February 01, 2013
Tasmanian Tigers at Beaumaris Zoo, Hobart c 1918. Courtesy of the Tasmanian Museum and Art Gallery.
The Tasmanian Tiger or thylacine was a marsupial carnivore unique to the Australian island Tasmania that was last confirmed in the wild in 1933. The last individual died in Hobart zoo in 1936, although there have been sporadic claims of sightings since then.
While some have attributed the decline of the species to disease, the new study shows that the thylacine could have been wiped out by humans alone.
"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 University of Adelaide professor Thomas Prowse, lead author of the study. "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 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," Prowse continued. "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."
Most of Australia's largest animals have been driven to extinction by humans. Today, the continent's biodiversity is just a fragment of what existed just prior to human contact.
Prowse et al (2013). No need for disease: testing extinction hypotheses for the thylacine using multi-species metamodels. Journal of Animal Ecology DOI: 10.1111/1365-2656.12029
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