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Polar bears are endangered by the changing climate as the ice where they hunt is disappearing.(Image credit: Jami Tarris/Getty Images)ShareShare by:
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Heat exposure may be prompting genetic shifts in polar bears in southern Greenland, according to a fresh analysis.
This species is struggling in the face of a shifting global environment. Worldwide sea ice amounts hit a historical low in February, and our planet’s increasing warmth is elevating sea levels. Such shifts pose a threat to polar bears, who make their homes and seek sustenance on the diminishing ice expanses.
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The study, detailed Dec. 12 in the publication Mobile DNA, “reveals, for the first time, that a distinct group of polar bears in Greenland’s warmest area are employing ‘jumping genes’ to swiftly modify their own DNA, perhaps as a last-ditch survival strategy against thawing sea ice,” conveyed lead researcher Alice Godden, a senior research affiliate at the University of Anglia in the U.K., in a written statement.
Jumping genes, alternatively called transposons or mobile genetic elements, represent segments of DNA capable of relocating from one position on the genome to another. Depending upon their point of insertion within the organism’s genetic blueprint, transposons have the capacity to influence how other genes manifest. Over a third of the polar bear genome comprises mobile genetic elements, while within plants, this proportion can reach as high as 70%. Conversely, transposons make up approximately 45% of the human genome.
Transposons seem to be instrumental in aiding polar bears to acclimate to environmental changes, according to the new study’s authors.
Map indicating temperatures across different polar bear habitats in Greenland.
A 2022 analysis featured in the journal Science spotlighted a secluded polar bear group in southern Greenland that demonstrated reduced dependence on sea ice. Separating from a group of bears in northern Greenland roughly 200 years prior, their DNA contrasted with that of their northern counterparts. This new investigation builds upon this prior knowledge.
The researchers scrutinized the DNA of 17 fully grown polar bears in Greenland, comprising 12 from the cooler northeast sector and five from the group in the warmer southeast. They drew comparisons of transposon activity within the two populations and subsequently related it to climate records.
In the Southeastern group, modifications were observed in genes connected to heat-induced stress, senescence, and metabolism, including fat processing, an essential adaptation when provisions become scarce. Per the study’s findings, this implies the bears “might be adjusting to their warmer climate conditions.”
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“By comparing these bears’ dynamic genes against local environmental data, we’ve determined that escalating temperatures seem to be instigating a marked surge in the activity of jumping genes within the DNA of southeastern Greenland bears,” Godden explained. “In essence, this signifies that different bear groups are undergoing alterations to varying sections of their DNA at differing rates, and this dynamism appears linked to their distinct environments and climates.”
Notwithstanding the potential capacity of bears to adapt to hotter climates and diminished ice cover, Godden cautioned that climate change continues to pose a significant danger to polar bears.
“We cannot afford to be complacent; this does offer a glimmer of optimism but does not indicate any reduction in the risk of polar bear extinction,” she stated. “We must persist in exerting every possible effort to curtail global carbon emissions and decelerate the pace of temperature increases.”
Sarah WildSocial Links NavigationLive Science Contributor
Sarah Wild serves as a freelance science journalist hailing from both Britain and South Africa. Her writings encompass particle physics, cosmology, and every scientific domain in between. She completed studies in physics, electronics, and English literature at Rhodes University, situated in South Africa, subsequently pursuing an MSc Medicine specializing in bioethics.
Since embarking on a professional journalism career, she’s authored books, garnered awards, and presided over national science newsrooms. Her journalistic contributions have been featured in esteemed publications such as Nature, Science, Scientific American, and The Observer, among others. In 2017, she was honored with a gold AAAS Kavli award in recognition of her investigative reporting on forensic science practices within South Africa.
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