Population Genetic Study of the Chewing Louse Geomydoecus ewingi

Abstract

Geomydoecus ewingi is a relatively well-known chewing louse that parasitizes the pocket gopher Geomys breviceps in the rodent family Geomyidae. Pocket gophers have been documented to exhibit long-term associations with their parasites, specifically lice. The flightless and obligate nature of the lice coupled with few opportunities to colonize new hosts has helped to make them model organisms for cospeciation studies. A main objective of my research was to determine the microevolutionary processes driving macroevolutionary patterns, such as cospeciation, in gopher-louse assemblages. Through the use microsatellite data, a series of population genetic analyses were conducted on lice parasitizing G. breviceps to better understand the population structure of lice among host individuals and across localities. With no previous microsatellite data available, I report 17 novel microsatellite loci in the parasitic chewing louse G. ewingi. Population genetic analyses infer significant structure among infrapopulations and potential inbreeding occurring within and among infrapopulations, possibly contributing to heterozygote deficiency and deviations from Hardy-Weinberg equilibrium. The microsatellite markers characterized in this study will be useful in future studies exploring the population dynamics in host-parasite systems, potentially yielding a better understanding of the processes underlying symbiotic associations.