Molecular evidence for polyphyly in the woody bamboo genus Dendrocalamus (subtribe Bambusinae)

Abstract

Dendrocalamus is an economically important woody bamboo genus from the Old World tropics. The traditional circumscription of the genus is not satisfactory owing to overlapping limits between Bambusa and Dendrocalamus. Limited earlier studies in the genus, using molecular techniques, have reported wide genetic variation, and there is disagreement among published infrageneric classifications in the genus. Thus, lack of sound taxonomy is hindering scientific conservation and management of the woody bamboos belonging to this genus. In the present study, amplified fragment length polymorphism markers (AFLPs), generated using five primer combinations, were used to investigate relationships among ten Dendrocalamus (D. strictus, D. hamiltonii, D. membranaceus, D. brandisii, D. sikkimensis, D. asper, D. giganteus, D. calostachyus, D. sahnii and D. somdevai) and five outgroup species (Bambusa balcooa, Dinochloa macclellandii, Melocalamus compactiflorus, Oxytenanthera abyssinica and Thyrsostachys siamensis) from subtribe Bambusinae. Neighbour-joining and maximum-parsimony analyses of AFLP dataset provided evidence for polyphyly in the current circumscription of Dendrocalamus. All Dendrocalamus taxa, except D. strictus, clustered into three monophyletic groups. The type species Dendrocalamus strictus was found to be genetically distant from the rest of the Dendrocalamus and did not cluster into any of these groups. Furthermore, Bambusa balcooa was recovered in a cluster containing D. hamiltonii and D. sikkimensis. The study did not find support for the various earlier infrageneric classifications within Dendrocalamus. The implications of the findings are discussed.