Scientists have discovered a way to capture DNA Observations from snow tracks – a promising non-invasive way to monitor elusive animals like polar bears.

The polar bear is a symbol of the Arctic, an elusive and vulnerable animal. Close monitoring of polar bear populations is critical to polar bear conservation, but polar bears are so difficult to find that critical data about population size and connectivity between those populations is lacking. I am. Scientists have now developed a helpful new tool: DNA analysis using skin cells shed from bear tracks in the snow.

Dr Melanie Lancaster of the World Wildlife Fund’s Global Arctic Program said: ‘Finding polar bears in the Arctic, let alone counting them and understanding how they are coping with climate change, is particularly difficult. “And it’s expensive and time-consuming.” , senior author of the study Frontiers of conservation science.

Innovative forensic techniques in preservation

The scientists were inspired by forensic techniques that can be applied to trace amounts of degraded DNA samples. These techniques eliminate the need to physically capture bears, which can be stressful and dangerous for both bears and humans, and is a concern for some local indigenous communities. Instead, scientists can look at the source of accidentally released DNA: environmental DNA.

A polar bear in Utchagvik, Alaska.Credit: Elizabeth Kruger, World Wildlife Fund

“Many Inuit have expressed concerns about invasive research methods,” said the article’s author, Elizabeth Krueger of the World Wildlife Fund. “People are concerned about the welfare of individual polar bears and the health and safety of those who may later harvest the bears. This is one reason we are so excited about new methods like this. The person collecting the samples does not need to see or even be seen by the polar bear.”

Environmental DNA: a non-invasive tool

A common form of environmental DNA is deposited when animals defecate. However, the quality of DNA is not always sufficient for the individual-level analysis required for preservation. Furthermore, in the case of territorial animals like her other two, seed Scientists tested lynx and snow leopards, and the collection of faeces can affect the animals’ behavior. So the researchers focused on the skin cells in snowy footprints.

“Trucks typically contain fresh cells and the DNA is intact due to the cold ‘storage’ temperatures. “The DNA that passes through the intestine is further degraded, making it more difficult to study,” said lead author Dr Michaela Helström from MIX Research Sweden AB.

Real-world tracking and sampling

The researchers collected snow from individual footprints made by polar bears in Alaska and Eurasian lynx in Sweden in the wild and in captivity. They also collected snow from footprints made by captive snow leopards. Additional substances such as hair, saliva, and mucus were also sampled to ensure that the traces yielded accurate genotypes.

Twenty-four wild polar bear tracks and 44 wild lynx tracks were sampled. The researchers melted and filtered the snow to collect environmental DNA and analyzed the microsatellites. Although the concentration of DNA recovered from footprints collected in the wild was very low, we were able to recover nuclear DNA from 87.5% of wild polar bear footprints and 59.1% of wild lynx footprints. We were able to genotype 13 of the wild polar bear samples and identify 12 different individuals.

They were able to genotype 11% of the lynx footprints, but this percentage increased significantly when scientists examined only footprints sampled by trained personnel. They were able to recover nuclear DNA from 76% of the samples collected by trained personnel and genotype 24% of the samples.

A step-by-step approach

This technology has great potential to inform conservation of these animals, better understand animal populations and behavior, and manage conflicts with humans through accurate animal identification. Although non-invasive sampling has a low success rate, it is easy to collect and can greatly expand sample size.

“We hope this method will be adopted by the polar bear research community as a new way to collect information about polar bears, with the participation of hunters, volunteers, and indigenous communities,” Lancaster said. “We also hope that this method can be extended to other animals that live in snowy environments. We have started by showing that this method works for lynx and snow leopards as well. I did.”

Reference: “Capturing environmental DNA from snow tracks of polar bears, lynx, and snow leopards for individual identification” Michaela Hellström, Elisabeth Kruger, Johan Neslund, Mia Bister, Anna Edlund, Patrick Hernvall, Viktor・Birgerson, Rafael Augusto, Melanie L. Lancaster, October 11, 2023. Frontiers of conservation science.
DOI: 10.3389/fcosc.2023.1250996