CHL PhD Scholar Shimona Kealy with Tasmanian Devil bones. Image by Stuart Hay

CHL PhD Scholar Shimona Kealy with Tasmanian Devil bones. Image by Stuart Hay

Unravelling the relationship between climate change and evolution

10th January 2018

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A new study led by ANU has found a strong link between a rapidly cooling climate about 14 million years ago and the decline of Australia's marsupial tigers, triggering the rise of the Tasmanian Devil and its relatives.

The extinct marsupial tigers once roamed mainland Australia and were a diverse group of species - the Tasmanian Tiger was the last one to die out 90 years ago.

The researchers discovered the group of animals, called thylacines, declined during this period when global temperatures suddenly dropped by about 7 degrees Celsius, transforming most of the wet, closed forests across Australia into dry, open woodlands.

ANU PhD scholar Shimona Kealy and Dr Robin Beck, from the University of Salford in the United Kingdom, conducted the most comprehensive dated tree-of-life study of this animal group, analysing 95 modern and fossil species, including six species of tigers.

"At this time of extreme cooling, we also see the rise of modern carnivorous marsupials such as the Tasmanian Devil and cat-sized quolls, which are dasyurids," said Ms Kealy from the ANU School of Culture, History and Language.

"We think the structure of tigers' feet and ankles might have made them better suited to closed forests with uneven surfaces, such as roots and logs, and less well suited to open woodlands.

"Dasyurids, on the other hand, have ear-bone structures that appear to be better adapted to open woodlands, allowing them to hear over greater distances than thylacines."

The researchers analysed features of skulls, teeth, jaws and the rest of skeleton, along with molecular gene sequences.

"While this study strongly suggests that the cooling, drying climate 14 million years ago was the key change that sparked the diversification of dasyurid species, the exact relationships between dasyurids and thylacines at this time requires further research," Ms Kealy said.

The study is published in BMC Evolutionary Biology. Story courtesy of ANU Newsroom

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