Despite their dwindling numbers, Arctic polar bears have come a long way over the years, originally descending from a single brown bear from Ireland, according to a new study.
DNA samples taken from polar bears from Greenland, Norway, Alaska and Russia proved that each individual’s lineage traced back to an Irish mama bear that lived 20,000 to 50,000 years ago.
The two different species also periodically mated during the last 100,000 years, according to the analysis of genetic indicators which are passed down through females. The revelation could help to quell the fears of scientists that cross-species mingling is a further threat to the Arctic bears than are struggling to cope with the effects of climate change.
In recent years, since the Arctic species have been pushed beyond their usual environment due to melting ice, several ‘pizzlies’ (a cross between polar and grizzly bears) have been spotted by researchers. Although it was known that polars evolved from a large family of brown bears 150,000 years ago, it was not known whether further inter-species mating had dramatically shaped the current gene pool.
“Hybridisation could certainly result in the loss of unique genetic sequences, which could push them toward extinction,” Beth Shapiro, lead researcher and a Pennsylvania State University professor, told AFP. “But scientists should reconsider conservation efforts focused not just on polar bears but also on hybrids, since hybrids may play an underappreciated role in the survival of certain species,” she added.
A team of scientists analysed DNA passed from females to their offspring in 242 living and ancient bears. “We found that the matrilines of the polar bears coalesce to a relatively recent common ancestor” – one which lived along Ireland’s Atlantic shore – said the study’s co-author Daniel Bradley.