Genetic Sampling of Palmer\u27s Chipmunks in the Spring Mountains, Nevada

Palmer\u27s chipmunk (Neotamias palmeri) is a medium-sized chipmunk whose range is limited to the higherelevation areas of the Spring Mountain Range, Nevada. A second chipmunk species, the Panamint chipmunk (Neotamias panamintinus), is more broadly distributed and lives in lower-elevation, primarily pinyon-juniper (Pinus monophylla-Juniperus osteosperma) habitat types. Panamint chipmunks are not closely related to Palmer\u27s, but field identification of the 2 species is unreliable. Palmer\u27s chipmunk is a species of concern in the state of Nevada and is listed by the International Union for Conservation of Nature (IUCN) as endangered. As such, conservation of Palmer\u27s chipmunks is a priority in the Spring Mountains National Recreation Area. We sampled putative Palmer\u27s chipmunks from 13 sites distributed across the Spring Mountains during 2010–2011. We removed Panamint chipmunks by using DNA-based identifications and then analyzed the genetic population structure of Palmer\u27s chipmunks by using a panel of 9 microsatellites. Of the 228 samples that were genotyped, 186 were Palmer\u27s; there was no evidence of hybridization between species. Four sites had exclusively Panamint chipmunks, 5 had exclusively Palmer\u27s chipmunks, and 3 had a mixture of the 2 species. In this study, Palmer\u27s chipmunks were exclusively captured at sites above 2400 m elevation, and Panamint chipmunks were exclusively captured at sites below 2200 m. Panamint chipmunks were trapped in areas typed as pinyon-juniper, but they were also trapped at sites typed as ponderosa pine (Pinus ponderosa) and mixed conifer. Both species were trapped at 3 sites; at all 3 sites, the lowerelevation traps contained Panamint chipmunks and the higher ones Palmer\u27s chipmunks. Population structure within Palmer\u27s chipmunks was minimal: heterozygosity was relatively high, and the populations displayed no signs of recent bottlenecks. Indications are that the distribution of Palmer\u27s chipmunk is limited to higher-elevation areas in the Spring Mountains, but within this area, Palmer\u27s chipmunk occurs as a single, large, well-connected, and stable population