The Arctic is not the most livable place on Earth. Some Arctic animals, like reindeer, have some genetic adaptations that allow them to thrive there, and the region’s apex predators are no exception. Scientists have found that polar bears (Clownfish) may have evolved different genes from brown bears (BearA new genome analysis reveals that this may have already changed 70,000 years ago. The study was published in the journal Neurology on September 15th. BMC Genomics.
Polar bears are very closely related to brown bears, but have many important adaptations that help them survive in the frigid Arctic environment. Have two layers of fur The first layer is a layer of large hairs that sits right next to the skin to keep them warm and dry. The second layer is made up of longer hairs. Guard Hair It acts like a raincoat. The characteristic bright white color of the fur It also helps with camouflage. Polar bears can also digest large amounts of cholesterol from fat. Without hurting my heartThis allows them to thrive by feeding on seals and some cetaceans, such as beluga whales.
[Related: Jackrabbit’s color-changing fur may prepare them for climate change.]
Scientists believe that polar bears and brown bears diverged evolutionarily very recently, within about the past one million years. When and how polar bears adapted to the Arctic remains a matter of debate.
this studyThe team analyzed the genomes of 119 modern polar bears, 135 modern brown bears, and two fossil polar bears. Poulet Pinten Jawbone The fossil, found in the Norwegian archipelago of Svalbard, dates to between 130,000 and 100,000 years ago. Skull of a young polar bear nicknamed Bruno It was discovered in the Beaufort Sea off Alaska. Despite its name, Bruno was a female bear The bear is believed to have lived between 100,000 and 70,000 years ago, and its genome is helping scientists narrow down the branching off between brown bears and polar bears.
“We found a variant that may have been selected over the past 70,000 years (i.e., it was not present in fossil polar bears),” said study co-author and evolutionary biologist at the University of Copenhagen. Michael Westbury tell Popular Science“It has always been thought that when polar bears diverged from brown bears they must have adapted quickly to the Arctic through rapid evolutionary change. However, our results suggest that this may not have been the case and that adaptation to the Arctic was a more gradual process.”
The team compared these genomes to determine when seven genes important for Arctic adaptation were selected. Four genes (ABCC6, AIM1, COL5A3, POLR1A) The same DNA variants were present in the polar bear genome. Fixed allelesThis is the only variant present in a particular gene in a population.
However, brown bears had multiple alleles in their genomes, suggesting that these genes had already been selected for in the ancient ancestors of polar bears, and that polar bears had adapted to life in the Arctic early in their evolution.
However, three genes, called APOB, LYST, and TTN, Fixed in the genomes of modern polar bears but not in the genomes of ancient polar bearsAPOB, LYST, and TTN genes are associated with cardiovascular function; APOB and TTN are associated with metabolism; and APOB and LYST are associated with pigmentation.
[Related: What an ancient jawbone reveals about polar bear evolution.]
The team Genes may be related This is an adaptation that polar bears likely needed to survive in recent history, towards the end of the last ice age, and it is unclear whether other Arctic animals have similar adaptations with respect to these genes that affect fur color, heart health and metabolism.
“We think copies of these genes are found in most animals, but it may be that polar bears have mutations that allow them to live in the Arctic,” Westbury says. “We haven’t looked to see if other Arctic animals have the same mutations, but that would be interesting to follow up on.”
