Scientists believe there are only a few hundred black-footed ferrets still living in the Western United States.
The carnivores once thrived on the plains between Canada and Mexico, eating prairie dogs and burrowing into their tunnels. But humans plowed up their habitat, and diseases like sylvatic plague reduced their numbers even further.
Climate change has made the situation worse, according to Tara Harris, conservation director at the Phoenix Zoo.
“When the prairie dogs don’t do well, the ferrets don’t do well,” Harris said, “and here we’ve had a megadrought across the West that is really impacting those prairie dog populations and therefore the black-footed ferrets.”
Harris runs a captive breeding program at the zoo. She said decades ago, it would have been nearly impossible to see one of the animals up close.
“They were once thought to be completely extinct. Not even in human care — like completely gone from the Earth,” Harris said.
Then one day in the 1980s, a ranch dog in Wyoming came home with a ferret in its mouth.
“It was a huge deal,” Harris said. “There were wanted posters all over Meeteetse, Wyoming, that there were records of in the Meeteetse museum, showing the black-footed ferret and offering a reward to find where in the world these animals came from.”
In the years that followed, the population has rebounded slightly, and scientists have been able to clone ferrets from genetic specimens that were collected in Wyoming in the 1980s. Last fall, the U.S. Fish and Wildlife Service announced that four new litters of ferrets were born from cloned parents at the Smithsonian’s National Zoo.
“I went back to Meeteetse, Wyoming, several years ago and released some of the captive-bred ferrets back onto that landscape,” said Ryan Phelan, co-founder of Revive & Restore, an organization involved with the cloning project. “It was thrilling.”
These new kits that were born last fall had parents that were clones. Can you explain what scientists have been able to achieve here?
“ Cloning has often gotten sort of a bad reputation, as if there is something wrong with the clones, and in fact, questions have come up in the science literature: Are clones actually even reproductively viable?
“Well, Revive & Restore, going back in time, took some of the cell lines that were there, presciently kept back in 1980 from some of the 18 ferrets that were brought into captivity back in 1981. That one group, only seven of those, went on to breed.
“So that means that all the related individuals before Revive & Restore started helping on this were all basically cousins or siblings, and we know what inbreeding can do. It can create real problems for the species.
“So we’ve been taking those, that cell line from one of those individuals, Willa, that had three times more genetic diversity, and now we’re passing it on to even the next generation.”
This is stored DNA that made this possible, as you say, from an animal named Willa that died in 1988. What kind of foresight did it take to save the DNA before anyone knew if cloning was even possible?
“ I would say a very prescient individual did this, and his name was Kurt Benirschke at the San Diego Zoo, who came up with this idea that we should be banking endangered species for scientific research for a future that none of us would even know how it would unfold.
“So this was before cloning was really happening. And that is why one of the things that we are working on is trying to cryopreserve endangered species now before we even lose more biodiversity, because we don’t know what technology’s going to be there 40 years from now.”
Can these new babies ever return to the wild? Is that the plan for them?
“ The plan would be not for these very valuable individuals, but for their offspring. But for right now, they’re extremely valuable, and they’re still part of a research program with U.S. Fish and Wildlife Service and the Smithsonian and San Diego Zoo Wildlife Alliance.”
We’ve been talking about cloning animals ever since Dolly the sheep was born in 1996, and all along, there has been a debate about unintended consequences of cloning.
For instance, if we clone an animal to save it from extinction, will that make us less likely to stop doing the things that put them in danger in the first place?
“ That is often referred to as the moral hazard of doing something that will have this bad unintended consequence years to come.
“And I really don’t believe anyone in their right mind could imagine it’s easier to cryopreserve than it is to preserve what we have. It will never be easy to bring species back from, literally, extinction. What we wanted to be able to do is preserve what we have and to keep as much genetic diversity as we can.
What kind of world would we bring some of these animals back to? For the black-footed ferret, for instance, much of their habitat was wiped out. Is it okay to bring an animal back if they can’t thrive on their own?
“ I believe there is habitat and there is increasingly habitat, as long as we can manage these populations and get them back into the wild, it bodes well for the future for many, many species, but we have to help them along the way.”
It’s not the only challenge for many of these species. The black-footed ferret is really suffering because of disease as well. Are you able to genetically modify the DNA of an animal like the black-footed ferret so that it’s not as susceptible to plague?
“ Yes. The answer is, plague is an ever-present problem on the American prairie. It’s carried by a native flea, but it is an invasive pathogen. And they are 100% susceptible.
“So we are running two different research projects where we’re looking at different regions of the genome that may provide greater resilience to the black-footed ferret. And another approach is to create the equivalent of a genetic vaccine that would be passed on through the germline. So both of them are early-stage research projects, but we’re very committed to seeing where we can go with it.”
This interview was edited for clarity.
This article was originally published on WBUR.org.
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