Genetic structure of an important widely distributed tropical forest tree, Shorea parvifolia, in Southeast Asia

Shorea parvifolia (Dipterocarpaceae) is a widely distributed tree species which is important in terms of ecosystem functioning as well as forestry in Southeast Asia. During glacial periods, substantial precipitation decline is believed to have occurred in Southeast Asia, which considerably changed the distribution of the species. Repeated glacial and inter-glacial fluctuations were found to have influenced the genetic structure of the species, which is important to know for conservation and sustainable use. Leaf samples were collected from 18 populations covering most of the natural distribution of this species including the Malay Peninsula, Sumatra, and Borneo Islands. We investigated these samples using sequence data for eight chloroplast DNA (cpDNA) regions and 14 nuclear EST-SSR loci. The nucleotide diversity of cpDNA is higher in Malay Peninsula populations but the genetic diversity of nuclear DNA is higher in Borneo populations. The genetic structure revealed by nuclear DNA clearly separated Borneo populations from the rest, with an FST value of 0.150, while the genetic structure obtained from cpDNA was less pronounced (FST value = 0.136). Tajima’s D and Fu and Li’s D* for cpDNA showed statistical significance only in populations from Borneo. These results suggested that there has been recent population expansion of S. parvifolia in Borneo.