We can now detect hedgehogs, for example, from DNA samples taken from the air.
Dr Siouxsie Wiles is a microbiologist and associate professor at the University of Auckland.
OPINION: In June 2018, the University of Otago’s Professor Neil Gemmell led a team of researchers from New Zealand, Scotland, England, Wales, Denmark, France, and the US to look for Scotland’s infamous Loch Ness Monster.
Would the team uncover evidence of some sort of Jurassic-age reptile, a plesiosaur perhaps, lurking in the depths of Loch Ness? Or was Nessie more likely to be a giant catfish, eel, shark, or sturgeon?
To try to answer those questions, Gemmell’s team took 250 water samples from Loch Ness and extracted the environmental DNA (eDNA) present. That eDNA comes from the cells we shed every day, whether we have feathers, scales, or skin, as well as from our excrement. The team then sequenced all the extracted eDNA and ran their data against global DNA databases.
So, what did they find? Well, no plesiosaur, catfish, shark, or sturgeon DNA. But lots of eel DNA, as well as fish, amphibian and bird DNA. They also found DNA from humans, cattle, dogs, sheep, deer, badgers, foxes and rabbits.
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In other words, there almost certainly isn’t a plesiosaur living in Loch Ness. But Nessie may well be a giant eel.
More importantly, though, Gemmell and his team neatly showed how eDNA from water can be used to document what’s living not just in the water, but on the land around that water too.
Now two new studies have asked, can we find out what’s living on the land by sampling eDNA from the air? Two separate research teams set up air samplers around Copenhagen Zoo in Denmark and Hamerton Zoo Park in Britain.
The samplers drew air through filters that captured any cells and particles present. The researchers extracted the eDNA from captured cells and particles, sequenced it, and ran it against the DNA databases to identify the species it came from.
This technique has already been shown to work for identifying bacteria, fungi and plants from air samples, so the researchers were really interested in whether it would work for animals too. And it did.
The team studying Copenhagen Zoo identified 49 vertebrate species: 30 mammals, 13 birds, four fish, one amphibian, and one reptile. These spanned animals kept at the zoo, those used to feed the zoo animals, and those living outside the zoo.
It was the same at Hamerton Zoo Park. The team there identified 25 species of mammals and birds. Again, they spanned zoo residents, their food, and some local wildlife. Happily, that local wildlife included the vulnerable European hedgehog.
Another exciting finding was just how far the eDNA travelled. For example, at Hamerton, meerkat DNA was identified in air sampled at the dingo enclosure a whopping 245 metres away.
New Zealand has some gnarly environmental problems to tackle, from the health of our rivers to our aspirations to be predator-free. Using eDNA to profile what’s in our water, air and soil is just the tool we need to inform our policies and practice.
It means we can now detect what we can’t always see – and that’s a game-changer.