Starter Grant: Genetic Differentiation of the Relict Herpetofauna of the Oases of Baja California

University Of Nevada Las Vegas, Las Vegas NV

Investigators

Abstract

The ability to obtain DNA sequence data and the development of rigorous analytical methods of allele genealogies have permitted the study of population structure within a phylogenetic framework. This phylogeographical approach has proved useful in understanding the histories of species shaped by Pleistocene climatic changes. The northwestern section of the peninsula of Baja California, Mexico is relatively cool and moist, whereas the central portion is arid. The rapid onset of desertification of central Baja California during the Pleistocene (1.8 million to 11,000 years ago) left disjunct pockets of mesic refugia, where previously transpeninsular, mesophilic species were able to remain. These humid areas correspond to Baja California's system of approximately 50 oases, isolated permanent or semipermanent bodies of springfed water. I will conduct a comparative phylogeographic study of five species of amphibians and reptiles found in those oases. The process of population differentiation is central to the origin of biological diversity. Reliable estimates of the timing of formation of the Baja California oases provide a general idea of when gene flow between the populations presumably ceased. This allows to ask important questions regarding differential rates of genetic differentiation between isolated populations of the same species, and interspecific differences on these rates.