Congruence of chloroplast DNA restriction site characters with morphological and isozyme data in Solanum sect. Lasiocarpa

Abstract

Chloroplast DNA restriction site characters were analyzed cladistically in species of Solanum sect. Lasiocarpa (subg. Leptostemonum), and results were compared with previously published analyses of morphological and isozyme characters. Cladistic analysis of the chloroplast DNA restriction site characters resulted in a single tree in which two main clades were detected: one comprised three morphologically distinct lowland Amazonian species, and the other included the Andean and the two Asian species. Character congruence among the three data sets was assessed with a previously described index and with a permutation test derived from this index. Taxonomic congruence was evaluated with a measure modified from that of another researcher. The three assessments of congruence indicate that the chloroplast DNA and isozyme analyses are the most incongruent, but they differ as to their evaluation of relative (in)congruence for the other comparisons. Combining the three data sets resulted in two most parsimonious trees whose topologies incorporate elements from each of the separate analyses. The combined chloroplast DNA and morphological analyses support a previously proposed hypothesis that the two Asian species are sister taxa and of a single origin, rather than having originated separately from two distinct South American groups. Key words: Solanum, chloroplast DNA, congruence, combined data, cladistics.