Systematics Section / ASPT
Kim, Seung-Chul , Lee, Chunghee , Jenks, Aaron A. , Mejias, Jose A. .
Phylogenetic relationships among the genera of the subtribe Sonchinae (Asteraceae: Lactuceae) based on ITS and matK sequences.
The subtribe Sonchinae is comprised of 11 genera and about 130 species. Due to incomplete sampling and insufficient molecular data in the previous studies, the phylogenetic relationships among the genera have not been completely resolved. In addition, monophyly of the genus Sonchus and its three subgenera as well as the origin and evolution of several Pacific endemic segregate genera were not assessed effectively. In this study, we have sampled extensively all three subgenera of the genus Sonchus (i.e., Dendrosonchus, Origosonchus, and Sonchus) and some other poorly represented genera (e.g., Launaea, Reichardia, and Actites). Both nuclear ITS and chloroplast matK gene sequences suggest that Reichardia and Launaea are monophyletic and diverged first within the subtribe. Two subgenera of Sonchus, Sonchus and Dendrosonchus, are polyphyletic, whereas subgenus Origosonchus is monophyletic. All but two sections of Sonchus, i.e., Pustulati and Tuberiferi, are highly polyphyletic. Three monotypic genera in the Pacific, Embergeria and Kirkianella in New Zealand and Actites in Australia, evolved from some members of Sonchus sections Arvenses and Maritimi. The Juan Fernandez Island endemic Dendroseris, is monophyletic and deeply nested within the subtribe Sonchinae. This suggests that the subtribe Dendroseridinae of Stebbins (1953) should not be recognized. The woody Sonchus alliance in the Macaronesian Islands is monophyletic, and Sonchus palustris and monophyletic section Pustulati are sister to the Macaronesian clade based on the ITS phylogeny. There are several major differences between nuclear ITS and chloroplast matK phylogenies that will need to be addressed.
1 - University of California, Botany and Plant Sciences, Riverside, California, 92521
2 - University of Sevilla, Departamento de Biología Vegetal y Ecología, Apartado 1095, 41080 Sevilla, , Spain
Presentation Type: Paper
Location: Cottonwood B (Snowbird Center)
Date: Monday, August 2nd, 2004
Time: 10:00 AM