Comprehensive molecular phylogeny of the sub-family dipterocarpoideae (Dipterocarpaceae) based on chloroplast DNA sequences

Abstract

Dipterocarpoideae, the largest sub-family of well-known plant family Dipterocarpaceae, dominates in South Asian rain forests. Although several previous studies addressed the phylogeny of the Dipterocarpaceae family, relationships among many of its genera from the Dipterocarpoideae sub-family are still not well understood. In particular, little is known about the relationships of the genera Vateriopsis, Stemonoporus, Vateria and inconsistence remains between phylogenetic results and taxonomic classifications of Shorea and Hopea species. We studied molecular phylogeny of the sub-family Dipterocarpoideae using the trnL-trnF spacer, trnL intron and the matK gene sequences of chloroplast DNA (cpDNA). This study is the first comprehensive phylogeny reconstruction for the sub-family Dipterocarpoideae based on cpDNA, as it includes most genera (14) and a large number of species (79) with most species endemic to Sri Lanka, as well as one species from Seychelles and one species from the genus Monotes from Madagascar. Phylogenetic trees were constructed using the Neighbor Joining (NJ) and Maximum Likelihood (ML) methods using combined set of sequences including all three cpDNA regions. The topologies of the NJ and ML trees were to a certain extent, consistent with the current taxonomy of Dipterocarpoideae based on morphology and with previous molecular phylogenies based on cpDNA. Furthermore, our results provided new evidence regarding the relationships of the following genera: Vateriopsis and Stemonoporus and about the validity of the previous morphology based classifications of Shorea species. In addition, the topology of our trees was consistent with the classification of Shorea species proposed by Maury (1978), Maury-Lechon (1979) and Symington (1943). Finally, our results provided evidence for the affinity of the genus Monotes to Asian Dipterocarpoideae rather than to Tiliaceae and indicated that it is a good candidate for outgroup species for future studies of the former sub-family.