Phylogeography of East Asian evergreen broad leaved trees and taxonomy on the Korean Quercus subgenus Cyclobalanopsis

초록

South Korea, East China and Japan are a hotspot for plant species richness and endemism caused by dynamic changes in land configuration during the Quaternary. Korean south coast floristic region are covered with forests dominated by broad leaved evergreen trees. Several species of Lauraceae and genus Quercus (subgen. Cyclobalanopisis) are the major component elements of the forests. However, the historical migration route of such evergreen tree species is poorly understood. We attempted, therefore, to reconstruct the phylogeographic history of Neolitsea sericea and Quercus acuta. In N. sericea, we investigated the intraspecific variation of cpDNA. Analyses were based on sequence data from the trnL–F, psbC–trnS and rps16 regions. Nine haplotypes were identified. The majority included ancestral types in the southwestern part of the main islands of Japan, with other region-specific haplotypes being found in populations on the Korean Peninsula, Taiwan (Isl. Lanyu) and elsewhere in Japan. A statistical parsimony network revealed two lineages derived from the basal group. One was represented on the Korean Peninsula, the other on Isl. Lanyu. The current distribution of N. sericea has been shaped by colonization via land bridges. During the glacial periods, two primary, but separate migration routes were followed -- from the southwestern part of the Japanese main islands to either the Korean Peninsula or Taiwan. In Q. acuta, seven microsatellite markers were genotyped using 330 individuals from 16 populations. We found that genetic diversity within populations was relatively high (average, HE = 0.702), also finding similarity as regards the mean values within Korean and Japanese regions. No significant genetic differentiation (FST = 0.037 ± 0.003) was detected across the species distribution range, and no clear geographic genetic structure was identified. The results, insignificant FST values and a lack of isolation by distance, point toward an admixture among