Oh, Sang-Hun .
Phylogeny and biogeography of Crossosomatales as inferred from chloroplast genes.
Crossosomatales, which originally comprised only Crossosomataceae, includes seven additional families that have been classified in several different orders: Aphloiaceae, Geissolomataceae, Ixerbaceae, Stachyuraceae, Staphyleaceae, Strasburgeriaceae, and the recently described Guamatelaceae. This newly circumscribed rosid order consists of about 60 species of trees and shrubs in 13 genera, and most of the families are monospecific or monogeneric. Members of Crossosomatales are distributed in diverse regions in both Northern and Southern Hemispheres with remarkable patterns of disjunction. This group would provide an excellent system to investigate the biogeography of both hemispheres, however, a robust phylogenetic framework is needed. Currently, phylogenetic relationships within Crossosomatales are poorly understood as is its placement among the rosids, making it difficult to infer an ancestral distribution. A phylogenetic study has thus been undertaken employing nucleotide sequences of 17 chloroplast genes from 11 species representing 7 families of Crossosomatales. MP and ML analyses of the cpDNA data with representatives of major lineages of rosids demonstrate that Crossosomatales is strongly supported as monophyletic and that the eurosid II clade is weakly supported as sister to Crossosomatales. Two subclades were strongly supported within Crossosomatales, one comprising the species distributed in the Northern Hemisphere and the other in the Southern Hemisphere. In the former clade, Staphyleaceae is sister to a clade of Crossosomataceae, Stachyuraceae, and Guamatelaceae. Stachyuraceae is sister to Crossosomataceae in the MP analysis, but it is sister to Guamatelaceae in the ML tree. Within the Southern Hemisphere clade, Geissolomataceae is strongly supported as sister to Ixerbaceae and Strasburgeriaceae. Biogeographic analysis suggests that species distributed in Europe, eastern and western North America, and Central and South America were derived from Asian ancestors via multiple migration events and that species distributed in New Caledonia and New Zealand evolved from an African ancestor that migrated eastward via transoceanic long-distance dispersal.
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1 - Cornell University, L. H. Bailey Hortorium, Department of Plant Biology, 412 Mann Library, Ithaca, New York, 14853, USA
Presentation Type: Oral Paper:Papers for BSA Sections
Location: Cottonwood C/Snowbird Center
Date: Wednesday, July 29th, 2009
Time: 10:45 AM