| Abstract Detail
Recent Topics Posters Steinmann, Victor Werner [1]. Biogeography and diversity of Euphorbia (Euphorbiaceae) in the New World. The genus Euphorbia (Euphorbiaceae) contains about 2000 species, of which nearly 500 occur in the New World. Molecular phylogenetic studies reveal that Euphorbia comprises four clades, and recent modifications in classification treat these as subgenera. Three subgenera are present in the Americas, but disparately so. Subgenus Esula contains only 35 New World species whereas subg. Euphorbia contains approximately 80 species. With about 360 species, subg. Chamaesyce is the most diverse. All three subgenera occur in North America, Central America, South America, and the Caribbean, but again not equally so. Most members of subg. Esula occur in temperate regions of the United States and Mexico, and only two additional species occur in the Caribbean and two others in South America. Half the species of subg. Euphorbia are restricted to South America; of the remaining, there are approximately 10 species in the Caribbean, 20 species in Mexico and Central America, and four species in the United States. Subgenus Chamaesyce is well represented in all regions. The earliest diverging lineages of all subgenera occur in the Old World. In subg. Euphorbia and Chamaesyce, the New World species apparently represent ancient monopyletic groups that have radiated within the Americas. In at least one subclade of subg. Chamaesyce, there has been a dispersal back to the Old World. Within subg. Esula there have been at least two relatively recent dispersals from the Old World and subsequent minor radiations. The center of diversity of the genus is in Mexico, where nearly 250 species are found. This is in contrast to the United States with about 115 species. The megadiverse countries of Brazil and Colombia possess relatively few Euphorbia, having about 60 species and 35 species respectively. Within the New World, there are many complex patterns of distribution, with various disjunctions and island colonizations and radiations.
Log in to add this item to your schedule
1 - Instituto De Ecología A.C., Avenida Lázaro Cárdenas 253, Apartado Postal 386, 61600 Pátzcuaro, Michoacán, Mexico
Keywords:
Biogeography
Euphorbia
Euphorbiaceae
New World.
Presentation Type: Recent Topics Poster
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P79014
Abstract ID:2581 |
