DISSERTATION RESEARCH: Shifting climates and stable niches: Assessing the impact of ancient climate cycles on phylogeographic structure within three Andean marsupials

This study investigates how extreme climate fluctuations of the Ice Ages over the past several hundred thousand years might have affected the geographic distributions, genetic structure, and diversity of species. Theory suggests that fluctuating climates may have acted as a force promoting diversification. To better understand the specific effects of ancient climate fluctuations on the diversification of species, this project focuses on a group of marsupials (Thylamys opossums) that live in the Andes Mountains of South America. Genetic data and computational tools will be used to make inferences about events that occurred in the distant past. With this genetic evidence in hand, hypotheses concerning the impact of ancient climate change on species diversity can be tested.

Only a handful of studies have examined the evolutionary patterns of Andean mammals in the context of ancient climate fluctuations, and prior to this work, none has considered these factors for Thylamys species. This project is significant and distinct from previous efforts because it will explicitly test alternative evolutionary hypotheses using multiple types of genetic data, ecological models of each population's geographic distribution, and sophisticated computational tools. When complete, this project will illustrate from multiple perspectives the impact of climatic shifts on biodiversity in Thylamys. Finally, the species considered here live in a biodiversity hotspot (the Tropical Andes), and a clear understanding of genetic patterns for this group can be used to guide localized conservation strategies for this unique group of mammals.