DATWYLER, SHANNON L.* AND ANDREA D. WOLFE. Department of Evolution, Ecology and Organismal Biology, Ohio State University, Columbus, OH 43210-1293. - Evolutionary and biogeographic relationships among the wooly-anthered Penstemons (Scrophulariaceae).
Penstemon subg. Dasanthera (Scrophulariaceae) is a small
group comprising 17 taxa distributed at high elevations in western
North America. The subgenus is characterized by a woody habit and
lanate pubescence on the anther surfaces. Hybridization has played a
significant role in the evolution of the subgenus. Phylogenetic and
biogeographic relationships within subg. Dasanthera are being
examined using nrITS and matK sequence data. Sequence
divergence is very low for both ITS (mean=0.0086) and matK
(mean=0.0046). However, these data suggest that subg.
Dasanthera represents the earliest divergence in
Penstemon. Furthermore, the monophyly of the subgenus is
supported. Both data sets suggest an origin of Penstemon in
the northern Rocky Mountains, followed by westward migration and
radiation of subg.Dasanthera in the Cascade and Sierra Nevada
Mountains. These data are insufficient for resolving relationships
among the Cascade/Sierra Dasanthera penstemons. To examine
evolutionary relationships among the Dasanthera penstemons,
inter-simple sequence repeat (ISSR) have been utilized to examine
species relationships. Five primers were surveyed for 128 individuals
representing all species of Penstemon subg. Dasanthera.
A neighbor joining tree was produced using a similarity matrix
constructed from Dice's coefficient. In addition, the potential for
use of ISSR fragments in cladistic analyses have been examined. This
study suggests the utility of ISSR markers for examining evolutionary
relationships and patterns of introgression among closely-related
taxa.
Key words: Biogeography, Hybridization, ISSR, ITS, matK, Penstemon