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Patel, Manisha V.

Botany

2007

MS

Current ecological and evolutionary studies have attempted to describe the factors contributing to species invasion success. Traits such as high competitive ability and phenotypic plasticity may contribute to successful establishment of an introduced species into new habitats. These traits may be subject to positive selection pressure in this new environment that may further contribute to invasiveness of the species. Phalaris arundinacea, native to Europe, has undergone genetic changes since its introduction and subsequent invasion in North America. Genotypes from the native (Czech Republic and France) and invasive (Vermont and North Carolina) ranges of P, arundinacea were used to determine whether genetic differences have led to differences in growth, reproductive output and phenotypic plasticity. Plants were grown in the greenhouse under low (21- 24°C /15.5-18°C day/night) and high temperature (31-34°C / 21-24°C day/night) and four moisture levels (25%, 50%, l00%, and l00%+) for 12 weeks. Survivorship of P. arundinacea declined with increasing temperature. Invasive genotypes had significantly greater total biomass, above-ground biomass, below-ground biomass, stem height, and tiller production than natives under all treatment conditions. Phenotypic plasticity for these traits was present in P. arundinacea, however, no differences were detected between native and invasive genotypes. Evolutionary changes have caused enhanced growth and reproduction in invasive genotypes and maintained phenotypic plasticity in P. arundinacea. The combination of aggressive growth and phenotypic plasticity may contribute to the invasion success of P. arundinacea within its introduced range.