A new study from the University of Adelaide has shown that humans, not diseases, were responsible for the extinction of the Tasmanian tiger.
The Tasmanian tiger, also known as thylacine, was a marsupial carnivore found in Tasmania until the species went extinct in the 1930s. According to researchers, the Tasmanian government encouraged the hunting of the animals from 1886 until 1909, paying bounties for thylacine carcasses. The last known wild Tasmanian tiger was captured in 1933.
"Many people, however, believe that bounty hunting alone could not have driven the thylacine extinct and therefore claim that an unknown disease epidemic must have been responsible," said Thomas Prowse, leader of the project and a research associate at the School of Earth and Environmental Sciences and the Environment Institute. "We tested this claim by developing a 'metamodel' - a network of linked species models - that evaluated whether the combined impacts of Europeans could have exterminated the thylacine, without any disease."
The researchers used a modified version of mathematical models developed by conservation biologists to simulate extinction risks to populations of endangered species, called a population viability analysis (PVA). Prowse and his colleagues added species interactions to the normal PVA model.
"The new model simulated the directs effects of bounty hunting and habitat loss and, importantly, also considered the indirect effects of a reduction in the thylacine's prey (kangaroos and wallabies) due to human harvesting and competition from millions of introduced sheep," said Prowse. "We found we could simulate the thylacine extinction, including the observed rapid population crash after 1905, without the need to invoke a mystery disease. We showed that the negative impacts of European settlement were powerful enough that, even without any disease epidemic, the species couldn't escape extinction."
(Image via Wikimedia Commons)