Darwin's finches of the Galapagos Islands, Ecuador, are a classic example of adaptive radiation, in which a single ancestral species has diversified into multiple descendant species. These birds have evolved an impressive array of specializations in beak form and function, in accordance with the diverse feeding niches they have come to occupy. The study builds on the recent discovery that the evolutionary diversification of beaks has led to incidental changes in the acoustic structure of finch vocal mating signals. The larger goal of the research is to understand how adaptive evolution and mating signal divergence contributes to species diversity. The research is conducted during annual field expeditions. Intensive sampling of birds at multiple field sites allows documentation of relationships between feeding ecology, beak form and function, vocal behavior, and patterns of mate selection. Finch bite performance is measured using portable force transducers and high-speed video will document beak movements during song production and possible tradeoffs. Song playback experiments will characterize the influence of acoustic variation on song function and reproductive isolation. The project also includes instruction, professional training, and outreach activities. A "real-time" web site will be developed for an undergraduate non-majors course to document field research and foster interactions between students and researchers; the study will be part of the National Center for Case Study Teaching in Science for K-12 students and teachers; new laboratory exercises for undergraduate majors and a graduate seminar course will also be an integral part of this project.
