Phylogenetic relationships among the perennial, endemic Apiaceae subfamily Apioideae of western North America: additional data from the cpDNA trnF-trnL-trnT region continue to support a highly polyphyletic Cymopterus
Sun, Feng-Jie Downie
Plant Diversity and Evolution Volume 128 No. 1-2 (2010), p. 151 - 172
published: Aug 1, 2010
ArtNo. ESP145012871009, Price: 29.00 €
Considerable confusion exists with regard to the delimitation of Cymopterus and its relationship to the other herbaceous, perennial genera of Apiaceae subfamily Apioideae endemic to western North America north of Mexico. Previous molecular systematic studies using nrDNA ITS and cpDNA rps16 intron sequences have shown that the genus Cymopterus is highly polyphyletic, with its species inextricably linked with those of Aletes, Lomatium, Oreoxis, Pseudocymopterus, Pteryxia, and several other genera of the region. The general lack of resolution of these trees and their overall low branch support values, however, suggested that additional data might be useful to establish monophyly of genera or identify major clades for further phylogenetic and revisionary studies. In this study, we analyze cpDNA trnF-trnL-trnT sequence data from 129 accessions of North American Apioideae (representing 111 species and 21 genera) using maximum parsimony, maximum likelihood and Bayesian inference methods individually and in combination with ITS and rps16 intron sequence data available through previous phylogenetic studies for the same set of accessions. While analyses of the trnF-trnL-trnT region result in maximally parsimonious trees of greater branch support and less homoplasy than those generated using either ITS or rps16 intron data sets, greatest resolution of relationships and highest branch support values are achieved when all DNA regions (representing over 3.5 kb of aligned data) are considered simultaneously. Three or four new major clades are revealed, yet none of these coincide with pre-established groups or traditionally recognized genera. The results obtained continue to suggest that Cymopterus is highly polyphyletic, as are most other genera endemic to western North America.