A phylogenetic analysis of Doronicum (Asteraceae, Senecioneae) based on morphological, nuclear ribosomal (ITS), and chloroplast (trnL-F) evidence

A phylogenetic analysis of the Old World genus Doronicum (26 species, 4 sub species) based on sequence data of the internal transcribed spacer (ITS) re gion of the nuclear ribosomal DNA, the chloroplast spacer trnL-F, and morph ology is presented. Congruence among the three data sets was explored by th e computing of several indices, all of which suggest homogeneity between on ly the two molecular matrices. We argue that the morphological data set con tains poor phylogenetic signal and advocate simultaneous analysis of the th ree data sets (total evidence approach) so that morphological characters ar e tested for homology by congruence with molecular data. The resulting phyl ogenetic hypothesis allows several well-supported conclusions including the placement of a Corsican endemic (D. corsicum), sister to the remainder of the genus, and the inference that an early southern European or Mediterrane an diversification took place in the genus. Shifts in morphological charact ers (e,g,, homocarpy to heterocarpy) are confirmed to have evolved several times. Results from comparative studies of sequence data of the chloroplast gene ndhF support inclusion of Doronicum in tribe Senecioneae. (C) 2001 Ac ademic Press.