Molecular phylogeny of Dipetrocarpaceae in Southeast Asia based on nucleotide sequences of matK, trnL intron, and trnL-trnF intergenic spacer region in chloroplast DNA

To obtain a refined molecular phylogeny of dipterocarp species in Southeast Asia, nucleotide sequences of matK, the intron of trnL, and intergenic spacer region between trnL and trnF in chloroplast DNA were determined in 16 species throughout 10 genera. In the resultant trees Southeast Asian dipterocarp species were divided into two clusters. One cluster consisted of Anisoptera, Vatica, Cotylelobium, and Upuna, all with the base chromosome number of x = 11. The second cluster consisted of Hopea, Shorea, Neobalanocarpus, Dryobalanops, Parashorea, and Dipterocarpus, mostly with the base chromosome number of x = 7. Dipterocarpus was the only genus that had the base chromosome number x = 11 in the latter cluster. This result suggests that the chromosome number changed from x = 11 to x = 7 after Dipterocarpus branched in the latter cluster. Other evolutionary changes of morphological characters are also discussed.