Changes in polar bear DNA that may help the animal adapt to warmer climates have been discovered by researchers. The study is believed to be the first time a statistically significant link has been found between rising temperatures and DNA changes in a wild mammal species.
Climate disruption threatens the survival of polar bears. Two thirds of them are he is expected to disappear by 2050, when their icy habitat melts and the weather gets hotter.
Now scientists from the University of East Anglia have found that some genes associated with heat stress, aging and metabolism behave differently in polar bears living in the south east. Greenlandsuggesting 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, mobile regions of the genome that can influence the functioning of other genes. The scientists studied genes in relation to temperature in two regions and associated changes in gene expression.
“DNA is the instruction manual inside every cell that determines 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 be driving a dramatic increase in the activity of jumping genes in the DNA of southeast Greenland bears.”
As local climate and diet change as a result of habitat and prey changes caused by global warming, bear genetics appear to be adapting, with a group of bears in the warmest part of the country showing more changes than communities further north. The study authors said these changes could help us understand how polar bears can survive global warming, provide information about which populations are most at risk and guide future conservation efforts.
That's because the findings, published Friday in the journal Mobile DNA, suggest that changing genes play a critical role in the development 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 quickly rewrite their own DNA, which may be a desperate survival mechanism against melting sea ice.”
Temperatures in northeast Greenland are cooler and less variable, while the southeast is a much warmer and less icy environment with wild temperature swings.
DNA sequences in animals change over time, but this process can be accelerated by environmental stress, such as a rapidly warming climate.
There have been some interesting DNA changes, such as in areas related to fat processing, that may help polar bears survive when food is scarce. Bears in warmer regions had a coarser plant-based diet compared to the fatty, seal-based diet of northern bears, and the DNA of southeastern bears appears to have adapted to this.
Godden said: “We identified several genetic hotspots where these jumping genes were highly active, with some located in protein-coding regions of the genome, suggesting that bears are undergoing rapid fundamental genetic changes as they adapt to their endangered sea ice habitat.”
The next step will be to study other polar bear populations, 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 critical to stop accelerating temperature rises by reducing the burning 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.”
