Analysis of the genome of polar bears has shown that this kind of seven to eight times older than previously thought, according to a paper published in the journal Proceedings of the National Academy of Sciences (PNAS).
Scientists from 13 universities in North America, Europe and Asia found that the polar bear as a species formed much earlier than previously thought, his age is not 600 thousand years, according to recent research, and 4-5 million — during this period the white and brown bears genetically separated, divided into separate species. Thus, the polar bears have witnessed the change of several climatic epochs in the world, which, as proved by scientists, reflected in their genome.
"We sequenced the genomes of white and brown bears, and grizzly bears, using genetic material from different years, in particular, from an individual who lived 120,000 years ago. This unique material, not only for some vertebrates can find this" — said the research, employee University Penn State (USA) Stefan Schuster (Stephan Schuster), quoted at the post.
Scientists have also found that polar bears are in terms of genetics, "much in common" with grizzlies that live in the south-eastern part of Alaska — to 5-10% of the genome of the same. Scientists explain that the two species interbred during warming periods, when their habitats overlap. Thus, there is reason to believe that in the current climate warming education hybrid pairs may become commonplace, the report said.
In addition, experts have created a computer model to show the interdependence of genetic evolution of polar bears, the size of their population and climate changes on the planet. Analysis of the model showed that the number of polar bears increased in the Early Pleistocene — in a period of significant cooling of the Earth, and then declined over time when there was warming. Scientists came to the conclusion that at present the number of polar bears has fallen far more than at any time of the species.
"Such a reduction, probably due to the fact that polar bears for their genetic history lost much of its diversity of the gene pool. So today they are much more unstable with respect to changes in the environment than ever before. Polar bears survived not one change of climate, but it is not ensure their survival as a species in the future, "- said the head of research, an employee of the University Buffalo (U.S.) Charlotte Lindqvist (Charlotte Lindqvist), quoted at the post.