Mating System and Gene Flow of Dipterocarps Revealed by Genetic Markers

Abstract

Tropical rain forests are becoming fragmented into small patches and simplified in structure and composition due to their exploitation for timber. Consequently, genetic variation may be decreased and the genetic differentiation between the patches may rise. Developing sustainable forestry regimes that retain genetic diversity is one of the major goals in tropical forestry today. Tropical tree species have predominantly allogamous mating systems, mediated by many kinds of pollinators, so the gene flow through pollen and seeds is one of the most important factors influencing genetic diversity in tropical forests. Recently, molecular markers have been used to determine the genetic diversity and differentiation of forest tree populations. In particular, microsatellite DNA markers, which are highly polymorphic, have been used to evaluate the gene flow through pollen and seeds within forests. We have also developed microsatellite DNA markers in dipterocarp species, and used these markers to analyze mating systems, genetic structures and gene flow in several dipterocarp species at ecological parmanent plots such as those in Pasoh Forest Reserve (Pasoh FR). We discuss, here, characteristics of the pollination and breeding systems in dipterocarps that have been revealed by microsatellite analysis, and the factors that influence them. Finally, the potential value and limitations of using molecular approaches to develop genetic criteria for gene conservation in sustainable forestry are discussed.