Molecular phylogeny of the Barnadesioideae (Asteraceae)

The small but morphologically diverse subfamily Barnadesioideae of the sunflower family, Asteraceae, is of special interest as it constitutes the sister-group to the rest of the family. Therefore it is of critical importance for elucidating the origin and early evolution of Asteraceae. Cladistic analyses of DNA sequence variation in the trnL intron and nuclear ribosomal ITS regions strongly support five major clades in the subfamily: Schlechtendalia, Chuquiraga-Doniophyton, Barnadesia-Huarpea, Dasyphyllum subgenus Dasyphyllum and a clade comprising Dasyphyllum subgenus Archidasyphyllum, Arnaldoa and Fulcaldea. Within Dasyphyllum subgenus Dasyphyllum, D. hystrix has a basal position, and sect. Macrocephala is supported as monophyletic, while sect. Microcephala lacks jackknife support. Within Barnadesia, B. parviflora has a very divergent ITS sequence and a basal position in the genus. The phylogenetic trees make some sense of the great morphological variation within the subfamily, although some clades identified here lack obvious defining morphological characteristics. Optimisation of geographical distributions onto the molecular phylogenies shows that the Barnadesioideae most likely originated in southern South America.