![]() Global or regional climate changes cause geographic ranges to shift in elevation. Changes in these barriers over time due to tectonic activity and erosion lead to fragmentation or mixing of populations, circumstances that can increase speciation or extinction rates in montane regions. Montane regions also present strong barriers – in the form of deep valleys, steep climatic gradients and abrupt changes in topography – to the distribution of populations and species. Strong elevational gradients of climate, soil and vegetation in montane regions provide diverse habitats from high to low elevations these heterogeneous habitats can accommodate high mammal diversity, especially of small mammals. Several biogeographic processes have shaped the topographic diversity gradient for mammals. This concentration of diversity in regions of high topographic complexity compared to adjacent lowlands and plains constitutes the topographic diversity gradient, one of the major biogeographic patterns across continents today. More than half of present‐day continental mammals occur in montane regions. Our work highlights the need for continued conservation and research efforts to identify how response to environmental change can be facilitated in isolated species and habitats. Our assessment of habitat associations suggests that the Humboldt yellow pine chipmunk almost entirely is restricted to the conifer systems of the PFR, while least chipmunks are prevalent in the other forests. minimus in the PFR, although the prevalence of infection was similar to other Tamias populations. amoenus carried higher pathogen loads than T. minimus had higher genetic diversity that was comparable to the other T. amoenus are highly genetically differentiated from other populations. amoenus in the Warner Mountains and Sierra Nevada, but maintain substantively lower genetic variation. ![]() amoenus of the PFR are closely related to T. We examined phylogenetic relationships, population divergence and diversity, and screened populations for a common pathogen, Borrelia hermsii, to gain insight into population health. Given the high frequency of hybridization in Tamias, we tested for hybridization between T. minimus) from the isolated PFR and compared genetic diversity between these populations and more “mainland” populations, including other subspecies of chipmunks. A subspecies of yellow pine chipmunk, the Humboldt yellow pine chipmunk (Tamias amoenus celeris), is associated with the whitebark and limber pine forests of the Pine Forest Range (PFR) in Nevada. The montane sky islands of the Great Basin are characterized by unique, isolated habitats and communities that likely are vulnerable to extirpation with environmental change.
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