Genetic lynx: North American lynx make one huge family. (This Week).

A new study of lynx in North America suggests the animals interbreed widely, sometimes with populations thousands of kilometers away. This genetic finding could be a boon for conservationists hoping to secure the cats' future.

The Canada lynx has recently been officially designated as a threatened species in the United States, spurring studies of the animals' distribution and behavior. Researchers have been squabbling over one thorny issue for decades: Do lynx populations live in isolated pockets or travel long distances to mix with other groups? Lots of long-distance interaction might point toward policies that maintain connections between known lynx habitats.

Researchers have long known that the Canada lynx population in any given area undergoes several-year cycles of boom and bust. Booms follow continentwide patterns, with population explosions starting far inland and fanning toward coast-lines like a trail of falling dominoes.

A major question for conservation policy is, What lies behind this surge? Some scientists contend that lynx communities are isolated and that the wavelike pattern arises from extrinsic factors such as weather conditions. Others explain the patterns by way of a dispersal mechanism, that is, under crowded conditions, lynx migrate to less populous areas.

New genetic data may help solve this riddle. Michael K. Schwartz at the United States Forestry Service (USFS) Rocky Mountain Research Station in Missoula, Mont., led a team of federal biologists in an examination of lynx DNA derived from 17 populations throughout North America.

Using mathematical models, the researchers compared the DNA samples and found that lynx from Alaska to Wyoming share strikingly similar genetic profiles. The findings suggest that the animals commonly travel far and wide, interbreeding with the populations encountered along the way.

"We found evidence of high gene flow ... which offers a lot of support for the dispersal hypothesis," says Schwartz. His team describes its findings in the Jan. 31 Nature.

Despite evidence for epic lynx journeys, it's been difficult to establish whether this behavior is typical and far-flung animals are closely related, says Keith Aubry of the USFS Pacific Northwest Research Station. The fact that lynx from Alaska to the Rocky Mountains are physically similar enough to be classed as a single subspecies "suggested that kind of connectivity," he notes. But the new genetic study confirms it, he says.

The cause of the domino effect during boom times in lynx populations has been difficult to determine by radio tagging and mapping, adds Lisette Waits of the University of Idaho in Moscow. Huge amounts of data from many years of observation are required. However, by using DNA, she says, it's possible to rapidly answer many questions regarding behavioral strategies.

The new finding may have far-reaching implications for lynx conservation policy and practice. To ensure a future for the lynx, "we must focus efforts on maintaining connectivity between lynx populations," proposes Schwartz.

He notes that the genetic materials used in this study are distinct from the lynx samples in a separate project that were recently the target of fraud allegations. Seven state and federal scientists stand accused of misrepresenting the origin of fur samples submitted for identification to the lab of L. Scott Mills, one of Schwartz' collaborators. Officials now are investigating the case.