The efforts of Chinese zoologists to avoid inbreeding and ensure heredity diversity of captive Siberian tigers are paying off, according to a scientist from the world's largest artificial breeding base for the rare species.
Scientists at the Hengdaohezi Feline Raising Center in Harbin, capital of Heilongjiang Province in northeast China, have conducted DNA tests on 200 of the 700-plus tigers in the park in an attempt to introduce selectivity into the breeding process.
"We have seen signs of genetic degeneration in the past due to inbreeding. We used to have at least one or two cubs with deformities among the newborns every year," said chief zoologist Liu Dan.
"Encouragingly, we haven't found any tiger cub born with birth defects in the last two years," Liu said. "This shows that DNA testing is conducive to preventing genetic degeneration of the Siberian tigers."
Siberian tigers, among the world's 10 most endangered species, mostly live in northeast China and the Far East area of Russia. Of the 400 estimated to live in the wild, only 10 to 17 live in northeast China.
The Siberian tiger is listed as "endangered" on the Red List of Threatened Species of the World Conservation Union and is also listed on the Convention on the International Trade in Endangered Species (CITES) Appendix I which prohibits the trade of live tigers or tiger parts.
To protect the rare tigers from extinction, China established the Harbin base in 1986. The base now has more than 700 Siberian tigers in captivity, including over 100 born this year, compared with only eight when it was set up. The population is expected to double by 2010.
The expansion of the captive Siberian tiger population excites zoologists at the center but also brings challenges.
"A female tiger usually mates with several male tigers so it's hard to know the identity of the real father of the tiger cub," Liu said.
Experts believe inbreeding of the tigers is partly blamed for the apparent genetic degeneration.
"With DNA testing, we can sort out the bloodlines of all the tigers and prevent inbreeding," Liu said.
The DNA test project was kicked off in June 2001 with support from the State Forestry Administration (SFA).
SFA has allocated more than 1 million yuan (US$127,748) for the project so far and the center has raised an additional 300,000 yuan. A significant proportion of the funds will be used to establish a DNA bank and the development of computer software which will calculate the optimum breeding match for tigers based on the DNA test results.
The long-term plan of the Harbin center is to train and release 620 Siberian tigers into the wild.
(Xinhua News Agency December 17, 2006)