A phylogeny of the Gochnatieae: Understanding a critically placed tribe in the Compositae
Subfamily Gochnatioideae is the sister group of ∼96% of the species in Compositae (Asteraceae). It is of particular interest not only because of its position in the phylogeny, but also because, in recent molecular studies, the node it occupies is not strongly supported making difficult
any inferences on the direction of character evolution in the family. The recognition of tribe Gochnatieae was one of the results of a comprehensive molecular analysis of the family that showed the traditional circumscription of the Mutisieae to be non-monophyletic. The four genera of Gochnatieae
(Cnicothamnus, Cyclolepis, Gochnatia, Richterago) were defined by the presence of apiculate anther appendages and dorsally smooth style branches. Gochnatia, which contained about 70 species, was the largest and most complex genus and in the last decade some
of its sections have been moved (or returned) to the rank of genus. This study includes a large selection of potential outgroups and over 60% of all species in the tribe, including all the genera and all but one of the sections of Gochnatia, to examine evolutionary relationships among
the taxa. Both cpDNA and nrDNA were used in a phylogenetic analysis using parsimony, likelihood, and Bayesian approaches. The results suggest a non-monophyletic Gochnatia that is here resolved by the recognition of segregate genera. Morphological characters support these new genera
and allow the adoption of a new classification for the Gochnatieae. A biogeographic analysis shows a possible southern South American/Andean origin followed by movement in three directions: into the Central Andes, into central and northern Brazil, and into Mexico and the Caribbean. The dating
analysis gives an age of the split of the core Gochnatieae from the Wunderlichieae-Cyclolepis clade, and hence the age of the tribe, of 36–45 Ma and an age of 23–25 Ma for the first split within the core Gochnatieae (Andean vs. Brazil-Mexico-Caribbean). Cnicothamnus
remains in Gochnatieae but Cyclolepis is designated incertae sedis.
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Document Type: Research Article
U.S. National Herbarium, Department of Botany, Smithsonian Institution-NMNH, MRC 166, Washington, D.C., 20560, U.S.A.;, Email: [email protected]
Museo de La Plata, Paseo del Bosque s/n, 1900 La Plata, BA, Argentina
Instituto de Biologia, Universidade Federal da Bahia, Campus Universitário de Ondina, 40170-110 Salvador, Bahia, Brazil
U.S. National Herbarium, Department of Botany, Smithsonian Institution-NMNH, MRC 166, Washington, D.C., 20560, U.S.A.
Instituto de Ecología y Sistemática, Carretera Varona Km 3½, Capdevila, Boyeros, AP. 8029, CP 10800, La Habana, Cuba; current address: Pasaje El Astillero No. 8, Vaqueros (4401), Salta, Argentina
Laboratorio de Botánica, Facultad de Agronomía, Universidad de la República, Casilla de Correos 1238, Montevideo, Uruguay
Publication date: 2014-08-28
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