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UBC Theses and Dissertations

American pika population genetic structure, demographic history, and behavior in an atypical environment Robson, Kelsey


Anthropogenic impacts on biodiversity are large and varied, from habitat destruction and fragmentation to climate change. In response to these threats, wildlife species must rapidly adapt within their geographic range, or disperse to different areas that have become environmentally suitable. If not, population decline, extirpation, and eventual species extinction will result. There is a current need for research into the ability of organisms to persist at the tolerance limits of their bioclimatic envelope, as this information will help assess potential responses to changing environments. The American pika (Ochotona princeps) is an appropriate model species for studies of adaptability and persistence in atypical environments. The geographic range of these climate-sensitive mammals extends across a large, variable landscape. Pikas typically inhabit alpine talus that is patchily distributed; as such, they are also a model species for studies of metapopulation dynamics in a fragmented landscape. This study used microsatellite genotypic data to investigate a) population genetic variation and demographic history, b) relatedness and inbreeding, and c) population structure and connectivity of American pika inhabiting an atypical environment in the Columbia River Gorge, Oregon. A total of 316 hair samples were non-invasively collected from 11 sites across an elevation gradient ranging from 46-1260 m. There were 155 pikas identified in the sample. For this system, high inbreeding and low genetic variation best characterized pikas within a site. A high degree of structure was detected among sites, and differentiation increased where topographical features potentially served as dispersal barriers. Although pikas inhabiting geographically proximate sites tended to cluster at similar elevations, there was little evidence of statistically significant migration. Indirect measures, however, such as within-site relatedness and inbreeding, strongly suggested a pattern of male-biased dispersal. This work addressed a knowledge gap in the pika literature by reporting on the population genetics and behavior of populations inhabiting an atypical environment. In order to properly evaluate the conservation status of the American pika, and inform sound management policies, it is necessary to consider the entire species distribution and compare populations from different parts of the range.

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