Saving an endangered species means more than just preserving its habitat and waiting for its numbers to recover. Take the case of the Florida panther, whose numbers had once dwindled precariously to only about thirty. Now, however, there is a ray of hope, because the number has risen to eighty-seven. But the reason for the success is controversial: New breeding stock of Texas panthers had been brought in to strengthen the inbred Florida panther line.
Nicholas School conservation ecologist Stuart Pimm and his colleagues hail the success of the breeding experiment in an article slated for publication in the January 2006 issue of the British journal Animal Conservation. The authors cite findings indicating that hybrid kittens born to Texas panthers are three times more likely to survive to adulthood than purebred ones. The hybrids are also expanding the known range of the panther habitat, they found.
The problem was that native Florida panthers were displaying genetic abnormalities including low sperm counts and heart defects. New genetic stock was needed to erase these problems, naturalists concluded.
In 1995, separate pairs of Texas female panthers fitted with radio collars were released in each of the four sections of the panthers' South Florida habitat. Five of these eight cats are known to have produced hybrid kittens. By 2003, all three of the surviving Texas adults had been removed from the wilds, since wildlife managers wanted to keep outside genetic exposure to a minimum, Pimm says.
In their study of the panthers, the Duke researchers reviewed the locations and movements of both purebred and hybrid panthers that other scientists had tracked by radio. "A lot of scientists said this kind of genetic rescue would not work," says Pimm. "They said if a species is rare, and its range is restricted, just adding individuals from the outside is not going to work. Some thought it would be a waste of time, a waste of money."