DISSERTATION RESEARCH Fossils and phylogeny: investigating the timing of diversification in a diverse lineage of Neotropical rodents (Caviomorpha: Octodontoidea)

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Biodiversity patterns are products of historical processes such as speciation and extinction, but living species preserve only part of this history. Lineages with robust fossil records and diverse ecological and biogeographic radiations offer greater insights. This project focuses on one such lineage, the Octodontoidea (degus and their relatives). These rodents are diverse (193 species across six families), found throughout the Neotropics, and their fossil record extends back to the Oligocene (78 fossil genera). This project will investigate the patterns, timing, and rates of diversification of these rodents by integrating information from fossils and their geologic ages with DNA sequences from living species. These data will be used to generate a temporal hypothesis for the group's evolution that will then be used to examine how historical and ecological factors have influenced evolutionary rates over time. This project offers theoretical insights and practical information for conserving biodiversity, as many living octodontoids are threatened or endangered. Conducting this research at Chicago's Field Museum will facilitate outreach to an international audience; results will appear on a digital touch-screen in the Museum's DNA Discovery Center and shared through programs in the Education and Membership departments. Besides providing key training to a graduate student, this grant will contribute to public databases where biodiversity and genetic data will be deposited.