Systematics Section / ASPT
Gillespie, Lynn J. , Soreng, Robert J. , Archambault, Annie .
Deep structure and reticulate evolution in a large polyploid genus: ITS and trnT-trnF data help crack the Bluegrass (Poa) puzzle.
POA, known for taxonomic difficulty, polyploidy and apomixis, is widely presumed to have evolved reticulately. Comparison of phylogenetic analyses of nuclear ribosomal ITS and trnT and trnF chloroplast DNA sequences revealed both ancient and recent reticulation events, while deep structure in the genus is largely stable. Five major clades are congruent between the ITS and TF trees, with only minor differences in structure and included species. These clades are, for the most part, consistent with morphological data and the existing subgeneric classification. A sixth clade present only in the ITS tree represents a novel grouping of species, and includes the circumboreal-arctic P. arctica species complex , two sect. Oreinos species, south Asian species, and most New Zealand species sampled. Additional incongruencies between the ITS and TF analyses provide evidence for the hybrid origin of the following taxa: 1) P. annua, an infrasectional polyploid hybrid; 2) P. abbreviata, an intersectional polyploid hybrid; 3) P. trivialis, a putative intersectional diploid hybrid; and 4) P. subg. Arctopoa, a putative intergeneric hybrid.
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1 - Canadian Museum of Nature, Research Division, Po Box 3443, Station D, Ottawa, Ontario, K1P 6P4, Canada
2 - Smithsonian Institution, Department of Botany MRC 166, National Museum Of Natural History, Po Box 37012, Washington, DC, 20560-0166, USA
3 - McGill University, Department of Plant Science, 21,111 Lakeshore Road, Ste-Anne-de-Bellevue, Québec, H9X 3V9, Canada
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 4:00 PM