Reexamination of a pocket gopher (Geomys) contact zone in Oklahoma and hybrid identification using microsatellites and mitochondrial DNA markers.

Abstract

Two species of pocket gophers, Geomys bursarius and G. breviceps, are found in central Oklahoma. These species were previously recorded as hybridizing in a contact zone located within Cleveland County. This contact zone was first studied in 1951 and most recently in 1985 but has yet to be analyzed using modern molecular techniques. Because pocket gophers are cryptic species, genetic analysis is needed for species identification. I investigated the frequency of hybrid offspring within the contact zone using mitochondrial and nuclear markers, and compared the historical contact zone boundaries to the current boundaries using GPS and GIS. Overall, gophers were found primarily in the eastern locations of the contact zone and a large distribution was found north of the original trapping locations around Stanley Draper Lake, an area in which they were not previously documented. The species identification conducted using RFLP analysis indicated all specimens were G. breviceps. Microsatellite data suggested two distinct genetic clusters. The clusters were divided into a north-south pattern and potentially represent two different species or two populations of G. breviceps that are isolated by distance. Three admixture individuals were identified using STRUCTURE. Future research including samples of both Geomys species outside of contact zones and further microsatellite analysis is needed to elucidate the nature of the two clusters.