Fine-scale genetic structure in populations of Quercus variabilis (Fagaceae) from southern Korea

Quercus variabilis Blume (Fagaceae) is a deciduous broad-leaved tree, and an important forest element among the hillsides of southern Korea. To date, there are contrasting results with respect to fine-scale spatial genetic structure among adults in populations of several oak species; some studies have shown evidence of significant within-population spatial genetic structure, while others found weak or little evidence of fine-scale genetic structuring within populations. We used allozyme loci, Wright's F statistics, and multilocus spatial autocorrelation statistics to examine the distribution of genetic diversity and the spatial genetic structure within three undisturbed populations at a landscape level (72.5 ha, 500 x 1450 m) on Dolsan Island, South Korea. The spatial autocorrelation analyses of adults showed little evidence of fine-scale genetic structuring within populations, which could be due to random mortality among related seedlings, resulting in extensive thinning within maternal half-sib groups. Alternatively, low genetic differentiation between adjacent populations (mean F-ST = 0.023) and little within-population spatial genetic structure suggest probable secondary acorn movement by animals. Our results are very similar to those observed in three populations of Quercus acutissima at a landscape level (15 ha, 250 x 600 m) on Oenaro Island, South Korea. Together, these studies describe relatively subtle differences in genetic structure among adjacent populations of oaks on southern islands in Korea.