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Abstract Detail


Systematics Section

Haber, Elizabeth [1], Van Ee, Benjamin [1], Oyserman, Ben [1], Berry, Paul E. [2].

Origin and diversification of Croton (Euphorbiaceae) in Madagascar, and the Mascerene and Comoros islands.

The genus Croton (Euphorbiaceae) has undergone a massive radiation on the island of Madagascar. We present an update of our ongoing research of the clade. We now have molecular data for more than half of the approximately 150 species of Croton recognized for Madagascar. DNA sequence data from three markers (nuclear ITS and chloroplast trnL-F and trnH-psbA) suggest a single radiation onto Madagascar, presumably from mainland Africa, with at least two dispersals back to the mainland. Croton species from the Comoros and Mascarene islands originated from Madagascar, rather than from continental Africa. This finding suggests that Croton on Madagascar may represents one of the largest island radiations in plants. Other discoveries from our Malagasy data include several putatively new species, an inference that the tree habit has evolved several times, and that Croton nobilis is sister to the rest of the Malagasy clade. We have begun to identify several natural groups, such as the Adenophorus clade, which is characterized by a combination of stellate trichomes, opposite leaves, and glands in the axils of the secondary veins. With this new data we will be updating the taxonomy of Malagasy Croton. This also establishes the foundation for a taxonomic revision of the 400-450 species of Croton in the Old World.

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1 - University of Michigan, Herbarium & Dept. Ecology and Evolutionary Biology, 3600 Varsity Drive, Ann Arbor, MI, 48108, USA
2 - University of Michigan Herbarium, Ecology and Evolutionary Biology, 3600 Varsity Dr, Ann Arbor, Michigan, 48108, USA

Keywords:
Croton
Madagascar
Biogeography
phylogeny
ITS
trnL-F
trnH-psbA.

Presentation Type: Oral Paper:Papers for Sections
Session: 9
Location: Ballroom B/Convention Center
Date: Monday, August 2nd, 2010
Time: 3:45 PM
Number: 9011
Abstract ID:535


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