Systematics Section / ASPT
Brouillet, Luc , Lowrey, Tim , Urbatsch, Lowell , Karaman, Vesna , Sancho, Gisela , Wagstaff, Steven J. , Semple, John .
Phylogenetic Analysis of tribe Astereae (Asteraceae) based on ITS sequence data.
The Astereae is the second largest tribe of the Asteraceae. It includes 220 genera and 3100 species. The tribe is distributed throughout the continents but is particularly concentrated in temperate habitats. Little is known about its evolutionary radiation. The infratribal classification is problematic with several schemes having been proposed. None of these subtribal classifications have been derived from a comprehensive phylogenetic analysis. Furthermore, only one cladistic analysis of the tribe has been performed and this (Zhang and Bremer, 1993) was based on morphological characters derived from a few representative taxa selected from traditional subtribes. The current study is a phylogenetic analysis of sequence data from the ribosomal ITS region using parsimony. Sequences from 737 taxa in the tribe and 15 outgroup taxa were used in the analysis. The results indicate a high level of homoplasy and rather low resolution in the trees due in large part to the relatively low number of informative characters in the ITS data as well as recent radiations in many of the lineages. Several important results do emerge from the analysis, nonetheless. The tribe is monophyletic and there is no support for current subtribal classifications. The basal clade consists of genera from southern Africa. Initial radiation of the tribe was largely in the southern hemisphere including lineages in South America, New Zealand/Australia, and the South Pacific, with an unusual early dispersal event into China resulting in the genus Nannoglottis. There have been several separate radiation events within and out of Africa. The large number of Astereae taxa in North America has resulted from a relatively recent radiation apparently derived from South American ancestors. Mapping of chromosome number data onto the trees indicates that the base number of the tribe is x= 9 with a number of independent dysploid reduction events having occurred.
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1 - Université de Montréal, Institut de recherche en biologie végétale, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
2 - University of New Mexico, Department of Biology, 167 Castetter Hall, Albuquerque, New Mexico, 87131, USA
3 - Louisiana State University, Department of Biological Sciences, 202 Life Sciences Building, Baton Rouge, Louisiana, 70803-1705, USA
4 - Louisiana State University, Department of Biological Sciences, 107 Life Sciences Bldg, Baton Rouge, Louisiana, 70803, USA
5 - Museo De La Plata, Department Cient. Plantas Vasculares, Museo De La Plata, Paseo Del Bosque S/N, La Plata, Buenos Aires, 1900, Argentina
6 - Landcare Research, Allan Herbarium, P.O. Box 69, Lincoln, 8152, New Zealand
7 - University of Waterloo, Department of Biology, Waterloo, Ontario, N2L 3G1, Canada
Presentation Type: Oral Paper:Papers for Sections
Location: Lake Erie/Hilton
Date: Monday, July 9th, 2007
Time: 4:00 PM