It’s always a sad day when you have to report on a species going extinct. This is what makes this occasion especially merry: researchers at The Australian National University (ANU) report that Gould’s mouse has been rediscovered on several small islands off the coast of Western Australia.
The species was assumed to have been wiped out some 150 years ago, likely due to the environmental changes spurred by the arrival and settling of Europeans, such as invasive species.
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“The resurrection of this species brings good news in the face of the disproportionally high rate of native rodent extinction, making up 41 percent of Australian mammal extinction since European colonisation in 1788,” Dr. Roycroft said.
“It is exciting that Gould’s mouse is still around, but its disappearance from the mainland highlights how quickly this species went from being distributed across most of Australia, to only surviving on offshore islands in Western Australia.It’s a huge population collapse.”
The team compared DNA samples taken from extinct Australian rodents and 42 of their living relatives, aiming to understand the dynamics of Australia’s native rodents since the arrival of Europeans.
They were surprised to find that the extinct Gould’s mouse was genetically indistinguishable from the Shark Bay mouse, which is still alive and well on several islands. In essence, although we’ve perceived these two groups as separate species, they are, in fact, the same.
Several other extinct species were also considered in this study. Based on the samples we have, the team reports that all of them showed high levels of genetic diversity immediately before their extinction. This suggests that the species had numerous populations spread wide across Australia prior to Europeans making landfall here.
“This shows genetic diversity does not provide guaranteed insurance against extinction,” Dr. Roycroft said. “They were likely common, with large populations prior to the arrival of Europeans. But the introduction of feral cats, foxes, and other invasive species, agricultural land clearing, and new diseases have absolutely decimated native species.”
“The extinction of these species happened very quickly. We still have a lot of biodiversity to lose here in Australia and we’re not doing enough to protect it.”
Biodiversity, both in the context of ecosystems and single species, is a measure of genetic variety. It’s life’s insurance policy — the theory is that if a pathogen or threat can take down one individual or species based on their genetic traits, there are other actors of the same species, or completely new species, which can take their place and have a chance to resist said threat. In the context of individual species, this ensures the survival of the species through natural selection. In the context of ecosystems, this ensures that critical processes such as water or nutrient recycling will still be performed even if one species goes extinct.
Biodiversity directly benefits us, as it underpins the healthy functioning of the world around us, ensuring we’re provided with air, water, and pollen for our crops. Degradation of this diversity wouldn’t be great for nature, but it wouldn’t be deadly, either — in time, new species will evolve to fit empty niches. However, it would definitely be a huge issue for us, as the loss of key species can represent a real threat to our short- and long-term survival as a civilization and a species.
The paper “Museum genomics reveals the rapid decline and extinction of Australian rodents since European settlement” has been published in the journal PNAS.