The evolutionary mechanisms causing intraspecific diversity in aposematic color and pattern remain enigmatic. The strawberry poison frog (Oophaga pumilio) has diversified into a broad array of colors that span the visible spectrum. The most divergent phenotypes of O. pumilio are restricted to separate islands in the Bocas del Toro archipelago in western Panama, whereas throughout the majority of its range (from Nicaragua to western Panama) this species exhibits a single red phenotype. During the Holocene, sea-levels increased and changes in climate caused shifts in habitat through time. In the Bocas del Toro archipelago, rising sea-levels isolated previously connected populations in higher elevation habitats (forming islands). In this study we use historic measures of demography, ancestral distribution estimates, spatiotemporally explicit demographic models and genetic simulations to investigate the genetic consequences of the isolation due to sea-level changes and demographic processes mediated by recent climatic fluctuations. We then evaluate the role of these factors in the evolution of color in O. pumilio by measuring and comparing the deep coalescence of a neutrally evolving nuclear gene and a hypothetical autosomal coloration gene. Our results support a major role for recent population expansion and reduced gene flow (from isolation on islands) in the diversification of color across populations.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics
- Color evolution
- Dynamic histories
- Natural selection
- Sexual selection