Blown Away

When deoxyribonucleic acid, better known as DNA, was first discovered in the late 1800s, it didn’t make much of a splash – but it would go on to revolutionize the field of biology. Today, DNA is used in everything from untangling evolutionary lineages to genetic engineering to storing data. And it is quickly becoming a powerful tool for conservation.

Environmental DNA, or eDNA, is composed of stray bits of material from an organism – be it hair, skin cells, bits of exoskeleton, mucus or some other source. By collecting and analyzing eDNA, scientists can uncover which species are present in a given ecosystem. They can even use it to track things like viruses, or detect the presence of human remains.

“It’s one of the very few generalizable tools for biodiversity science,” says Elizabeth Clare, a molecular ecologist and professor at York University.

Prior to the discovery of eDNA, researchers had to rely solely on things like camera traps or direct observation to determine which species inhabited an area. These techniques can give a good idea of the relative abundance of certain species, but they miss a lot – especially rare or hard-to-find organisms. As the climate crisis continues to devastate ecosystems across the globe, eDNA has proven to be a vital tool for monitoring species richness.

For the first several years that eDNA-analyzing technology was available, it was only used to study soil or aquatic environments such as streams, rivers, lakes and fisheries. Researchers didn’t expect to be able to extract tiny fragments of genetic material from other sources. But Clare and some of her colleagues suspected that they might be able to collect eDNA samples from other places – including the air. In 2020, while serving as a senior lecturer at Queen Mary University of London, she proposed the idea to the institution, which was actively seeking “high risk, high reward” research initiatives. “Long story short, we pitched this idea of trying to filter DNA out of air samples, and they funded it,” Clare says.

She pulled together a team and got access to an outdoor zoological park. They chose the location because it had a variety of unique, non-native animals (there aren’t very many sources of elephant DNA in the U.K. that their samples could be confused with) and because, at the time, it was free of visitors due to COVID-19 lockdowns. The researchers took air filter samples from all around the zoo over the course of several months. At first, Clare says, they were nervous that they might not find anything to analyze – what if wind or rain carried all of the detectable eDNA away?

The experiment was an overwhelming success, indicating that eDNA can be extracted from the air

As it turns out, the team had nothing to worry about. “There was DNA everywhere,” says Clare. The experiment was an overwhelming success, indicating that eDNA can be extracted from the air with relative ease.

Unbeknownst to Clare and her co-workers, however, another research team led by Kristine Bohmann at the University of Copenhagen was conducting a very similar experiment around the same time – also at a zoo. Both teams discovered one another’s research when they tried to submit their results to the same journal.

“Basically, the papers perfectly replicated each other,” Clare recalls. “Which is neat.” Rather than make it a competition to see who could get published first, the researchers decided to continue submitting their papers together, stipulating that whichever journal accepted one would have to accept both. After a couple of tries, the journal Current Biology published both papers in tandem.

This open, collaborative approach has benefited Clare and her colleagues while working on other projects as well. After reading about the eDNA samples pulled from air at the zoo, a physicist reached out to Clare with an idea: what if scientists harnessed existing air quality monitors to study eDNA?

Air quality monitoring stations are designed to capture and analyze particulates in the lower atmosphere. They help alert people to the presence of dangerous pollution or concentrated wildfire smoke, and they exist in virtually every country around the globe. What’s more, they’re often stationed in or near highly biodiverse areas, such as national parks. If most, or even some, of these sensors are scooping up eDNA in addition to particles like lead, smoke or soot, it could be a game changer for biodiversity monitoring.

Clare and her co-authors are currently exploring this idea. But regardless of how essential air quality monitoring stations end up being for monitoring species richness, one thing is certain: the discovery of airborne eDNA has blown the future of biodiversity research wide open. ■