Systematics/Phytogeography / Taxonomie/ Section
Gernandt, David S. , Hernandez Leon, Sergio , Flores Renteria, Lluvia .
A cpDNA based scenario for the diversification of pines in Mexico and Central America.
The northern hemisphere genus Pinus includes at least 51 species in Mexico and Central America. These species are clearly members of six of eleven subsections (Cembroides, Nelsoniae, Strobus, Contortae, Australes s.l., and Ponderosae). A seventh subsection (Pinus) is represented in the Caribbean. We used a cpDNA data set (matK, rbcL, and the trnH-psbA spacer) for 110 pine species to evaluate the hypothesis that ancestors of several lineages migrated to Mexico and Central America following a dramatic cooling event in the Eocene. To estimate the number of transitions from U.S. to Mexico/Central American pines, species distributions were coded as characters and mapped onto a cpDNA phylogeny. Using a relaxed molecular clock that assumes a Late Cretaceous separation of Pinus from Picea and Cathaya, we generated a chronogram that estimates a Miocene stem age for all 11 Pinus subsections. The ages for the nodes identified as representing U.S. to Mexico/Central American transitions will be described, and fossil evidence of earlier subsectional divergences will be discussed.
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1 - Instituto de Biología, Universidad Nacional Autonoma de Mexico, Departamento de Botánica, A. p. 70-367, Mexico, D.F., 04510, Mexico
2 - Instituto de Ecología, Universidad Nacional Autonoma de Mexico, Ecología Evolutiva, 3er Circuito Exterior, Cd. Universitaria, Mexico, D.F., 04510, Mexico
Presentation Type: Oral Paper:Papers for Sections
Location: Room 6/Woodward
Date: Tuesday, July 29th, 2008
Time: 9:30 AM