Population Genetic Diversity in The Genus Dryobalanops Gaertn. f. (Dipterocarpaceae) Based on Nuclear Microsatellite Markers

The genus Dryobalanops Gaertn. f. is a small but important genus that contains seven species and is found in the Southeast Asian tropical rain forests. Seven polymorphic nuclear microsatellite markers were analyzed in 46 natural populations of six extant Dryobalanops species (N = 700 individuals) covering the distribution range in Western Malesia. The mean gene diversity at the species level ranged from 0.392 in D. rappa to 0.635 in D. aromatica. The FST value ranged from 0.156 in D. keithii to 0.283 in D. beccarii and all FST values were highly significantly greater than zero. These results suggest that gene flow between populations has been limited and intensive genetic drift has occurred in all of the species. Plants with narrowly distributed species such as D. keithii and D. rappa, which are endemic to Borneo, tend to have lower levels of genetic diversity compared with widespread species such as D. aromatica. STRUCTURE analysis revealed that at least two of the six species could be effectively discriminated each other. The results of this study will be helpful for building effective conservation schemes as well as for providing basic data for future provenance trials of Dryobalanops species.