The evolution of color polymorphism in a pair of poison-dart frogs

A central goal of evolutionary biology is to understand the origin and maintenance of genetic and phenotypic variation in natural populations. Examining cases of adaptive variation, in particular, across different environments provides an opportunity to understand the essential evolutionary forces underlying biological diversification. Color polymorphism is a particularly promising system for the study of adaptive variation, because color patterns provide quantifiable and often dramatic differences within species that are conspicuously affected by natural selection. For my dissertation research, I examined color variation in two species of poison-dart frogs, Dendrobates pumilio and D. granuliferus, to investigate several fundamental questions in phenotypic evolution, including whether color traits are highly constrained in aposematic species, whether genetic isolation allows for the evolution of color polymorphism, and whether variation in conspicuousness evolves to match variation in toxicity. Contrary to prevailing theories, my results demonstrate that color traits are actually highly labile in D. pumilio, that divergence in coloration in D. pumilio led to genetic isolation rather than vice versa, and that conspicuousness is actually negatively associated with toxicity in D. granuliferus. Together, these results challenge some of the major tenets of aposematic theory and support new theories that may prove more appropriate for understanding aposematic evolution in species with environmentally derived toxicity.