SENTERS1, ANNE E.*, DOUGLAS E. SOLTIS1, PAMELA S. SOLTIS1, MICHAEL ZANIS1, SANGTAE KIM2, JAMES D. THOMPSON1, AND ELIZABETH A. ZIMMER3. 1School of Biological Sciences, Washington State University, Pullman, WA 99164, 2Seoul National University, Seoul, Korea, 3Laboratory of Molecular Systematics, Smithsonian Institution, Washington D.C. 20560. - Phylogenetic relationships among eudicots based on a combined data set of four genes: rbcL, atpB, 18S rDNA, and 26S rDNA.
Relationships among core eudicot clades (the asterid, rosid,
Caryophyllales, Santalales, Berberidopsidales, and
Myrothamnaceae/Gunneraceae clades) remain one of the last major
questions of deep-level phylogeny in the angiosperms. To resolve
these relationships, we assembled a large data set of entire 26S
ribosomal DNA sequences for approximately 250 angiosperms. The 26S
rDNA is just under 3.4 kb in length and consists of conserved core
areas, as well as more rapidly evolving expansion segments. Because
of is length and regions with different evolutionary rates, it appears
to be highly useful for resolving relationships at this level. We
constructed several different data sets and analyzed them using
parsimony: 1) 26S rDNA sequences were added to the existing 567-taxon
matrix (Soltis et al.), 2) a smaller data set was constructed for only
those angiosperms for which all four genes were available. We also
used a compartmentalization approach, reconstructing ancestral
sequences for major clades. Our preliminary analyses provide
additional support for the major core eudicot clades and the
relationships of early-branching eudicots.
Key words: 26S rDNA, angiosperms, eudicots, phylogeny