Spotted-tailed quolls appear to have the top of the food chain in their sights as dwindling Tasmanian devil numbers lead to changes in their genetics.
The decline in devils, the state's top predator species, because of highly contagious facial cancer, has left quolls with less competition, researchers say.
The spotted marsupials used to hunt before dawn to avoid devils but have shifted to hunting in the early evening when some devils are around, University of Tasmania marsupial carnivore expert Menna Jones said.
Quolls were benefiting from devils' decline, spending more time feeding on carcasses, she said.
"We can see the activity of the spotted-tail quoll has shifted significantly in the regions where Tasmanian devils have severely reduced numbers," Professor Jones said.
Predator population declines were happening around the world and had cascading ecological effects, Prof Jones said.
The steep drop in Tasmanian devil numbers has affected the quolls' evolutionary genetics, with researchers analysing 345 over 15 years to look for changes.
In areas where facial tumours were killing off devils, there was less movement of genes between quoll populations, researchers said.
There were also more differences between the genes of quolls in different geographical areas when it came to muscle development, movement and feeding behaviour.
"It's likely these genetic traits that appear to be shifting are involved in food competition between quolls and devils," Prof Jones said.
"There is less competition and more food, reducing the need for quolls to move around as much or as far as they once would have.
"There's also changing evolutionary pressure on physical performance associated with escaping from devils and fertility of the quoll populations as devil numbers decline."
The research, authored by a global team including University of Tasmania experts, was published in the peer-reviewed journal Nature Ecology and Evolution.
