The use of microsatellite variation to infer population structure and demographic history in a natural model system

To assess the reliability of genetic markers it is important to compare inf erences that are based on them to a priori expectations. In this article Mi e present an analysis of microsatellite variation within and among populati ons of island foxes (Urocyon littoralis) on California's Channel Islands. W e first show that microsatellite variation at a moderate number of loci (19 ) can provide an essentially perfect description of the boundaries between populations and an accurate representation of their historical relationship s. We also show that the pattern of variation across unlinked microsatellit e loci can be used to test whether population size has been constant or inc reasing. Application of these approaches to the island fox system indicates that microsatellite variation may cam considerably more information about population history than is currently being used.