Cloning to save a skunk from extinction

The black-footed skunk has almost disappeared from the face of the Earth. Miraculously saved thanks to the American wildlife service, this cousin of the weasel suffered from a dangerous defect, because all of his representatives were descended from seven skunks. The risk of congenital diseases has just been avoided thanks to a cloning program, the first in the history of conservation.

Posted at 12:00

Mathieu Perreault

Mathieu Perreault
The print

Willa and Elizabeth Ann

A black-footed skunk named Willa, who died in 1988. And another named Elizabeth Ann, born in 2021, 33 years later. A few black-footed skunks are given a name. But for Ben Novak, these two animals are very special. “Elizabeth Ann is a clone of Willa, explains biologist from the American NGO Revive & Restore. We hope, through cloning, to increase the chances of black-footed skunks surviving in the wild. They were reintroduced after they disappeared, thanks to a captive breeding program. But there are only seven individuals among their ancestors. So the risk of inbreeding is very high. Cloning Willa would increase the genetic diversity of the species. ”


Ben Novak holds Elizabeth Ann after her birth

Elizabeth Ann was born in early 2021 but has a problem with her uterus that prevents her from reproducing. “This year we will do a second Willa cloning campaign,” says Novak. If that’s possible, it’s because Willa’s cells were cryopreserved at the San Diego Zoo.

Disappearance and rebirth


A black-footed skunk

The black-footed skunk (also called black-footed skunk in Canada) was considered extinct in the early 1980s, but an isolated population was discovered in 1981 in Wyoming by the US Wildlife Service. “They captured the last 24 individuals of this population in 1987, but 6 of them died soon after from a virus,” says Novak. Wildlife biologists managed to breed 14 of the 18 survivors in captivity. But due to inbreeding, there were actually only seven distinct individuals with the original lineage in captivity. ”

“In the early 1990s, we started reintroducing black-footed skunks to the states they had disappeared from,” continues the biologist. We still maintain the captive breeding program, as most populations are unable to support themselves. Then we add captive-born animals to populations that need them. Willa is one of six black-footed skunks captured in 1987 that died of a virus before they could breed in captivity.

There are no black-footed skunks in countries other than Canada and the United States. The black-footed skunk has disappeared due to urbanization, which has also affected its main prey, the prairie dog. In Canada, the Toronto Zoo participates in the U.S. captive breeding program for the black-footed ferret.

The a bc of cloning


Elizabeth Ann at 4 months

Revive & Restore takes a pet ferret egg and removes all reproductive genetic material. Some Willa cells are inserted into the pet’s ferret egg. The clone is then on its way. In the first round of cloning, five clones were successfully implanted into female domestic ferrets, but only Elizabeth Ann was born.

Why not use a black-footed skunk from the captive breeding program as a surrogate mother? “Because there are only 150 individuals in the program and we still need them to revive wild populations,” says Novak. The enucleated domestic ferret egg contains genetic material, “mitochondrial” DNA. But the amount of DNA in the egg cell’s mitochondria is 100,000 times less than a cell’s total DNA. So it doesn’t contaminate the black-footed skunk genome, says Novak.

The passenger’s cake


The carrier pigeon, drawn by the American naturalist Jean-Jacques Audubon in the 19th centuryAnd century

The other project on which Revive & Restore puts a lot of energy is the “de-extinction” by cloning the carrier pigeon, which gave its name to the tourtière (who disappeared more than a century ago). “We will start with the eggs of a common pigeon, from which we would remove the genetic material and replace it with genes from biological samples of carrier pigeons that have been well preserved,” says Novak. But there are still a few steps in the ethical approval of the project. ”


Hunting the carrier pigeon with the net, according to the British illustrator James Patisson Cockburn (1779-1847)


The Louisiana passenger pigeon hunt in 1875, according to British magazine illustrator Bennett Smith Sports and dramatic news illustrated

The carrier pigeon was considered the most abundant bird species in the world when America was discovered. The last specimen, Martha, became extinct at the Cincinnati Zoo in 1914. Jacques Cartier mentioned the abundance of the carrier pigeon as early as 1534 when he stopped at Île Saint-Jean, now Île-of Prince Edward Island. The hunt rang the death knell for the carrier pigeon in the 19th century.And century.

The ibex and the mammoth


Celia, the last ibex of the Pyrenees, was stuffed.

Cloning is the dream of specialists in extinct species. In 2003, an American gene therapy company, Advanced Cell Technologies, unsuccessfully attempted to clone Celia, the last Pyrenean ibex, captured in 1999 and died in captivity. Celia’s clone, made up of a cell from her cryopreserved skin, died minutes after her birth due to a malformed lung.


Artist’s impression of a mammoth

“The project that captures the public’s imagination the most is the ‘extinction’ of the mammoth,” says Novak. In this case, we will start with elephant eggs. The Californian biologist published a list of a dozen animals that could be subject to “de-extinction” in 2018, in the journal Genoa.

Texas Cougar and Florida Panther


The Florida panther

At least one other species has been saved from inbreeding. This is the Florida panther, rescued from congenital diseases by the arrival of eight female Texas pumas in 1995. “There were only about 30 Florida pumas left,” says Novak. Many suffered from undescended testicles. But obviously, at the time, we weren’t talking about cloning. The Texas puma is a close cousin of the Florida panther, but it is a different species. With our approach, we will preserve the genetic makeup of the black-footed skunk. ”

Florida cow


A cow

Inbreeding is not a disaster for all species. In June, biologists observed that the world’s rarest cetacean, a porpoise called vaquita, has likely had the same number of individuals for several decades. “There are only about 10 vaquitas, a species that has been stuck for tens or hundreds of generations in the Gulf of Northern California,” says Jacqueline Robinson of the University of California, San Francisco, who is the lead author of the study published in Science.


A Californian condor

“We have never reported vaquitas anywhere else on the planet. They are caught in fishermen’s nets and their population has declined over the course of the twentieth centuryAnd century. Their secret is an innate ability to suppress dangerous genetic mutations. Other species that have survived a very small number of individuals may have the same genetic suppression capacity, the Californian biologist suggests. “The California condor only had about ten individuals left in zoos in the late 1980s when it was reintroduced into the wild. There are now 500 in nature. ”

Learn more

  • 1000
    Number of black-footed skunks in the wild in the United States and Canada

    SOURCE: Revive and restore

    Number of distinct populations of black-footed ferrets in the wild in Canada and the United States

    SOURCE: Revive and restore

  • 4
    Number of black-footed skunk populations that no longer require input from the species reintroduction program

    SOURCE: Revive and restore

    30 to 50
    Number of black-footed skunks that are added to wild populations each year through the captive breeding program

    SOURCE: Revive and restore

  • From 500,000 to 1 million
    Estimated number of black-footed skunks in the early 19th centuryAnd century

    SOURCE: Revive and restore

    From 3 to 5 billion
    Estimated number of carrier pigeons in the 18th centuryAnd century

    SOURCE: Revive and restore

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