Reintroduction and genetic structure: Rocky mountain elk in yellowstone and the western states

Abstract

Translocation is a common tool for restoring wildlife populations; however, potential genetic consequences include reduced levels of diversity within and increased divergence among populations. Elk (Cervus elaphus) were extirpated across much of North America by the early 20th century, but subsequent translocation programs restored the species to much of its historic range. The effects of these reintroductions on current patterns of genetic diversity in the western United States are largely unknown. We predicted that populations initiated with few founders and those experiencing slow postreintroduction growth would exhibit lower levels of diversity than other reintroduced populations. We used 12 microsatellite markers to examine patterns of genetic variability across 5 reintroduced populations of elk and 2 source herds from the Greater Yellowstone Ecosystem. The northern and southern Yellowstone source herds, which migrate to wintering areas separated by more than 260 km, exhibited similar levels of genetic diversity and high levels of gene flow, identified through both direct (i.e., assignment tests) and indirect measures. Levels of genetic diversity also were relatively high in all populations (unbiased heterozygosity, HE = 0.51-0.60; allelic richness based on a sample size of 21, AR21 = 3.3-4.0) and did not differ significantly between source and reintroduced populations or among reintroduced populations. We observed low to moderate levels of differentiation (Weir and Cockerham's F ST statistic, δ = 0.01-0.08) and small genetic distances (Nei's standard genetic distance, DS = 0.02-0.11) between populations. The relatively high levels of genetic diversity and low differentiation observed among our sampled populations are in stark contrast to observations of low diversity and high differentiation among isolated reintroduced populations of elk in the eastern United States. These results suggest that gene flow that includes other elk populations in the western United States may aid in preserving genetic diversity and limiting genetic divergence. © 2007 American Society of Mammalogists.