New DNA study uncovers secret of native rodents’ rat ‘race’ in New World
“Australia and New Guinea have more than 150 species not found anywhere else in the world, such as the Rakali – or ‘water rat’, which is often seen around Canberra’s lakes,” Dr Roycroft said.
“Until now, we knew very little about the evolution and origin of native rodents, especially the species from New Guinea.”
The research team used a new method to obtain DNA from museum specimens up to 180 years old, including many extinct and elusive species.
“A Guadalcanal mouse from the Solomon Islands dates back to the 1880s and the species has not been seen since. It is listed as critically endangered and likely extinct,” Dr Roycroft said. We were curious about revisiting these old specimens using modern technology.”
The study revealed that the formation of mountains in New Guinea 5 million years ago was the trigger for the spread of native rodents in the region. The expansion of New Guinea has opened up new adaptations for rodents, including through increased connections to Australia, the Solomon Islands and the Maluku Islands.
“We know that Australia’s native rodents originated in Asia and arrived in our area by water – possibly a pregnant animal drifting over a piece of driftwood. Now we have an accurate timetable and an explanation of why We see so many species today,” Dr Roycroft said.
“Our research shows that native rodents are excellent at colonizing new areas. When they first arrived in Australia, they adapted to many new environments – including arid deserts.”
Dr Roycroft said having additional information about the history of native rodents could prove crucial to the future of these species. “Native rodents have profound intrinsic value in our ecosystems. They are ecosystem engineers; they aerate the soil by burrowing and foraging, and they help disperse seeds and fungal spores,” she said.
“They also function in food webs and are an important source of native predators and, in turn, feed on plants, fungi and small animals themselves.”
“But they also have the highest extinction rate of any mammal group in Australia, due to extreme habitat loss and introduced predators. If we lose even one native species, it can disrupt the balance of the ecosystem.”
“Understanding how our native rodents evolved and adapted will help us protect those species that are left of us.”
This research has been published incontemporary biology” magazine.