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Updated at 7:39 a.m., Friday, July 6, 2007

UH research reveals phenomenon in invasive weed

News Release

Researchers at the College of Tropical Agriculture and Human Resources at UH Manoa reveal a unique and important biological phenomenon in invasive weeds in the July 4 issue of the Public Library of Science ONE (PLoS ONE), a highly rated journal series publishing high-impact research on a broad range of topics.

The UH team conducted research on fountain grass (Pennisetum setaceum), which is highly invasive in Hawai'i and variably invasive in other parts of the world, and addressed whether genetic variation in the species allow it to adapt to new environments globally. Their work explored the correlation between neutral genetic variation in the grass, quantitative genetic variation and invasiveness of the plant worldwide and within its home range.

Samples of fountain grass taken from various parts of the world responded uniformly to a range of treatments in experiments. The genetic analysis showed that the species is genetically uniform throughout its range in Africa, Hawai'i and in its place of origin Egypt, yet the grass is able to tolerate and thrive in a wide spectrum of environmental variation. This "plasticity" contributes significantly to the invasiveness of the species under certain conditions, particularly in disturbed environments, or geologically recent areas, such as Hawai'i.

"These findings are remarkable in that it is often assumed that genetic diversity underlies invasive success invasive species are able to adapt to local conditions," said Ania Wieczorek, project leader and assistant specialist in the Department of Tropical Plant and Soil Sciences. Fountain grass was found to show the opposite trend, with no genetic diversity and yet it is a highly successful invader in many environments. The species is pre-adapted to thrive under a broad range of ecological conditions.

"The results have important implications for management of fountain grass where it is invasive. The results also contribute significantly to our understanding of basic evolutionary processes that affect species in new environments," said Wieczorek.

Wieczorek's team is comprised of Johannes J. Le Roux, doctoral candidate, and Carol T. Tran, research support, in the Department of Tropical Plant and Soil Sciences; and Dr. Mark G. Wright, assistant specialist in the Department of Plant and Environmental Sciences.

This research was funded by a USDA-TSTAR grant.

More information on the project, which addresses a number of invasive species, is available at http://www.pacificlandgrants.org/video/InvasiveFINALREV.wmv.