Geographic Drivers of Genetic and Plumage Color Diversity in the Blue-Crowned Manakin

Abstract

Investigating parallel roles of geography and environmental heterogeneity in diversification provides insights on how neutral and selective forces drive evolution of biological systems. Here, we investigate whether geographic and climatic distances explain either genetic or phenotypic variation in Blue-crowned Manakins (Lepidothrix coronata), a polychromatic bird species that is broadly distributed in the Neotropics. We tested the hypotheses of isolation by distance and environment through an integrative approach using genetic, colorimetric, geographic, and environmental data. Through structural equation modeling and multiple matrix regression with randomization statistics, we tested whether intraspecific genetic or phenotypic (plumage color) diversity is associated with variation in geographic and environmental distances among localities. Genetic and color diversity were not correlated: color variation was marginally associated with latitude; and genetic distances were explained by linear and least-cost geographic distances, conforming to predictions of isolation by distance and by environment. We suggest a combined effect of genetic drift and environmental heterogeneity in driving the genetic diversification at the regional scale, and adaptation to local environments operating in the diversification of adult male plumage coloration.