://dx.doi.org/10.1086/693473">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, 09 Aug 2017 05:00:00 GMT Call for ASN Graduate Student Representatives http://amnat.org/announcements/NomGCtoECRep.html The American Society of Naturalists Graduate Student Council invites applications for two new graduate student representatives to join us! As a member of the Graduate Student Council you have the chance to participate in the workings of the society and interact with many of the great researchers who are members of the ASN. The ASN is committed to developing a variety of initiatives to provide more valuable services to its student members. Representatives take part in several committees that include choosing ASN-sponsored workshops, helping choose winners of the annual student research grant, organizing student events at conferences, participating in various committees, and running the website for grad student ASN members at http://asngrads.com/. In 2017 ASN formed two new committees: the diversity committee and the advocacy committee, which need student representation. This is a great chance to be part of shaping the mission and activities of these committees, so please let us know if you are interested in participating in either one. Each year we seek two new members to join for a 3-year term. We are also open to new roles or ideas for things you think the Grad Council could do to encourage student involvement and interaction among researchers. If you are interested in joining, send an email to Emlyn Resetarits (eresetarits@utexas.edu) by August 30 with the subject line “ASN GC application” and attach a single pdf document containing your CV and a short paragraph (less than 1 page) about what you hope to contribute or why you want to join the grad council. Emlyn Resetarits Ecology, Evolution and Behavior Graduate Program University of Texas at AustinKim Gilbert&nbsp;(GC rep 2014-2015): "Serving on the ASN grad council is a fantastic opportunity to not only meet faculty, post-docs, and students from a wide range of universities, but to become more involved in a great community of researchers in ecology and evolution. You learn about how journal societies run, as well as the ins and outs of organizing conference events. You also serve as an important representative for all graduate student members of the ASN to ensure the society is doing its best to meet student&#39;s needs at conferences or through other opportunities." Emily Weiss (GC rep 2013-2014): Serving on the Grad Council really was an incredibly enriching experience for me, and I hope that many other students will apply and get to have that experience too. Rafael Maia&nbsp;(GC rep 2013-2014): "I served the council for a couple years and strongly recommend it. Great society, exciting possibilities!" Courtney Fitzpatrick&nbsp;(founding GC rep): "Grad students: excellent opportunity to get involved, meet collaborators/mentors, and learn about your scientific society!" <p>The American Society of Naturalists Graduate Student Council invites applications for two new graduate student representatives to join us!</p> <p>As a member of the Graduate Student Council you have the chance to participate in the workings of the society and interact with many of the great researchers who are members of the ASN. The ASN is committed to developing a variety of initiatives to provide more valuable services to its student members.</p> <p>Representatives take part in several committees that include choosing ASN-sponsored workshops, helping choose winners of the annual student research grant, organizing student events at conferences, participating in various committees, and running the website for grad student ASN members at http://asngrads.com/. In 2017 ASN formed two new committees: the diversity committee and the advocacy committee, which need student representation. This is a great chance to be part of shaping the mission and activities of these committees, so please let us know if you are interested in participating in either one.</p> <p>Each year we seek two new members to join for a 3-year term. We are also open to new roles or ideas for things you think the Grad Council could do to encourage student involvement and interaction among researchers.</p> <p>If you are interested in joining, send an email to Emlyn Resetarits (<a href="mailto:eresetarits@utexas.edu">eresetarits@utexas.edu</a>) by August 30 with the subject line &ldquo;ASN GC application&rdquo; and attach a single pdf document containing your CV and a short paragraph (less than 1 page) about what you hope to contribute or why you want to join the grad council.</p> <p>Emlyn Resetarits<br /> Ecology, Evolution and Behavior Graduate Program<br> University of Texas at Austin</p><p><strong>Kim Gilbert&nbsp;</strong>(GC rep 2014-2015):<br /> &quot;Serving on the ASN grad council is a fantastic opportunity to not only meet faculty, post-docs, and students from a wide range of universities, but to become more involved in a great community of researchers in ecology and evolution. You learn about how journal societies run, as well as the ins and outs of organizing conference events. You also serve as an important representative for all graduate student members of the ASN to ensure the society is doing its best to meet student&#39;s needs at conferences or through other opportunities.&quot;</p> <p><strong>Emily Weiss (</strong>GC rep 2013-2014):<br /> Serving on the Grad Council really was an incredibly enriching experience for me, and I hope that many other students will apply and get to have that experience too.</p> <p><strong>Rafael Maia&nbsp;</strong>(GC rep 2013-2014):<br /> &quot;I served the council for a couple years and strongly recommend it. Great society, exciting possibilities!&quot;</p> <p><strong>Courtney Fitzpatrick</strong>&nbsp;(founding GC rep):<br /> &quot;Grad students: excellent opportunity to get involved, meet collaborators/mentors, and learn about your scientific society!&quot;</p> Wed, 09 Aug 2017 05:00:00 GMT “Assessing the influence of temporal autocorrelations on the population dynamics of a disturbance specialist plant population in a random environment” http://amnat.org/an/newpapers/OctEager.html The effects of autocorrelated disturbances on disturbance specialist plants and their seed banks It has been known for a long time that soil disturbances influence the population dynamics of many plant species. For disturbance specialist plant populations like wild sunflower (Helianthus annuus), these disturbances are essential for the germination of seeds, and subsequent population growth. Such natural disturbances occur in a relatively random, unpredictable fashion than disturbances in an agricultural setting, and thus traditional approaches to modeling population dynamics generally do not work. Additionally, data suggests that these disturbances do not happen independently, that the presence or absence of a disturbance during one time period affects disturbance profiles during later time periods. One way to incorporate all of these ideas into a study of disturbance specialist plants is to use mathematical models, which are an efficient and useful way of determining how various disturbance regimes affect the size, composition and eventual fate of plant-seed bank systems. Eric Eager and colleagues created a mathematical model and used extensive simulations to find that increasingly-positive autocorrelations in the presence of disturbance had different effects on plant-seed bank populations depending on population viability. More-viable populations responded negatively to increasingly positive autocorrelations due to an increased chance for a string of “bad” years to derail population sizes, while less-viable populations responded positively to such autocorrelations, with an increased chance of a string of “good” years providing an opportunity for populations to increase when small. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>The effects of autocorrelated disturbances on disturbance specialist plants and their seed banks </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>t has been known for a long time that soil disturbances influence the population dynamics of many plant species. For disturbance specialist plant populations like wild sunflower (<i>Helianthus annuus</i>), these disturbances are essential for the germination of seeds, and subsequent population growth. Such natural disturbances occur in a relatively random, unpredictable fashion than disturbances in an agricultural setting, and thus traditional approaches to modeling population dynamics generally do not work. Additionally, data suggests that these disturbances do not happen independently, that the presence or absence of a disturbance during one time period affects disturbance profiles during later time periods. </p><p>One way to incorporate all of these ideas into a study of disturbance specialist plants is to use mathematical models, which are an efficient and useful way of determining how various disturbance regimes affect the size, composition and eventual fate of plant-seed bank systems. </p><p>Eric Eager and colleagues created a mathematical model and used extensive simulations to find that increasingly-positive autocorrelations in the presence of disturbance had different effects on plant-seed bank populations depending on population viability. More-viable populations responded negatively to increasingly positive autocorrelations due to an increased chance for a string of “bad” years to derail population sizes, while less-viable populations responded positively to such autocorrelations, with an increased chance of a string of “good” years providing an opportunity for populations to increase when small. <a href="http://dx.doi.org/10.1086/692911">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, 08 Aug 2017 05:00:00 GMT “Fatal attraction? Intraguild facilitation and suppression among predators” http://amnat.org/an/newpapers/NovSivy-A.html Abstract Competition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (Canis lupus) control in Alaska as a quasi-experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of non-apex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of non-apex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of non-apex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales. 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;">C</span>ompetition and suppression are recognized as dominant forces that structure predator communities. Facilitation via carrion provisioning, however, is a ubiquitous interaction among predators that could offset the strength of suppression. Understanding the relative importance of these positive and negative interactions is necessary to anticipate community-wide responses to apex predator declines and recoveries worldwide. Using state-sponsored wolf (<i>Canis lupus</i>) control in Alaska as a quasi-experiment, we conducted snow track surveys of apex, meso-, and small predators to test for evidence of carnivore cascades (e.g., mesopredator release). We analyzed survey data using an integrative occupancy and structural equation modeling framework to quantify the strengths of hypothesized interaction pathways, and we evaluated fine-scale spatiotemporal responses of non-apex predators to wolf activity clusters identified from radio-collar data. Contrary to the carnivore cascade hypothesis, both meso- and small predator occupancy patterns indicated guild-wide, negative responses of non-apex predators to wolf abundance variations at the landscape scale. At the local scale, however, we observed a near guild-wide, positive response of non-apex predators to localized wolf activity. Local-scale association with apex predators due to scavenging could lead to landscape patterns of mesopredator suppression, suggesting a key link between occupancy patterns and the structure of predator communities at different spatial scales. <a href="http://dx.doi.org/10.1086/693996">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, 07 Aug 2017 05:00:00 GMT “Maladaptive plasticity masks the effects of natural selection in the red-shouldered soapberry bug” http://amnat.org/an/newpapers/OctCenzer.html Maladaptive plasticity generated by gene flow masks the effects of natural selection in soapberry bugs When species are introduced to new areas, they can have profound effects on the evolution of native species. When the golden rain tree was introduced to Florida from Taiwan in the 1950s, some native soapberry bugs started eating its seeds instead of seeds of their native host plant, balloon vine. After several decades, two distinct types of soapberry bugs had evolved, each suited to one plant. Like many invasive species, golden rain trees continued to spread in Florida over the last 30 years, increasing the number of soapberry bugs using this host instead of balloon vine. When soapberry bugs travel from golden rain tree back to balloon vine, they mate with local bugs and produce offspring with a mix of genes adapted to each host. This mixing of genes (‘gene flow’) that haven’t evolved together can produce unexpected detrimental effects, similar to what happens when two separate species mate. Meredith Cenzer shows that this gene flow is causing soapberry bugs to respond incorrectly to their environment. She first confirms that long beaks are favored on balloon vine due to the large seedpods protecting its seeds, and that bugs living on balloon vine in nature are still genetically ‘longer beaked’ than those on golden rain tree. However, when bugs grow up on balloon vine, they develop short beaks that can’t reach the seeds of this host. As a result, populations of soapberry bugs living on the two plants in nature no longer look adapted to their local host, because the effects of growing up on each plant hide genetic differences. This unexpected evolutionary consequence of an invasive plant is making it increasingly difficult for soapberry bugs to maintain the ability to use their original native host in Florida. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Maladaptive plasticity generated by gene flow masks the effects of natural selection in soapberry bugs </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 species are introduced to new areas, they can have profound effects on the evolution of native species. When the golden rain tree was introduced to Florida from Taiwan in the 1950s, some native soapberry bugs started eating its seeds instead of seeds of their native host plant, balloon vine. After several decades, two distinct types of soapberry bugs had evolved, each suited to one plant. </p><p>Like many invasive species, golden rain trees continued to spread in Florida over the last 30 years, increasing the number of soapberry bugs using this host instead of balloon vine. When soapberry bugs travel from golden rain tree back to balloon vine, they mate with local bugs and produce offspring with a mix of genes adapted to each host. This mixing of genes (‘gene flow’) that haven’t evolved together can produce unexpected detrimental effects, similar to what happens when two separate species mate. </p><p>Meredith Cenzer shows that this gene flow is causing soapberry bugs to respond incorrectly to their environment. She first confirms that long beaks are favored on balloon vine due to the large seedpods protecting its seeds, and that bugs living on balloon vine in nature are still genetically ‘longer beaked’ than those on golden rain tree. However, when bugs grow up on balloon vine, they develop short beaks that can’t reach the seeds of this host. As a result, populations of soapberry bugs living on the two plants in nature no longer look adapted to their local host, because the effects of growing up on each plant hide genetic differences. This unexpected evolutionary consequence of an invasive plant is making it increasingly difficult for soapberry bugs to maintain the ability to use their original native host in Florida. <a href="http://dx.doi.org/10.1086/693456">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, 04 Aug 2017 05:00:00 GMT “Estimation of individual growth trajectories when repeated measures are missing” http://amnat.org/an/newpapers/SepBrooks.html Soay Sheep have growth-reproduction tradeoff. Plus, new R package for modeling growth trajectories avoids bias of LMMs What are the consequences of reproductive investment on parental growth in wild animals? This question was investigated by Mollie Brooks, Christopher Clements, Josephine Pemberton, and Arpat Ozgul at the Universities of Zurich and Edinburgh using Soay sheep. Soay sheep, roaming wild on the Isle of Hirta in the St. Kilda archipelago off Scotland, have been tagged and recaptured each year since 1985 (see St Kilda Soay Sheep Project). This provides a long time series of the sheep’s demography including reproduction and survival, along with weights each summer. However, time series of wild animal populations frequently contain missing values because every individual cannot be captured every year. Focusing on the body mass time series, the authors developed an R package that handles missing values better than other common methods. Using this approach, Brooks et al. found that female sheep that give birth to a lamb in any given year grow about half as much as would otherwise be expected in that year. This is due to the energetic costs of being a mother, such as pregnancy and nursing. Sheep also have reduced growth in years when the population is large, probably because of greater competition for food or increased parasite burdens. Adverse winter weather also affects the sheep’s growth. Looking across individuals, the researchers found that sheep with consistently high growth rates are higher quality in other aspects as well; they live longer and produce more lambs across their life span; they are also more likely to start reproducing at an early age. Differences in individual quality could be caused by genetics or prolonged parasite infections. These patterns of body mass growth will probably have consequences for population growth because survival and reproduction depend on how much energy an animal has stored in its body, and this better understanding may help to predict population fluctuations in the future. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Soay Sheep have growth-reproduction tradeoff. Plus, new R package for modeling growth trajectories avoids bias of LMMs </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 are the consequences of reproductive investment on parental growth in wild animals? This question was investigated by Mollie Brooks, Christopher Clements, Josephine Pemberton, and Arpat Ozgul at the Universities of Zurich and Edinburgh using Soay sheep. Soay sheep, roaming wild on the Isle of Hirta in the St. Kilda archipelago off Scotland, have been tagged and recaptured each year since 1985 (see <a href=http://soaysheep.biology.ed.ac.uk>St Kilda Soay Sheep Project</a>). This provides a long time series of the sheep’s demography including reproduction and survival, along with weights each summer. However, time series of wild animal populations frequently contain missing values because every individual cannot be captured every year. </p><p>Focusing on the body mass time series, the authors developed an R package that handles missing values better than other common methods. Using this approach, Brooks et al. found that female sheep that give birth to a lamb in any given year grow about half as much as would otherwise be expected in that year. This is due to the energetic costs of being a mother, such as pregnancy and nursing. Sheep also have reduced growth in years when the population is large, probably because of greater competition for food or increased parasite burdens. Adverse winter weather also affects the sheep’s growth. </p><p>Looking across individuals, the researchers found that sheep with consistently high growth rates are higher quality in other aspects as well; they live longer and produce more lambs across their life span; they are also more likely to start reproducing at an early age. Differences in individual quality could be caused by genetics or prolonged parasite infections. </p><p>These patterns of body mass growth will probably have consequences for population growth because survival and reproduction depend on how much energy an animal has stored in its body, and this better understanding may help to predict population fluctuations in the future. <a href="http://dx.doi.org/10.1086/692797">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, 03 Aug 2017 05:00:00 GMT “What are the environmental determinants of phenotypic selection? A meta-analysis of experimental studies” http://amnat.org/an/newpapers/SepCaruso.html Across study systems, natural selection is stronger in environments where mean fitness is low Natural selection on plant and animal populations is not uniform, but varies in space and time. Is this variation in natural selection more likely to be caused by some aspects of the environment than by others? To answer this question, a team of researchers from universities in Canada, the UK, the US, and Sweden compiled data from more than 90 studies that experimentally manipulated aspects of the environment and estimated natural selection on plant and animal populations. The researchers used this dataset to test two predictions about which aspects of the environment are more likely to cause natural selection to vary in space and time. The researchers did not find support for the prediction that aspects of the biotic environment (such as predation and competition) are more likely to cause selection to vary in space and time than aspects of the abiotic environment (such as temperature and precipitation). Instead, they found that manipulating the biotic environment had a similar effect on selection estimates as manipulating the abiotic environment. In contrast, the researchers found support for the prediction that aspects of the environment that have a large effect on the average fitness (survival and reproduction) of plant and animal populations are more likely to cause selection to vary in space and time. Specifically, they found that selection estimates were larger in experimental treatments where manipulating the environment reduced average fitness. These results indicate that the aspects of the environment that cause selection to vary in space and time are predictable. Specifically, the aspect of the environment that has the largest effect on mean fitness should be the most important cause of variation in selection. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Across study systems, natural selection is stronger in environments where mean fitness is low </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;">N</span>atural selection on plant and animal populations is not uniform, but varies in space and time. Is this variation in natural selection more likely to be caused by some aspects of the environment than by others? </p><p>To answer this question, a team of researchers from universities in Canada, the UK, the US, and Sweden compiled data from more than 90 studies that experimentally manipulated aspects of the environment and estimated natural selection on plant and animal populations. The researchers used this dataset to test two predictions about which aspects of the environment are more likely to cause natural selection to vary in space and time. </p><p>The researchers did not find support for the prediction that aspects of the biotic environment (such as predation and competition) are more likely to cause selection to vary in space and time than aspects of the abiotic environment (such as temperature and precipitation). Instead, they found that manipulating the biotic environment had a similar effect on selection estimates as manipulating the abiotic environment. </p><p>In contrast, the researchers found support for the prediction that aspects of the environment that have a large effect on the average fitness (survival and reproduction) of plant and animal populations are more likely to cause selection to vary in space and time. Specifically, they found that selection estimates were larger in experimental treatments where manipulating the environment reduced average fitness. </p><p>These results indicate that the aspects of the environment that cause selection to vary in space and time are predictable. Specifically, the aspect of the environment that has the largest effect on mean fitness should be the most important cause of variation in selection. <a href="http://dx.doi.org/10.1086/692760">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, 03 Aug 2017 05:00:00 GMT “Cannibalism and infectious disease: friends or foes?” http://amnat.org/an/newpapers/SepVanAllen.html Cannibalism spreads disease? Not so fast! It can be a little more complicated... To a cannibal, a potential meal (a.k.a. the victim) may represent either a perfectly balanced protein snack or a breeding ground of virulent pathogens and parasites. The risk of disease transferred from victim to cannibal may weigh heavily against its nutritional advantages. Thus, potential disease transmission is no small part of why cannibalism is often considered a dangerous pursuit, at least from the cannibal’s perspective. This common line of thinking suggests that parasites may benefit more from cannibalism than the cannibal, even though cannibalism is ubiquitous in nature. This may be true for us humans, but for most species, cannibalism can actually stop or slow the spread of disease. Ben Van Allen and colleagues in the Elderd lab at LSU and Rudolf lab at Rice University combined their expertise in disease ecology and cannibalism theory to show that, as cannibalism increases in a population, it becomes harder and harder for parasites to invade and disease outbreaks to occur. Even if a parasite perfectly survives the transfer from victim to cannibal, as host population death rates increase due to cannibalism, the environment becomes worse for parasite transmission. Essentially, cannibalism can eliminate infected individuals and their disease from the population before epidemic thresholds are reached and outbreaks start. While there are parasites that may benefit from cannibalism indirectly by exploiting loopholes in the host life cycle, this work suggests that for some populations, cannibalism may be just what the doctor ordered. Read&nbsp;the&nbsp;Article More forthcoming papers &raquo; <p><b>Cannibalism spreads disease? Not so fast! It can be a little more complicated... </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>o a cannibal, a potential meal (a.k.a. the victim) may represent either a perfectly balanced protein snack or a breeding ground of virulent pathogens and parasites. The risk of disease transferred from victim to cannibal may weigh heavily against its nutritional advantages. Thus, potential disease transmission is no small part of why cannibalism is often considered a dangerous pursuit, at least from the cannibal’s perspective. This common line of thinking suggests that parasites may benefit more from cannibalism than the cannibal, even though cannibalism is ubiquitous in nature. This may be true for us humans, but for most species, cannibalism can actually stop or slow the spread of disease. Ben Van Allen and colleagues in the Elderd lab at LSU and Rudolf lab at Rice University combined their expertise in disease ecology and cannibalism theory to show that, as cannibalism increases in a population, it becomes harder and harder for parasites to invade and disease outbreaks to occur. Even if a parasite perfectly survives the transfer from victim to cannibal, as host population death rates increase due to cannibalism, the environment becomes worse for parasite transmission. Essentially, cannibalism can eliminate infected individuals and their disease from the population before epidemic thresholds are reached and outbreaks start. While there are parasites that may benefit from cannibalism indirectly by exploiting loopholes in the host life cycle, this work suggests that for some populations, cannibalism may be just what the doctor ordered. <a href="http://dx.doi.org/10.1086/692734">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, 03 Aug 2017 05:00:00 GMT