HAGERTY, B.E.*; TRACY, C.R.; University of Nevada, Reno; University of Nevada, Reno: Identification of population structure for a rare and cryptic species: implications for conservation

The underlying spatial structure of populations within a species provides perspective for conservation planning. Direct methods are often used to estimate movements of individuals among populations and other ecological processes. However, direct methods typically involve widespread radio-tracking, which can be expensive and labor-intensive at the least, and perhaps infeasible to obtain adequate statistical power to discern general population phenomena in wide ranging species. Often, indirect methods, using genetic markers, can be used to estimate movement of individuals among places, and to infer ecological and evolutionary processes. These methods can be particularly useful with rare and/or cryptic species. The desert tortoise (Gopherus agassizii) is both a rare and cryptic species inhabiting the Mojave Desert of the southwestern United States. Adequate direct measurements are difficult because the species� ecological properties. Desert tortoise is long-lived, spends a majority of its time below ground in burrows, is cryptically colored, inhabits an extensive range, and is classified as threatened due to declining population numbers. We have genotyped individuals across the range of the Mojave desert tortoise using highly variable microsatellite markers to identify the underlying spatial structure of the Mojave populations. We find that there are genetically distinct clusters of the desert tortoise, and that these clusters reflect natural barriers to movements of individuals within the species� range. The results of our study have important implications for the conservation this rare and cryptic species.