Molecular phylogeny of Sri Lankan Dipterocarpaceae in relation to other Asian Dipterocarpaceae based on chloroplast DNA sequences

Abstract

The Dipterocarpaceae, a well-known tropical tree family of Asian rainforests, is the most dominant component of Sri Lankan rainforests. The origin of Sri Lankan Dipterocarpaceae and their relationship with other Asian members of the family are still unknown. We studied this relationship using chloroplast DNA nucleotide sequences. DNA sequences of trnL-trnF spacer and trnL intron regions from 27 Sri Lankan species, and 62 other species belonging to 14 genera were included in the study. The neighbor joining (NJ) tree was constructed using aligned sequences of both regions. Monotes madagascariensis was used as an out-group. The obtained result is, to a certain extent, consistent with the current morphology based on taxonomy of Dipterocarpaceae. The Sri Lankan endemic genus Stemonoporus formed a monophyletic clade. The other Sri Lankan species of Hopea, Dipterocarpus, Vatica, Cotylelobium, Vateria and most of Shorea formed separate groups on the phylogenetic tree. This may indicate that Sri Lankan Dipterocarpaceae evolved independently after Sri Lanka became geographically isolated from the Indo- Malaysian region.