This article was first featured hakai magazine, Online publication on coastal ecosystem science and society. For more articles like this, please visit hakaimagazine.com.
Eight years ago, I first met researchers from the Save the Tasmanian Devil Program (STDP) in Tasmania, Australia, to learn about their work to protect endangered marsupials. It has expanded. I’ve been following this story ever since, including tracking how the Devil of Forestia Peninsula (the focus of my original article published in late 2015) lived in his “new life.”
Transmissible cancers like Devil Facial Tumor Disease (DFTD) are virtually unheard of in vertebrates, but understanding how cancers are transmitted and how they evade the immune system will help prevent cancer. impact on both conservation and oncology. For that research to take place, a healthy population of Tasmanian devils must exist. Therefore, between late 2015 and early 2016, STDP transferred 49 captive-bred devils from the isolated Forestier Peninsula to the estimated 30 wild devils already living on the adjacent Tasman Peninsula. added. Establishing new, controlled, disease-free devil populations (some devil populations already exist on Maria Island, just off Tasmania’s east coast) will help researchers develop vaccines. You will gain more time.
Their release was supposed to be a moment of hope for the endangered species, but it was marred by discoveries on another Tasmanian peninsula, about 50 kilometers west of the ocean. Local residents found the business card of a demon with a large tumor on its face, or DFTD.
A routine test came back with worrying results that it was a new cancer.
This new disease, called DFT2, is genetically different from DFT1 (the original cancer). The method of infection and symptoms are the same, posing a serious additional threat to this species.
However, the discovery of DFT2 provides an important clue to solving the mysteries of cancer. It turns out that the devil is not a victim of bad luck. The devil is especially prone to DFTD. There are three known wild infectious cancers in vertebrates worldwide, two of which are present in the Tasmanian devil.
“It was a big surprise. We thought that contagious cancers were very rare, like lightning strikes, and that the devil was just a very unfortunate species.” says Elizabeth Murchison, who studies cancer and transmissible cancers. DFT1 and DFT2 are probably not the first cancers to appear in the devil, and are unlikely to be the last.
The demons’ habit of biting each other helps the spread of disease, and their low genetic diversity creates ideal conditions for cancer to evade the marsupial’s immune system. Another factor in Demon’s inability to fight infections may be problems with the peripheral nervous system, where both DFT1 and DFT2 occur. But perhaps the culprit is environmental pollutants, as suggested in my original article. Murchison said the imprint mutations left behind in the devil’s DNA indicate that the two cancers were naturally occurring. “There’s nothing to suggest external exposure to chemicals or radiation or anything like that,” she says.
Fortunately, the discovery of the second cancer did not delay vaccine development. Andrew Fries, a senior research scientist at the Menzies Institute of Medical Research at the University of Tasmania, said there were similarities between these cancers, which would make it easier for his team to develop vaccines for both. Trials of an experimental DFT1 vaccine will begin in 2024, and development of vaccines targeting both cancers is already underway. To reach the devil, authorities plan to distribute bait drops containing the vaccine through Tasmania’s vast wilderness.
Although full-fledged development is still years away, the devil no longer appears to be in imminent danger of extinction. Although exact numbers are unknown, demon populations remain strong in many regions, at least for now, thanks to pilot projects to improve genetic diversity through the release of healthy demons.
“Disease doesn’t actually make a species go extinct. Once the disease pushes the species to the limit, everything else comes along and drives them out,” he says. said Carolyn Hogg, a researcher at the University of Sydney who has studied endangered species for many years. 25 years.
“Everything else” for the devil includes low genetic diversity, habitat loss, and road traffic deaths. Nocturnal garbage-collecting animals cannot resist the lure of rotting roadside carcasses that are easily picked up in the world’s traffic accident capital. In 2021, motorists killed more than 100 devils on just 25 kilometers of road in north-west Tasmania.
“If you have just five breeding females in a small population, and two of them are hit by a car on the road, you could lose 40% of the breeding population in one event,” Hogg said. say.
That’s exactly what happened to the Demon of Forestia Peninsula that I wrote about in my original article. The driver killed 16 of 49 people within six weeks of his release. Through subsequent tracking, Hogg and her team discovered that devils raised in captivity for generations were more likely to use roadways than wild devils.
“They can’t be released near major road networks because they’re behaviorally accustomed to the sound of cars,” Hogg says.
Since then, STDP has conducted a further 11 releases of healthy Tasmanian devils across the state to improve the genetic diversity of existing wild populations. What has changed is that instead of releasing captive-bred devils, they are relying on the wild descendants of Maria Island’s disease-free population. As a national park, Maria Island is traffic-free (except for vehicles used by park rangers). It is inhabited by wild demons who are not used to the sound of cars and have a better chance of survival.
Relying on Maria Island’s wild devils is the best option to increase the wild devil population until a vaccine is developed. But the introduction of marsupials to the island, which was demon-free until 2012, still faces criticism, just as it did in 2015. In 2021, BirdLife Tasmania reported that introduced devils wiped out the island’s 3,000 breeding population over a period of more than a decade. A pair of small penguins. There are many little penguins in the wild. Tasmania has hundreds of offshore islands and is home to an estimated 110,000 to 190,000 breeding pairs.
“We knew it was going to happen,” Hogg said. A risk assessment determined that the benefits of having a place to breed wild devils disease-free and improve genetic diversity “outweigh the loss of birds,” she said.
But the news isn’t all bad. Researchers believe the introduction of the carnivore has allowed the population of the maria, which is listed as endangered on the mainland, to thrive by pushing the predatory possums up the trees. Cape Barren geese, whose numbers declined after the introduction of marsupials, have also learned to coexist with the devil. What about the population of little penguins? Maria Island’s population began to decline around the same time as the populations of neighboring islands, suggesting additional environmental factors are likely at play.
But in Australia, from the tiny penguin to the Tasmanian devil, the conservation of endemic species and how best to manage them remains a controversial and emotional topic. Rumor has it that conservationist ‘vigilante groups’ are secretly rewilding devils smuggled from Tasmania to mainland Australia. But Hogg says given mainland devils’ susceptibility to disease, they could develop new cancers as well. And without the protection of natural barriers that isolate devil populations, such as the narrow isthmus of the Forestier and Tasman peninsulas and the waters around Maria Island, it is impossible to prevent the spread of cancer.
For now, until a vaccine is developed, Maria Island’s disease-free population will stand between the devil and extinction.
This article was first published in Hakai Magazine and is republished here with permission.