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Origin of the pantropical and nutriceutical Morinda citrifolia L. (Rubiaceae): comments on its distribution range and circumscription
Author(s) -
Razafimandimbison Sylvain G.,
McDowell Timothy D.,
Halford David A.,
Bremer Birgitta
Publication year - 2010
Publication title -
journal of biogeography
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.7
H-Index - 158
eISSN - 1365-2699
pISSN - 0305-0270
DOI - 10.1111/j.1365-2699.2009.02229.x
Subject(s) - morinda , pantropical , rubiaceae , biology , clade , botany , genus , phylogenetic tree , traditional medicine , medicine , biochemistry , gene
Aim Morinda citrifolia L., commercially known as noni or the Indian mulberry plant, is morphologically variable and the only widely distributed member of the pantropical genus Morinda sensu stricto (Rubiaceae). This large distribution has been attributed partly to the ability of the seeds of the large‐fruited M. citrifolia L. var. citrifolia L. to be transported by oceanic drifting. This form of M. citrifolia var. citrifolia has been predicted to be the progenitor colonizer of the island endemic Morinda species. Using a phylogenetic approach and large sampling of the widespread, large‐fruited M. citrifolia var. citrifolia , we assessed the potential area of origin of M. citrifolia and tested the hypothesis that the large‐fruited M. citrifolia var. citrifolia is an ancestral colonizer. Location Tropics. Methods We performed Bayesian analyses of 22 species of the tribe Morindeae (including 11 individuals of the three currently recognized varieties of M. citrifolia ) based on combined nrETS, nrITS, rps 16 and trn T–F sequence data. Geographic origins of the studied taxa were mapped onto the Bayesian majority rule consensus tree. Results Nine sequenced individuals of M. citrifolia from diverse geographic locations formed a highly supported clade, which was sister to the Australo‐Micronesian clade that included M. bracteata var. celebica and M. latibracteata . These sister clades are part of the broader Asian, arborescent Morinda clade. We found no support for the current varietal classification of M. citrifolia . Main conclusions Our analyses suggest a Micronesian origin of M. citrifolia . This implies that the large‐fruited M. citrifolia var. citrifolia might well have been present in the Pacific before the arrival of the Micronesian and Polynesian ancestors from Southeast Asia. The wide distribution of this form of M. citrifolia var. citrifolia is attributed partly to the trans‐oceanic dispersal of its buoyant seeds, self‐pollination and its ability to produce flowers and fruits year‐round. The hypothesis that the widespread, large‐fruited M. citrifolia var. citrifolia is the progenitor colonizer of the island endemic Morinda species is inconsistent with its derived position within the Asian, arborescent Morinda clade and with the fact that the nine sampled individuals of M. citrifolia form a clade.