Scientists Clone Disease-Threatened Ferret Species to Introduce Genetic Diversity

Endangered black-footed ferret in an outdoor preconditioning pen at the National Black-footed Ferret Conservation Center in Colorado. Photo by Stewart Brand for the U.S. Fish and Wildlife Service.

For the conservation of endangered black-footed ferrets, scientists are going beyond protected areas and habitat restoration. Biotech companies and wildlife conservation organizations are working together to implement reproductive cloning to introduce genetic diversity into the disease-threatened ferret species. If successful, this method will create a more resilient population and show that reproductive cloning has the potential to save more of our vulnerable native species.

In 1988, a Wyoming rancher was surprised when his dog dropped the carcass of a black-footed ferret on the front porch because the ferret species was previously thought to be extinct. The native ferrets feed exclusively on prairie dogs as prey and used to hunt them in the grasslands of the American West, but when ranchers and farmers started to poison and exterminate the prairie dogs, numbers of the ferret species dwindled. The population of black-footed ferrets living on this Wyoming ranch were gathered for a captive breeding program because of the endangered status of the species, and now all living black-footed ferrets are genetic descendants of just seven closely related ferrets. 

When you think of the conservation of endangered native species, has artificial cloning ever crossed your mind? It has been on the minds of those at Wyoming Game & Fish and the San Diego Zoo since the 1980s. Due to their foresight, there is a plan to possibly save the only ferret native to North America through artificial (or reproductive) cloning. 

Meanwhile, Tom Thorne of Wyoming Game and Fish was observing and collecting black-footed ferrets in the state. He later sent tissue samples from frozen ferrets to Oliver Ryder, the director of conservation genetics at San Diego Zoo Global, to be kept at the “Frozen Zoo,” thinking it might be useful at some point. In 1988, tissue samples from a black-footed ferret named Willa arrived at the zoo. The Frozen Zoo is a resource for conservation, assisted reproduction, evolutionary biology, and wildlife medicine and now boasts a collection of cryogenically frozen tissues representing 1,100 species. In addition to conservation efforts, whole-genome sequencing projects for African elephants, two-toed sloths, and gorillas have all benefited from the Frozen Zoo. 

Hans Spemann, a German embryologist, set the stage for applying the use of artificial cloning of animals when he discovered embryonic induction, the process that directs the development of groups of cells into particular tissues and organs, in 1935. Many developments have been made since, including the successful birth and life of Dolly the Sheep, the first mammal to have been successfully cloned from an adult somatic cell.

Elizabeth Ann, the first cloned black-footed ferret and first-ever cloned U.S. endangered species, at 54-days old. Photo By USFWS Mountain Prairie via Wikimedia Commons.

In December 2020, Elizabeth Ann (the black-footed ferret pictured above) became the first-ever cloned endangered native species to be born in the United States. She was cloned using Willa’s frozen cells collected and sent to San Diego’s Frozen Zoo more than 30 years ago. Researchers inserted the nucleus from Willa’s cells into an egg from which the nucleus has been removed. When the egg began to divide normally, it was transferred into the uterus of a domestic ferret, who birthed Elizabeth Ann. This is a process used in reproductive cloning, called somatic cell nuclear transfer.

Biotechnology nonprofit Revive & Restore and Viagen Pets, a company that clones pets, worked together on this project, culminating in the birth of Elizabeth Ann in late 2020. She lives in a Fish and Wildlife Service black-footed ferret breeding facility in Fort Collins, CO, and is closely monitored. Blood tests have confirmed her to be 100% black-footed ferret. She is the only black-footed ferret who isn’t a genetic descendant of the 7 ferrets found on the ranch in the 80s. 

Due to its small gene pool, the species is so threatened by disease that scientists inoculated 120 black-footed ferrets with experimental COVID-19 vaccines this summer. Black-footed ferrets currently have such similar genetics that one disease could wipe out the entire population. If additional cloning is successful and it is safe to introduce Elizabeth Ann into the genetic pool, she will bring much needed genetic diversity to a deeply inbred population. This exciting research has implications for future reproductive cloning and offers a last resort path for the conservation of other important endangered species.

This article was edited by Rebecca Stevens and Ashley Schefler.