Scientists Clone Two Black-Footed Ferrets From Frozen Tissues in Conservation Effort

Researchers have cloned two black-footed ferrets from preserved tissue samples in an effort to conserve the creatures, the United States Fish and Wildlife Service announced last week. The animals are the second and third ferret clones in history—the first was born in December 2020.

Black-footed ferrets are endangered, and scientists hope the new clones can increase the genetic diversity of the species. The limited genetic diversity of the current population makes the animals more susceptible to diseases and genetic abnormalities, decreases their fertility rates and makes it harder for them to adapt in the wild, hampering their recovery.

“Genetic diversity is critical for resilience to environmental change,” Megan Owen, vice president of conservation science at the San Diego Zoo Wildlife Alliance, which contributed to the cloning effort, tells the Washington Post’s Dino Grandoni. “It’s basically the raw material of adaptive evolution.”

The two new clones, named Noreen and Antonia, are healthy, and they have been reaching their expected developmental and behavioral milestones. Noreen was born at the National Black-footed Ferret Conservation Center in Colorado, while Antonia was born at the Smithsonian’s National Zoo & Conservation Biology Institute.

One of three ferret species, black-footed ferrets are native to North America and have lived on the continent for at least 100,000 years. Long and skinny, with light fur everywhere except for their black face masks, feet and tail tips, the mammals are nocturnal and mostly live underground.

An estimated 500,000 to 1 million black-footed ferrets lived during the late 1800s, and they historically roamed 12 states, northern Mexico and southern Canada. But in the 20th century, their numbers declined dramatically as farmers eradicated prairie dogs, which make up most of a black-footed ferret’s diet. Diseases including canine distemper and a form of plague wiped out ferrets and prairie dogs alike.

Researchers thought the last black-footed ferret might have died in 1979. But in 1981, a ranch dog brought a dead ferret home, leading to the discovery of a small population of the species near the town of Meeteetse, Wyoming.

In the following years, officials captured 24 ferrets and started a breeding program. Since then, they have grown the species’ population and introduced ferrets back into the wild at 34 sites across eight states, Canada and Mexico. The Fish and Wildlife Service estimates several hundred black-footed ferrets currently live in the wild.

While this effort preserved the species, it also set up a problem: All living black-footed ferrets are descended from only seven of the wild-caught animals, severely limiting their genetic diversity.

But the three cloned ferrets come from frozen tissue samples collected in 1988 from a ferret called Willa, which had been stored at the San Diego Zoo Wildlife Alliance’s Frozen Zoo.

Willa never reproduced, so her genes are not part of the captive black-footed ferret gene pool. Her samples contain three times as many unique genetic variations than the average in the current population, according to the Fish and Wildlife Service.

To clone the ferrets, researchers injected a cell from Willa into a domesticated ferret egg, per the Washington Post.

The Fish and Wildlife Service announced the birth of the first clone, Elizabeth Ann, in 2021. She lives at the National Black-footed Ferret Conservation Center and is healthy, but she has been unable to give birth.

Elizabeth Ann has a condition called hydrometra, where fluid fills the uterus. One of her uterine horns, where the fallopian tubes open into the uterus, did not fully develop. Since this condition is not unusual in black-footed ferrets, researchers don’t think it’s related to the cloning, per the Fish and Wildlife Service.

Once the two newborn ferrets reach maturity later this year, researchers will try to get them to have babies to pass on their genetic diversity.

Some of the ferret cloning project’s collaborators are also working to freeze tissue samples from every endangered species in the U.S., in case they can help combat extinction of these species in the future, reports Scientific American’s Cari Shane.

The cloning research doesn’t replace the need for recovering ferrets in the wild, and the Fish and Wildlife Service is continuing to work on reintroducing animals, monitoring ones currently living in the wild and preserving their habitats.

“Some people think if you have [species] in a freezer, you don’t need them in the wild,” Seth Willey, a Fish and Wildlife Service deputy assistant regional director, tells Scientific American. “That’s just not true… We can’t lose what we have in the wild. But if we do, it’s good to have an insurance policy.”

Will Sullivan | | READ MORE

Will Sullivan is a science writer based in Washington, D.C. His work has appeared in Inside Science and NOVA Next.