"These are fairly closely related lineages that they're trying to sort out," said Michael Russello, a conservation geneticist at the University of British Columbia in Kelowna who was not involved in the study.
"I think it is remarkable that they were able to find individuals from unmanaged populations that actually are purebreds of a given subspecies."
Genetic Surprises
The numbers of purebred tigers the researchers found likely overestimate the proportion of unmanaged animals with pure lineages, because many of the owners who sent samples to the team had some idea of their tiger's ancestry.
Of the 50 tigers without any pedigree, 7 could be assigned to a particular lineage based on the new genetic test.
Luo thinks that 15 to 23 percent of tigers not part of conservation breeding programs are likely to be potentially useful for preserving genetic variation unique to endangered subspecies.
Given the size of the captive population, that would mean thousands of additional useful animals.
The test can also reveal mixed ancestry. Owners of 11 tigers who thought they had purebreds turned out to own mutts instead.
"It's extremely important to know those individuals that have a hybrid origin," Russello said. Those animals should be excluded from breeding programs.
In addition, the researchers found that the captive tigers harbored at least 46 new genetic patterns that have not been found in wild animals so far.
Some of these occurred only in mixed-lineage tigers, which are currently thrown out of breeding programs when discovered.
While the findings come as welcome news, most conservationists agree that breeding programs are a last-ditch resort and that efforts should focus on protecting existing wild populations.
Tigers once ranged from the Indian subcontinent to Siberia.
Today that swath has been reduced to small remnant habitats, often depleted of prey. (Related: "Tiger Habitat Plummeted 40 Percent in 10 Years, Survey Finds" [July 20, 2006].)
"We are not at that stage where we are looking to reintroduce tigers from captive populations," said Mahendra Shrestha, who directs the Save the Tiger program based in Washington, D.C.
"The main challenge we are facing now is providing good quality habitat."
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