Genetic structure of the threatened Hopea chinensis in the Quang Ninh Province, Vietnam.

Hopea chinensis Hand-Mazz (synonym H. hongayensis Tardieu), is a wind and insect pollinated species. It is a threatened species known only from two locations: Quang Ninh (Vietnam) and Guangxi (China). As an endemic species, it is worth preserving both for dipterocarp biodiversity, as well as for its medicinal use and economic importance as a fine wood. The genetic diversity and population genetic structure of H. chinensis was investigated, using natural populations distributed throughout the Ba Mun and Cai Lim islands, Quang Ninh Province, Vietnam. A total of 65 alleles were detected. The adult allelic richness was higher than that found in juveniles and seedlings in both populations. Inbreeding was found to be significant in Ba Mun adults (F(ST) = 0.139), as well as in Cai Lim juveniles and seedlings (F(ST) = 0.283 and 0.345, respectively). Evidence of a bottleneck could be detected in the juveniles and seedlings of the Cai Lim population. A Bayesian analysis and F(ST) values suggested high genetic differentiation among the age classes of the Ba Mun and Cai Lim populations. Whereas the adults of the Ba Mun population showed evidence of inbreeding, the next generations showed more potential heterozygotes. In contrast, the adults in the Cai Lim population showed no significant inbreeding, but the observed heterozygosity in the next generation was lower than expected, suggesting significant inbreeding. The H. chinensis populations on islands are developed well and showed re-generation under good condition. Thus, the forestry protector should conserve and protect the natural spatial structure of H. chinensis on each island as their natural habitats and keep them through natural regeneration.