9801524 Blake Neotropical montane regions are areas of high diversity and endemism, and are, therefore, special areas of concern for conservation of biodiversity. Because of their island-like distribution, these montane regions provide a natural laboratory for studying processes responsible for the generation of biodiversity, including evolutionary differentiation among populations and species. In this project, we shall use mitochondrial DNA sequence data to determine the evolutionary relationships among species and populations of birds known as tropical redstarts (Myioborus). The small warblers are distributed at higher elevations from the southwestern United States to Argentina with many endemics in Central America, the Andes, and the Venezuelan highlands (Pantepui region), although a few species are widely distributed. Relationships between Venezuelan and Andean populations are enigmatic because species that appear to be the most similar sometimes are the most distant geographically. Furthermore, resolution of the intriguing question of whether species in the ancient Pantepui region of Venezuela are ancestral to Andean species or are derived from them can be only by a phylogenetic analysis of their relationships. This study will use DNA sequences to establish relationships, reconstruct the historical biogeography, and examine the evolution of body size and shape, as well as plumage coloration, in Myioborus. The results of the study will allow us to establish taxonomic limits within the genus, more accurately assess biodiversity patterns in the group, and contribute to our general understanding of organismal diversification in the Pantepui region of Venezuela and of the historical relationships between Central and South American montane avifaunas.
