We are using DNA sequence data from the control region of the mitochondrial genome to assess phylogeographic patterns among populations of the Western toad (Bufo boreas)with an emphasis on the subspecies predominant in California (B.b.halophilus).  This work assesses the influences of major geographic features in California on the historical pattern of distribution of these toads.  Moreover, these results are impacting the entire taxonomic structure of the Bufo boreas complex including the Yosemite toad, considered a separate species (Bufo canorus).  This project is led by former master's student Molly Stephens, now working on her Ph. D. at the University of California, Davis.  This work has been done in collaboration with Brad Shaffer of University of California, Davis.