PARENT SESSION
Oral Session 142: Mammalian Ecology.
Presiding: S Vignieri and D Berteaux
Friday, August 6, 8:30 AM to 12:00 PM, Meeting Room F 151.

The impact of habitat spatial structure on pika (Ochotona princeps) dispersal dynamics.

Merideth, Susan^*,1, Peacock, Mary¹, Brussard, Peter¹, ¹ University of Nevada, Reno, Reno, NV

ABSTRACT- The North American pika (Ochotona princeps) is an alpine mammal that is confined to talus habitat, which is naturally fragmented at both local and regional scales. To determine how isolation and habitat structure affect population genetic structure in this species, pika populations were sampled at six sites within and between two mountain ranges connected by a high-elevation pass in northeastern Nevada. Seven polymorphic microsatellite loci revealed high levels of genetic diversity (average heterozygosity = 0.59, range: 0.55-0.63) within these populations. Genetic distance, measured by F_ST and Cavalli-Sforza and Edwards chord distance (CD), was consistently higher between populations from different mountain ranges separated by 20 - 75 km (F_ST: 0.13 - 0.22; CD: 0.42 - 0.49) than between populations within the same range separated by 1.5 - 35 km (F_ST: 0.04 - 0.12; CD: 0.27 - 0.39). However, within a single mountain range, populations separated by 35 km exhibited only moderate genetic differentiation (F_ST = 0.12; CD = 0.39), which suggests that dispersal frequently occurs among patches at a local spatial scale. We found a significant isolation-by-distance pattern across populations using a 2-way Mantel test (CD: r = 0.747, p = 0.015), and we found genetic distance to be significantly correlated with spatial distance including a barrier between mountain ranges using partial Mantel tests (F_ST: R² = 0.601, p = 0.05; CD: R² = 0.813, p = 0.03). We found that spatial distance clearly influences genetic distance in these populations, and unsuitable, low-elevation habitat of approximately 3 - 8 km in extent between mountain ranges acts as a barrier to gene flow in this species.

Key words: Ochotona princeps, microsatellites, North American pika, population genetic structure