Abstract Detail

Systematics Section

Voshell, Stephanie [1], Baldini, Riccardo [2], Kumar, Rohit [1], Tatalovich, Nicholas [1], Hilu, Khidir [3].

Phalaris (Canary Grasses, Poaceae): Elucidating trends in floret evolution and polyploidy using molecular phylogenetics.

The 21 species of Phalaris L. (Poaceae, Aveneae) are distributed in temperate areas and tropical mountains of Africa and in 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 displaying less species diversification. The multi-continent and varied patterns of distribution, notable variation in morphological traits, and the evident role of polyploidy in its evolution rendered Phalaris as a potentially valuable case study for speciation in conjunction with chromosomal evolution and biogeography in Poaceae. We reconstructed the first phylogenetic tree for the genus using nuclear ITS and plastid trnT-F sequences to assess species relationships and map trends in floret differentiation and patterns of polyploid evolution. The study demonstrated the single origin of x=6 chromosome number and revealed the sister group relationship of this lineage to the monophyletic x=7 lineage. Clades recovered in the phylogenetic analyses reflect geographic affinities and show diploid-polyploid associations. A trend in sterile lemma reduction is evident from sister genera in respective Pooideae clades to terminal lineages of the ingroup, with members of the early diverging x=6 lineage displaying relatively large lanceolate morphotypes followed by gradual reduction in size, culminating in almost obsolete sterile lemmas in one of the terminal x=7 clades.

Broader Impacts:

1 - Virginia Tech, Biological Sciences, Derring Hall, Blacksburg, VA, 24061, USA
2 - Università degli Studi, Dipartimento di Biologia Evoluzionistica, Via G. La Pira 4, Firenze, 50121, Italy
3 - VIRGINIA TECH, Department Of Biology, 2119 Derring Hall, BLACKSBURG, VA, 24061-0406, USA

Keywords:
Phalaris
phylogenetics
Polyploidy
ITS
trnT-F.

Presentation Type: Oral Paper:Papers for Sections
Session: 44
Location: Lindell A/Chase Park Plaza
Date: Wednesday, July 13th, 2011
Time: 9:45 AM
Number: 44006
Abstract ID:95