ABDUL-SALIM, KOBINAH. Harvard University Herbaria, 22 Divinity Ave., Cambridge, MA 02120. - Biogeography of Symphonia (Clusiaceae): support for an African origin?
Symphonia (Clusiaceae) is a tropical woody plant genus with a
center of diversity in Madagascar, and one species, S.
globulifera disjunct in Africa and the neotropics. Two contrasting
hypotheses have been proposed regarding this distribution pattern and
the origins of the genus: one suggesting an African origin, the other
suggesting a Malagasy origin. A phylogeny constructed using sequences
of the internal transcribed spacer (ITS) region of nuclear ribosomal
DNA show that the Malagasy and neotropical species form two
monophyletic groups, each sister to an intervening African clade.
Calibration of this phylogeny with an African fossil from the late
Eocene and a Mexican fossil from the oligo-miocene boundary resulted
in dating (a neotropical radiation at 40.3-26.8 Ma and a Malagasy
radiation at 16.0-8.6 Ma) which supported an African hypothesis.
Key words: biogeography, Clusiaceae, ITS sequences, phylogeny, Symphonia