Before I could join the race to clone the thylacine and bring it back from extinction, Australian scientists attempted to take on the task-- ultimately abandoning it. Scientists working with the Australian Museum made several efforts to extract and replicate viable DNA from a preserved thylacine joey, but found that it was too damaged to be viably cloned. Even if scientists did clone the animal, there's little reason to believe that the program would successfully revive the species.
Cloning to save an endangered animal has severe limitations. In many cases, an animal's lack of genetic diversity contributes significantly to its status as an endangered species. Cheetahs, for example, are all very closely related because few survived the ice age. In critically endangered species like the California condor, the Javan rhinoceros, and the red wolf, conservationists have to work with extreme caution to breed animals that are genetically varied, despite severely depleted populations. For obvious reasons, cloning would do nothing to increase genetic variability among these animals.
Cloning also fails to address the underlying problems that cause an animal to become endangered or extinct. There is little use in creating more Florida panthers, for example, if the Florida panther still has no place to live. In many cases, these projects are also impractical. What's the use in cloning an endangered gazelle in captivity instead of simply breeding the gazelle to a healthy mate? Cloning could also give the impression that extinction isn't really forever, giving the public a dangerous perspective that it's okay to take endangered species lightly. The implications are severe.
Nevertheless, there is some hope that cloning might help endangered species. In 2007, Betsy Dresser of the Audubon Nature Institute told National Geographic that cloning can be one of many tools to help save endangered animals. She describes San Diego's "frozen zoo" of genetic material, which she hopes can be used in the future to replenish stock of critically endangered animals. An animal frozen today could help to improve genetic variability in fifty years.
In many cases, endangered animals can be carried by surrogate mothers of other, more populous species-- thus helping to address one of the pitfalls of cloning. The San Diego zoo has already successfully cloned the banteng, an endangered wild bovine. The young were born healthily to domestic cattle and are thriving in captivity. Similarly, domestic dogs could carry the cloned embryos of Mexican gray wolves, while domestic cats could carry African sand cats, and domestic rabbits could give birth to endangered volcano rabbits. The use of these clones may not revive the species, but it does no harm to wild animals and may help to preserve genetic variations among critically endangered animals.
Ultimately, there's little reason to believe that cloning can revive an extinct species, or that it offers a comprehensive solution for endangered animals. However, as part of a larger, more dedicated effort to preserve endangered animals, cloning may be one small but useful tool. In the future, we might expect to see more extensive use of cloning-- especially through artificial insemination of domestic animals-- in preventing the loss of some of our world's most critically endangered species.