New research has revealed a link between rising temperatures and changes in the DNA of polar bears, which may help them adapt and survive in increasingly challenging conditions. This is reported by Phys.org, writes UNN.
Details
A study conducted by scientists at the University of East Anglia (UEA) found that some genes associated with heat stress, aging, and metabolism behave differently in polar bears living in southeastern Greenland. This suggests that they may be adapting to warmer conditions.
The discovery suggests that these genes play a key role in how different polar bear populations adapt or evolve in response to changing local climates and diets.
The authors note that understanding these genetic changes is crucial for guiding future conservation efforts and research, as it allows us to see how polar bears can survive in a warming world and which populations are most at risk.
This comes against the backdrop of predictions that more than two-thirds of polar bears could become extinct by 2050, with complete disappearance expected by the end of the century. Temperatures in the Arctic Ocean are also at an all-time high and continue to rise, shrinking vital ice platforms that bears use to hunt seals, leading to isolation and food shortages.
How the study was conducted
The study, published in the journal Mobile DNA, analyzed blood samples from polar bears from northeastern and southeastern Greenland to compare the activity of so-called "jumping genes" — small mobile elements of the genome that can affect the function of other genes — their relationship to temperatures in these two regions, and corresponding changes in gene expression.
Scientists found that in northeastern Greenland, temperatures were colder and less variable, while in the southeast, they fluctuated and were significantly warmer, with less ice cover, creating many challenges and changes in the local environment. This area is similar to the conditions predicted for the species in the future.
Lead researcher Dr. Alice Godden from the UEA School of Biological Sciences cautioned that while the results offer some "hope" for polar bears, efforts to limit global warming must continue.
DNA is the instruction inside every cell that determines how an organism grows and develops. By comparing the active genes of these bears with local climate data, we found that rising temperatures appear to cause a sharp increase in the activity of jumping genes in the DNA of bears from southeastern Greenland.
"This effectively means that different groups of bears have different parts of their DNA altered and do so at different rates, and this activity appears to be linked to their specific environment and climate.
"This is an important discovery, as 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 in the face of melting sea ice," Godden added.
Implications for polar bear survival
Dr. Godden added: "While the rest of the species is threatened with extinction, these particular bears provide a genetic blueprint for how polar bears can rapidly adapt to climate change, making their unique genetic code an important target for conservation efforts.
"However, we cannot be complacent. This offers some hope, but it does not mean that the risk of extinction for polar bears is decreasing. We still need to do everything we can to reduce global carbon emissions and slow down temperature increases."
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Over time, human DNA sequences can change and evolve, but environmental stress, including a warmer climate, can accelerate this process. This study is considered the first time that a statistically significant link between rising temperatures and DNA changes has been found in a wild mammal species.
Changes were also found in the expression of genes related to fat processing, which is important during periods of food scarcity and may mean that southeastern bears are gradually adapting to the coarser plant-based food available in warmer regions, in contrast to the fat-rich seal diet of northern populations.
Dr. Godden and her colleagues analyzed genetic activity data collected for that study from 17 adult polar bears — 12 from northeastern and five from southeastern Greenland.
Dr. Godden noted that the next step will be to study other polar bear populations — there are about 20 subpopulations worldwide — adding: "I also hope that this work will highlight the urgent need to analyze the genomes of this valuable and enigmatic species before it's too late."
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