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Extinction: Bringing animal species back from the brink

Inside the National Black-footed Ferret Conservation Center in Carr, Colorado, Dr. Della Garelle, a veterinarian with the US Fish and Wildlife Service, is leading efforts to bring one of America’s most endangered species back from the brink of extinction.

“Sunday mornings” were invited to see the physical examination of the ferrets’ garrets before the breeding season. “We have to test the products because, well, it’s a breeding program, right? So, we can’t be shy,” she said.

Even a few decades ago, reproduction was not considered possible; The species was believed to be extinct due to habitat loss and disease. But in 1981 the federal government tracked down the only known colony and started a breeding program with just seven ferrets.

That makes Yellow “very related” to all the other ferrets among the descendants of the seven founders, Garrel said. And “very related” can be a tricky thing in the genetic pool. “Yes, absolutely,” she said. “More diversity is better. Then, you’re more prepared for things like change, climate and so on.”

Since 1991, more than 4,000 genetically-identical ferrets have been released into the wild, where they help restore ecosystem balance. But with such a small gene pool, disease can wipe them all out.

That’s where wildlife biologist Robin Bortner comes in. He tries to become a ferret matchmaker. And there’s no bigger catch in this dating pool than Elizabeth Ann, a black-footed ferret created using interspecies somatic cell nuclear transfer cloning. In 2020 she was the first endangered species native to North America to be cloned, using decades-old DNA from a black-footed ferret named Willa.


Elizabeth Ann, a black-footed ferret created by cloning using frozen DNA from a ferret in the 1980s.

CBS News

“Are we basically looking at a carbon copy of a black-footed ferret from the ’80s?” asked Vigliotti.

“Yeah, right,” Bortner replied.

Willer’s cells have been frozen since 1988 and are housed at the San Diego Frozen Zoo, the world’s largest bank of living animal cells. By collecting and storing all this DNA, Frozen Zoo is at the forefront of an emerging field: extinction.

There are over 10,000 specimens, everything from leather to feathers.

“When I was collecting cells from northern white rhinos, there were 50 alive. And then now, there are two left,” says curator Marlis Haque.


A frozen cell from a northern white rhinoceros. Only two species are still alive.

CBS News

“What does this bowl of dew mean to you?” asked Vigliotti.

“This is the future of the species,” said Barbara Durant, the zoo’s director of reproductive science. He said their bank of cells could help save an estimated one million species at risk of extinction, mostly because of us.

And in some cases, a species’ declining population can only be corrected by us. Durant said, “If we disappear, a lot of things will come back. But some populations are so small, or they don’t even exist except here, that they can’t regenerate without us.”

And that next frontier of regeneration may come through cloning, when tissue cells are grown in the lab and then transplanted into a donor egg whose nucleus and DNA have been removed. That egg then develops into an embryo, which is implanted in a surrogate. The result? a cloned ferret dog like Elizabeth Ann; And, most recently, Kurt, an endangered Przewalski’s horse now at the San Diego Zoo Safari Park.

This extinction science raises some questions: “What about the DNA of species that disappeared eons ago?”

At Colossal Biosciences in Dallas, Texas, this new technology company has raised millions of dollars to bring back extinct species like the dodo bird (which died out in the 1600s) and the woolly mammoth (which went extinct three thousand years ago). )

“I hear mammoth and dodo in the same sentence and, you know, that’s science fiction to me,” Vigliotti told Colossal Bioscience founder Ben Lam.

“Yeah, I mean, it does,” Lam said, “until it doesn’t.”

Lam said the first cloned woolly mammoth could be born within five years and eventually reintroduced to its native tundra habitat. A dodo chick may take longer, because we don’t yet know how to clone birds.

“If you’re willing to accept something that’s similar to the dodo in some physical way, but not identical, if you want something exactly like the dodo, we’ll get there a lot sooner,” says paleogeneticist Beth Shapiro.

As Shapiro explains, an animal’s DNA begins to break down in the wild as soon as it dies. Thus, there is no fully preserved dodo or woolly mammoth genetic material left. (And, sorry, this is where we tell you that dinosaur fossils are too old to contain usable DNA.)

But Shapiro can still extract fragments of DNA from bones he finds in the field. “We’ll see places where the permafrost, the frozen dirt, where many of these bones are preserved, is melting,” he said.

Bits of DNA are then extracted from those bones, sequenced in a lab and used as a template to edit the DNA in the cells of the Asian elephant, the mammoth’s closest extant relative, to create an animal closer to the real thing.

Vigliotti asked, “Why is dissolution so exciting that it opens the banks?”

“People are attracted to the impossible, or what they perceive as impossible,” Shapiro replies. “Do I want to see $225 million invested in traditional conservation? Yes. Do I also want to see this money invested in Colossal to build these new tools? Absolutely yes. And that’s where I see the real value of this technology as we move the species from being like mammoths.” Can use these same tools to prevent.”

But science can take longer than expected. It was recently discovered that Elizabeth Anne was unable to reproduce. “We discovered, unfortunately, that her reproductive tract had not developed completely normally,” said Robin Bortner.

But the work goes on, because the easiest way to save a species is to protect it before it’s gone. Do frozen zoos and the world’s animal cell banks help in that battle, Vigliotti asked?

“It’s, in many cases, the only thing that’s going to help,” says Barbara Durrant. “Once the cells are here, they can be here indefinitely. So, it’s important that we get the cells now and then we can develop strategies for the future.”

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Story Production Sari Aviv. Editor: George Pozderek.

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Jonathan Vigliotti

Jonathan Vigliotti

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