Electronic Thesis and Dissertation Repository

Degree

Doctor of Philosophy

Program

Biology

Supervisor

Nusha Keyghobadi / Brock Fenton

Abstract

Despite the use of the host for dispersal by most parasite species, the extremely loose relationship typical between highly mobile hosts and generalist ectoparasites may lead to very different gene flow patterns between the two, leading in turn to different spatial genetic structure, and potentially different demographic history. I examined how similar gene flow patterns are between Cimex adjunctus, a generalist ectoparasite of bats present throughout North America, and two of its key bat hosts. I first analyzed the continent-scale genetic structure and demographic history of C. adjunctus and compared it to that of two of its hosts, the little brown myotis and the big brown bat, using microsatellite and mitochondrial data. Second, I compared spatial genetic structure of C. adjunctus with Cimex lectularius, or common bed bug, which associates with a broader range of host species. Third, I compared the effect of land cover on spatial genetic structure of C. adjunctus and of the big brown bat in the Great Lakes region. My results support the emerging hypothesis that generalist ectoparasites and their highly mobile hosts display weak, but positive, correlation in spatial genetic structure and demographic history.

Generalist parasites associate with different hosts, which are, in some cases, evolutionarily divergent from each other. In such cases, it is not clear how hosts may affect adaptive genetic variation in the parasites. In the Cimex genus, parasite species associate with a range of hosts, including bats, humans, and swallows. I examined how hosts affect adaptive genetic variation in these generalist ectoparasites. I analyzed variation at two salivary protein genes, one coding for an apyrase and the other for a nitrophorin, in 10 species of Cimex. These proteins affect the way parasites feed on their hosts, by preventing clotting and vasoconstriction, and may experience selection depending on host ecology or physiology. I also analyzed allelic divergence at the same two genes in a single species, C. adjunctus, associated with several bat species in North America. My results suggest selection and adaptation to the host at genes coding for salivary proteins of blood-feeding ectoparasites across the Cimex genus, and also within C. adjunctus.