Changes in polar bear DNA caused by warming climate could help animals survive in new habitats

As the Arctic Ocean reaches its warmest temperatures in the past 125,000 years and continues to heat up, scientists warn that more than two-thirds of the world’s polar bears could disappear by 2050. While the threat of extinction driven by melting sea ice and declining food sources has long been documented, a new study suggests climate change may also be reshaping polar bears at a genetic level, potentially giving some populations limited capacity to adapt to their warmer environments.

The research focuses on polar bears living in Greenland and examines how rising temperatures may be influencing their genome. The study's authors argue that, if bears are still able to find sufficient food and mates, these genetic changes could help them survive in climates that differ significantly from the cold Arctic conditions they evolved in, as highlighted in an article by The Conversation.

The study identified a strong link between increasing temperatures in south-east Greenland and changes in polar bear DNA. Greenland’s polar bear populations experience starkly different climates depending on region, with the south-east considerably warmer than the north-east. Researchers found that polar bears in south-east Greenland are genetically distinct from those in the north-east. According to the analysis, the south-east population likely migrated from the north and became geographically isolated around 200 years ago, allowing genetic differences to accumulate over time.

To investigate these changes, the researchers used publicly available genetic data from a University of Washington research group. The dataset was based on blood samples collected from polar bears in both northern and south-eastern Greenland. Rather than focusing solely on DNA sequences, the new study examined RNA, which reflects which genes are actively being used by the organism.

DNA instructions are copied into RNA through a process called transcription, and RNA then guides the production of proteins through translation. RNA sequencing also captures activity from transposable elements, or TEs—often called “jumping genes.” These are mobile fragments of DNA that can move around the genome and influence how other genes function.

The original Washington-based team had extracted RNA from polar bear blood samples and sequenced it. The new study analyzed this RNA data to assess gene expression in relation to environmental conditions. Climate records from the Danish Meteorological Institute were matched with the genetic data, allowing researchers to examine how rising temperatures might be affecting polar bear biology at the molecular level.

While DNA typically changes slowly over generations, environmental stressors such as heat can accelerate genetic activity. Transposable elements play a key role in this process. In polar bears, around 38.1% of the genome consists of TEs. For comparison, TEs make up about 45% of the human genome and can account for more than 70% of plant genomes. These elements belong to different families and behave in varied ways, but all share the ability to move and reinsert themselves at new locations in the genome.

Bears reacting to increased stress, change in diet driven by climate change

Under normal conditions, small molecules known as piwi-interacting RNAs (piRNAs) help suppress TE activity and maintain genomic stability. However, when environmental stress becomes intense, these protective mechanisms can be overwhelmed. The study found that warmer conditions in south-east Greenland were associated with widespread activation of TEs across the polar bear genome.

Researchers observed that TE sequences in south-east bears appeared younger and more numerous than those in northern bears. More than 1,500 TEs were “upregulated,” meaning their activity levels were higher, pointing to recent genetic changes. Some of these active elements overlap with genes involved in stress responses and metabolism, suggesting a possible role in helping bears cope with warmer temperatures.

The study also found altered behaviour in genes linked to heat stress, ageing, and metabolic processes in the south-east population. In addition, TE activity was detected in genomic regions related to fat metabolism. This is particularly significant for polar bears, whose survival depends on efficient fat storage and use when food is scarce.

Researchers suggest these changes may reflect a gradual adjustment to different diets. While northern polar bears rely heavily on fatty seals, bears in warmer southern regions may be forced to consume a broader, rougher, and more plant-based diet. The genetic shifts observed in the study hint that climate change is not only threatening polar bear habitats but is also actively reshaping their biology as they respond to increasing environmental stress.

By Nazrin Sadigova