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Australian Mouse Presumed Extinct for More Than a Century Found Alive on Island

The living Shark Bay mouse turned out to be genetically identical to the formerly extinct Gould’s mouse

Genetic tests reveal that the Shark Bay mouse (pictured) from Shark Bay, Western Australia, is actually a living population of Gould's mouse, which had been thought to be extinct for more than a century. (Australian Wildlife Conservancy / Wayne Lawler)
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When European settlers arrived in Australia, a small rodent called Gould’s mouse swiftly disappeared, with the last specimens having been collected in the 1850s. But now, after more than 150 years of being presumed extinct, genetic tests have revealed that Gould’s mouse lives on, reports Gemma Conroy for the Australian Broadcasting Corporation (ABC).

The study, published this week in the journal the Proceedings of the National Academy of Sciences, was originally aimed at uncovering the genetic diversity of living and extinct Australian rodents, reports Krista Charles for New Scientist. But the genetic comparisons of eight extinct rodent species with 42 of their living relatives ended up revealing that a mouse found on an island in Shark Bay in Western Australia known as the Djoongari or Shark Bay mouse was in fact genetically identical to the Gould’s mouse specimens in museum collections.

“When we started the study, we weren’t expecting to find that Gould’s mouse and the Shark Bay mouse were the same species,” Emily Roycroft, an evolutionary biologist at Australian National University and lead author of the research, tells Becky Ferreira of Vice via email. “The result initially came as a surprise, especially given how geographically separated the records of Gould’s mouse (in Victoria/New South Wales) are from the Shark Bay mouse (isolated on an island off the coast of Western Australia).”

In a statement, Roycroft says that the resurrection of Gould’s mouse is worth celebrating against a backdrop of Australia’s “disproportionally high rate of native rodent extinction.”

According to the paper, Australia has the ignominious distinction of having the highest historical rate of mammal extinctions in the world, losing 34 species since European colonization in 1788. Roycroft says in the statement that native rodents have been hit especially hard, comprising 41 percent of those lost species.

One of the study’s other findings was that genetic diversity among the eight extinct rodent species was relatively high right up until their disappearance. This discovery suggests that these populations were healthy prior to the arrival of Europeans and their respective declines were probably steep and sudden.

"This shows genetic diversity does not provide guaranteed insurance against extinction," Roycroft says in the statement. She adds that these species were all probably quite common, and had large populations before European arrival, which would have introduced a host of new threats such as feral cats, foxes and other invasive species as well as agricultural land clearing and plant diseases.

“Our study shows just how much we can learn about the species we’ve otherwise lost to extinction, using genomic data from museum specimens,” Roycroft tells Vice. “If we can generate this type of data from across all of Australia’s native species, not just rodents, we can learn more about the broader pattern and pace of extinctions. This will allow us to fully take stock of what we’ve already lost to extinction, but also help inform conservation efforts for surviving species into the future.”

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