Public Release:  Biological invasions can begin with just 1 insect

PLOS

TORONTO, Sept. 12, 2007 -- A new study by York University biologists Amro Zayed and Laurence Packer has shown that a lone insect can initiate a biological invasion.

Zayed, a recent graduate of Packer's lab, examined patterns of genetic diversity in both native European and invasive North American populations of a solitary bee. He concluded that the invasion was most likely founded by one mated female. The study was published today in the open access journal PLoS ONE.

"This is a shocking result, especially since bees suffer from huge genetic problems in small populations," says Zayed, now a postdoctoral fellow in the Department of Entomology at the University of Illinois.

"We're now seeing that the introduction of even one single insect can cause a potentially costly invasion, so we have to be extremely vigilant with reducing the number of animals that are unintentionally transported around the globe," he says.

The study contradicts a popular theory of invasive biology: the more individuals introduced to an area, the higher the success of the invasion. This concept is commonly referred to as the "propagule pressure hypothesis."

Zayed adds that numbers are not the only factor controlling the success of invasions. "Chance and the specific characteristics of invasive species and their introduced habitats can be more important," he says.

Packer, a professor in York's Department of Biology, notes that exotic invasive species are considered a major threat to biodiversity conservation, and can cause huge economic losses.

"Understanding how exotic species establish and spread in their new habitats is the first step to solving the invasive species problem," Packer says.

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Notes for editors:

York University is the leading interdisciplinary research and teaching university in Canada. York offers a modern, academic experience at the undergraduate and graduate level in Toronto, Canada's most international city. The third largest university in the country, York is host to a dynamic academic community of 50,000 students and 7,000 faculty and staff, as well as 200,000 alumni worldwide. York's 11 faculties and 24 research centres conduct ambitious, groundbreaking research that is interdisciplinary, cutting across traditional academic boundaries. This distinctive and collaborative approach is preparing students for the future and bringing fresh insights and solutions to real-world challenges. York University is an autonomous, not-for-profit corporation.

Citation: Zayed A, Constantin S²A, Packer L (2007) Successful Biological Invasion despite a Severe Genetic Load. PLoS ONE 2(9): e868. doi:10.1371/journal.pone.0000868

PLEASE ADD THE LINK TO THE PUBLISHED ARTICLE IN ONLINE VERSIONS OF YOUR REPORT: http://www.plosone.org/doi/pone.0000868

PRESS ONLY PREVIEW:http://www.plos.org/press/pone-02-09-zayed.pdf

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