HILS, MATTHEW H.*, MICHAEL ZANIS, MICHELLE MCMAHON, AND DOUGLAS E. SOLTIS. Department of Biology, Hiram College, Hiram, OH 44234, and School of Biological Sciences, Washington State University, Pullman, WA 99164-4236. - Phylogeny and diversification of ovary position in Miconieae, Merianieae, and Blakeeae (Melastomataceae).
Although epigyny traditionally has been considered to be derived from
hypogyny, recent evidence suggests that ovary position is more dynamic
than this longstanding view of unidirectional change indicates.
Melastomataceae show a complete range of ovary positions and are an
ideal family in which to study ovary diversification in a phylogenetic
context. Parsimony analysis of ITS sequence data for 33 species among
18 genera in Miconieae, Merianieae, and Blakeae indicates that these
three tribes form a well-supported monophyletic group with
Merianthera as sister to a large well-supported clade that is a
polytomy with five branches. In this polytomy: most Miconieae form
one poorly resolved clade; three genera of Miconieae (Bellucia,
Henriettea, and Henriettella) and two genera of Blakeae
(Blakea and Topobea) form two well-supported clades;
and three genera of Merianieae make up the two remaining branches of
the polytomy. It is noteworthy that Merianthera is sister to
all other genera because it is the only Merianieae with an inferior
ovary: all remaining members of the tribe exhibit superior ovaries.
Initial mapping onto our shortest trees of published reports of ovary
positions reveals that: the outgroup genera all have superior
ovaries; Merianthera, with an inferior ovary, is the
first-branching member of the ingroup; and the large sister clade
comprises members with a complete range of ovary positions, with many
intermediates. Although further character analysis is needed,
diversification of ovary position within these melastomes may be
dynamic and contradictory to the traditional view of unidirectional
change from superior to inferior ovary position.
Key words: ITS phylogeny,Melastomataceae,ovary diversification