Genetic diversity and differentiation of Quercus semiserrata Roxb. in northern Thailand revealed by nuclear and chloroplast microsatellite markers

This study describes the level of genetic diversity and differentiation of 10 populations of Quercus semiserrata Roxb. in northern Thailand, divided into four groups (A-D) based on their geographical location. Variation at eight nuclear (nSSR) and nine chloroplast (cpSSR) microsatellite loci was examined. The eight nuclear microsatellite loci employed detected a total of 139 alleles (n = 392), and 16 haplotypes based on length variants at the nine cpSSR loci were identified. Populations in group B harbored the highest gene diversity (H) and allelic richness (Ar) in both their nSSRs and cpSSRs (nSSR, H = 0.79 and Ar = 7.3; cpSSR, H = 0.5 and Ar = 2.5), the nSSRs of populations in group C had the lowest gene diversity and allelic richness, while the cpSSRs of populations in group A had the lowest gene diversity and haplotypic richness. Calculations (AMOVA) of each population's contributions to the total diversity and allelic richness indicated that most (86.62%) of the variation in nSSRs was due to differences within populations, but most (63.72%) of the total genetic variation in chloroplast haplotypes was due to differences among populations within groups. The ratio of pollen flow to seed flow was estimated to be 94:1. Pairwise F-ST/(1 - F-ST) values were significantly correlated with geographic distances among populations for cpSSRs (r = 0.337; P < 0.05), but not nSSRs. UPGMA and NJ phylogenetic trees based on Nei's genetic distances for nSSRs were constructed. The results suggest that four populations in group B (Khun Wang, Obluang, Doi Suthep and Doi Inthanon) had the highest genetic diversity and high numbers of chloroplast haplotypes. Therefore, these populations should be given the highest priority for conservation of this species. This is the first report concerning the genetic diversity and differentiation of this species, and provides basic genetic information that should facilitate attempts to conserve the species. (C) 2007 Elsevier B.V. All rights reserved.