Nearly 100 years after its extinction, the Tasmanian tiger may be alive again. Scientists want to revive the striped carnivorous marsupial, officially known as thylacine, which used to roam the Australian bush.
The ambitious project will use advances in genetics, ancient DNA retrieval and assisted reproduction to bring the animal back.
“We would strongly argue that we should first and foremost protect our biodiversity from further extinction, but unfortunately we see no slowdown in species loss,” said Andrew Pask, a professor at the University of Melbourne and head of the Thylacine Integrated Genetic Restoration Research Lab, leading the initiative.
“This technology offers an opportunity to correct this and can be applied in exceptional circumstances where keystone species have been lost,” he added.
The project is a collaboration with Colossal Biosciences, founded by tech entrepreneur Ben Lamm and geneticist George Church of Harvard Medical School, who are working on an equally ambitious, if not more daring, $15 million project to return the woolly mammoth in a modified form. to bring.
About the size of a coyote, the thylacine disappeared pretty much everywhere except on the Australian island of Tasmania about 2,000 years ago. As the only apex marsupial predator to live in modern times, it played a key role in its ecosystem, but that also made it unpopular with humans.
European settlers on the island in the 1800s blamed thylacines for the loss of livestock (although in most cases feral dogs and mismanagement of human habitat were actually the culprits), and they hunted the shy, semi-nocturnal Tasmanian tigers to the point of extinction.
The last captive thylacine, named Benjamin, died in 1936 from exposure at the Beaumaris Zoo in Hobart, Tasmania. This monumental loss occurred shortly after thylacines were granted protected status, but it was too late to save the species.
The project involves several complicated steps incorporating advanced science and technology, such as gene editing and building artificial wombs.
First, the team will construct a detailed genome of the extinct animal and compare it with that of its closest living relative — a mouse-sized carnivorous marsupial called the fat-tailed dunnart — to identify the differences.
“We then take living cells from our dunnart and edit their DNA in every place where it differs from the thylacine. We are essentially manipulating our dunnart cell to become a Tasmanian tiger cell,” Pask explained.
Once the team successfully programmed a cell, Pask said stem cell and reproductive techniques using dunnarts as surrogates “would turn that cell back into a living animal.”
“Our ultimate goal with this technology is to restore these species to the wild, where they played an absolutely vital role in the ecosystem. So our ultimate hope is that one day you’ll see them in the Tasmanian bushland again,” he said.
The fat-tailed dunnart is much smaller than an adult Tasmanian tiger, but Pask said all marsupials give birth to tiny young, sometimes as small as a grain of rice. This means that even a mouse-sized marsupial could serve as a surrogate mother for a much larger adult animal like the thylacine, at least in the early stages.
Reintroducing the thylacine to its former habit should be done very carefully, Pask added.
“Any release like this requires studying the animal and its interaction in the ecosystem over many seasons and across large areas of landlocked land before considering a full-scale rewilding,” he said.
The team has not set a timeline for the project, but Lamm said he thought progress would outpace efforts to bring back the woolly mammoth, noting that elephants take much longer to gestation than dunnarts.
The techniques could also help living marsupials, such as the Tasmanian devil, avoid the fate of the thylacine as they struggle with the increasing wildfires caused by the climate crisis.
“The technologies we’re developing to eradicate the thylacine all have immediate conservation benefits — right now — to protect marsupials. Biobanks of frozen tissue from living marsupial populations have been collected to protect against extinction from fires,” Pask said. via email.
“However, we still lack the technology to take that tissue — make marsupial stem cells — and then turn those cells into a living animal. That’s the technology we’ll be developing as part of this project.”
However, the way forward has not been cut and dried. Tom Gilbert, a professor at the GLOBE Institute at the University of Copenhagen, said there are significant limitations to de-extinction.
Recreating the entire genome of a lost animal from DNA in ancient thylacine skeletons is a huge challenge, and so some genetic information will be missing, explains Gilbert, who is also director of the Center for Evolutionary Hlogenomics at the Danish National Research Foundation. He has researched reviving the extinct Christmas Island rat, also known as the Maclear’s rat, but is not involved in the thylacine project. The team won’t be able to recreate the thylacine exactly, but instead will create a hybrid animal, an altered form of thylacine.
“It is unlikely that we will get the full genome sequence of the extinct species, so we will never be able to completely recreate the genome of the lost form. There will always be parts that cannot be changed,” Gilbert said via e -mail.
“They will have to choose which changes to make. And so the result will be a hybrid.”
It’s possible, he said, that a genetically imperfect hybrid thylacine could have health problems and might not survive without a lot of help from humans. Other experts question the concept of spending tens of millions of dollars on extinction attempts when so many living animals are on the brink of disappearing.
“For me, the real benefit of any de-extinction project like this is the awesomeness of it. It seems very justified to me simply because it will get people excited about science, nature and conservation,” Gilbert said.
“And we certainly need that in the great citizens of our world if we are to survive in the future. But… do the stakeholders realize that what they will get will not be the thylacine, but an imperfect hybrid? What we are doing” There is no need for more people to be disappointed (or) deceived by science.”