Recent Topics Posters
Romashchenko, Kostyantyn , Peterson, Paul M. , Garcia-Jacas, Nuria , Soreng, Robert J. , Susanna, Alfonso .
A phylogeny of Stipeae (Poaceae) based on nuclear DNA (ITS) sequence data.
The Stipeae consists of grasses that are perennial, caespitose, single-flowered with indurated, awned lemmas. The group has an intriguing, complex evolutionary history, and a clear phylogenetic hypothesis has never been presented. The tribe includes nearly 450 species in the New and Old Worlds, and between nine and 30 genera, some recently resurrected out of Stipa. A molecular phylogenetic analysis based on ITS sequence data of 203 specimens representing 23 genera and 150 species indicates there are two main lineages: European clade (Stipa s.s.) that includes European, Mediterranean species, and an Asian-American clade. Many of the basal lineages in the Asian-American clade (Ptilagrostis, Oryzopsis, Celtica, Timouria, Achnatherum s.l., and Jarava in Stipa subg. Pappostipa) share typical “achnatheroid” characteristics of protruding, hyaline lemma lobes and unigeniculate awns. A clade that contains Oryzopsis (incl. Piptatherum), Anatherostipa (incl. Aciachne), Ptilagrostis (monophyletic), and Piptochaetium (monophyletic) appears near the base of the Asian-American clade. Achnatherum s.l. and Jarava s.l. appear to be polyphyletic. The Jarava ichu group (includes type) is sister to Nassella. Stipa subg. Pappostipa is a basal monophyletic lineage. Some species of Achnatherum form clades with species of Jarava s.s. and other species of Achnatherum form clades with members of Stipa subg. Ptilostipa. Asian Achnatherum clade has five species in Stipa sect. Aristella-Achnatheropsis and is sister to four species in Stipa sect. Smirnovia, and sister to 11 species of Austrostipa. Stipa sect. Leiostipa (S. richteriana and S. korschinsky) is apparently paraphyletic and belongs to the European clade that includes Stipa sects. Leiostipa, Barbata, Pennata, Pulcherrima, Eriocaulis, Atlantica, Stenophylla, and Rubentiformis. Our analysis supports a European clade that includes only species of Stipa and the American species of Stipeae should be placed in other genera.
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1 - Smithsonian, Botany, National Museum of Natural History, MRC-166 PO BOX 37012, Washihgton, DC, 20013-7012, US
2 - Smithsonian, Botany, National Museum of Natural History, Washington, DC, 20013-7012, USA
3 - Botanical Institution of Barcelona, Botany, p/g Migdia S/N, Barcelona, Cataluna, 08038, Spain
4 - Smithsonian Institution, Department of Botany MRC 166, National Museum Of Natural History, Po Box 37012, Washington, DC, 20560-0166, USA
Presentation Type: Recent Topics Poster
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM