Levels and partitioning of genetic diversity of Camellia japonica (Theaceae) in Korea and Japan

We analyzed allozymes from 620 trees to estimate the levels of allozyme diversity within and genetic differentiation among populations of Camellia japonica in Korea and Japan. Both at the population and species levels, C. japonica (mean expected heterozygosity, He = 0.169 and 0.190) maintains high levels of genetic diversity. Although Korean populations of the species are located in edge of its distribution, they (0.209) harbor higher levels of genetic diversity than that found within populations in Japan (0.145). The mean G ST value among 16 populations (0.091) of C. japonica was similar to those among six Korean (0.055) and 10 Japanese populations (0.086). The results indicate that a low degree of allozyme differentiation between populations in Japan and Korea, though the land connection between the southern Korean peninsula and southern Japanese archipelagos no longer existed after the middle Pleistocene. There was no significant correlation between genetic distance and geographic distance, indicating that isolation by distance may not be a primary factor for shaping genetic structure among populations. Instead, genetic diversity and structure in populations of C. japonica may result from the balance between occasional gene flow and genetic drift.