Genetic diversity and population structure of Rubroshorea curtisii, a hill dipterocarp species: implications for conservation

Forests help to reduce global warming by capturing and storing atmospheric carbon. Understanding the genetics of keystone species at a population level is vital for the management and sustainable utilization of forest genetic resources. A comprehensive population genetics study was carried out on Rubroshorea curtisii, an important widespread hill dipterocarp species in Peninsular Malaysia. A total of 41 populations across its distribution range in Peninsular Malaysia were collected to elucidate the genetic diversity and ultimately provide management guidelines for this species. The population samples were analysed using 10 polymorphic microsatellite loci and sequenced with three chloroplast DNA (cpDNA) regions. A total of 145 alleles were derived from the microsatellite loci, and 21 haplotypes were identified based on 1,113 bp of concatenated cpDNA sequences. The populations showed moderately high genetic diversity (mean H_E = 0.627 for microsatellite gene diversity and H_T = 0.574 for average haplotype diversity) but low genetic differentiation (F_ST = 0.036). Using Bayesian clustering, the studied populations can be divided into two groups, one of which shows further substructuring. Further sub-structuring in Cluster 1 led to sub-clustering of 1a and 1b. Bottleneck analysis did not detect any recent bottleneck events. Based on our findings, priority areas for in situ and ex situ conservation and minimum population size are recommended for the sustainable utilization of R. curtisii.