A new high-tech way of tracking polar bears could help save the iconic species.
DNA from snow tracks could help monitor the threatened animals, say scientists.
Researchers have developed a non-invasive form of DNA analysis using skin cells shed in the bears’ footprints in the snow.
Study senior author Dr. Melanie Lancaster, of the World Wide Fund for Nature Global Arctic Programme, said: “It is particularly challenging, expensive, and time-consuming to find polar bears in the Arctic, let alone count them and understand how they are coping with climate change.”
The research team was inspired by forensic techniques that can be applied to tiny, degraded DNA samples.
They explained that, with such techniques, it isn’t necessary to physically capture bears, which can be stressful and dangerous for both the animals and humans, and is a source of concern to some local Indigenous communities.
Instead, scientists can look at sources of DNA shed in passing environmental DNA.
“Many Inuit express concern about invasive research methods,” said co-author Elisabeth Kruger of the World Wildlife Fund.
“People are concerned about the welfare of the individual polar bear and the health and safety of people who may harvest the bear later.
“This is one of the reasons we are so excited about new methods like this – the person collecting the sample never needs to even see or be seen by the polar bear.”
A common form of environmental DNA is deposited when animals defecate.
However, the DNA quality is not always good enough for the individual-level analysis needed for conservation.
And for territorial animals such as the two other species the scientists tested – lynxes and snow leopards – sampling feces could affect the animals’ behavior.
The researchers instead turned to skin cells in snowy footprints.
Lead author Dr. Micaela Hellström, of MIX Research Sweden AB, said: “The tracks usually contain fresh cells, and the DNA is intact because of the cold ‘storage’ temperature.
“DNA that has passed the gut is much more degraded and therefore more challenging to work on.”
The research team collected snow from individual tracks made by Alaskan polar bears and Swedish Eurasian lynxes in the wild and in captivity.
They also collected snow from tracks made by a captive snow leopard.
Materials such as hair, saliva, and mucus were also sampled, confirming that the tracks provided accurate genotypes.
A total of 24 wild polar bear tracks and 44 wild lynx tracks were sampled.
The research team melted and filtered the snow to collect environmental DNA, and then carried out microsatellite analysis.
Although the concentrations of DNA retrieved from tracks sampled in the wild were very low, it was possible to retrieve nuclear DNA from 87.5 percent of wild polar bear tracks and 59.1 percent of wild lynx tracks.
A total of 13 of the wild polar bear samples could be genotyped, identifying 12 different individuals.
One in nine of the lynx tracks (11 percent) could be genotyped, but when the scientists only looked at the tracks sampled by trained personnel, the figure rose substantially.
They were able to retrieve nuclear DNA from 76 percent of samples collected by trained personnel, and to genotype 24 percent of those sampled, according to the findings published in the journal Frontiers in Conservation Science.
The researchers say that the technique has “huge potential” to aid the conservation of polar bears, to better understand their populations and behavior, and to manage conflict with humans.
Although non-invasive sampling has a lower success rate, they say the ease of collection means that it can “significantly expand” sample sizes.
“We hope this method will be taken up by the polar bear research community, with the involvement of hunters, volunteers, and Indigenous communities, as a new way to collect information on polar bears,” said Dr. Lancaster.
“We also hope the method will be expanded to other animals living in snowy environments – we have shown it works for lynx and snow leopards as a start,” she added.
Produced in association with SWNS Talker
