Keeley, Sterling C. , Bunwong, Sukonthip .
The Relationships of Vernonieae (Compositae) from Thailand to those in Africa, Madagascar and Asia.
The tribe Vernonieae originated in east Africa/Madagascar and is now found throughout that continent, into India, south Asia, Malaysia, New Guinea and Australia. Except for the African species, little is known about the relationships among taxa. There are ~100 species in five subtribes distributed across these latter areas; half are in Thailand where there are also numerous endemic species. The majority of Thai taxa are in the subtribes Centrapalinae, Erlangeinae and Gymnantheminae, otherwise best represented in Africa. Thailand is key to gaining a picture of Vernonieae evolution in the Old World because of its position at the biological crossroads for both plants and animals moving westward from Malaysia and China and eastward from Africa, India and the Middle East. Additionally, while encompassing a relatively small geographical area Thailand has a large number of different habitat types, elevational ranges and ecological zones that are often sharply juxtaposed. Such conditions are known to favor the formation of new species and ones with characters differing considerably from those of their parents. In a group such as the Vernonieae this process is aided by the formation of hybrids, something that happens readily within the tribe, even among distant relatives. Nuclear ITS and cpDNA sequence studies (ndhF, trnLc-f, matK) have revealed complex biogeographical relationships between African taxa and those found in Asia and Malaysia. In the work reported here, Thai Vernonieae are shown to have relatives in more than one African lineage, thus suggesting multiple dispersal events, and also with a lineage of Australasian species. Connections to Africa are more numerous and taxa are more closely related than is the case for Malayasian species. This indicates the major direction of migration has been from west to east, and that multiple geographically overlapping colonizations are most likely responsible for the current distribution of the Vernonieae in south Asia.
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1 - University of Hawaii, Department of Botany, 3190 Maile Way, Room 101, Honolulu, Hawaii, 96822-2279, USA
2 - Khon Kaen University, Biology, Khon Kaen, 40002, Thailand
Presentation Type: Oral Paper:Papers for Sections
Location: 556A/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 1:30 PM