Meeting Abstract
Sexual selection can drive rapid divergence in mating traits and behaviors, which may facilitate speciation by creating behavioral isolation among phenotypic variants. Behavioral responses to the diverged trait can limit gene flow among young lineages; however, the evolutionary outcomes depend profoundly on whether the behaviors are genetically inherited or learned. Here, we tested the hypothesis that color-mediated behaviors in the polymorphic poison frog Oophaga pumilio are learned, and explored the ability of such learned behavior to drive color evolution and speciation using mathematical modeling. Male and female O. pumilo, in general, respond more strongly to their own color morphs than to different color variants in wild populations. We showed in a cross-fostering lab experiment that these color-mediated behaviors are learned through interactions with the parents, especially the mother, perhaps during egg provisioning at the tadpole stage (i.e. maternal imprinting). Deterministic simulations in diploid population genetics models revealed dual roles in both learned female preference and learned male aggression bias. Stronger female preferences result in higher trait-preference linkage disequilibrium (a proxy of degree of reproductive isolation), but tend to lead to loss of polymorphism via positive-frequency dependent selection. Male aggression bias can generate negative-frequency dependent selection that keeps polymorphism from going to fixation, but result in lower trait-preference linkage disequilibrium when bias strength is asymmetric between phenotypes. Given this, the divergent color-mediated behaviors in O. pumilio thus appear to serve a more complex role in speciation than previous studies have assumed.
