A Cloned Ferret Named Elizabeth Ann Could Help Save Her Species
Reengineering Life is a column from Future Human about the ways humans are using biology to reprogram our bodies and the world around us.
A black-footed ferret named Willa died more than 30 years ago, but now her DNA lives on through her clone, Elizabeth Ann. Black-footed ferrets are one of the most endangered species in the United States, and Elizabeth Ann may be key to saving her species from extinction.
Created from a few of Willa’s frozen cells, Elizabeth Ann was born on December 10, 2020. She represents the first successful attempt by scientists to clone an endangered North American species, according to a February 18 announcement by the U.S. Fish and Wildlife Service. Elizabeth Ann’s birth is a step forward for using cloning for conservation purposes, but the technique may not be useful for every endangered species.
Black-footed ferrets were once found across huge swaths of North America’s Great Plains, from Southern Canada to Northern Mexico. But today, only about 350 or so of the animals exist in Wyoming, South Dakota, Montana, and Arizona because of a substantial decline in prairie dogs, their main food source. Over the past century, populations of prairie dogs have plummeted due to habitat loss, hunting, and disease.
Until 1981, the prairie dog hunters — as the ferrets are also called — were believed to be extinct. Then a sheep dog named Shep discovered some on a ranch in northwestern Wyoming. State officials caught the ferrets and began a breeding program to recover the species.
Today, all black-footed ferrets are descended from just seven individuals. Such a small gene pool makes them more prone to genetic diseases, abnormalities, and smaller litter sizes. Cloning long-dead animals that are genetically different enough could help boost genetic diversity and disease resilience by introducing “new” DNA into the black-footed ferret population. Willa has no living descendants, so her DNA isn’t part of the current gene pool.
“There will be additional clones of Willa,” Bridget Baumgartner, PhD, a program manager at Revive & Restore, the California-based conservation nonprofit that helped with the cloning effort, tells Future Human. The organization is interested in using biotechnology to save endangered and extinct species, including bringing back the woolly mammoth, which died out about 3,700 years ago.
Baumgartner says the clones themselves won’t be released to mix with the wild ferret population. Instead, Elizabeth Ann and others will be kept as research animals at the U.S. Fish & Wildlife Service’s National Black-Footed Ferret Conservation Center in Colorado. If the clones are healthy, they’ll eventually be allowed to breed with black-footed ferrets in captivity. The resulting offspring could then be released, carrying those genes into the wild population.
Elizabeth Ann was made possible by the forethought of the Wyoming Game and Fish Department, which preserved a sample of Willa’s cells in 1988 and shipped them off to the San Diego Zoo’s Frozen Zoo, a storage bank that houses cryopreserved genetic material from hundreds of animal species and subspecies. When geneticist Kurt Benirschke, PhD, founded the zoo in 1975, cloning technology was in its infancy. Still, Benirschke thought collecting cells from animals might someday be useful.
When cloning was first introduced, the idea of using it for conservation met some resistance. “People rightly pointed out that if you made a bunch of clones, you’d have a monoculture,” Baumgartner says. “The population would all be identical. You wouldn’t have the genetic diversity that you need.”
She says it’s the combination of the Frozen Zoo and the cloning technique that makes it a promising option for conservation. Not every endangered species has a tissue sample banked away somewhere.
To make Elizabeth Ann, government biologists turned to Revive & Restore, which analyzed Willa’s DNA. They then partnered with Texas-based ViaGen, a biotech company that clones livestock, horses, and pets. ViaGen charges around $50,000 to clone dogs and $25,000 to clone cats, or $1,600 to preserve their genes (plus a $150 annual storage fee). Singer Barbra Streisand used ViaGen to clone two of her dogs.
ViaGen uses a cloning technique called somatic cell nuclear transfer, which requires taking a mature cell, such as a skin cell, from an animal that scientists wish to copy. That’s where Willa’s cells came in. They transferred the nucleus of one of Willa’s cells — which contain her DNA — into a ferret egg that had its own DNA-containing nucleus removed. The egg was then allowed to develop into an embryo in a test tube. Scientists then transferred the embryo to the womb of a domestic ferret — the kind kept as pets — to avoid any risks that the cloning procedure could have on an endangered animal.
The need for a closely related animal species that could serve as a surrogate is another barrier to using cloning for conversation.
Cloning is used in agriculture to provide farmers with more copies of the best animals in the herd, which are then used as breeding animals. The process is woefully inefficient though, and the majority of cloned animal embryos never develop into healthy individuals. It took 277 attempts at cloning embryos to produce Dolly the sheep, the first cloned mammal, who was born in 1996. In 2003, scientists at the San Diego Zoo cloned two Javan banteng calves, an endangered type of cattle native to Southeast Asia. One of the calves had to be euthanized because it was abnormally large — a common side effect of cloned cattle.
Elizabeth Ann seems healthy now, but scientists will need to observe her for the remainder of her life, watching out for any abnormalities in her appearance, behavior, reproductive ability, or overall health.
The cost, inefficiency, and potential side effects of cloning mean it might not be the most practical way to protect endangered species, but it might be able to help some.
Noreen Walsh, director of the U.S. Fish and Wildlife Service’s Mountain-Prairie Region, where the National Black-footed Ferret Conservation Center is located, says traditional conservation efforts for the species will still be needed. Those include relocating prairie dogs to expand the ferret habitat, as well as mitigating sylvatic plague, a bacterial disease that has devastated prairie dog populations.
Eventually, cloning could help the black-footed ferret population rebound and perhaps even be used to save more species from the brink of extinction.