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JACKSON - Researchers are proposing genetic testing to determine whether grizzly bears in the Yellowstone region interbreed with grizzlies from elsewhere.

Scientists with the U.S. Geological Survey proposed the study Wednesday in a meeting of the Interagency Grizzly Bear Committee in West Yellowstone, Mont.

Federal judges in Montana and Idaho are presiding over three separate lawsuits challenging a decision by the U.S. Fish and Wildlife Service in April to remove grizzlies from the endangered-species list.

One argument against delisting is the population's lack of genetic diversity. Some say that could threaten the long-term health of bears in the ecosystem.

Scientists say grizzlies from Canada or northwest Montana must breed with bears in the Yellowstone ecosystem at least once every generation to maintain the genetic diversity of the Yellowstone population.

"We have no documentation of that happening," said Chuck Schwartz, leader of the Geological Survey's grizzly bear study team.

There is genetic evidence of a hybrid bear in the northern ecosystem, but Schwartz said that bear probably is the offspring of a problem bear that was relocated to Canada years ago.

Researchers plan to collect genetic samples from all bears captured or killed in the Yellowstone ecosystem. Geneticists will then compare the DNA of the Yellowstone grizzlies with grizzlies in northern Montana and Canada to see if interbreeding has occurred.

If no sign of genes from elsewhere appears in Yellowstone grizzlies by 2020, researchers suggest capturing one or two bears from elsewhere and releasing them in the Yellowstone region every 10 years.

Although there is no evidence of interbreeding right now, the Yellowstone population has been expanding into southern Montana. However, researchers say grizzlies are much more likely to be killed by vehicles and hunters when they get closer to human development.

Franz Camenzind, executive director of the Jackson Hole Conservation Alliance, called the genetic health of Yellowstone grizzlies a "huge concern" because of the population's isolation and modest numbers. The population is estimated at 600.

"It's long overdue that they start a rigorous genetic diversity study," he said.

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