Date of Award

5-2026

Degree Type

Thesis

Degree Name

Master of Science

Department

Biology

Program

Biology (MS)

First Advisor/Chairperson

Kurt Galbreath

Abstract

Parasite phylogenetics can offer windows into the cryptic evolutionary history of hosts, often highlighting events that are not recorded by the phylogenetics of the host. Pikas (small lagomorphs) host a diverse parasite community comprising endoparasites (e.g., coccidians, nematodes, and cestodes) and ectoparasites (e.g., fleas and mites). Phylogenetic analysis of pika endoparasites has revealed pikas evolved in Asia and colonized North America in two waves, and that contact between these two pika lineages allowed parasites to be transferred from one lineage to another and to survive the extinction of their original host. To uncover these cryptic histories, understanding the biogeography of parasites is essential. Comparisons of the distribution of the pika endoparasites with those of pika ectoparasites in North America revealed widespread and relictual lineages of both. Phylogenies of North American pika fleas mirrored the patterns seen in pika cestodes, with relictual populations of fleas belonging to lineages that arrived in North America before the arrival of extant pikas. The discovery of Margopsylla tolli from collared pikas in the Northwest Territories of Canada provides additional context to the history of pikas in North America. Margopsylla tolli parasitizes both Ochotona collaris in Alaska and northern Canada and Ochotona hyperborea in eastern Siberia and Manchuria. The presence of this species on both sides of the Bering Strait is suggestive of late Pleistocene contact between O. collaris and O. hyperborea, supporting previous findings from pika pinworms.

Access Type

Open Access

Additional Files
SupplementaryTable1_FleaSpecimenData.csv (4 kB)
Supplementary Table 1. Flea specimen data
Joshua Pletcher.pdf (27 kB)
Signed Signature Page
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