Population genetic analyses of chewing lice (Geomydoecus ewingi) parasitizing pocket gophers (Geomys breviceps)

Lice (Ischnocera: Trichodectidae) are relatively well-known ectoparasites that parasitize only mammals, specifically pocket gophers in the rodent family Geomyidae. Because parasites depend upon their hosts for survival, they often have complex ecological interactions with their hosts that persist over long evolutionary timescales. Host-parasite systems and their histories between can be used to analyze a variety of ecological and evolutionary questions. Due their conservative morphology and resulting limited dispersal ability, pocket gophers have been documented to have long-term associations with their parasites, specifically lice. This research is concentrated on the population genetics of louse populations, and to determine the microevolutionary processes driving macroevolutionary patterns such as cospeciation in gopher-louse assemblages. Chewing lice (Geomydoecus ewingi) parasitizing the Baird’s pocket gopher (Geomys breviceps) were examined. Gophers and their lice were collected from three localities in College Station, Texas. A novel genomic microsatellite library was constructed from G. ewingi  lice for the purpose of creating loci specific primers. Lice were screened for each of the 15 polymorphic loci using PCR reactions. Population structure was assessed with analyses indicating the majority of the genetic variation existed within individuals. The findings also suggest there is hierarchical structuring of louse genetic diversity, which generally corresponds to geography rather than host individuals.