Systematics Section / ASPT
Vaezi, Jamil , Brouillet, Luc .
Identification of the parents of Symphyotrichum anticostense (Asteraceae: Astereae), an allodecaploid species, using three nuclear genes despite concerted evolution and incomplete lineage sorting.
Polyploidy is an important evolutionary process in flowering plants. Symphyotrichum anticostense (Fernald) Nesom is a neo-endemic, rare species from northeastern North America, mostly in the Gulf of St. Lawrence region (Quebec, New Brunswick, Maine). It is a high allopolyploid (2n=10x=80), hypothetically derived from a hybrid between S. boreale (T. & G.) Prov., possibly tetraploid (2n=4x=32), and S. novi-belgii (L.) Nesom, a hexaploid (2n=6x=48). Symphyotrichum is a relatively recent, rapidly radiating genus characterized by abundant interspecific hybridization and auto- and allopolyploidy. In the current study, we are using three molecular markers from the nuclear genome, ITS, glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and myo-inositol phosphate synthase (MIPS), to demonstrate the hybrid nature of the taxon and its relationships to the putative parents, and explore the possibility of multiple origins of the allopolyploid. ITS sequences of S. anticostense, despite concerted evolution and recombination, retain traces of both parents. The GAPDH and MIPS trees show incongruence in the relationships among individuals. Given the recently divergent evolution of Symphyotrichum, this conflict could have resulted from incomplete lineage sorting of alleles with respect to speciation events. Nonetheless, alleles from both parents are detected in the allopolyploid. This is not definite proof, however, of the parentage of the allopolyploid because of incomplete lineage sorting within the genus and the ploidy level of the presumed parents. The relationships shown by these markers are complex but raise the possibility of multiple geographic origins for S. anticostense.
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1 - Université de Montréal, Institut de recherche en biologie végétale, 4101 rue Sherbrooke est, Montréal, Québec, H1X 2B2, Canada
Presentation Type: Poster:Posters for Sections
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM