Allozyme diversity and genetic structure in Korean populations of Eurya emarginata (Theaceae)

Levels of genetic diversity, population genetic structure, and gene flow in six Korean populations of Eurya emarginata were investigated based on allozyme variation using starch gel electrophoresis. Although most Korean populations are relatively small and isolated, with respect to their habitats, they maintain high levels of genetic variation. Fourteen of the 18 putative isozyme loci surveyed were polymorphic in at least one population. Overall, mean genetic diversity within populations (Hep = 0.296) was higher than those for most species with very similar life history traits. Analysis of fixation indices showed an overall slight deficiency of heterozygotes relative to Hardy-Weinberg expectations (54% were positive). Although significant differences in allele frequencies among populations were found for all 14 polymorphic loci (P < 0.05), about 92% of the total variation in the species is common to all populations (GST=0.079). Indirect estimates of the number of migrants per generation (Nm) (2.02, calculated from the mean GST; 1.10, calculated from the mean frequency of six private alleles) indicate that gene movement among populations of E. emarginata is comparable with those for plants with similar life history traits. It is likely that factors such as dioecy, high fecundity, long generation time, and occurrence in late-successional forests may contribute to maintain high levels of genetic diversity within populations and low levels of genetic divergence between adjacent populations of the species.