Genetic diversity and population structure of Korean alder (Alnus japonica; Betulaceae)

The genetic diversity and population genetic structure of Alnus japonica (Thunb.) Steudel in Korea were studied and compared with those of alder from Canada. Nineteen of the 25 loci studied (76.0%) showed detectable polymorphism. The mean genetic diversity within populations was 0.207, which was higher than that for two Canadian alder species (Alnus rugosa (Du Roi) Spreng. and Alnus crispa (Ait.) Pursh). Analysis of fixation indices, calculated for all polymorphic loci in each population, showed a substantial deficiency of heterozygotes relative to Hardy-Weinberg expectations. The mean population differentiation value of A. japonica in Korea (G ST = 0.095) is similar to those of A. rugosa in Canada (G ST = 0.052). These low values of G ST in two countries, reflecting little spatial genetic differentiation, may indicate extensive gene flow (via pollen and (or) seeds) and (or) recent colonization.