Development of variable microsatellite loci and range-wide characterization of nuclear genetic diversity in the important dryland shrub antelope bitterbrush (Purshia tridentata)

Abstract

Antelope bitterbrush (Purshia tridentata Pursh DC; Rosaceae) is an arid-land shrub that occupies an important ecological niche in various fire-dominated communities across much of the western United States. Because of its importance as a browse for large mammals and a food source for granivores, P. tridentata is frequently planted by Federal agencies in arid-land revegetation. We are currently analyzing the range-wide genetic diversity of this species as part of a larger effort to develop seed movement guidelines. In this study, we describe the development of eight novel nuclear microsatellite loci and characterize the amount and apportionment of range-wide nuclear genetic diversity. The eight microsatellite loci exhibited a high level of polymorphism (13–33 alleles per locus) and in general, observed levels of heterozygosity did not deviate form Hardy–Weinberg expectations. An initial screen of 196 individuals from 12 widely distributed populations revealed a moderate amount of genetic differentiation (FST=0.09, p<0.001). Moreover, these loci successfully produced PCR products in cross-species amplifications with two closely related Purshia species. These results demonstrate the utility of these markers and provide useful measures of neutral genetic diversity and population differentiation.