Dr. Melanie Lancaster, leading the study in Frontiers in Conservation Science as the senior author, emphasized the formidable challenges associated with locating and assessing polar bear populations in the Arctic. The process is notably difficult, expensive, and time-consuming. Understanding the bears’ responses to climate change adds an additional layer of complexity to these conservation efforts.
The trace of every contact
The scientists drew inspiration from forensic methodologies capable of analyzing small and degraded DNA samples. Unlike the stress-inducing and perilous process of physically capturing bears, a concern for both bears and humans, the researchers opted for a non-invasive approach. By examining sources of DNA naturally shed during the bears’ movements, a method known as environmental DNA, the scientists aimed to gather crucial information without disrupting the animals or causing distress to local Indigenous communities.
Elisabeth Kruger, an author of the article from the World Wildlife Fund, highlighted the apprehensions voiced by many Inuit regarding invasive research techniques. These concerns primarily revolve around the well-being of individual polar bears and the safety of those who might engage in bear harvesting later on. The enthusiasm surrounding innovative methods like the one discussed stems from the fact that individuals collecting samples no longer need direct interaction with polar bears. This approach mitigates potential risks to both the bears and the people involved, addressing the community’s anxieties.
Environmental DNA is frequently derived from animal feces, offering a common source for genetic material. Nevertheless, the quality of DNA obtained from feces doesn’t consistently meet the standards required for detailed individual-level analysis crucial to conservation efforts. Moreover, for territorial species like the lynx and snow leopard, collecting fecal samples may influence the animals’ behavior. Consequently, the scientists opted for an alternative approach, focusing on skin cells found in snowy footprints.
Dr. Micaela Hellström, the lead author from MIX Research Sweden AB, emphasized the advantage of using tracks for DNA analysis. These footprints typically harbor fresh cells, and the cold temperatures act as a natural preservation, maintaining the integrity of the DNA. In contrast, DNA extracted from feces, having passed through the digestive system, tends to be more degraded, posing greater challenges for analysis.
Following their footsteps
The researchers gathered snow from individual tracks left by Alaskan polar bears and Swedish Eurasian lynxes, both in their natural habitats and in captivity. Additionally, snow from tracks made by a captive snow leopard was collected. Complementary biological materials like hair, saliva, and mucus were also sampled, affirming the accuracy of the genotypes obtained from the tracks.
A total of 24 wild polar bear tracks and 44 wild lynx tracks were subjected to sampling. The snow was melted and filtered to extract environmental DNA, followed by microsatellite analysis. Despite the low concentrations of DNA recovered from tracks in the wild, the researchers successfully retrieved nuclear DNA from 87.5% of wild polar bear tracks and 59.1% of wild lynx tracks. Thirteen wild polar bear samples were genotyped, revealing 12 distinct individuals.
While only 11% of lynx tracks could be genotyped initially, the percentage substantially increased when focusing on tracks sampled by trained personnel. From samples collected by trained individuals, 76% yielded nuclear DNA, with 24% successfully genotyped.
A paws-off approach
The application of this technique holds immense promise in advancing the conservation efforts for these animals. It provides a valuable tool for gaining insights into their populations, behavior, and facilitates the effective management of human-animal conflicts by enabling precise identification of individual animals. While non-invasive sampling may have a lower success rate, its ease of collection has the potential to substantially enhance sample sizes, thereby broadening the scope of research and understanding in these critical areas.
Lancaster expressed the aspiration that the polar bear research community, in collaboration with hunters, volunteers, and Indigenous communities, will embrace this method as a fresh approach to gathering information about polar bears. Additionally, there is a hope that this methodology can be extended to encompass other animals inhabiting snowy environments. The successful application of the technique to lynxes and snow leopards is seen as an initial step in demonstrating its adaptability to a broader range of species in similar habitats.
Resources
- ONLINE NEWS Frontiers. (2023, December 4). Following in polar bears’ footprints: DNA from snow tracks could help monitor threatened animals. Phys.org. [Phys.org]
- JOURNAL Hellström, M., Kruger, E., Näslund, J., Bisther, M., Edlund, A., Hernvall, P., Birgersson, V., Augusto, R., & Lancaster, M. L. (2023). Capturing Environmental DNA in Snow Tracks of Polar Bear, Eurasian Lynx, and Snow Leopard Towards Individual Identification. Frontiers in Conservation Science, 4. [Frontiers in Conservation Science]
Cite this page:
APA 7: TWs Editor. (2023, December 4). DNA from Snow Tracks Reveals Polar Bears’ Secrets: A New Method to Monitor the Threatened Species. PerEXP Teamworks. [News Link]
