Systematics Section / ASPT
Stefanovic, Sasa , Kuzmina, Maria , Costea, Mihai .
Delimitation and relationships of major lineages within Cuscuta subgenus Grammica (dodders; Convolvulaceae).
SUBGENERA Monogyna, Cuscuta, and Grammica are recognized traditionally within the parasitic genus Cuscuta based primarily on the morphology of styles and stigmas. The largest and most diverse group, subgenus Grammica, comprises some 120-130 species (approximately ¾ of the species-richness within the genus) and is distributed primarily throughout the New World, with Mexico and South America as its centers of diversity. While this group is well characterized morphologically by two styles with globular stigmas, neither its monophyly nor the relationships within Grammica were subjected to a broad and explicit phylogenetic study. In order to circumscribe the subgenus and assess the relationships among its major lineages, we conducted the first phylogenetic study of Grammica using plastid and nuclear sequence data (trnLF and ITS) from a wide taxonomic sampling covering its morphological, physiological, and geographical diversity. The results indicate the presence of 15 well-supported clades. Some of those clades correspond to a large degree to earlier taxonomic treatments (e.g., subsections sensu Yuncker), but majority of the groups are identified in this study for the first time. The backbone relationship among these clades, however, remains unresolved in many cases. Morphological, taxonomical, and biogeographical implications of these results are discussed. Also, a minimum of three potential cases of species of hybrid origin were confirmed or newly documented from strongly conflicting nuclear and plastid gene trees.
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1 - University of Toronto at Mississauga, Biology, 3359 Mississauga Rd N, Mississauga, Ontario, L5L1C6, Canada
2 - Wilfrid Laurier University, Biology, 75 University Ave N, Waterloo, Ontario, N2L3C5, Canada
Presentation Type: Oral Paper:Papers for Sections
Location: 144/Performing Arts Center
Date: Tuesday, August 1st, 2006
Time: 3:15 PM