It is the gene that in mammals codes for the most important protein in LDL (low density lipoprotein), commonly known as ‘bad’ cholesterol.
When the researchers compare the gene set from polar bears with that of humans, changes in the apoB gene are prominently evident. Just as changes in the genes have led to changes in the fur colour from brown to white, a natural selection has led to changes in the genes that regulate the transport of fat in the blood and the breakdown of fat in the body. The researchers also show that the polar bear has developed the capabilities to live in the Arctic during just a couple of hundred thousand years – and this is a very fast evolution. The sensational findings are published on 8 May in the recognised journal CELL whose front page features a photo from the article. The comprehensive research project involved participants from China, the USA, Greenland and Denmark. The researchers believe that the brown bear migrated to the north during a warmer climate period and when a cold period subsequently set in, a group of brown bears may have become isolated and therefore forced to quickly adapt to the new colder conditions. It is thus significantly younger than previously thought,” says Professor Rune Dietz from the Arctic Research Centre, Department of Bioscience, Aarhus University.
First and foremost, the polar bear as a species is less than 480,000 years old. “We compared genes between brown and white bears and were surprised. With new data an international research team now documents that the separation from the brown bear into an independent species has gone very quickly. The polar bear has evolved over time from the common brown bear by changing its fur colour to white, the ideal colour to blend in with its ice-covered surroundings.
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