Scientists say bears in southern Greenland are genetically different from those in the north, suggesting they may be adapting.
Researchers have detected changes in the DNA of polar bears that could help the animals adapt to warmer climates, in a study believed to be the first time a statistically significant link has been found between rising temperatures and DNA change in a wild mammal species.
Climate disaster threatens the survival of polar bears. Two-thirds of them are expected to disappear by 2050 as their frozen habitat melts and the weather gets warmer, writes The Guardian.
Now scientists at the University of East Anglia have found that some genes related to heat stress, aging and metabolism behave differently in polar bears living in southeast Greenland, suggesting they may be adapting to warmer conditions.
The researchers analyzed blood samples taken from polar bears in two regions of Greenland and compared “bouncy eyelashes“: small, mobile parts of the genome that can influence how other genes work. The scientists analyzed the genes according to the temperatures in the two regions and the associated changes in gene expression.
“DNA is the instruction book inside every cell, guiding how an organism grows and develops,” said lead researcher Dr. Alice Godden. “By comparing the active genes of these bears with local climate data, we found that rising temperatures appear to cause a dramatic increase in the activity of jumping genes in the DNA of bears in southeast Greenland.”
As the local climate and diet evolves as a result of habitat and prey changes forced by global warming, bear genetics appear to adapt, with the group of bears in the warmest part of the country showing more change than communities further north. The study authors said these changes could help us understand how polar bears might survive in a warming world, understand which populations are most at risk and guide future conservation efforts.
That’s because the results, published Friday in the journal Mobile DNA, suggest that changing genes play a crucial role in how different polar bear populations evolve.
Godden stated: “This discovery is important because it shows, for the first time, that a unique group of polar bears in the warmest part of Greenland uses ‘jumping genes’ to rapidly rewrite their own DNA, which could be a desperate survival mechanism against melting sea ice.”
Temperatures in northeast Greenland are cooler and less variable, while in the southeast there is a much warmer and less icy environment with sharp temperature fluctuations.
Animals’ DNA sequences change over time, but this process can be accelerated by environmental stress, such as rapid climate warming.
Some interesting DNA changes were observed, such as in areas related to fat processing, which could help polar bears survive when food is scarce. Bears in warmer regions have a tougher, plant-based diet compared to the fatty, seal-based diet of northern bears, and the DNA of southeastern bears seems to adapt to this.
“We identified several genetic hotspots where these jump genes were highly active, some located in protein-coding regions of the genome, suggesting that bears are undergoing rapid and fundamental genetic changes as they adapt to the disappearance of their sea ice habitat,” Godden also said.
The next step will be to examine other populations of polar bears, of which there are 20 worldwide, to see if similar changes occur in their DNA.
This research could help protect bears from extinction. But scientists said it was essential to stop the acceleration of temperature rise by reducing the burning of fossil fuels.
