Vacuuming DNA out of the air can reveal which animals are present in an area, two teams have independently shown. The approach could make it much easier to monitor wildlife in terrestrial environments around the world, and even help study airflow.
鈥淭his could have a profound impact on a lot of different fields,鈥� says at York University in Toronto.
Looking at which aquatic animals are present by searching for so-called environmental DNA, or eDNA, in water has already had a massive impact on fisheries and conservation, says Clare. It听has also helped detect rare species.
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When Clare did a recent report on eDNA, she initially wrote that it could be detected in air as well as in water and soil, because she assumed it could. But when she went looking for references to back this up, all she found was one Japanese high school project, so her team decided to try it for themselves.
Meanwhile, at the University of Copenhagen in Denmark had come up with the same idea. After initial lab experiments, both teams field-tested the approach in zoos where the animals present are known.
Bohmann鈥檚 team vacuumed air through fine filters for between 30 minutes and 30 hours at various sites in Copenhagen Zoo and then analysed the samples using the eDNA techniques developed for water or soil samples.
Her team detected DNA from animals in outside enclosures up to 300 metres away from the sampler, missing just a few species around the edge of the zoo and some birds kept in cages on the other side of a building.
In a sample taken in the tropical house, Bohmann鈥檚 team even detected DNA from guppies in a tank as well as from the other denizens. Initially, the team thought there were some false positives, too, but all the species identified turned out to either be fed to the animals in the zoo, or to live in or around it.
In tests at Hamerton Zoo Park in the UK, Clare鈥檚 team got very similar results, also identifying DNA from food animals and local wildlife as well as zoo residents. The fact that two teams independently replicated each other鈥檚 results shows this approach really does work, says Clare.
Several groups are already planning on trying out this approach for monitoring biodiversity in wilderness areas, says Clare. Many existing methods are quite invasive, she says, such as catching animals to see which are present. And even methods such as camera traps require animals to pass through certain areas.
The approach could find all sorts of other uses too, says Clare. For instance, when the source of DNA is known, it could be used as a way of tracking airflow.
What form the airborne DNA is in isn鈥檛 known, says Clare. The teams might be detecting DNA in, say, cast-off skin cells. But it is also possible cells are breaking up and releasing naked DNA into the air.
References: bioRxiv, and
