for National Geographic News
Contrary to popular opinion, not all cold-loving animals can simply retreat north in the face of global warming. New research into vanished populations of arctic foxes suggests there is no easy escape route.
Scientists who investigated the fate of arctic foxes living in Europe during the end of the last ice age say the animals most likely died out after becoming isolated by rapidly rising temperatures.
Since arctic foxes are highly mobile animals, the findings don't bode well for other, slower creatures that are sensitive to climate warming, the Swedish-led study team warned. (Related: "Polar Bears Suffering as Arctic Summers Come Earlier, Study Finds" [September 21, 2006].)
"What our results show is that Arctic species don't retreat, they just disappear," said zoologist Love Dalén of Stockholm University.
A team headed by Dalén and Anders Götherström of Uppsala University compared the DNA of arctic foxes in Scandinavia to genetic samples from animals that lived to the south some 20,000 years ago, when the previous ice age was drawing to a close.
If the prehistoric foxes had retreated north as temperatures rose, their DNA should be reflected in current populations in northern Scandinavia, the study team said.
But the genetic analysis of fossil bones unearthed in Germany, Belgium, and western Russia indicated no ancestral link to arctic foxes living today.
The researchers found instead that Swedish and Norwegian populations are descended from foxes that had spread thousands of miles west from eastern Siberia as the northern ice sheets melted.
"The arctic foxes in mid-latitude Europe became extinct," the team concludes in the current issue of the journal Proceedings of the National Academy of Sciences. "Their genes did not contribute to the make-up of present-day populations."
Clues to the disappearances may come from the way Scandinavian arctic foxes are responding to current climate change, Dalén said.
"What we see is that the populations are decreasing, but they aren't really moving," he said.
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