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Systematics Section / ASPT

Vicentini, Alberto [1].

Evolutionary history of the plant genus Pagamea Aubl. (Rubiaceae) in tropical South America- molecular markers, morphology and geographical variation.

Pagamea comprises ca. 50 species (at least 10 undescribed) of trees and shrubs that occur in forests and scrublands of nutrient-poor soils (white sands) throughout tropical South America, ranging from the Atlantic Coast of Brazil to the Choco region of Colombia. Pagamea is sister to Gaertnera, whose phylogenetic history was recently reconstructed, indicating a rapid radiation throughout the Paleotropics. The molecular phylogenies for 110 accessions of Pagamea and for both chloroplast (rps16_intron and rpl20-rps12 intergenic spacer) and nuclear (Per42, Met) non-coding regions are contrasted with patterns of morphological variation (phenetic analyses) and the geographical distribution of species. Phylogenetic results indicate a rapid diversification also for Pagamea, though an older history than that of Gaertnera. Chloroplast data support the monophyly of morphological species or species-groups, but also indicate that morphological convergence has obscured species delimitation in the past. Phylogenetic patterns of nuclear and chloroplast data are not completely congruent and appear to indicate both scenarios of hybridization and of incomplete lineage sorting. Dioecy has evolved multiple times within Pagamea. Changes in breeding system and in microhabitat specialization appear to have played important roles in the diversification of this lineage. Results highlight the importance of combining molecules, morphology and geography for understanding species-level patterns and processes. (Project supported by NSF, GCA/WWF, ASPT, ICTE, MBG, UMSL, CNPq-Brasil, LabGen-INPA).


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Related Links:
Alberto Vicentini's homepage


1 - University of Missouri St Louis, Department of Biology, 8001 Natural Bridge Road, St Louis, Missouri, 63121-4499, USA

Keywords:
Pagamea
Rubiaceae
species boundaries
molecular systematics
species-level
South America
Amazon.

Presentation Type: Poster
Session: 33-99
Location: Salon C, D & E - Gov Ballroom/Hilton
Date: Tuesday, August 16th, 2005
Time: 12:30 PM
Abstract ID:446


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