WOLFE, ANDREA D.*, CHRISTOPHER P. RANDLE, AND SHANNON L. DATWYLER. Department of Evolution, Ecology, and Organismal Biology, The Ohio State University, Columbus, OH 43210. - Phylogeography and character evolution of the genus Penstemon (Scrophulariaceae).
The 275 species of Penstemonare distributed in North America
from Alaska to Guatemala and coast-to-coast, exclusive of the Canadian
shield. The area of richest species diversity is the Intermountain
Region and the area of lowest diversity lies east of the Rocky
Mountains. Penstemonhas been divided into six subgenera. The
primary morphological characters defining subgenera are anther
dehiscence and pubescence patterns. We used nrITS sequence data to
reconstruct the phylogeny of Penstemon. The strict consensus
tree was used to assess biogeographic and taxonomic relationships, the
evolution of anther dehiscence and pubescence, the shift from bee- to
bird-pollination syndromes, and evolution of polyploidy. Our results
suggest an origin of Penstemonin 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. Our results also
suggest that anther characters are insufficient to define subgenera
and that bird-pollination and polyploidy have originated independently
numerous times in Penstemon.
Key words: biogeography, character evolution, Cheloneae, Penstemon, Scrophulariaceae