EarthTalk: Can Cloning Save Endangered Species?
Dolly the sheep will forever be remembered as the first cloned mammal, but someday cloning could become our best hope for saving endangered species.
© Craig Marren, Flickr CC
Dear EarthTalk: Why are many environmentalists against artificial cloning of living organisms? Isn’t it a good way to save endangered species? — Louis Bachman, Chico, CA
As many endangered species near extinction, cloning seems like a viable solution to rebuild populations. Using DNA from already deceased animals, cloning can even increase the diversity of a gene pool. There are only seven white rhinos confirmed to be alive today, for example, so adding only a few more through cloning could mean the difference between extinction and survival of the entire species. Why, then, do many environmentalists oppose the artificial cloning of endangered species?
Cloning is often thought of as unnatural and inhumane, but it was, in fact, the first method of reproduction and is still very common in nature today. Asexual reproduction, the oldest form of cloning, is used by aspens, stick insects and Kentucky Bluegrass.
Artificial cloning began in 1928, when Hilde Mangold took a first step: injecting DNA into an egg. By 1952, the first animal was successfully cloned. It was a tadpole. Perhaps the most notable clone in recent history, Dolly the Sheep, was the first mammal to be cloned from an adult cell. The first endangered animal to be cloned was the Gaur in 2001. But along with these successes were many failed and forgotten clones. Even the cloning of common, well-understood animals is difficult. Dolly the Sheep was the result of the 434th cloning attempt and only lived to just over half the average lifespan of a sheep. When the animals are endangered and their reproductive physiology is not well understood, cloning gets even more difficult.
Cloning of endangered species has a wildly low success rate; usually under one percent. Even successful clones are often not able to themselves reproduce and usually live shorter than average lives. Because of the potential for reducing the already low numbers of existing population of endangered species, scientists often use close relatives for eggs and as mothers to gestate the cloned embryos. This often results in the mother rejecting the egg or if the clone is born, reproductive complications.
Due to such inefficiencies, most environmental leaders are not bullish on cloning endangered species. “The potential of cloning is intriguing, but it's been very little tested in terms of its practical application,” says Oliver Ryder, an endangered species expert at the San Diego Zoo. “The way to preserve endangered species is to preserve them in their habitat.”
Despite not being a viable current method for saving endangered animals, cloning could very well be effective in the future. “Frozen zoos” in San Diego and Brazil hold the genetic material of extinct and endangered animals and could be used if need be and if the technology improves. In the meantime, and as Ryder points out, efforts to stop poaching and the destruction of habitats—rather than high-tech fixes like cloning—could go much further to preserve species.
CONTACT: San Diego Zoo Institute for Conservation Research, institute.sandiegozoo.org.