Phylogeny and Biogeography of North American and Asian <I>Pedicularis</I> (Orobanchaceae)

Abstract

Pedicularis is a genus of over 600 species distributed throughout tundra and alpine habitats of the Northern Hemisphere. Phylogenetic relationships of North American species to Asian species were reconstructed by sampling sequences from nuclear ribosomal internal transcribed spacer (ITS) regions and the plastid matK region of 28 North American species, collected in the field or sampled from herbarium specimens, and 134 accessions of 102 Asian and three European species, obtained from GenBank. Maximum parsimony (PAUP) and Bayesian (MrBayes) analyses of ITS and combined ITS and matK data reveal two robustly supported monophyletic North American clades derived from Asian ancestors. Biogeographic analysis (S-DIVA) suggests Asia plus Japan, the Cascade Range, or Rocky Mountains as highly probable ancestral areas without involving Beringia for one clade. In the other clade, Asia plus the Rocky Mountains is specified as the most probable ancestral area, but less probable alternatives also include Asia plus Europe, Japan, or Beringia. Once established in North America, dispersal/divergence throughout North America occurred out of Rocky Mountain and/or Cascade Range ancestral centers of distribution. Beringian and European species are derived from North American centers rather than being part of ancestral areas for North American species.