Mother of all polar bears from Ireland
Baku, July 9 (AZERTAC).The Arctic`s dwindling population of polar bears all descend from a single mama brown bear which lived 20,000 to 50,000 years ago in present-day Ireland, according to a study released Thursday.
DNA samples from the great white carnivores -- taken from across their entire range in Russia, Canada, Greenland, Norway and Alaska -- revealed that every individual`s lineage could be traced back to this Irish forebear.
The analysis of genetic material inherited only through females also showed that brown and polar bears mated periodically over the last 100,000 years.
But whether the subsequent inter-species mating was incidental or whether it fundamentally shaped the animal`s gene pool was unknown.
To delve deeper, an international team of scientists led by Shapiro analysed mitochondrial DNA in 242 ancient and living brown and polar bears.
Mitochondrial DNA are part of cells with their own DNA that are passed exclusively from females to offspring, in this case from mother bear to cub.
Previous research had traced the earliest female brown bear ancestor for modern polar bears back 14,000 years to the Alaskan ABC islands.
In order to discern this pattern, there had to have been occasional mating after the two species split, she added.
Because they evolved in separate environments, neither species could survive long in the other`s ecological niche due to different body shapes, metabolism, and hunting habits.
Polar bears, for example, are expert swimmers, whereas brown bears are more adept at climbing.
There are currently 20,000 to 25,000 polar bears left in the wild, according to the International Union for the Conservation of Nature (IUCN).
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