The plan to bring “a dingo with a pocket” back from extinction: NPR

A now extinct Tasmanian tiger (thylacine) was spotted at Hobart Zoo in Tasmania in 1933.

Universal History Archive/Universal Pictures Group via Getty Images

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Universal History Archive/Universal Pictures Group via Getty Images

A now extinct Tasmanian tiger (thylacine) was spotted at Hobart Zoo in Tasmania in 1933.

Universal History Archive/Universal Pictures Group via Getty Images

If you haven’t heard of the Tasmanian tiger, it’s not because it’s not worth discussing: it’s not a feline but a dog-like marsupial, a predator that humans hunted to extinction. The last known specimen died in a zoo in 1936.

Now, “de-extinction” company Colossal Biosciences wants to genetically resurrect the Tasmanian tiger, also known as the thylacine (Cynocephalus thylacinus) or the Tasmanian wolf.

“Whatever you call it, this mythically beautiful carnivorous marsupial was a true masterpiece of biological progress,” the company said of the project. “Yet the story of its extinction is a tragedy of human interference and aggression.”

The thylacine had trademark stripes and, rare in the animal world, abdominal pouches in both females and males. Australian researchers have called it “a dingo with a pocket” or “a dog with a pocket” – but its DNA also has a lot in common with the kangaroo.

Colossal, which has previously aired plans to resurrect the woolly mammoth, intends to give the thylacine “a second chance at life”.

Here is an overview of some of the big questions raised by the project:

Is the thylacine able to live again?

Humans have been blamed for the animal’s extinction, particularly after a bounty scheme was established in Tasmania to protect sheep and other animals. But in 2017, Andrew Pask, professor of biosciences, conducted research that revealed that the thylacine also suffered from a lack of genetic diversity.

“Today’s population would be very susceptible to disease and would not be very healthy” if it still existed, Pask said in 2017.

Pask is now part of Colossal’s new project to bring back the thylacine. When asked if his views on his viability had changed, he said via email that the plan would incorporate various DNA sources.

“We have now sequenced many thylacine specimens and hope to continue to do so in this new partnership with Colossal,” Pask said in an email to NPR. “Even species with low genetic diversity can return to a healthy population if managed properly.”

The goal, he said, is to bring back “a good number” of animals to help ensure a healthy diversity in the new population. And while the thylacine was thought to be struggling in the wild, any new populations would be closely monitored, he noted.

How would animals be created?

For one thing, it’s not cloning.

“Cloning is a very specific scientific process. This process requires a living cell,” evolutionary biologist Beth Shapiro of the University of California, Santa Cruz told NPR when mammoth resurrection discussions gained traction in 2015. .

Instead, Colossal plans to essentially create a hybrid animal, with many characteristics of a Tasmanian tiger. Its scientists will use CRISPR gene-editing technology to splice pieces of recovered thylacine DNA into the genome of a Dasyurid – a family of carnivorous marsupials such as the numbat and the Tasmanian devil that are the closest relatives of the extinct animal.

The modified core would then be inserted into a Dasyurid egg – and when it developed into an embryo, it would be implanted into a surrogate.

How would the thylacine affect the habitat of Tasmania?

“The thylacine was the only apex predator in Tasmania’s ecosystem, so no other animals could have taken their place once they were lost,” Pask said. “We saw the impacts of this on the Tasmanian devil population which was nearly wiped out by a facial tumour.”

The return of an apex predator “would remove sick and weak animals from the population to control the spread of communicable diseases and also improve the genetic health of any populations it affects,” he added.

The thylacine has played this role for thousands of years, Pask said, and its return now could restore balance to Tasmania’s entire ecosystem.

When could the first embryo be created?

It could happen in the next few years. By comparison, Colossal hopes to deliver its first woolly mammoth calves within the next five or six years, using elephant surrogates.

A timeline for the thylacine has not been revealed. But Ben Lamm, founder and CEO of Colossal, noted via email that the Tasmanian tiger’s expected gestation period of up to 42 days would be much shorter than that of an elephant-mammoth hybrid.

“A lot of our mammoth timeline is based on the calves’ nearly two-year gestation,” Lamm said. “I think it’s safe to assume that the thylacine proxy might be one of the first animals to be brought back.”

Would the Tasmanian tiger ever be brought to mainland Australia?

“Whether we’re returning the thylacine to the mainland is a really interesting question,” Pask said, noting that the animal is believed to have been found in Australia as far back as 2,000 or 3,000 years ago.

“If thylacine were effective in eradicating some of our invasive pest species such as rabbits, cats and foxes, their reintroduction to the continent could have major conservation benefits for other ecosystems,” he said. declared.

But, he added, such an idea would need to be tested and studied in captive areas before wider release could be considered.

Sure, they could – but should they?

Boosting genetic diversity and helping ecosystems are the same reasons Beth Shapiro cited when speaking out in favor of using gene editing. But while Colossal focuses on trying to bring back extinct animals, Shapiro suggests the focus should be on the wildlife we ​​currently have struggling, like the black-footed ferret (which was once believed to be extinct).

“Maybe we could use this technology to give these populations a little genetic booster and maybe a chance to fight the diseases that are killing them,” she told NPR in 2017. to a crisis – a conservation, biodiversity crisis. This technology could be a very powerful new weapon in our arsenal against what is happening today. I don’t think we should discount it out of fear.”