Brolar-Bear Hybrids Could Take Over Northern Siberia, Expert Warns

'Brolar'-bear hybrids could take over parts of northern Siberia, an expert has warned.

Brown bears and polar bears living in Yakutia have been observed merging into each other's habitat, meaning they could mate in coming years, said Innokentiy Okhlopkov, director of the Institute for Biological Problems of Cryolithozone at the Russian Academy of Sciences' Siberian Branch, TASS reported on Monday.

This would result in brown- and polar-bear hybrids—a phenomenon that has been observed before but remains rare.

Okhlopkov told the Russian media outlet that brown bears specifically have been spotted wandering into the lower reaches of Yakutia's arctic zone, where the polar bears live.

Climate change is thought to be the main cause of this. Arctic ice—which is a polar bear's habitat—is rapidly disappearing due to the warming climate, meaning the species wander inland. At the same time, brown bears begin wandering into arctic territories as the ice melts and prey becomes available to them there.

Stock Photos Polar and Grizzly Bear
A combination of stock images: polar bear and a grizzly bear. Getty

Brown bears and polar bears have been known to mate before. The resulting hybrids have been dubbed "pizzly bears," as brown bears are also sometimes referred to as grizzly bears.

Scientists already know that the two species are able to produce fertile offspring but remain rare, Charlotte Lindqvist, a bear genetics expert and associate professor of biological sciences at the University at Buffalo College of Arts and Sciences, told Newsweek.

"So far, observations of recent hybridization have been rare, possibly caused by uncommon and atypical mating preferences of a few individuals. But the two species may be coming into increasing contact due to climate change and change in their typical habitats, causing brown bears to move into polar bear habitats and polar bears spending more time on land in the summer. It is likely we will encounter more hybrids of the two species in the future," Lindqvist said.

"Hybridization between the two species can have various impacts. If hybridization causes hybrids to be poorly adapted to either habitat of the two species, they may not survive for long. However, in a changing environment, particularly the shrinking of the main habitat of the polar bear—the Arctic Sea ice—we can easily imagine that the introduction of new genes (for example, brown bear genes into the polar bear species) may change the polar bear as we know it, with hybrids perhaps even outcompeting one or both of the parent species."

A polar- and brown-bear hybrid was spotted in Canada in 2006. The bear was mostly white but had brown marks on its fur. It also had a strangely shaped muzzle. The bear was shot, and DNA tests showed that it was, in fact, a hybrid, TASS reported.

A June 2022 study from the University at Buffalo, co-authored by Lindqvist and published in the Proceedings of the National Academy of Sciences, found that polar bears and grizzly bears could actually have been mating for thousands of years.

Scientists found that DNA data from an ancient polar-bear tooth shows there was "at least one ancient introgression event from brown bears into the ancestor of polar bears, possibly dating back over 150,000" years.