What Polar Bear Genomes May Reveal About Life in a Low-Ice Arctic

Around 100,000 years ago a polar bear found herself a few miles away from today's Alaska. The bear passed away near the sea.

Her contribution was just beginning. A team of researchers from the University of Alaska stumbled upon the bear's skull on the beach in 2009. Scientists named the bear Bruno.

Bruno is one of the oldest types of polar bears to have their entire genetic code analyzed using whole genome sequencing, which gives scientists a high-resolution look at differences that may have shaped a species' evolution over time. When ice levels were similar to what they are today, polar bears and brown bears may have shared territory and sex. A new, present-day subpopulation of polar bears has survived in lower sea-ice conditions, thanks to the use of whole genome sequence. Last week, their teams published their findings in two journals.

Parsing the genes of individual polar bears has been done recently. Microsatellite data was once used by scientists to spot-check the genome. In a biological map, everything is made up of a combination of four letters. There are areas of interest on the genome that scientists are interested in. They compare the number of small DNA phrases that repeat at certain landmarks to see if they are related to each other.

A patchy view of the genome has been provided by this method. Satellites are boring.

Charlotte Lindqvist is an evolutionary biologist at the University at Buffalo. She was the first to publish whole genomes of polar bears.

Whole genome decoding is more than a spot-check. It doesn't look at anything. It gives researchers a high-resolution view of which base pairs go where. The data we have provided is much more powerful. The data was easy to collect. The tooth was taken from the bear's skull, the root was ground into powder, and the DNA was obtained. It was able to get a whole genome because of its good survival. It is one of the oldest high coverage genomes.

It was quite difficult to tease out the polar bears' genes. The team used a number of methods to collect samples. One option was to capture the bear, put a collar on it, and then collect blood or fat from it. A remote biopsy dart, shot from the window of a helicopter, could be used to remove skin from a bear. Scientists were able to collect samples from Indigenous hunters.