Marisa Lim L&S Sciences
Investigation of contact zone interaction by DNA analysis of historical specimens of the California ground squirrel (Otospermophilus beecheyi)
Comparison of DNA sequences between different populations often reveals genetic lineages that warrant further study to assess the validity of current species delineations. Recent genetic work on the California ground squirrel uncovered three morphologically cryptic lineages. The Northern and Central lineages come into contact near Lake Almanor. The Central and Southern lineages meet near Mono Lake. Preliminary work found genetic differences distinguishing the Northern and Central lineages, despite the apparent absence of a geographic barrier to gene flow. In contrast, the Central and Southern lineages are genetically mixed (based on nuclear and microsatellite data), although the crest of the Sierra Nevada mountains appear to divide much of their range. My research seeks to understand the processes that lead to species formation and the biological barriers that keep species apart in this system. This summer, I will continue the genetic analysis for these three lineages and add assessments of hybrid viability.