POPULATION REDUCTIONS AND GENETIC-VARIABILITY IN BLACK-TAILED PRAIRIE DOGS

Black-tailed prairie dogs (Cynomys ludovicianus) have been subjected to intense population reduction efforts over much of their range, often resulting in scattered, remnant colonies, and possibly resulting in altered genetic characteristics. Consequently, I examined the relationships between population size reductions and the amount of genetic variability in black-tailed prairie dogs at Wind Cave National Park, South Dakota, where a wide range of colony sizes and past management histories existed. Blood samples were collected from 377 prairie dogs at 8 colonies, and were analyzed using starch-gel electrophoresis. Colonies varied in size from < 20 individuals, at colonies that had been through recent population bottlenecks as the result of control efforts, to thousands of individuals at colonies that were relatively unmanaged. Mean heterozygosity values within populations ranged from 0.027 to 0.040, but showed no relationship to the severity of recent population reduction. Allele frequencies at all loci were heterogeneous among colonies and F(ST) (fixation index) values were moderate to high (mean F(ST) = 0.115), indicating moderate to high levels of genetic differentiation among colonies. Genetic divergence was as much as 4 times greater among colonies that had undergone recent population bottlenecks than among colonies that were relatively unmanaged. Current prairie dog management practices at Wind Cave National Park were not found to decrease the level of genetic variability in prairie dog populations, probably because of rapid recovery from low population sizes and occasional successful immigration.