DNA analysis of an unusual fossil ofpolar bone (the polar bear) found in Norway confirms thatthis species separated from the brown bear 150,000 years agoand that it survived an interglacial period warmer than the current one. The study sheds new data on the origins and evolution of one of the species most threatened today by climate change.
To reach this conclusion, the researchers compared theMitochondrial DNAof a canine tooth and a polar bear jaw fossils discovered in 2004 in the Norwegian archipelago of Svalbard, with that of modern polar and brown bears from the Admiralty, Baranof and Chichagof islands in Alaska. “Our results confirm that the polar bear is an evolutionarily young species that separated from brown bears about 150,000 years ago, and that it evolved extremely rapidly during the late Pleistocene, probably as new habitats and food sources emerged. in response to climate change just before the last interglacial period, “says Charlotte Lindqvist, a researcher at the University of Buffalo and author of the study published today in the journalPNAS. The fossil, which is between 110,000 and 130,000 years old, is close to the time when the split between the two species occurred.
To date, very few polar bear fossils have been found, because “as they live on ice, their remains fall to the bottom of the sea or are eaten by scavengers; they are not deposited in sediments like other mammals”, says Oystein Wiig , co-author of the research. Theisotopic studiesdetermined that the bearhe fed, like their current congeners, ofseals.
This is the mitochondrial genome of the oldest mammal ever studied, as it is twice the age of the mammoth, the authors say.
