Reviving Endangered or Extinct Species
You might have seen the Jurassic Park movies. In the original feature film, based on the Michael Crichton novel, scientists use DNA preserved for tens of millions of years to clone dinosaurs. They run into trouble, however, when they realize that the cloned creatures were smarter and fiercer than expected. Could we really clone dinosaurs?
In theory? Yes. You would need:
A well-preserved source of DNA from the extinct dinosaur, and
A closely related species, currently living, that could serve as an egg donor and surrogate mother.
In reality? Probably not.
It's extremely unlikely that dinosaur DNA could survive undamaged for such a long time. However, scientists have been working to clone species that became extinct more recently, using DNA from well-preserved tissue samples. A number of projects are underway to clone extinct species, including the wooly mammoth.
In 2009, scientists had their first near-success resurrecting an extinct animal. Using goats as egg donors and surrogates, they made several clones of a wild mountain goat called the bucardo—but the longest-surviving clone died soon after birth. Even if the effort eventually succeeds, the only frozen tissue sample comes from a female, so it will only produce female clones. However, scientists speculate they may beable to remove one X chromossome and add a Y chromosome from a related goat species to make a male.
Cloning endangered species is much easier, mainly because the surviving animals can donate healthy, living cells. In fact, several wild species have been cloned already, including two relatives of cattle called the guar and the banteng, mouflon sheep, deer, bison, and coyotes. However, some experts are skeptical that cloning can help a species recover. One big challenge endangered species face is the loss of genetic diversity, and cloning does nothing to address this problem. When a species has high genetic diversity, there is a better chance that some individuals would have genetic variations that could help them survive an environmental challenge such as an infectious disease. Cloning also does not address the problems that put the species in danger in the first place, such as habitat destruction and hunting. But cloning may be one more tool that conservation scientists can add to their toolbox.