William Muir, professor of animal sciences, and Richard Howard, professor of biology, used computer modeling and statistical analyses to examine the hypothetical risks of introducing genetically modified organisms into wild populations.

"We examined these hypothetical situations because the range of new transgenic organisms is almost unlimited," Muir said. "It is constructive for those developing such organisms to be able to anticipate how they could pose a hazard."

The new computer models have shown that the risk of extinction is greater than believed before, identifying three new scenarios in which genetically modified organisms could result in the extinction of a natural population.

"In the broadest sense, this research tells one how to do risk assessment and what GMOs need further containment," Muir said.

In 2000, Muir and Howard found that a release of fish that were larger and therefore had higher mating success but also had shorter life expectancy, could drive a wild population extinct in as few as 40 generations. Muir and Howard labeled this the "Trojan gene hypothesis."

But further investigation has found other scenarios that could lead to extinction.

In one scenario, a genetic modification increases the size of the male, which results in the male finding more mates and also living longer. But if the modification also has a third effect of making the male less fertile, the predicted result is that the wild population will be extinct in just 20 generations.

"We consider this an extreme risk," Howard said. "That's the most severe time frame we've encountered so far."

Howard said this risk could arise if fertility was restricted in a genetically modified organism a
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Contact: Steve Tally
tally@purdue.edu
765-494-9809
Purdue University
18-Jun-2002