Funk, Vicki A. .
The Compositae Metatree: the next generation.
The Compositae are the most successful family of flowering plants containing 1 of every 10 species. It is monophyletic and the sub-familial classification and ideas about relationships within the family remained largely unchanged until the 1990ís. The results of recent broad-scale molecular studies of the tribes (involving > 40 collaborators) were used to produce a meta-tree formed by linking the respective trees together on a known base tree. By examining the distribution of the terminal taxa a biogeographic pattern emerges. The extant lineages from the basal grade are southern South American in origin followed by a subsequent radiation in Africa that gave rise to most of the tribes we know today. Nested in the African radiation are individual clades in Asia, Eurasia, Australia, the Americas, etc. Highly nested in the base tree there is a North American origin and diversification of the Heliantheae Alliance that involved repeated incursions into Mexico and South America. The South American radiation followed by the African explosion might suggest a Gondwanan origin for the family, but the few data that exist from pollen records and geology seem to indicate a more recent origin for the family. The existence of the monotypic genus Hecastocleis A. Gray inserts a North American taxon in between the South American basal grade and African radiations which might indicate long distance dispersal, or a North American or even an Asian presence. The sister-group to the western hemisphere clade Heliantheae Alliance is the small tribe Athroismeae, from eastern tropical Africa, leaving an unknown area, possibly Asia, between Africa and western North America. This global picture of the Compositae provides a framework for studies of characters such as pollen, corolla shape, chromosome number, phytochemistry, and many others. We now have a better picture of the origin and evolution of the Compositae.
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1 - National Museum of Natural History, Smithsonian Institution, Department of Botany, MRC-166, P.O. Box 37012, Washington, DC, 20013-7012, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood D/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 10:15 AM