Phylogeny of prickly poppies,Argemone (Papaveraceae), and the evolution of morphological and alkaloid characters based on ITS nrDNA sequence variation

Abstract

Evolutionary relationships withinArgemone (Papaveraceae) were inferred from nucleotide variation in nuclear ribosomal DNA. A complete representation of the genus was achieved by using herbarium material to a large extent (74%). Four distinct clades can be recognized based on the molecular results. The support for the different clades varies greatly due to a very uneven distribution of characters. Although some clades are largely unresolved, some unexpected relationships, for example the sister group relationship of the relict speciesA. subintegrifolia to the rest ofArgemone, were found. The evolution of morphological and alkaloid characters against the background of the obtained phylogeny is discussed. Whereas the morphological characters provide some support for the phylogeny found, the alkaloid characters turned out not to contain much phylogenetic information. Past difficulties in recognizing phylogenetic relationships withinArgemone result from largely continuous morphological variation and from parallelisms correlated with and probably caused by polyploidization.