Groundbreaking research has revealed that polar bears diverged from brown bears a mere 70,000 years ago, shedding new light on the remarkable adaptations that enabled these Arctic icons to thrive in one of the harshest environments on Earth.
Sequencing the genome of a polar bear.
The origins of polar bears: Molecular ecologists publish surprising results — A team of molecular ecologists from the University of Copenhagen have just published a revealing report on the origins of polar bears. Examination of the genomes of more than 100 polar bears, 100 brown bears and a pair of fossilized polar bears indicates the two species split just 70,000 years ago — far faster than that other estimate.
The team probed the genetic variations that distinguish polar and brown bears, paying particular attention to genes for fur type, pigment and cardiovascular function. Life in the Arctic has resulted in polar bears developing some interesting abilities — like a double-layer fur coat and the ability to exist on a diet rich in cholesterol-filled blubber
Adapting to the Icy Realm
Polar bears are the undisputed kings of the Arctic, boasting an array of physical and physiological features that help them stay on top. They have thick, insulating fur and a double-layered coat to hold their heat in, as well as their bulk size and round bodies allow them to lose less heat.
However, the researchers found that polar bears have also evolved ways to process the diet of fat and cholesterol which is instrumental for living in their Arctic digs. Brown bears would contract heart disease and die young on a diet with so much fat, but polar bears have developed unique genetic adaptations that enable them to safely metabolize the fatty acids that are typical of their primary source of nutrition: seal blubber.
A polar bear’s fur is made up of two layers of hair: long, thick-guard hairs to repel water and keep it dry that cover a dense, insulating undercoat — this remarkable adaptation likely evolved as early as the last ice age and has helped enable the polar bear be the apex predator in its high-arctic ecosystem. This lead the authors of this new research study to think that perhaps they were relatively recent adaptations, which we might conclude is yet another marvel of polar bears being able adapt so quickly just by evolution.
Conclusion
The fact that polar bears diverged from brown less than 70,000 years ago is an astounding testimony to both the strength of evolution and how well adapted to their environment these iconic Arctic creatures are. Through investigating the genes of the polar bear genome, researchers have discovered an enormous amount of information on the genetic mechanisms behind their efficient existence in one of most challenging environments on Earth. In an era of climate change, which is having far-reaching effects on the Arctic as well as the rest of Earth, these findings serve to underscore the threats that global warming poses to one of our most iconic and unique wildlife species and vulnerable ecosystems.
