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Abstract Detail


Voshell, Stephanie [1], Hilu, Khidir [2].

Phylogeography of Canary Grasses (Phalaris): Impact of chromosome and floret evolution.

Phalaris (Poaceae) contains 21 endemic to cosmopolitan species, found throughout the temperate and sub-tropical regions of the world with distinct centers of diversity in the Mediterranean Basin and western North America. The species display annual or perennial habit and possess basic chromosome numbers of x=6 and 7, with polyploidy confined to the later cytotype. Phalaris presents a valuable opportunity to study long distance dispersal, historic hybridization and polyploidy events, and the impact of floret structure on natural range expansion in grasses. We present here the first phylogeographic study showing the historic events of migration, speciation and dates of divergence in the genus using Bayesian inference and dispersal-vicariance analyses. The genus emerged in the Mediterranean Basin during the Miocene epoch (23-5.3 MYA). A basal split occurred between the x=6 and x=7, with the former group (3 species) remaining in the Mediterranean region and the later group expanding into Africa and Asia and evolving various ploidy levels. Dispersal to North America via the Bering Land Bridge resulted in diversification in the Americas based on diploid speciation. The greater speciation and dispersal success of the diploid x=7 cytotype compared to its x=6 counterpart raises questions about the significance of this early chromosome rearrangement. Florets with prominent and pubescent sterile lemmas, as seen in the New World species, may be advantageous for dispersal via animal transport.

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1 - Virginia Tech, Biological Sciences, 2119 Derring Hall, Blacksburg, VA, 24061
2 - VIRGINIA TECH, Department of Biology, 2119 Derring Hall, BLACKSBURG, VA, 24061, USA


Presentation Type: Oral Paper:Papers for Topics
Session: 50
Location: Magnolia/Riverside Hilton
Date: Wednesday, July 31st, 2013
Time: 1:45 PM
Number: 50002
Abstract ID:695
Candidate for Awards:None

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