CAMERON, KENNETH M. The Lewis B. & Dorothy Cullman Program for Molecular Systematics Studies, The New York Botanical Garden, Bronx, NY 10458 USA. - An exapnded phylogenetic analysis of Orchidaceae using three plastid genes: rbcL, atpB, and psaB .
The most comprehensive intergeneric phylogeny of Orchidaceae to date
was published two years ago by Cameron et al. This was based on 171
rbcL sequences, and indicated that the family would be best
divided into five subfamilies: (Apostasioideae (Cypripedioideae
(Vanilloideae (Orchidoideae, Epidendroideae)))). However, bootstrap
support for the arrangement of these subclades was poor, and there was
little resolution among tribes and subtribes within Epidendroideae,
the most diverse group of orchids. More recently, phylogenetic
hypotheses for the family have been published or presented using
smaller sets of sequences from mitochondrial and nulcear loci. These
mostly agree with the rbcL tree, but also suffer from a general
lack of resolution and/or internal clade support. To address these
issues, two additional plastid loci (atpB and psaB) have
been sequenced for the most of the same genera used in the rbcL
study. Analysed separately, they differ only slightly from the
rbcL tree. In combination, however, the tree is well resolved,
and many lineages are supported by the bootstrap. Molecular data sets
for Orchidaceae will soon be as numerous as those for other large
families, and will allow for a new intrafamilial classification of the
family based on well supported phylogenies within the near future.
Key words: atpB, Orchidaceae, psaB, rbcL