Phylogenetics of Lopezia (Onagraceae): Evidence from Chloroplast DNA Restriction Sites

Nineteen taxa representing all six sections and 17 of the 22 species of Lopezia have been examined for restriction site mutations of chloroplast DNA using homologous probes from Lopezia miniata subsp. miniata. Restriction sites were analyzed using maximum parsimony, weighted parsimony, maximum likelihood, and neighbor-joining. The results of these analyses support the monophyly of sect. Riesenbachia. Sections Jehlia and Lopezia may, however, be paraphyletic depending on the placement of L. racemosa subsp. racemosa. Section Nannolopezia is clearly derived from within sect. Lopezia and should be reduced to synonymy. A single reduced consensus cladogram is presented that fails to resolve the placement of sect. Riesenbachia and the placement of L. racemosa subsp. racemosa, L. miniata subsp. miniata, and L. concinna within sect. Lopezia. The chloroplast DNA results indicate that 'snapping' stamens, a means of mechanically depositing pollen on visiting pollinators, have evolved only once in the genus. Hummingbird pollination, which is plesiomorphic in the genus, may have been secondarily regained in sect. Jehlia after its loss to fly pollination.