Morphological Evolution, Vocal Performance, And Speciation In Darwin's Finches

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Darwin's finches of the Galapagos Islands, Ecuador, are well known for having evolved a wide diversity of beak forms, ranging from the thin probing beaks of warbler finches to the massive seed-crushing beaks of large ground finches. Recent data suggest that the evolutionary diversification of beak shape has driven corresponding changes in mating song structure, because of the functional role played by the beak in song production. This project aims to characterize patterns, causes, and consequences of correlated evolution between beak shape and vocal traits. During three field expeditions, finches will be captured, banded, measured, released, and their songs recorded. Evolutionary correlations between beak shape and vocal traits will be assessed, the functional role of the beak in sound production characterized, and the relationship between song structure and song function evaluated, using playback experiments.This project is significant in addressing the mechanisms and dynamics of speciation (speciation refers to the process by which new species are generated). In Darwin's finches and many other animal groups, speciation is driven by the evolutionary diversification of mating signals. Mating signals provide cues about species identity and thus help to maintain genetic barriers among evolving lineages. The causes of mating signal diversification, however, have remained largely undocumented. The present project will document the contribution of ecological diversity and anatomical adaptation in shaping mating signal diversification.