Climate drives genetic diversity loss in American Pika () populations in the Great Basin.

American pikas () are small, thermally sensitive mammals that primarily live in montane and alpine environments. The Sierra Nevada lineage () 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 , with particular focus on northwestern Nevada; and (ii) assessed the influence of primary productivity and climate-related variables on genetic diversity within , as well as at the broader species level. Great Basin populations exhibited the lowest levels of genetic diversity. Within , 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.