Genetic diversity and conservation of two threatened dipterocarps (Dipterocarpaceae) in southeast Vietnam

Abstract

Two threatened dipterocarp species, Dipterocarpus costatus and Dipterocarpus alatus are well-known endangered species in lowland forests of southeastern Vietnam, primarily from habitat loss and over-exploitation of their wood. To develop conservation strategies for these species, we analyzed 242 samples using nine microsatellite markers to determine the genetic variability within and among five populations of D. alatus and three of D. costatus, representing the natural range of dipterocarps in Southeast Vietnam. Results indicated low levels of genetic variability within populations with an average gene diversity of 0.223 for D. alatus and 0.152 for D. costatus. Results of bottleneck tests indicated a reduction in population size of both species (P > 0.05). Genetic differentiation among populations was high (FST = 0.347 for D. costatus and 0.274 for D. alatus), indicating limited gene flow (Nm = 0.662 for D. costatus and 0.47 for D. alatus) and isolated populations related to geographical distances. Analysis of molecular variance showed high genetic variation within populations (72.92% for D. alatus and 60.81% for D. costatus) compared to among populations. Bayesian analysis and UPGMA tree also indicated the two optimal genetic clusters related to geographical distances. These results will provide a platform for the conservation, management and restoration of these species.