Genetic variation of teak (Tectona grandis Linn. f.) in Myanmar revealed by microsatellites

Genetic variation of teak (Tectona grandis Linn. f.) in 16 populations in Myanmar was investigated using ten nuclear microsatellite markers. Eight population pairs from two main regions in the north and the south of Myanmar were sampled. Each population pair consisted of an unlogged and a recently logged forest, each represented by 50 adult trees and 50 seedlings from the natural regeneration. For comparison, two land races from Benin (West Africa) were included. The major objectives of the study are to characterize the patterns of genetic variation of teak in natural populations, to examine genetic differentiation between adult trees and natural regeneration, and to investigate the impact of selective logging on genetic structures of teak. Genetic variation was high in all investigated populations. Slightly elevated levels of inbreeding were observed in the regeneration in comparison to the adults. Populations from the northern and the southern regions were strongly differentiated, but the differentiation between adults and natural regeneration and between unlogged and logged forests was low and not significant. Mantel tests indicated an isolation by distance (IBD) within the northern and the southern regions. High genetic diversity was also observed within the land races from Benin, which grouped to the southern populations. We failed to detect effects of logging on genetic diversity patterns or inbreeding in adults and regeneration, suggesting that high genetic diversity can even be sampled and maintained in disturbed forests. The observation of significant IBD and high differentiation between the populations of the north and the south of Myanmar suggests to include populations from widely separated forests in conservation programs, and to delineate provenance regions for the harvest and transfer of teak seeds and seedlings.