Scientists examined blood from 17 Greenland polar bears and found genomic signals — including increased transposon activity and altered genes for aging, heat stress and fat metabolism — concentrated in a warmer southeastern population. These changes may reflect recent molecular responses to Arctic warming and possible dietary shifts, but they are preliminary and based on a small sample. Researchers call for broader, long-term surveys to confirm whether these patterns indicate adaptation and to guide conservation.
Arctic Heat May Be Rewriting Polar Bears’ DNA — Early Genetic Signs Of Climate Stress
Lead image: AWeith / Wikimedia Commons
Average temperatures are rising worldwide, but the Arctic has warmed far faster than most regions — roughly four times the global average in recent decades. Polar bears depend on sea ice to hunt and reproduce, and scientists estimate that more than two-thirds of the species could be gone by 2050 if current warming trends continue.
Researchers from the University of East Anglia analyzed blood samples from 17 adult polar bears in Greenland to look for genomic responses to these rapidly changing conditions. The sample included 12 individuals from northeastern Greenland and five from an isolated southeastern population thought to have migrated there about 200 years ago. Over the past 60 years the northeast has remained relatively colder and more stable, while the southeast has become warmer, more variable, and has lost more sea ice — a pattern that may foreshadow conditions elsewhere in the Arctic.
What the Study Found
The team detected differences in parts of the genome of southeastern bears that suggest recent molecular responses to environmental stress. Specifically, genes associated with aging, heat stress and metabolism are showing altered activity in the southeastern population, according to lead author Alice Godden. The study, published in the journal Mobile DNA, focused on transposons — so-called 'jumping genes' that can move within the genome and influence how other genes are expressed.
In the southeastern bears researchers observed relatively recent bursts of transposon activity spreading across the genome. Such mobilization can increase genetic variation and, in some cases, create opportunities for populations to respond to new stressors.
Possible Dietary And Physiological Shifts
The study also found signals in genomic regions tied to fat processing, which the authors suggest could reflect a dietary shift among southeastern bears away from a seal-dominated, high-fat diet toward more diverse or plant-based food sources. However, the researchers emphasize that these are early signals and do not prove adaptive benefit.
'We cannot be complacent — this offers some hope but does not mean that polar bears are at any less risk of extinction,' Godden told The Guardian. 'We still need to be doing everything we can to reduce global carbon emissions and slow temperature increases.'
Limitations And Next Steps
The authors note important caveats: the sample size is small (17 individuals), the results are correlational, and more populations must be examined to determine whether similar genomic responses are occurring elsewhere. Broader surveys of polar bear populations, repeated sampling through time, and ecological data on diet and health will be essential to confirm whether these genomic changes represent early adaptive responses or transient stress signatures.
Although the findings offer an intriguing glimpse into how a top Arctic predator's genome may be responding to rapid environmental change, they do not reduce the urgent need for emissions cuts and targeted conservation to protect polar bears and their icy habitat.
