Meeting Abstract
Assortative mate preferences (i.e. preferring mates of a similar phenotype to one’s self) are hypothesized to limit gene flow and accelerate reproductive isolation among young lineages. However, male-male competition can restrict, and may, in many mating systems, override female preference. The strawberry poison frog (Oophaga pumilio) is one notable example of a species with dramatic phenotypic divergence that may be involved in reproductive isolation. Female mate preferences have co-diverged with color in most populations tested, but the extent to which such assortative preferences can effectively reduce gene flow among color morphs when accompanied with male-male competition is not clear. Here, we experimentally evaluated the relative importance of color-mediated female preference and male-male competition, testing the hypothesis that male territorial contest results limit the female from choosing her preferred color. We first set up a dyadic contest between two different colored males; upon establishing a stable hierarchy (i.e. a clear winner and loser), we introduced a female with a preference for the loser male’s color. This breeding trio was kept together until they produced tadpoles, which we then genotyped to reveal paternity as direct evidence of reproductive success. Results showed that females were more likely to (but did not exclusively) mate with the winner male that had the less attractive color. Our results highlight the importance of male-male competition, a less-studied part of sexual selection, in shaping the process of phenotypic divergence and speciation.
