Cloning could be lifeline for threatened species

The cloning techniques which produced Dolly the sheep should be used to preserve and even rescue animal species on the brink of extinction, according to a conservation expert.

Dr William Holt of London Zoo's scientific arm, the Institute of Zoology, suggested yesterday that the cloning technique, which it was revealed in February has taken cells from an adult sheep and used them to produce an exact genetic copy, could be applied particularly to species which live in fragile habitats.

"If you could get the cloning technology working, then you could reconstruct the population," he said. As an example, he cited the Australian hairy- nosed wombat, which is found in New South Wales.

Fewer than 50 specimens are known to exist, confined to a small area. "It would only take a bush fire," he commented. "They could be wiped out overnight."

The furore over Dolly, which led to widespread arguments over whether it was morally justifiable and whether it should be allowed in humans, may have overshadowed useful aspects, Dr Holt suggested.

"The initial reaction to cloning is that there isn't any application to conservation. But that's not true."

A team in Japan is already trying to help a threatened species of ibis birds, where only two exist, by cloning technology which injects the ibis's cells into the the embryo of a closely-related ibis species. As the embryo develops into a chimera - a mix of species - it can then be crossed again with cells from the rare ibis, until over time the rare animal re-emerges.

"It might seem like this is encouraging inbreeding, which in a normal population is a problem," Dr Holt said. "But when you're down to so few examples of a species, inbreeding is already happening."

He acknowledges that the weakness of this process is the same as with the cloning of sheep for pharmaceutical and farming purposes: because the cloned animals contain identical genes, they are less able to resist disease and environmental change which a more diverse gene pool could withstand. Clones from small populations would be especially prone to genetic disease.

Advances in reproductive technology are already helping to preserve and enlarge threatened species. In general, they have been adapted from the methods first developed either for humans or farm animals, including frozen embryo storage and implantation, in vitro fertilisation (IVF) and artificial insemination. Embryo transfer has been used in eland, baboon, deer and marmoset species, while IVF has been used to breed Indian desert cats and tigers. Artificial insemination has bred giant pandas, rare ferrets and antelopes.

Pregnancy testing for zoo animals is also proceeding rapidly, being applied both to captive elephants and to wild black rhinos in Zimbabwe.

t Frogs are dying in their thousands in British ponds, apparently because of a mixture of previously unrecognised virus and an opportunistic parasite brought in from abroad with ornamental fish.

Andrew Cunningham, of London Zoo, said that in the past five years 100,000 frogs appear to have died from causes which left them bleeding from their mouths and internal organs. A study has identified three potential causes, including two viruses, known in Italy and Australia, and the pond parasite, known in South Africa.