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Mixing species may be only way to save world's rarest
Mixing species may be only way to save world's rarest
BY SUSANNE QUICK
Milwaukee Journal Sentinel
Posted on Fri, Apr. 08, 2005
MILWAUKEE - (KRT) - It sounds like the plot of a cheesy sci-fi film: A futuristic army of clones saves the giant panda from extinction.
But it isn't.
Researchers from San Diego to New Orleans are examining and testing the powers of cloning technology. They are hoping that if all else fails, genetic duplicates can save animals such as the Sumatran rhino and Siberian tiger from extinction.
Already scientists have cloned the African wildcat, Asian banteng and a rare cow-like species called a gaur.
The clone of the latter species didn't last long - just a few hours - but cloning conservationists say they are making significant strides, despite charges that they are wasting their time, misusing otherwise needed conservation funds and creating creatures that not only don't belong on the planet but actually may be too unique to "re-create."
Notwithstanding these concerns, zookeepers and researchers across the country literally are banking - in "frozen zoos" - as much animal tissue as they can.
The hope is that someday, if a species disappears, zoos will have the material to resurrect it, said Bruce Beehler, deputy director of the Milwaukee County Zoo. Although he has yet to bank any animal tissue, he believes the technology holds promise - as do other reproductive assistance techniques for endangered animals, such as in vitro fertilization and artificial insemination.
"Cloning is just one tool," said Betsy Dresser, a senior vice president of the Audubon Nature Center in New Orleans and director of the Audubon Center for Research of Endangered Species. And so far, that tool has been used successfully by her team to create African wildcats and an antelope-like creature called a bongo.
Dresser, who has been active in conservation for 27 years, said she's a "strong believer there's not just one answer" to the question of how to rescue animals from extinction.
But critics such as Bruce Whitelaw, a researcher at the world-renowned Roslin Institute in Scotland, said cloning for conservation is ridiculous. He believes conservationists should be addressing issues such as human overpopulation, habitat depletion and poaching. If these aren't addressed, there will be no place for these animals in the future _- even if their DNA has been stored.
Dresser remains adamant in the face of such criticism.
"Wouldn't it be awful if we saved land for these animals, but, oops, we discover we have no animals," to repopulate it, she asked.
She said a lot of the criticism she hears stems from concerns about money - that she's diverting money from other conservation projects. But the money she receives, she said, is from people who want to fund this particular technology - not other efforts.
Others say such arguments miss the point that money and various scenarios of the future are the least of the concerns. More important is that the basic technology that allows for cloning actually could undermine the conservation effort.
First, a clone is a genetic duplicate of another animal. If you're in the business of trying to bolster the genetic legacy of a dwindling species, throwing in a bunch of genetic copies is not going to help. What you're essentially doing then is "narrowing the genetic variations," within an already genetically depleted or inbred population, said Arthur Caplan, a bioethicist at the University of Pennsylvania.
Dresser deflects that criticism by pointing out that if zoos start saving DNA now, they'll have a number of animals to clone from in the future. And with a careful breeding program, severe inbreeding could be avoided.
Then there's the issue that despite the fact these animals are called "clones," their genetic make up is a bit muddier than the name implies.
The wildcats, bongos, bantengs and gaurs that have been cloned are what scientists refer to as "chimeras" - creatures whose DNA is a genetic blend of different species.
To clone an animal, scientists start with an adult cell, such as a skin cell, and extract its nuclear DNA. Meanwhile, they extract the nucleus from a donor egg - generally from the same species - and place the egg next to the skin DNA. They zap the two, or dose them with a chemical, and if everything goes well, the egg grows into a genetic copy of the original animal.
But cloning is an inefficient process. It requires a large number of eggs, as well as live animals to carry the clones. And endangered species, by definition, are few in number. So researchers have to look to other species for these raw materials.
Take the example of the African wildcat. Dresser and her colleagues used domestic cats to supply eggs and wombs. The experiment seemed to work - healthy animals were produced. But are they wildcats? Certainly, the majority of DNA in their cells are from their wildcat donor. But there is also a little input from the goo inside the domestic cat egg in the form of mitochondrial DNA.
The final product, then, is an African wildcat with a whiff of domesticity.
Dresser doesn't think the extra DNA has much impact. She said the animals look and behave like wildcats, not domestic cats.
But it's hard to say for sure - especially when the wildcats' behavior is evaluated in a captive environment.
There's also the issue of the in utero experience: What influence do the chemicals and hormones that float around the mother's body have on the developing embryo - particularly if the mother is of a different species?
And the situation gets even trickier when researchers contemplate cloning animals that have no close living relatives, said Oliver Ryder, a researcher at the San Diego Zoo who was involved in cloning two endangered bantengs.
Take, for instance, the giant panda. Chinese scientists have made little headway in their attempts to clone this endangered species because even though adult pandas are about the same size as a well-fed Eastern black bear, their cubs are radically different.
The panda gives birth to a cub about the size of a stick of a butter - a baby closer to the size of a rabbit kit than a black bear cub.
Researchers first tried to clone pandas by using rabbit eggs and wombs. After several unsuccessful attempts, they tried using the domestic cat as a surrogate. That didn't work either.
The Chinese have halted the project, but their difficulties have not been lost on others.
George Amato, director of the Science Resource C enter at the Wildlife Conservation Society in New York, isn't sure what the future holds for cloning in conservation.
"When you consider the Sumatran rhino, of which there are only 15 breeding pairs in captivity and maybe a few hundred in the wild," you have to be open to these emerging technologies, he said.
The challenge, he said, is not for conservationists to gripe about the best way to save these animals, but to get the public to care about endangered species as much as they do the latest "celebrity criminal trial," he said.
Because until they get the public involved, nothing is going to save these creatures.
© 2005, Milwaukee Journal Sentinel.
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