Voshell, Stephanie , Baldini, Riccardo , Kumar, Rohit , Tatalovich, Nicholas .
Canary Grasses (Phalaris, Poaceae): Biogeography and Evolution Bridging Five Continents.
The 22 species of Phalaris L. (Poaceae) are distributed in temperate areas of both hemispheres, tropical mountains of Africa and in Central-South America. The genus contains annual and perennial diploids based on x=6 and 7 and polyploids based on x=7, with the x=6 species displaying less diversification. The multi-continent and varied patterns of distribution, notable variation in morphological traits, and the evident role polyploidy has played in its evolution rendered the genus as a potentially valuable case study for speciation in conjunction with chromosomal evolution and biogeography. We reconstructed here the first phylogenetic tree for Phalaris using nuclear ITS and plastid trnL-F and rps16 intron sequence information to assess species relationships, trends in floret differentiation and patterns of polyploid evolution. The study demonstrated the single origin of x=6 chromosome number and its sister group relationship to the monophyletic x=7 species. The emerging clades reflect geographic affinities and show diploid-polyploid associations. A trend in sterile lemma reduction and modification in inflorescent structure are evident across the tree. The study suggests that Mediterranean Europe where the x=6 species are native is the area of origin for the genus and that Western North America is a secondary center of differentiation.
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1 - Virginia Polytechnic Institute and State University, Biological Sciences, Blacksburg, VA, 24061, USA
2 - Università degli Studi, Via G. La Pira 4, Biologia Evoluzionistica, Firenze, 50121, Italy
Presentation Type: Poster:Posters for Sections
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM