9317685 Patton This proposal requests funding to examine a set of interrelated questions regarding the biogeographic patterns and speciation processes in the South American tropical forest rodent genus Proechimys. This is a large taxonomic assemblage, composed of at least nine species groups and approximately 25 species, but in which species boundaries are fuzzy and for which no hypothesis of genealogical relationships exists. As one of the most locally abundant and broadly distributed components of the terrestrial small mammal community of the Neotropical forests, these rats offer great promise as model organisms to examine the biogeographic history of the Amazon Basin, as well as to determine processes of divergence in that region. The PI proposes to complement his ongoing analyses that have emphasized craniodental morphology, karyology, and protein molecules with mitochondrial DNA sequence data for determination of species boundaries and phylogenetic reconstruction of the species groups. We will employ enzymatic amplification of DNA from the Cytochrome-b coding gene, via the polymerase chain reaction methodology. We will also explore the utility of nuclear sequences, examining variation in the globin and aldolase gene families. Emphasis will be placed on the determination of species boundaries, and on the examination of the riverine hypothesis as a force in diversification within the Amazon Basin.
