Polar Bears Facing Tomorrow’s Heat Show Genetic Warning Signs Today

The findings offer a preview of how most polar bears may respond to climate change genetically.

Polar bears living in one of Greenland’s warmest regions are showing unusual genetic activity that scientists say could provide a clue to how these iconic predators respond to vanishing Arctic ice. Scientists from the University of East Anglia found that bears already living in warmer conditions show different genetic patterns than their cousins in colder regions.

The finding matters because these warm-climate bears are essentially living in the future. Temperatures they experience today are what many polar bears may face later this century, when scientists expect two-thirds of all polar bears to be gone.

Researchers compared blood samples from 17 bears in two parts of Greenland. The northeast stays brutally cold. The southeast? Not so much. Temperatures there swing wildly from about 20 below zero to about 80 degrees Fahrenheit.

When the team analyzed the blood, they found about 1,500 pieces of genetic material behaving differently in the warmer bears. These pieces, nicknamed “jumping genes,” can move around and potentially affect how other genes work

Polar Bear Genes Respond Differently to Heat

The study, published in Mobile DNA, showed that warmer bears also cranked up production of special proteins that help cells survive stress.

Does this mean polar bears are adapting to survive climate change? Not necessarily. The study only looked at what’s happening in their blood right now, not whether these changes get passed down to cubs. It’s more like watching someone sweat on a hot day. Yes, their body is responding to heat, but that doesn’t mean their kids will be better at handling summer.

The most active pieces of DNA belonged to a family called LINEs. Transposable elements make up about 38 percent of the polar bear genome. Many of the most active ones in this study were LINEs. In the warmer bears, the pattern suggested a higher share of “younger” LINEs (and LTRs), which can indicate more recent activity.

Bears in the warmer region also showed changes in genes related to stress, fat processing, and immune function. One gene that fights viruses was less active, though researchers aren’t sure why.

The team only studied five bears from the warm region and 12 from the cold one—a pretty small group. And they looked at blood, not the reproductive cells that would pass traits to offspring.

Looking Ahead

Southeast Greenland is unusual for polar bears. Instead of flat Arctic tundra, it has mountains, forests, and deep fjords. Sea ice comes and goes unpredictably. Bears there have been cut off from other populations for hundreds of years because of ocean currents.

That isolation might explain some of the genetic differences. But temperature seems to play a role too. When researchers factored in how warm each bear’s home region was, the genetic patterns lined up.

It isn’t hyperbole to say these polar bears are facing a serious problem. They hunt seals from sea ice platforms, and that ice is disappearing fast. The International Union for Conservation of Nature predicts a 71 percent chance that polar bear numbers will drop by more than 90 percent in the next 40 years.

Studying bears already living in warmer conditions might help scientists predict what happens next. But genetic responses alone won’t save polar bears. They need ice to hunt. Without it, even the most adaptable bears will struggle.

The research does offer something valuable: a way to measure stress in polar bears. If these same genetic patterns show up in other populations as temperatures rise, it might become one way to track stress as conditions warm, but it’s early.

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