Tasmanian tigers have been extinct for almost a century, but from one agenetwork engineering and de-obsolete company is on a mission to change that. More commonly known as tasmanian tiger, the key species is not a tiger at all, but a carnivorous marsupial native to Australia, Tasmania and New Guinea, also known as the thylacine.
Tasmanian and wider Australian ecosystems have suffered biodiversity loss and ecosystem degradation since species were driven to extinction by human hunting almost a century ago. Australia has one of the highest rates of mammal extinction in the world, and the loss of an apex predator could cause waves of ecological damage that could lead to the spread of diseaseincreasing wildfires and invasive species and disrupting natural biogeochemical cycles.
The development of the technology used to eradicate the extinct Tasmanian tiger will also help protect all marsupials around the world, which are highly susceptible to increasing levels of biodiversity loss in Australia. A successful thylacine birth will usher in a new marsupial-assisted reproductive technology that could aid other marsupial conservation efforts.
This is the second de-extinction project from Colossal, which announced plans to restore the woolly mammoth to the arctic tundra in September 2021.
Tasmanian tiger expert Andrew Pask, PhD, and Ben Lam, co-founder and CEO of Colossal, spoke to Discovery to explain their ground-breaking plan to bring Tasmanian tigers back into balance with wider Australian ecosystems.
What is de-extinction and how is it done?
PASK: “De-extinction differs from cloning in that we don’t have a living cell (from our extinct animal) to start the process. So in this case we must look for the nearest living relative to serve as a host for bringing back our extinct species. In the case of the thylacine, it’s the fat-tailed dunart, a mouse-sized carnivorous marsupial. We then sequence the genomes of our extinct animal and the closest relative and compare them. We then take live cells from our dunnarts and edit their DNA at every point where it differs from the thylacine. We are essentially engineering our dunnart cage to become a Tasmanian tiger cage. We then use standard stem cell and reproductive techniques to turn that cell back into a living animal. Our ultimate goal with this technology is to restore these species to the wild, where they play an absolutely essential role in the ecosystem. So our ultimate hope is that you’ll see them back in the Tasmanian bush one day.”
LAMM: “Our goals are to get as close as possible to the original extinct species in terms of its size, shape and behavior. I’ve seen some people take issue with the word “de-extinction” over the past few years, and I think people should be less concerned with the semantics of the word “de-extinction” and more concerned with developing tools to rapidly advance conservation and saving species. The technologies we’re developing have massive conservation applications. We’re also bringing back genes and phenotypes that have gone extinct. If you create a proxy species that has all the phenotypic traits you’re looking for, how is that not eliminating extinction, if the resulting proxy animal fills the ecological gap created by its absence?”
Who benefits from de-extinction?
LAMM: “In addition to local ecosystems, the broader conservation community also benefits from de-extinction work. In addition to the benefits of restoring wildlife and helping to balance an ecosystem that humanity has had a hand in degrading, Colossal is developing a focus on marsupial conservation and gestation technologies that will support broader marsupial conservation efforts. For example, we are developing an exo-pouch that the joeys will further develop after birth. Exo-pouches can be used for existing marsupial species, such as the Tasmanian devil. The Tasmanian devil gives birth to 20 or 30 young. However, the mother only has four nipples, so only a handful of babies survive. Our exo-pouch that we are developing for the thylacine project could be extremely useful for conservationists working with Tasmanian devils to pick up those extra 20+ joeys and give them room for further incubation. In addition, Colossal is working on artificial wombs of full stage that can help in l ex-utero development right from the embryos. These gestational technologies alone will be transformational for marsupial conservation.”
PASK: “People are rapidly changing the environment. Global temperatures are rising, adverse weather events (such as the devastating Australian bushfires of the past few years) are predicted to increase in frequency and severity, and we are introducing pest species across the planet. Unless we step in to help these species, we will lose huge amounts of biodiversity. The technologies we are developing to eliminate the thylacine have immediate conservation benefits—right now—to protect marsupial species. Biobanks of frozen tissue from living marsupial populations have been collected to protect them from extinction by wildfires. However, we still lack the technology to take that tissue—to create marsupial stem cells—and then turn those cells into a living animal. This is the technology we will develop as part of this. Even genome editing has the ability to help protect marsupials against invasive pest species or increase genetic diversity and population health.”
What are the methods of de-extinction?
PASK: “We still cannot create life from dead cells. So in any de-extinction project, the goal is to get as close as possible to the extinct animal by editing the genome of living cells from the closest living relative. the key resources for this work are a good genome of your extinct species. Because the thylacine is a relatively recently extinct species, there are many specimens in museum collections and the DNA is fairly intact, allowing us to build an excellent plan of the thylacine. are also working very hard to identify key regions of the thylacine genetic code that are essential for its unique development. This developmental and functional work is now supported by outstanding computational biology and gene editing teams in colossal to build our thylacine genome. The things TIGRR and Colossal are most excited about are the incredible conservation resources this project will create for currently threatened or endangered marsupial species.”
Why choose to bring back the Tasmanian tiger?
LAMM: “From a colossal perspective, we are interested in pursuing de-extinction projects where the reintroduction of recovered species can fill an ecological gap created when the species went extinct and help restore the degraded ecosystem. Now that the mammoth team is fully staffed and making great progress, we began looking for our second species to pursue. After meeting Dr. Pask and seeing his work on the Tasmanian tiger, as well as weighing the benefits of his de-extinction, we were excited to collaborate with him and the University of Melbourne to help bring back a replacement for the thylacine. The thylacine is a great candidate for de-extinction because it only went extinct in 1936 due to hunting by humans and the ecosystem we’re trying to bring it back to is still intact We also have amazing tissue samples and genomes collected and lots of extra skins , which are sequenced for population genomic studies. Pask’s more than a decade of work on lacine makes him (and his lab) the best subject matter expert we could have hoped for on the project. Finally, we are excited about how our work on the thylacine will lead to marsupial-focused conservation and gestation technologies that we did not pursue before starting the project.”
PASK: “The tassie devil face virus is a classic example of what can happen when an ecosystem becomes imbalanced by the loss of an apex predator. The ripples from these ecosystem impacts are immeasurable, but the rewilding of wolves in Yellowstone has shown how vital and complex some of these interactions can be. In the case of the wolf’s return, it not only affected the mammals in the system, but also the vegetation as far as changing the course of the rivers in the valley. animals occupy key positions in an ecosystem, and when no other animal can replace that niche, the effects are profound. In Tasmania, it’s only been about 100 years since there was a thylacine population in the ecosystem, so hopefully we can recoverable and a lot of damage has been done before.”
PASK: “The Tasmanian tiger is the only marsupial apex predator that has lived in modern times – so there are no other native species that could replace it. It is very difficult to predict what a non-native predator might do to an ecosystem, which is why introducing species into new habitats can lead to ecological catastrophes. The best thing we can do to protect our ecosystems is to prevent species from going extinct. But when a cornerstone species has been lost from that environment, the next best thing we can do is try to bring that animal back.”
When can we see Tasmanian tigers again?
LAMM: “We’ve been quite vocal about our ambitious goals of getting our first mammoth calves in the next five to six years. While we don’t yet have a timeline for the thylacine, gestation time for marsupials is measured in weeks compared to 22 months for elephants. Much of our mammoth chronology is based on the nearly two-year gestation of calves. I think it’s safe to assume that the proxy thylacine could be one of the first animals to be brought back.”
What are the disadvantages of de-extinction?
PASK: “In the case of the thylacine, the benefits of bringing this species back would outweigh any potential risks. Any release like this requires studying the animal and its interaction in the ecosystem over many seasons and across large areas of enclosed land before you would think of a full wild restoration. The impact of the loss of the thylacine can already be seen with the rapid spread of new diseases such as Tasmanian devil facial tumor disease, which nearly drove another marsupial species to extinction. We would strongly advocate that first and foremost we need to protect our biodiversity from further extinction, but unfortunately we are not seeing a slowdown in species loss. This technology offers a chance to correct this and can be applied in exceptional circumstances where keystone species have been lost – to prevent further damage to the ecosystem.”
Are there other species you want to return?
LAMM: “Right now we are extremely focused on the woolly mammoth and thylacine de-extinction projects. As we move forward with these two projects, we will continually evaluate other species where de-extinction efforts can create a positive impact on a degraded ecosystem and advance conservation science.”