The gene pool of the 3,600 tigers that remain in the wild is dangerously shallow, says a group of biologists at Stanford University. By keeping different tiger subspecies separate -- as they are now -- the flow of tiger genes constricts, putting the big cats at higher risk of inheriting lethal diseases.
Simply increasing the number of tigers isn't the key to saving species, says Elizabeth Hadley, Stanford biologist and co-author of a recent study in the Journal of Heredity. Instead, allowing tigers to breed across further distances -- by building wildlife corridors or crossbreeding wild and captive tigers -- will bolster the cats' long-term survival.
The Stanford scientists draw a parallel between tigers and Florida panthers. In 1995, there were only 30 Florida panthers. Crossbreeding those cats with closely-related panthers may have saved the Florida panther from extinction. By 2008, Florida panthers tripled in number -- and at the same time, the rate of genetic disorders dropped.
This study highlights the importance of individual tigers, shooting holes in the argument that zoos can kill animals in the name of genetic diversity. "This is very much counter to the ideas that many managers and countries have now -- that tigers in zoos are almost useless and that interbreeding tigers from multiple countries is akin to genetic pollution," Hadley says.