| Summary: | Species are often confronted with rapid environmental change that require an adaptive response to maintain viability. The source of this environmental change can be natural, but is frequently anthropogenic in nature. In this thesis, I document the biological consequences of rapid environmental change in a sensitive mammal, the American pika (Ochotona princeps). In Chapter 2, I used microsatellite genetic makers to investigate the consequences of landscape modifications for pika populations relative to two major developments in British Columbia, Canada: a large open-pit copper mine (Highland Valley Copper) under partial reclamation and a bisecting major highway (97C). I found evidence for restricted movement associated with human-modified landscapes and showed evidence for fragmentation potentially resulting from the highway. Rapid environmental change often elicits a stress response in animals involving elevated glucocorticoids. In Chapter 3, I applied a novel technique to measure chronic stress in pikas by measuring extracted corticosterone from hair samples. Applying this method along two elevational transects of populations in North Cascades National Park, WA, allowed me to assess individual factors influencing stress in the American pika. My results showed elevated stress levels associated with smaller body sizes, female pikas, and with low early-spring ambient temperatures. This study provided direct physiological evidence for thermal stress in a climate-sensitive mammal and provides a useful tool for assessing climate stress in the American pika. Selective pressure from such thermal stress can result in local adaptation via natural selection. In Chapter 4, I used genotyping-by-sequencing to assess genotype-environment associations along these same elevational transects. The results showed a consistent genomic response to climate conditions across both transects and provide preliminary evidence for cold stress and hypoxia in the American pika. Additionally, I resolved consistent evidence for a downslope bias in gene flow, which may interfere with the upslope movement of individuals that is predicted with ongoing climate change. Taken together, these chapters show consistent patterns of restricted gene flow and thermal stress in the American pika and show the potential that climate-mediated natural selection is resulting in the development of local climate adaptations. === Irving K. Barber School of Arts and Sciences (Okanagan) === Biology, Department of (Okanagan) === Graduate
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