Climate drives genetic diversity loss in American Pika (<i>Ochotona princeps</i>) populations in the Great Basin

American pikas (<i>Ochotona princeps</i>) are small, thermally sensitive mammals that primarily live in montane and alpine environments. The Sierra Nevada lineage (<i>O. p. schisticeps</i>) has experienced numerous local extinctions, most of which occurred in hotter, drier regions such as the Great Basin. Few genetic studies have assessed these at-risk populations. This study aims to fill that gap by conducting fine-scale genetic analyses on populations in low-elevation Great Basin habitat in northwestern Nevada. Specifically, we: (i) quantified genetic diversity and structure among populations within <i>O. p schisticeps</i>, with particular focus on northwestern Nevada; and (ii) assessed the influence of primary productivity and climate-related variables on genetic diversity within <i>O. p schisticeps</i>, as well as at the broader species level. Great Basin populations exhibited the lowest levels of genetic diversity. Within <i>O. p. schisticeps</i>, population genetic diversity was positively correlated with annual precipitation-while at the species level temperature explained the most variation in genetic diversity. These results provide insight into climate-driven range contractions predicted for this species and inform conservation and management decisions.