Multidimensional Scaling for the Taxonomy of Papavereae

Abstract

ABSTRACT To determine the relationship among the Papaveroideae, a data set, originally gathered for classification of the Papaveroideae using DNA restriction sites, was subjected to an multidimensional scaling (MDS) analysis, leading to a more appropriate taxonomy of the Papavereae tribe (especially in Papaver, Stylomecon, and Roemeria genera). The spatial configuration of Papavereae was developed on the basis of absolute distances of taxa in relation to Papaver alpinum and made possible the 3D projection of the tribe. The configuration consisted of two different sets and provided a divergent rank image of taxa from the cladistic assumption. In one of these sets, taxa of Roemeria and the Papaver section Argemonidium, were not mixed, but formed two distinct groups in view of the genera. Papaver hybridum was the closest species to Roemeria, but Papaver pavoninum was the farthest and most distant taxon. In case of annual poppy species of the other set, the Papaver somniferum and Papaver macrostomum were not nested with Papaver dubium (Papaver rhoeas was the nearest relative), while Papaver gracile was the farthest and most distant taxon. Regarding poppy biennials and perennials of this second set, Papaver atlanticum was closer to Papaver caucasicum than to Papaver bracteatum. The MDS also revealed an unclarified taxonomic problem of the Papavereae, that of the infratribal links of Papaver alpinum (section Meconella). The dissimilarities of distant species, Papaver pavoninum and Papaver gracile, as opposed to opposite sets, suggested that Papaver alpinum could not be inserted in the set Roemeria-Argemonidium or in a hierarchy of all Papavereae taxa, but instead belonged, with 99.5 percent probability, to the set of Pseudopilosa, Meconidium, Macrantha, Rhoeadium and Papaver sections. Application of MDS at different systematical levels (tribe, set, or species) matched dissimilarities of taxa and the links within the taxa, ensuring true projections according to real views of Papavereae.