Genetic Variation and Evolutionary History of the Threatened Dipterocarpus turbinatus C.F.Gaertn. Detected Using Microsatellites

Abstract

Dipterocarpus turbinatus C.F.Gaertn. is a valuable timber tree indigenous to the lowland tropical forests of southern and central Vietnam. It is in danger of extinction due to fragmented habitats and overexploitation. Therefore, assessing the genetic diversity and demographic history of this species is essential to providing a platform for conservation activities. Herein, we analyzed 281 D. turbinatus trees from 10 populations representing their natural distribution range in Vietnam using nine polymorphic microsatellites to provide valuable information for conservation activities. We detected genetic diversity within these populations (0.285 and 0.328 for observed and expected heterozygosity, respectively), as well as population genetic differentiation (a Wei and Cockerham value of 0.202 and a Hedrick value of 0.32). Clustering analysis based on different approaches revealed three genetic clusters which were significantly correlated to gene flow across the geographic distribution range of D. turbinatus in tropical evergreen forests. Approximate Bayesian computation suggested that the D. turbinatus populations had an evolutionary history consistent with divergence during the last glacial maximum. Based on our results, we recommend the in situ conservation of several populations with high genetic diversity, high allelic richness, or private alleles, and the gathering of the seeds of the remaining populations for ex situ conservation.