Biology ETDs

Publication Date

Spring 4-13-2020


Host-parasite systems exist across complex and ecologically heterogeneous landscapes, and may occur across taxonomically and ecologically disparate host species. Under these conditions, mechanisms underlying microevolutionary processes (i.e. gene flow, genetic drift) are not always clear, and may be mediated by numerous co-occurring factors specific to individual hosts. Host traits such as host immunology, demographics, phylogeny and ecology may act in concert to shape host-parasite relationships, and ultimately evolutionary processes. The research described herein used phylogeographic, phylogenomic, and population genetic methods to further understanding of how host traits impact the evolutionary ecology of trematode systems, using avian schistosomes (Digenea: Schistosomatidae) as a model. Much of this work specifically focused on the genus Trichobilharzia and an important snail host Physa acuta. These studies in aggregate found that host habitat preference, migratory patterns and demographics were all important factors in mediating parasite transmission. Further within Trichobilharzia spp., which are parasites of ducks, two species which utilize P. acuta were found to have substantially different population genetic patterns. Data from this study suggest that duck habitat preference can increase or dilute Trichobilharzia transmission. Further data suggest that certain combinations of hosts may facilitate transmission into a broader geographic range. At the macroevolutionary level this study finds support that host-switching has likely been an important mechanism of schistosome diversification, and did not find evidence suggesting a strong co-phylogenetic pattern among parasites and intermediate hosts. In total this research provides a framework for understanding how host traits may act to shape parasite transmission and subsequent evolution.

Project Sponsors

National Science Foundation, The National Institutes of Health




parasite evolution, Schistosomes, Trichobilharzia, duck parasites, Schistosomatidae, Trematoda

Document Type


Degree Name


Level of Degree


Department Name

UNM Biology Department

First Committee Member (Chair)

Sara V. Brant

Second Committee Member

Eric S. Loker

Third Committee Member

Christopher Witt

Fourth Committee Member

Thomas Turner

Fifth Committee Member

Charles Criscione