To assess conservation needs in certain areas, researchers first need to find out what animals call the region home. This task is often accomplished using trail cameras, but gaining a big picture view of a habitat is challenging when relying on literal snapshots.
As species continue to decline at a rapid pace globally, researchers need non-invasive tools that can swiftly determine which critters lurk close by, reports Michael Le Page for New Scientist.
Now, two research teams from the University of Copenhagen and Queen Mary University of London are working on a method that filters DNA from the air to detect which animals are near, reports Erik Stokstad for Science. Both studies were published this week on the preprint server bioRxiv, awaiting peer-review. The results demonstrate how environmental DNA (eDNA) can be used to detect terrestrial animals.
“There’s more than just spores; there are cells and hair and all kinds of interesting things that float through the air,” Julie Lockwood, a molecular ecologist at Rutgers University not involved in either study, tells Science.
Previously, Elizabeth Clare, a molecular ecologist now based at York University, published a study in the journal PeerJ detailing how eDNA from naked mole rats could be detected from air samples obtained in a laboratory setting, Science reports. To see if scientists could apply this tech to real-world situations, Clare and her team at the Queen Mary University tested air samples from 15 locations at the Hamerton Zoo Park in Huntingdonshire, United Kingdom. The air from indoor and outdoor enclosures were sampled using a pump and filter for 30 minutes each.
Seventy-two samples were sequenced using the polymerase chain reaction technique (PCR), a method used to amplify segments of DNA collected on the air filters. From the samples, the research team was able to identify 17 species of animals that lived within the zoo enclosures or roamed around it, such as deer and hedgehogs. Some of the DNA collected came from the zoo residents’ meaty meals, including chicken, cow, or pig. In total, the team determined 25 species of birds and mammals.
The researchers at the University of Copenhagen had a similar experiment where they went to the Copenhagen Zoo and vacuumed air from three different locations for anywhere between 30 minutes to 30 hours, New Scientist reports. Using the eDNA collected on the filters, the team detected animals up to 300 meters away from the vacuum pump. The method the team used to filter DNA was so sensitive that when the scientists sampled an enclosed area, DNA from guppies swimming in tanks were also picked up. A total of 49 species of vertebrae were detected, Science reports.
Similar methods were previously used to detect species in aquatic settings. The technique identified eDNA from rare species like the great crested newt and olm, an aquatic salamander, New Scientist reports.
Scientists suspect the method may detect animals in hard-to-reach or see areas, such as dry environments, caves, or burrows. However, the method still needs some finetuning. Researchers still need to evaluate how far eDNA may travel in the air depending on its environment, how different animals shed DNA, and how eDNA can be contaminated, Science reports.
Despite the unknowns, various scientists are planning on using the method to monitor wildlife, Clare tells New Scientist.
“The ability to detect so many species in air samples using DNA is a huge leap. It represents an exciting potential addition to the toolbox,” Matthew Barnes, an ecologist at Texas Tech University who was not involved with the study, tells Science.