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The last known Tasmanian tiger — which was not a feline at all, but a dog-like marsupial with bold stripes across its back and abdominal pouches — died in captivity in 1936. Genetic engineering could resurrect this species, also known as the thylacine. But should it?
Colossal Biosciences, a Texas-based biotechnology company, wants to bring back the thylacine using a gene editing technology called CRISPR, Bill Chappell reported for NPR. DNA from preserved thylacine specimens would be inserted into the genome of one of the extinct animal’s closest living relatives: members of the dasyurid family, which are carnivorous marsupials. This altered, thylacine-like cell could be placed within an embryo and implanted into a surrogate.
According to the company, the result would be a genetic hybrid that behaves like its progenitor and fits the same ecological niche. "The thylacine was the only apex predator in the Tasmanian ecosystem, so no other animal was able to fill its place once it was lost," Andrew Pask, a scientist involved in the project, told NPR. In theory, introducing this hybrid into Tasmanian forests could restore balance to the ecosystem by controlling an abundance of herbivores, such as wallabies and kangaroos.
There is a precedent for reintroducing long-absent keystone species. In 1926, after the last gray wolves of Yellowstone National Park were killed, a new ecological order emerged: Large herds of elk took up residence in the park, overgrazing native trees and vegetation. This fractured ecosystem persisted for 70 years, until wolves were reintroduced in 1995. Their reemergence had a transformative impact, triggering what’s known as a “trophic cascade” — a series of changes that ripple down the food chain, benefiting the entire ecosystem.
The wolves kept the elk on the run. As they dispersed, overgrazed mountainsides and eroded riverbanks bloomed once more with aspens, willows and cottonwood trees. With them, beavers — consummate ecosystem engineers — returned as well, building dams that create healthier habitat for birds, amphibians and other species. Even the rivers became more fixed in place, stabilized by regenerating vegetation.
The thylacine may have played a similar role in Tasmania for thousands of years, and Pask believes that reintroducing an apex predator — albeit in hybrid form — could result in "removing the sick and weak animals from the population and improving the genetic health of all the populations it impacts."
Still, “de-extinction” via emerging genetic technologies raises concerns. Critics fear that the allure of bringing species back from the dead could rob critical attention and funding from efforts to protect vulnerable wildlife and ecosystems. Money spent resurrecting animals could be put to better use preventing extinctions in the first place, according to a 2017 study.
Others point to the need to consult Indigenous peoples in Tasmania about the effects of bringing a proxy thylacine into their lands. Finally, there’s the welfare of individual animals that would inevitably be harmed in experiments. Carol Freeman, a researcher at the University of Tasmania, told Scientific American it would be many years before new thylacines “could have anything like the life they may have had — and deserve — in the wild.”
Cover image: Tasmanian rainforest and stream (© Keiichi Hiki)