Biology Faculty Proceedings, Presentations, Speeches, Lectures


Color Polymorphism in Damselflies and Chickens

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Lund Unviersity Thursday Biology Seminar, Lund, Sweden, October 15, 2015

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Darwin and Wallace each struggled to explain the variation in evolution’s color palette. In Darwin’s view, colorful ornaments were a common outcome of sexual selection, whereas Wallace ascribed them to natural selection. A century later, we recognize that both forms of selection interact in complex ways to determine color phenotypes. Here I will describe two case studies of color evolution within invasive populations. Species invasions provide unique opportunities to characterize how traits respond to novel (and often extreme) forms of selection. Surprisingly, our syntheses of historical, genetic and experimental data from invasive chickens and damselflies suggest that density-dependent selection promoted color variability in both groups via very different mechanisms. In damselflies, color polymorphism allowed females to adapt to changes in social environment that ensued invasive spread. In chickens, plumage variation that resulted from hybridization collapsed during colonization of marginal habitats. While our understanding of these complex systems is far from complete, patterns seen thus far reveal how demographic features of biotic invasions could facilitate rapid evolution by both Darwinian and Wallacian mechanisms.



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