Deer mice at greater extinction risk from global warming than thought

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London, May 24 (ANI): The deer mice, which survived previous climate change about 12,000 years ago, may not be able to withstand the current global climate change, warn experts.

Excavation of fossils spanning the last 20,000 years from a cave in Northern California, has helped researchers learn that climate change, about 12,000 years ago, adversely affected North American small-mammal communities, but the deer mice, one highly adaptable species, had managed to survive.

However, Stanford biologists insist the balance of biodiversity within North American small-mammal communities is so out of whack from the last episode of global warming that the current climate change could push them past a tipping point, with repercussions up and down the food chain.

The experts opine that at the end of the Pleistocene epoch, populations of most species experienced a significant loss of numbers.

Almost a third of the big, so-called "charismatic" animals, such as mammoths and mastodons, dire wolves and short-faced bears went extinct. However, there was no knowledge on the survival of smaller animals.

Jessica Blois, lead author of the study, said: "If we only focus on extinction, we are not getting the whole story. There was a 30 percent decline in biodiversity due to other types of changes in the small-mammal community."

Elizabeth Hadly, professor of biology and a co-author of the paper, said: "We were interested in the small animals because we wanted to know about the response of the survivors, the communities of animals that are still on the landscape with us today. We focused not only on the Pleistocene transition, but also the last 10,000 or so years since then."

Blois and Hadly excavated deposits in Samwell Cave, in the southern Cascades foothills. They also sampled the modern small-mammal community by doing some live trapping in the area of the cave.

Hadly said: "In the Pleistocene, there were about as many gophers as there were voles as there were deer mice. But as you move into the warming event, there is a really rapid reduction in how evenly these animals are distributed."

Some species became extremely rare, others quite common. And the species that became king of the landscape - by virtue of its very commonness - was the deer mouse.

She added: "That is a pretty big, somewhat startling result. What these data tell us is that in the Pleistocene they were not dominant at all.

Also, Blois explained: "Small mammals are so common, we often take them for granted. But they play important roles within ecosystems, in soil aeration and seed dispersal, for example, and as prey for larger animals."

Hadly added: "Deer mice just kind of eat everything, they live everywhere and they don't operate with the same complexity in an ecosystem that these other animals take as their roles".

However, the deer mice may not be able to sustain in the current climate change.

Hadly said: "The temperature change over the next hundred years is expected to be greater than the temperature that most of the mammals that are on the landscape have yet witnessed as a species.

"The small-mammal community that we have is really resilient, but it is headed toward a perturbation that is bigger than anything it has seen in the last million years."

The study has been published online by Nature on May 23. (ANI)

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