Changes to polar bear DNA could help them adapt to global heating, study finds | Wildlife
Changes in the DNA of polar bears that could help the animals adapt to warmer climates have been detected by researchers, in a study believed to be the first time a statistically significant link has been found between rising temperatures and altered DNA in a wild mammal species.
Climate change threatens the survival of polar bears. Two-thirds of them are expected to be gone by 2050, as their icy habitat melts and the weather gets warmer.
Scientists from the University of East Anglia have found that certain genes linked 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 “jumping genes”: small moving pieces of the genome that can influence the functioning of other genes. The scientists studied genes in relation to temperatures in the two regions and associated changes in gene expression.
“DNA is the instruction manual inside every cell, which guides how an organism grows and develops,” said lead researcher Dr Alice Godden. “By comparing the active genes of these bears to local climate data, we found that rising temperatures appear to lead to a dramatic increase in jumping gene activity in the DNA of bears from southeast Greenland.”
As local climates and diets evolve due to changes in habitat and prey caused by global warming, bear genetics appear to adapt, with the group of bears in the warmer part of the country showing more changes than communities further north. The study authors said these changes could help us understand how polar bears might survive in a warming world, better understand which populations are most at risk, and guide future conservation efforts.
Indeed, the results, published Friday in the journal Mobile DNA, suggest that changing genes play a crucial role in the evolution of different polar bear populations.
Godden said: “This discovery is important because it shows, for the first time, that a unique group of polar bears in the warmest part of Greenland are using ‘jumping genes’ to rapidly rewrite their own DNA, which could be a desperate survival mechanism against melting sea ice.
Temperatures in northeast Greenland are colder and less variable, while in the southeast the environment is much warmer and less frigid, with large temperature fluctuations.
DNA sequences in animals change over time, but this process can be accelerated by environmental stress such as rapid climate warming.
There have been some interesting changes in DNA, particularly in areas related to fat processing, that could help polar bears survive when food is scarce. Bears in warmer regions had a harsher, plant-based diet than northern bears’ diet of fats and seals, and the DNA of southeastern bears seemed to adapt to this.
Godden said: “We identified several genetic hotspots where these jumping genes were very active, with some located in protein-coding regions of the genome, suggesting that bears are undergoing rapid and fundamental genetic changes as they adapt to their disappearing sea ice habitat. »
The next step will be to look at other populations of polar bears, numbering 20 worldwide, to see if similar changes are occurring in their DNA.
This research could help protect bears from extinction. But scientists say it is crucial to stop the accelerating rise in temperatures by reducing the consumption of fossil fuels.
Godden said: “We cannot be complacent, this offers some hope but does not mean polar bears are at any less risk of extinction. We still need to do everything we can to reduce global carbon emissions and slow rising temperatures.”
