The last time humanity was able to see a living thylacine was on September 7th, 1936, in a zoo in Hobart, Australia. Since then, scientists have preserved the body in a jar full of ethanol, at the Melbourne Museum. On Monday, a team of Australian researchers informed they studied the body of the marsupial predator and concluded that the species was genetically predisposed to disappear. Also, they found why this animal was so similar to distant members of the dog family.
The thylacine lived isolated between the regions of New Guinea and Tasmania since around 10,000 to 13,000 years ago. When they disappeared, the majority of the scientists linked the cause to humans, who started hunting them for different reasons after they arrived in Australia.
However, like many other species – the Passenger pigeon, for example, once millions of individuals throughout North America – the Tasmanian tiger was in danger long before because it suffered from genetic weakness. It was practically destined to disappear from Earth’s surface.
Of course, scientists said the genetic of the species is just one of the reasons. Humans “without doubt” helped the thylacine disappear.
The first men who reached Australia introduced the dingo (Canis lupus dingo) and isolated the Thylacine mostly in Tasmania. In the nineteenth century, European colonists used to pay a bounty of £1 per carcass because they saw the animal as a threat to their sheep. This happened until 1909 when the rewards were suspended, and the people had to gather the tigers in zoos to protect them.
The 108-year-old infant tiger let the researchers create one of the most complete genome sequences in history. It’s the most detailed one ever made of a thylacine, a full genetic blueprint. In fact, some scientists believe this study can lead them to engineer a way to clone the species and bring the animal back to life.
“They were this bizarre and singular species. There was nothing else like them in the world at the time,” said the evolutionary developmental biologist from the University of Melbourne, Charles Feigin, who was involved in the study. “They look just like a dog or wolf, but they’re a marsupial.”
Threatened by its own genes
This is not the first time that experts generate a genetic sequence from the thylacine. Years ago, scientists at the Smithsonian Institution in Washington DC used a Tasmanian tiger’s hair to build a mitochondrial genome – which is a small part of DNA that is passed from generation to another.
However, they used tissue from a one-month-old thylacine to perform this study and obtain a much longer nuclear genome. The scientists said that this genome lets people know more about a species’ ancestors than a mitochondrial genome.
When the team studied the nuclear genome, they saw that the number of individuals started to decline around 70,000–120,000 years ago, many years before humans reached Australia.
Something similar, according to Nature, was once saw in the genome of the Tasmanian devil (Sarcophilus harrisii). Feigin said that the animals turned more vulnerable in front humans when the temperature of the area started to decline.
Thanks to the nuclear genome, the Australian team discovered that the Tasmanian tiger resembles wolves and some other relatives of dogs because they both had similar predatory lifestyles. Although the thylacines and the canines don’t have any relation but a 160-million-year old ancestor, the shapes of their head look quite similar.
Two alike and unrelated predators
Associate professor and lead researcher, Andrew Pask from the University of Melbourne, said that he has “always known” that the thylacine was “susceptible to diseases” because it did not have “much genetic diversity.”
According to Pask, the Tasmanian tiger is an “unbelievable” example of ”convergent evolution,” which is a process where two different organisms end looking practically the same because they both had to evolve in similar environments or ecological niches.
Despite the similarities between the dingo and the thylacine, Pask said that the tiger had more in common with kangaroos.
“We’ve always known that the Tasmanian tiger did not have much genetic diversity, so it would be more susceptible to diseases,” he said. “It’s very much like the Tasmanian devil in that respect and we’ve always thought that happened once it became isolated on Tasmania between 10,000 and 15,000 years ago. But what we found is that the population declined about 70,000 years ago, long before it was isolated meaning it probably had more to do with changes in the climate back then.”
Probably not today, or tomorrow. But the team informed this result might help them recreate the species and bring it back from extinction. Additionally, they concluded that this information would definitely help them to protect the Tasmanian devil and make it more healthy.