Despite evidence that species’ traits affect rates of bird diversification, biogeographic studies tend to prioritise earth history in Neotropical bird speciation. Here we compare mitochondrial genetic differentiation among 56 co-distributed Neotropical bird species with varying ecologies. The trait ‘diet’ best predicted divergence, with plant-dependent species (mostly frugivores and nectivores) showing lower levels of genetic divergence than insectivores or mixed-diet species. We propose that the greater vagility and demographic instability of birds whose diets rely on fruit, seeds, or nectar . known to vary in abundance seasonally and between years . relative to birds that eat primarily insects, drives episodic re-unification of otherwise isolated populations, resetting the divergence ‘clock’. Testing this prediction using coalescent simulations, we find that plant-dependent species show stronger signals of recent demographic expansion compared to insectivores or mixed-diet species, consistent with this hypothesis. Our study provides evidence that localised ecological phenomena scale up to generate larger macroevolutionary patterns.
All Science Journal Classification (ASJC) codes
- Ecology, Evolution, Behavior and Systematics