Systematics/Phytogeography / Taxonomie/ Section
Stefanovic, Sasa , Costea, Mihai .
Multiple instances of reticulate evolution in the parasitic genus Cuscuta (dodders; Convolvulaceae).
The frequency and relative importance of hybridization in plants has been an area of intense debate. Although this evolutionary mechanism has received considerable attention from plant biologist, there are no well-supported cases of reticulate evolution involving holoparasitic plants to date. Recent molecular phylogenetic analyses revealed that the subgenus Grammica, the largest and most diverse group of the stem parasitic genus Cuscuta, consists of 15 major clades. We describe here five cases of strongly supported discordance between phylogenies derived from plastid and nuclear data and interpret them as results of five independent hybridization events. Three of these cases could represent relatively recent reticulations because each of them involves more closely related species, always confined within the same major clade as their putative parental species, and are currently sympatric or parapartric with them. The two remaining cases involve species whose potential progenitors are derived from different major groups of subgenus Grammica, and which are allopatric in their present distribution. This is consistent with more ancient hybridization events. Exemplary taxa illustrating these two cases (i.e., Cuscuta subsection Denticulatae and Cuscuta sandwichiana, respectively) are discussed in more detail.
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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
Date: Wednesday, July 30th, 2008
Time: 1:15 PM