The thylacine, aka the Tasmanian tiger, disappeared mysteriously from mainland Australia thousands of years ago (although a handful of people occasionally claim to still see this striped creature wandering around the outback). The general consensus is that the species was wiped out from the mainland due to the arrival of dingoes or increased human activity around 3,000 years ago. However, new evidence suggests that it was a drought that killed the beast.
Scientists from the University of Adelaide extracted ancient DNA from fossilized thylacine bones and museum specimens to find out what drove the mainland individuals into the backlogs of natural history. Their results were recently published in the Journal of Biogeography.
“The thylacine was a marsupial carnivore, now infamous for its recent human-driven extinction from Tasmania following the arrival of Europeans and their bounty hunting schemes,” explained project leader Associate Professor Jeremy Austin.
“Thylacines once lived across most of the Australian mainland, but by the time Europeans arrived in the late 1700s they were found only in Tasmania. They became extinct about 150 years later, with the last of the species dying in Hobart Zoo in 1936. But the reasons for their disappearance from mainland Australia and continuing survival in Tasmania has remained a mystery.”
The information gathered from the fossilized bones and museums specimens are the largest dataset of thylacine DNA to date. First of all, they noticed that mainland thylacines split into eastern and western populations in southern Australia around 25,000 years ago. The evidence also suggested that the mainland extinction was extremely quick, not the result of inbreeding or loss of genetic diversity.
Scientists previously posited that thylacines survived on Tasmania because the island does not have any dingos, However, this new evidence suggests that thylacines also experienced a population crash even without the presence of competitive predators or a dramatically increased presence of humans. Therefore, another factor had to be at play.
They concluded that the main cause of extinction was probably due to a sharp change in mainland Australia's weather patterns, which occurred around the time of their demise.
“We found evidence of a population crash, reducing numbers and genetic diversity of thylacines in Tasmania around the same time,” said Austin. “This mirrors what happened with another carnivorous marsupial, the Tasmanian devil, which still lives in Tasmania. Unlike the devil, however, it appears that the population of thylacines was expanding at the time of European arrival.”
“Tasmania would have been somewhat shielded from the warmer, drier climate because of its higher rainfall but it appears that this population was also affected by the El Niño event before starting to recover.”
So there you have it, climate change caused the demise of the Tasmanian tiger. Unless, of course, they really are still sneaking around unbeknownst to us.