Polar bears are icons of the Arctic.Detailed monitoring of their populations is crucial for their conservation—but because polar bears are so difficult to find,we are missing critical data about population size.Scientists have now developed a new tool to help:DNA analysis using skin cells left in the bears' footprints in the snow.
The scientists were inspired by the techniques that can be applied to tiny,degraded DNA samples.With these techniques,it isn't necessary to physically capture bears,which can be stressful and dangerous for both bears and humans.Instead,the researchers can turn to the snow tracks of polar bears and look at sources of DNA left in passing—environmental DNA. "The tracks usually contain fresh cells,and the DNA is intact because of the cold' storage' temperature,"said Dr.Melanie Lancaster of the World Wide Fund,lead author.
The scientists collected snow from individual tracks made by Alaskan polar bears in the wild. Additional materials like hair and saliva(唾液)were sampled,confirming that the tracks provided accurate genotype(基因型)
24 wild polar bear tracks were sampled.The researchers melted and filtered the snow to collect environmental DNA,then carried out micro-satellite analysis.Although the concentrations (浓度)of DNA taken from trucks sampled in the wild were very low,13 of the wild polar bear samples could be genotype,identifying 12 different individuals.
This technique has huge potential to inform conservation of these animals,to better understand their populations and behavior.Although the sampling has a lower success rate,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 local communities,as a new way to collect information on polar bears,"said Lancaster."We also hope the method will be expanded to other animals living in snowy environments."
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