Could sucking DNA out of the air help save endangered species?
Sucking DNA out of thin air can be used to identify animals, and could prove a useful tool to help identify – and preserve – endangered species, research has shown.
The technique can be used to identify nearby animals, even if they can’t be seen.
Researchers from two institutions monitored DNA in the air at a zoo and used it to identify animals, hinting that sampling DNA from the air could be a useful technique in tracking animal numbers.
Kristine Bohmann, head of a research team at the University of Copenhagen, said: "Capturing airborne environmental DNA from vertebrates makes it possible for us to detect even animals that we cannot see are there.
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"Earlier in my career, I went to Madagascar hoping to see lots of lemurs. But in reality, I rarely saw them. Instead, I mostly just heard them jumping away through the canopy.
"So, for many species it can be a lot of work to detect them by direct observation, especially if they are elusive and live in very closed or inaccessible habitats."
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Animals can be monitored in many ways – directly by camera and in-person observation, or indirectly by what they leave behind, like footprints or faeces.
But these methods can be time-consuming. For example, monitoring animals by camera requires knowledge of where to put the cameras on the animal's path, sifting through thousands of pictures, and usually a bit of luck.
Elizabeth Clare, lead researcher of a team at Queen Mary University of London, said: "Compared to what people find in rivers and lakes, monitoring airborne DNA is really, really hard, because the DNA seems super diluted in the air.
"But our zoo studies have yet to fail for different samplers, genes, locations, and experimental approaches. All of it worked and surprisingly well."
Environmental DNA, or eDNA, is a well-established technique used most frequently to monitor aquatic organisms by sequencing eDNA from water samples.
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Bohmann said: "Air surrounds everything, and we wanted to avoid contamination in our samples while optimising true detection of animal DNA.
“Our newest work with airborne eDNA involves what we usually do when processing eDNA samples, just tuned up a little bit."
Each research group conducted its study at a local zoo by collecting samples at various places in the zoo, including inside walled-in enclosures like the tropical house and indoor stables, as well as outdoor enclosures in the open air.
Christina Lynggaard, first author and postdoctoral fellow at the University of Copenhagen, said: "To collect airborne eDNA, we used a fan, like one you would use to cool down a computer, and attached a filter to it. We then let it run for some time."
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The fan draws in air from the zoo and its surroundings, which could contain genetic material from any number of sources; for instance, from breath, saliva or fur.
Lynggaard said: "It could be anything that can become airborne and is small enough to continue floating in the air.
"After air filtration, we extracted the DNA from the filter and used PCR amplification to make a lot of copies of the animal DNA. After DNA sequencing, we processed the millions of sequences and ultimately compared them to a DNA reference database to identify the animal species."
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