Warming Arctic Drives Rapid Genetic Changes in Southeastern Greenland Polar Bears

A new scientific investigation has established a clear correlation between escalating global temperatures and discernible alterations within the DNA of polar bears, suggesting an inherent, rapid survival mechanism is being activated in these vulnerable Arctic inhabitants. Researchers affiliated with the University of East Anglia (UEA) observed divergent patterns in the activity of genes governing heat-stress response, metabolic regulation, and aging when comparing polar bears from the relatively warmer, less-icy southeastern region of Greenland against their counterparts in colder northern areas.

This critical discovery provides essential data for conservation strategy development, illuminating potential pathways for polar bear persistence amidst a warming climate and aiding in the identification of the populations facing the most immediate peril. The study's findings are particularly significant as over two-thirds of the global polar bear population is projected to face extinction by 2050, with total species loss anticipated by the century's end, given the continued rise in Arctic Ocean temperatures and the resulting reduction in vital sea ice hunting platforms.

The core of this research focused on the behavior of transposable elements (TEs), often called 'jumping genes,' within the genetic material of bears residing in the southeastern sector of Greenland, an environment that mirrors future climate predictions for the species. Lead researcher Dr. Alice Godden, from UEA's School of Biological Sciences, reported a marked surge in the mobilization of these TEs within the DNA of the southeastern bears. This suggests a swift genetic restructuring is underway, potentially serving as an immediate adaptation strategy against the pervasive loss of sea ice habitat. Furthermore, the analysis detected modifications in gene expression areas associated with fat processing, hinting at an evolutionary adjustment to potentially rougher or less energy-dense diets compared to the seal-heavy diet of northern populations.

To map this intricate gene activity, the scientists employed RNA sequencing technology on blood samples collected from a total of 17 adult bears: five from the southeast and twelve from the northeast. This methodology allowed for the confirmation that this is the inaugural study to directly connect rising ambient temperatures to measurable changes in the DNA of a wild mammal species. Dr. Godden noted that these highly active genetic hotspots, some situated within protein-coding regions, signify rapid, fundamental genetic rewriting as the bears contend with their diminishing sea ice environment. The research was published in the journal Mobile DNA.

This research builds upon prior work from the University of Washington, which had already indicated that the southeastern Greenland population was genetically distinct from the northeastern group, having become separated approximately 200 years ago. The Greenland Institute of Natural Resources has noted that the Southeast Greenland population, located between 60 and 64 degrees north, is the most genetically distinct group globally, surviving with limited sea ice by hunting from freshwater ice originating from glaciers. The Greenland Government adopted a specific polar bear protection area in South East Greenland in 2023 to safeguard this unique group.

The study highlights that while this adaptation presents a measure of hope, the overarching necessity for global commitment to limiting temperature escalation remains paramount for the species' long-term viability. Dr. Godden emphasized that while this provides a genetic roadmap for adaptation, it does not diminish the immediate threat, stressing that sustained global efforts to curb carbon emissions are indispensable.