WOLFE, ANDREA D.*, NIDIA ARGUEDAS, JEFFERY J. MORAWETZ, and JOSE DIAZ. Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, 1735 Neil Avenue, Columbus, OH 43210. - Molecular phylogenetics of Penstemon (Scrophulariaceae s.l.).
Penstemon is the largest genus endemic to North America. We
have included 175 of the 275 species in a phylogenetic reconstruction
based on ITS nucleotide sequence data. A subset of these species have
been surveyed with nucleotide data from from several noncoding regions
of the chloroplast genome, including the trnT-F and
trnC-D loci. Individual cpDNA loci are not sufficient for
resolving relationships among species of Penstemon. However,
the combination of sequences from different cpDNA noncoding regions,
and the combination of data sets from nuclear and chloroplast genomes
facilitate a resolution of the Penstemon phylogeny. Our results
suggest the diversification of Penstemon has occurred recently
and places Penstemon as an exemplar of a continental
evolutionary radiation. Previous biogeographic hypotheses for the
origin of Penstemon in the Rocky Mountains, a subsequent
migration to the west early in the history of the genus followed by
migration throughout the Intermountain region, the southwest and
finally east of the Rocky Mountains are supported by these results.
Key words: ITS, Penstemon, phylogeny, Scrophulariaceae, trnC-D, trnT-F