VANDEN HEUVEL, BRIAN DAVID* AND C. RANDAL LINDER. Integrative Biology Section, The University of Texas at Austin, Austin, TX 78712. - A Molecular Phylogeny for Cercocarpus H.B.K. (Rosaceae) using the External Transcribed Spacer of the Nuclear Ribosomal Repeat.
Cercocarpus H.B.K. (Rosaceae) has undergone three revisions,
each varying widely in the ranks assigned to taxa and the number of
species. Discrepancy among revisions is due primarily to a continuum
of morphological variation within and between taxa. We have developed
a molecular phylogeny to address this discrepancy. The ITS region of
the nuclear ribosomal repeat contained insufficient phylogenetically
informative sequence variation, so we developed the external
transcribed spacer (ETS) of the nuclear ribosomal repeat. The ETS has
more informative variation than the ITS and a unique central region
which has shown to be an important marker within this group. The
correct taxonomic affiliation of C. traskiae, California's
rarest tree, will also be addressed.
Key words: Cercocarpus, ETS, external transcribed spacer, molecular phylogeny, Rosaceae