A phylogeny and classification of Agrostis (Poaceae: Pooideae: Agrostidinae)
ID: 613 / 324
Proposed Symposium Title: A phylogeny and classification of Agrostis (Poaceae: Pooideae: Agrostidinae)
Paul M. Peterson1*, Robert J. Soreng1, Konstantin Romaschenko1, Patricia Barberá2, Alejandro Quintanar3, Carlos Aedo4, Jeffery M. Saarela5
Affiliations: 1 Department of Botany MRC-166, National Museum of Natural History, Smithsonian Institution, Washington DC 20013-7012, USA 2 Department of Africa and Madagascar, Missouri Botanical Garden, St. Louis, Missouri 63110-2291, USA 3 Herbarium MA, Unidad de Herbarios, Real Jardín Botánico, Consejo Superior de Investigaciones Científicas, 28014 Madrid, Spain 4 Department of Biodiversity and Conservation, Real Jardín Botánico, Consejo Superior de Investigaciones Científicas, 28014 Madrid, Spain 5 Beaty Centre for Species Discovery and Botany Section, Research and Collections, Canadian Museum of Nature, Ottawa ON KIP 6P4, Canada
To investigate the evolutionary relationships and biogeographical history among the species of Agrostis and other allied genera within the subtribe Agrostidinae, we generated a phylogeny based on DNA sequences from nuclear ribosomal (ITS) and three plastid regions (rpl32‐trnL spacer, rps16‐trnK spacer, and rps16 intron). Based on our phylogeny of 229 samples, representing 117 species (77 species from Agrostis as currently recognized), we identified two strongly supported clades within Agrostis, clade Longipaleata (Agrostis subg. vilfa) and clade Brevipaleata (A. subg. Agrostis). The species of Agrostis in clade Longipaleata usually have florets with paleas 2/5 to as long as the lemma whereas species in clade Brevipaleata have florets with paleas less than 2/5 as long as the lemma, minute, or absent. Core phylogenetic analysis of Agrostis reveal three strongly supported clades: European-Northwest African, Asian and African in Longipaleata, and three strongly supported clades: Asian, European (a grade), North American and South American in Brevipaleata. Of the four genera commonly associated with Agrostis e.g., Polypogon, Lachnagrostis, Chaetopogon and Chaetotropis, only Polypogon maintained its status as a separate genus while the remaining genera were subsumed within Agrostis or Polypogon. Polypogon was identified as an intergeneric hybrid originating via ancient hybridization between unknown representatives of Agrostis clade Longipaleata (plastid DNA) and Calamagrostis clade Americana (nrDNA). Several species of Lachnagrostis that follow the same pattern were included in Polypogon, while remaining species in Lachnagrostis in our study, including the type (L. filiformis), were identified as ancient intersubgeneric hybrids within Agrostis.