Species in the genus Tangara are distributed throughout the New World tropics and vary in their morphology, behavior, and ecology. We used data from the cytochrome b and ND 2 genes to provide the first phylogenetic perspective on the evolution of this diversity. Reconstructions based on parsimony, maximum likelihood, and Bayesian approaches were largely congruent. The genus is monophyletic and consists of two main clades. Within these clades, DNA sequence data confirm the monophyly of most previously recognized species groups within Tangara, indicating general concordance between molecular data and impressions based on geographic distribution, morphology, and behavior. Within some currently recognized species, levels of DNA sequence variation are larger than expected, suggesting multiple taxa may be involved. In contrast, some currently recognized species are only weakly differentiated from their sister species. Biogeographic analyses indicate that many early speciation events occurred in the Andes. More recently, dispersal events followed by subsequent speciation have occurred in other geographic areas of the Neotropics. Assuming a molecular clock, most speciation events occurred well before Pleistocene climatic cycles. The time frame of Tangara speciation corresponds more closely to a period of continued uplift in the Andes during the late Miocene and Pliocene.
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We thank scientific collectors and curators at the following institutions for providing tissue samples used in this study: Louisiana State University Museum of Natural Science, Field Museum of Natural History, Academy of Natural Sciences of Philadelphia, Museum of Vertebrate Zoology at the University of California at Berkeley, the Smithsonian Tropical Research Institute, the University of Michigan Museum of Zoology, and the American Museum of Natural History. For assistance with specimen collection, we thank Francisco and Fernando Sornoza, M. Jácome, J.E. Sánchez, E. Carman, M.I. Gómez, L. Chavez, H. Araya, E. Toapanta, Beto Chavez Mora, and V. Zak. For assistance in the lab, we thank R. Combs and B. Sharp. The manuscript benefited from comments provided by J.V. Remsen, M.L. Isler, P.R. Isler, and two anonymous reviewers. Financial support for this project was provided by the National Geographic Society, the National Science Foundation, the American Ornithologists' Union, and the American Museum of Natural History.