Wednesday, November 16, 2016

Lab-meeting on November 22: talk on sexual dimorphism in amphibians by Stephen De Lisle


Posted by Erik Svensson

Next week's EXEB-meeting will deal with the evolutionary ecology of sexual dimorphism by new postdoc Stephen De Lisle, who recently defended his PhD at Toronto University in Canada, under the supervision of Prof. Locke Rowe. Stephen has worked with amphibians, particularly newts, using a combination of experiments in mesocosms on single species, and phylogenetic comparative methods of amphibian diversification. An Abstract is appended below.

Time: Tuesday, November 22, 10.00
Place: "Darwin", 2nd floor, Ecology Building

   Ecological Aspects of Sexual Dimorphism


Sexual dimorphism represents a striking source of diversity in nature, and much of this diversity cannot be fully explained by the direct effects of sexual selection.  This talk focuses on empirically testing and conceptually unifying some of the non-exclusive adaptive causes of sexual dimorphismFirst, I present evidence from a newt indicating significant ecological sexual dimorphism and a possible role for at least some direct ecological causal component of dimorphism. I propose a framework for demonstrating an ecological cause of sexual dimorphism, via character displacement between the sexes, and marshal the first direct evidence in support of this hypothesis. I expand this program to examine how competition-driven disruptive selection, ecological sexual dimorphism and speciation interact during the early stages of adaptive radiation in newts.  These analyses suggest clade-wide character displacement between the sexes, and that evolution of ecological sexual dimorphism may play a key role in niche divergence among nascent species. Finally, I extend the test of dimorphism’s role in diversification to a higher level of organization, across Amphibians. I show that the evolution of sexual dimorphism is and has been a key driver of amphibian diversification by increasing speciation rates and reducing extinction.  These results suggest the novel hypothesis that sexual dimorphism may promote diversification by allowing lineages to exploit sex-specific ecological opportunity. The general conclusions are that sexual dimorphism can have significant ecological impact and even direct ecological causes, and contra traditional views, the evolution of sexual dimorphism in ecologically important traits can have important positive impacts on adaptive diversification.

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