Microsatellite analysis reveals genetic variability and population divergence history of the threatened Hopea pierrei Hance in tropical forests

Hopea pierrei Hance is a valuable woody species of the tropical forests of southern Vietnam, which is threatened due to habitat alteration and overexploitation. This genetic diversity and population structure have not been assessed. To preserve this species, information on the genetic diversity and population structure was investigated using nine microsatellite loci for 245 adult trees from nine populations representing its geographic distribution range in Vietnam. A moderate genetic diversity was detected in H. pierrei (AR = 2.7, HE = 0.480). We found significant heterozygosity deficits in all populations, except for Mo Rai. In addition, H. pierrei had experienced the effects of recent bottlenecks in some populations. We compared population genetic differentiation in the same area and between different areas, and showed low genetic differentiation in the same area and high genetic differentiation for pairwise populations between different areas. However, a restricted gene flow between populations was detected (Nm = 1.536) compared to a wide distribution range. Geographic distance and an increase in population isolation due to anthropogenic disturbances can decrease gene exchange among different areas. With different clustering approaches, the Bayesian analysis and discriminant analysis of principal components revealed four major clusters, corresponding to four distribution areas. Our study provided significant insights into genetic variability and proposes the relevance of conservation of the threatened H. pierrei in the future. The approximate Bayesian computation showed that the first time of H. pierrei occurred during the middle Pleistocene ice age, and the divergence times occurred during the interglacials.