In the fjords of southeastern Greenland, a small population of polar bears hunts seals from glacial ice fragments rather than the vast sea-ice platforms their species evolved to depend on. These bears have long intrigued scientists because they persist in conditions that should, by conventional understanding, be marginal for polar bear survival. Now, a 2025 genomic study has revealed something remarkable happening inside their DNA: segments called transposable elements, or “jumping genes,” are behaving differently in these bears compared to their relatives in the colder northeast, activating gene expression patterns associated with tolerating warmer temperatures.
The finding, published in the journal Mobile DNA, offers the first direct evidence that at least one polar bear subpopulation is responding to environmental pressure at the genomic level, not just by changing behavior but by reshuffling how its genes work. It is a sign of biological resilience. But as of June 2026, other research across the Arctic tells a more sobering story: in many regions, polar bear genomes are falling out of step with their rapidly changing habitats, and the genetic diversity they need to adapt is shrinking.
Jumping genes are rewriting the playbook in Greenland
Transposable elements are stretches of DNA that can copy themselves and move to new positions within a genome. When they land near a gene, they can change how actively that gene is expressed, essentially turning biological dials up or down. In most organisms, this activity is tightly regulated because uncontrolled jumping can be destructive. But in the right circumstances, it can also generate rapid variation, the kind of genomic flexibility that might matter when an environment shifts faster than traditional mutation rates can keep up with.
The Mobile DNA study compared polar bears from northeastern Greenland, where extensive sea ice still forms seasonally, with those from the southeast, where ice is scarce and temperatures are higher. Researchers found that the southeastern bears showed distinct transposable element activity, with gene expression differences in pathways plausibly linked to heat stress response. The implication is that these genomic shifts may be helping the bears cope with conditions their species did not evolve to handle.
What the study does not yet show is whether these expression changes translate into measurable survival advantages. No published field data confirm that southeastern Greenland bears thermoregulate more effectively or hunt more successfully on land than their northeastern counterparts. The genomic signal is real, but the link to real-world fitness remains unproven.
Canadian bears face a growing genetic mismatch
While the Greenland findings hint at adaptation, research on Canadian polar bears paints a more urgent picture. A study published in Ecology Letters used a technique called genetic forecasting to assess how well the genomes of bears across Canada’s Arctic match the environments they currently inhabit and will face under projected warming and sea-ice loss. The results, summarized by the U.S. Geological Survey, were stark: maladaptation is expected to already be widespread, meaning the genetic profiles of many Canadian bears are already misaligned with the conditions around them.
The study found evidence that Canadian subpopulations have undergone local adaptation over time, with bears in different regions carrying genetic variants suited to their specific conditions. But the research concluded that bears in the Canadian high Arctic face the greatest risk, because the environments there are projected to change the most dramatically while those populations have the least genetic preparation for warmer, ice-free conditions.
These projections depend on climate and sea-ice models that carry their own uncertainties. The actual pace of change could be faster or slower than predicted. And no direct demographic data have been published confirming that high Arctic Canadian bears are currently declining at rates consistent with the genetic mismatch the models describe. Still, the direction of the evidence is clear: for many bears, the environment is moving faster than their genomes can follow.
Shrinking ice, shrinking gene pools in the Barents Sea
A third line of evidence comes from the Svalbard archipelago and surrounding Barents Sea, where researchers tracked genetic changes in polar bears over two decades, from 1995 to 2016. Published in Proceedings of the Royal Society B, the study documented measurable loss of genetic diversity and increased genetic differentiation among groups during that period. The pattern is consistent with what biologists call fragmentation: as sea-ice corridors that once connected bear populations shrink and disappear, the animals become more isolated, and gene flow between groups slows.
Genetic diversity is the raw material of adaptation. When it declines, a population’s ability to respond to new pressures narrows. The Barents Sea data showed this erosion happening in real time across a 21-year window. What the study does not address is whether the trend has accelerated, stabilized, or reversed since 2016. No peer-reviewed follow-up covering more recent years has been published.
The concern is straightforward: if populations lose too much diversity, even beneficial mutations or transposable element activity may not be enough to generate the variation needed for survival under continued warming.
Deep-time context: what polar bear genomes remember
To understand what current genetic shifts mean, scientists need baselines from the past. Foundational genomic research provides that context. A widely cited study published in Cell established the polar bear reference genome, identifying candidate genes involved in dietary fat metabolism and cardiovascular function that distinguish polar bears from their closest living relative, the brown bear. This work supplies the genetic map against which all subsequent polar bear studies are measured.
Research using ancient Late Pleistocene genomes, published in BMC Genomics, helped scientists determine when key cold-adapted alleles became fixed in the polar bear lineage, separating deep-time specializations from more recent genetic changes. And a study in the Proceedings of the National Academy of Sciences documented past hybridization between polar and brown bears during previous periods of climate upheaval, showing that warming episodes have historically reshaped polar bear genomes through interbreeding and population bottlenecks.
These studies confirm that polar bears have weathered dramatic environmental shifts before. But the timescales involved, spanning thousands to hundreds of thousands of years, are vastly longer than the decades over which the current Arctic transformation is unfolding.
The unanswered questions that matter most
Several critical gaps remain in the science. One involves potential tradeoffs from transposable element activity. Increased jumping gene movement can disrupt established gene networks, including those governing immune function. If transposons rearrange DNA near immune-related genes, bears that gain heat tolerance could simultaneously become more vulnerable to pathogens expanding northward as the Arctic warms. No published study has examined this possibility in polar bears.
Another gap concerns how much usable genetic variation remains within subpopulations across the Arctic. The Barents Sea data show diversity declining in one region, but comprehensive, repeated sampling across the species’ full range has not been conducted. Some populations may still harbor enough variation to respond adaptively if environmental change slows. Without broader surveys, scientists cannot fully gauge the species’ remaining evolutionary capacity.
Perhaps the most important missing piece is field-level confirmation. Genomic studies can identify shifts in gene expression and predict mismatches between organisms and their environments. But until researchers connect those molecular signals to measurable outcomes, including survival rates, reproductive success, and body condition, the conservation implications remain partly theoretical.
Adaptation is real but may not outrun the pace of Arctic warming
Taken together, the research as of mid-2026 supports a picture that is more complex than either optimism or despair. Polar bears are not genetically static. The Greenland transposable element findings show that at least some subpopulations are undergoing real genomic responses to changing conditions, and the species’ deep evolutionary history confirms it has survived past climate disruptions.
But the strongest contemporary data, from Canada and the Barents Sea, point toward growing genetic strain. Maladaptation appears widespread in Canadian populations. Diversity is eroding in the Barents Sea. And the pace of Arctic warming, with September sea ice extent continuing its long-term decline, leaves little room for the slow, generational process of natural selection to keep up.
For conservation planning, the takeaway is that genetic resilience exists but cannot be assumed to be sufficient. Protecting sea-ice habitat and maintaining connectivity between populations remain essential, not because polar bears lack the biological capacity to change, but because that capacity has limits. The race between adaptation and habitat loss is real, and the outcome is not yet determined.
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*This article was researched with the help of AI, with human editors creating the final content.
