Genetic structure and variation of five Shorea leprosula natural populations based on microsatellite marker

Abstract

Shorea leprosula is an economically and ecologically important timber species and one of the most common tropical lowland rain forest tree species in Southeastern Asia. Eleven microsatellites DNA loci were used to investigate the genetic structure and diversity among five natural populations from Sumatera (CS and NS), Peninsular Malaysia (SM) and Borneo (WKa and WKb). Results indicated that expected mean heterozygosity (He) was high (0.721) with values ranging from 0.542 to 0.788, with the highest values found in the populations from west Kalimantan (WKb). Most of the populations showed high and positive fixation indices indicating excess of homozygotes. This implies a high level of inbreeding which may be caused by selfing or/and mating among relatives. A gene diversity analysis showed that 89.9% of the variation was harbored within populations and 11.1% (FST= 0.111) was due to differences among populations. STRUCTURE analysis showed that five natural populations were clustered into two main groups namely: i) Sumatera-Peninsular Malaysia, and ii) Borneo. Mean gene flow (Nm) was high (2.00) indicating extensive gene flow in the past among the natural populations. Three populations (WKb, NS and SM) were identified to be genetically unique and we recommended for further consideration in formulation of genetic conservation strategies.