Genetic variation and population structure in Fraser fir (Abies fraseri): a microsatellite assessment of young trees
The island-like populations of Fraser fir (Abies fraseri (Pursh) Poir.) have been isolated since the end of the late-Wisconsinian glaciation on the highest peaks of the Southern Appalachian Mountains and therefore offer an opportunity to investigate the genetic dynamics of a long-fragmented forest tree species. An analysis of eight microsatellite markers isolated from Fraser fir found that the species was out of Hardy- Weinberg equilibrium, with a significant deficiency of heterozygosity and a high degree of inbreeding (FIS = 0.223) relative to other conifers, perhaps associated in part with the young life stage of the trees included in the analysis. The analysis detected a significant but small amount of genetic differentiation among Fraser fir populations (FST = 0.004) and revealed that the geographical and latitudinal distances between populations, but not population area, were significantly correlated with their pairwise genetic differences. Both gene flow and postglacial migration history may have influenced the genetic architecture of the species. The results will be useful in the genetic conservation of Fraser fir, a species experiencing severe mortality following infestation by an exotic insect.