(NewsNation) — As Arctic sea ice declines, researchers have observed hybridization between polar bears and grizzly bears as the two species come into more frequent contact.

In a study published last week in Conservation Genetics Resources, researchers found no evidence of widespread hybridization in samples collected from 1975 to 2015. Only eight previously known hybrid bears were identified among over 800 animals tested.

The researchers did detect some ancient polar bear DNA in grizzly bears from Alaska’s ABC Islands and surprisingly, in some Alberta, Canada, grizzlies. This suggests historical interbreeding may have been more widespread than previously thought.

Researchers created a powerful new genomic tool to assess the genetic diversity and adaptive potential of polar bears, a species vulnerable to climate change.

The “Ursus maritimus V2 SNP chip,” described in the study allows scientists to analyze over 7,000 genetic markers in polar bear DNA.

The genetic analysis of the tool confirmed the previously determined ancestry of these hybrids.

Some were identified as F1 hybrids (first-generation crosses between polar bears and grizzly bears). Others were confirmed as backcrosses to grizzly bears (hybrids that had mated with grizzly bears)

All of the F1 hybrid individuals could be traced to a single female polar bear, consistent with previous research.

The study found no evidence of grizzly bear genes in the analyzed polar bear population, suggesting there were no ancestral hybridization events that then backcrossed into the polar bear gene pool.

Despite increased sightings of grizzly bears within polar bear ranges, the lack of additional hybrids suggests that contemporary hybridization between 1975 and 2015 was rare.

The researchers emphasize that while widespread hybridization was not observed in this study, continued monitoring is important as climate change may lead to more frequent contact between the species in the future.