According to a new study led by the University of East Anglia (UEA), polar bears could be showing early signs of genetic adaptation to rising temperatures. The study identified changes in their DNA linked to heat stress, ageing, and metabolism.
The study focused on polar bears in south-east Greenland, an area of the Arctic that is warmer and more unstable than most other polar bear habitats. The researchers suggest that these genetic changes could enable the bears to adapt to changing climates and diets as the Arctic Ocean warms and sea ice diminishes. Consequently, with fewer stable ice platforms, polar bears, which use them to hunt, have less access to seals and are becoming increasingly isolated and food-stressed.
Current predictions for polar bears are bleak, according to scientists. Up to two-thirds of the bears could disappear by 2050 due to climate change, and the species could face near-total extinction by the end of the century. In 2008, the US government granted the species protected status under the Endangered Species Act.
Amid these dire forecasts, the discovery of genetic and DNA changes offers a glimmer of cautious optimism, although researchers emphasise that it does not negate existing projections. Dr Alice Godden, a molecular biologist based at the UEA, said the animals are in “real danger.”
“[2050] is really not that far away, unfortunately,” she said. “As the rest of the species faces extinction, these specific bears provide a genetic blueprint for how polar bears might be able to adapt quickly to climate change, making their unique genetic code a vital focus for conservation efforts.”
The study, published in Mobile DNA, analysed blood samples from polar bears in north-east and south-east Greenland, comparing the behaviour of so-called “jumping genes” under different temperature conditions and their effect on gene activity.
“For the first time, a unique group of polar bears in the warmest part of Greenland is using ‘jumping genes’ to rapidly rewrite their own DNA,” Godden explained, describing it as a “desperate survival mechanism against melting sea ice.”
“DNA is the instruction book inside every cell, guiding how an organism grows and develops,” she added. “Different groups of bears are having different sections of their DNA changed at different rates,” changes that seem to be “linked to their specific environment and climate.”
Godden warned, however, that it is too soon to celebrate. While the findings offer some hope, she says, they do not reduce the need to address global warming and do not mean polar bears are no longer at risk of extinction. She urged the global community to avoid “complacency.”
This is the first study to identify a statistically significant link between climate conditions and DNA changes in a wild mammal population. Changes were also observed in genes linked to fat metabolism, suggesting that bears in south-east Greenland may be slowly adapting to poorer diets as melting sea ice reduces access to their usual fatty, seal-based prey.
This builds on a previous University of Washington study, which identified genetic differences between polar bear populations in northern and southern Greenland after around 200 years of separation.
Godden said that further research is now needed on other polar bear populations, stressing the urgency of understanding how the species responds to climate pressure before it is too late.
