Using Dna and Rocks to Interpret the Taxonomy and Patchy Distribution of Pocket Gophers in Western Washington Prairies

The Mazama pocket gopher (Thomomys mazama) occurs in prairies, open fields, and subalpine meadows in northwestern California, western Oregon, southwestern Washington and in the Olympic mountains. With increasing development pressures in the southern Puget Sound area, T. mazama populations have been disappearing, thus several subspecies occurring in this region are considered to be species of conservation concern. These subspecies are patchily distributed in glacial outwash prairies. Based on molecular genetic analyses, we have found that the four extant prairie subspecies ranging from Fort Lewis to Olympia are not genetically differentiated, thus probably warrant taxonomic revision such that they will all be included as one subspecies. Examination of soil samples from sites with and without pocket gophers suggested that soil rockiness may influence the distribution of T. mazama in Puget Sound prairies.