A new method of extraction of air DNA samples to revolutionize the study of biodiversity

Knowing and understanding biodiversity is the first step to protect it. This week the magazine Current Biology presents a new technique, based on the collecti

A new method of extraction of air DNA samples to revolutionize the study of biodiversity

Knowing and understanding biodiversity is the first step to protect it. This week the magazine Current Biology presents a new technique, based on the collection of ambient DNA samples through the air, which can provide a new and valuable tool for the control of wildlife, by allowing scientists to detect the presence of Animal species non-invasively.

Two studies, carried out by two teams other than researchers confirm the feasibility of the approach, which was tested in two European zoos: in Hamerton (United Kingdom) and Copenhagen (Denmark). While each team used a slightly different system to filter DNA, both managed to detect the presence of numerous species both inside and outside the enclosures.

The Danish team collected air samples through three devices: a commercial vacuum with water filter and two fans with integrated filters (the smallest, the size of a golf ball).

Scientists picked up samples in three zones: the okapis stable (animal sharing family with giraffe), in the tropical garden and at an exterior point located between different enclosures. "The results left us amazed: in only 40 samples we detect the presence of 49 species of birds, amphibians, reptiles and fish," says Kristine Bohmann, professor at the University of Copenhagen and project director.

"In the house of the rainforest we detect even the presence of the pond guppys (a small fish originally from America), the lazy and the boa, we also take samples in a single place from the outside and we detect many of the animals that have Access to the enclosures of that part of the zoo, for example, the kee (bird of the parrots family), the ostrich and the rhinoceros ".

The British team, on the other hand, used sensitive filters coupled to vacuum pumps to collect more than 70 air samples, also at different points of the zoo (indoors and outdoors). "When we analyze them, we were able to identify the DNA of 25 species, such as tigers, lemurs or dingos, 17 of which lived at the zoo," says Elizabeth Clare, professor at the University of York in Canada and the Queen Mary University of London .

"Samples even from the outside of closed buildings; the animals were inside, but their DNA escaped". In addition, the researchers also detected species released from the surroundings. "We collected environmental DNA from animals that were hundreds of meters, such as hedgehogs or squirrels, without a significant decrease in the concentration of the sample".

Living organisms leave DNA molecules in suspension in the surrounding environment when they interact with it. In recent years, the collection of environmental genetic material has become an important tool in aquatic ecosystems. However, the authors of the two articles point out that their application in the monitoring of terrestrial animals is not yet consolidated.

"The non-invasive nature of this method makes it especially valuable to observe vulnerable or endangered species, as well as those found in environments of difficult access, such as caves and burrows." Add Clare. "They do not have to be visible so that we know they are in the area if we can, literally, get remains of their air DNA."

One of the main challenges that environmental DNA removal must be resolved is to ensure that the results are reliable, since the analyzes of this type are very sensitive and prone to contamination. "Air is a difficult substrate to work, since everything is involved and the risk of contamination is high," explains the Christina Lynggaard researcher, which is part of the Danish team.

"We wanted to make sure that the species that we detected came from the zoo and not, for example, the laboratory, so to ensure we take air samples inside the laboratory and sequences as well." At its current stadium, the new technique only allows identifying animals already known, not discovering new species. "We depend on having the DNA of the species in a reference database to be able to compare the sequences," explains Lynggaard.

Both teams were also capable of detecting the presence of animals within the food of the zoo species, such as chickens, cows, horses or fish. The use of environmental DNA monitoring in natural environments still requires more evidence to discover its full potential, but both teams coincide in pointing out their ability to transform the way in which researchers study and monitor biodiversity.

And, ultimately, to support conservation efforts. "Air sampling could revolutionize terrestrial biomonitorization and offer new opportunities to track the composition of animal communities or to detect the invasion of non-native species," sums ELIZABETH Clare.

Updated Date: 07 January 2022, 02:12

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