On an early autumn morning, a group of researchers from the Globe Institute at the University of Copenhagen embarked on an intriguing expedition into a Danish forest. Armed with plastic boxes, these scientists sought to “vacuum” animal DNA from the air.
The boxes, rigged with DNA air samplers, were strapped onto tree trunks, air filters attached, and then powered on. As the boxes powered up, a faint hum indicated that they were collecting airborne particles.
Over the next three days, the researchers returned to the forest on numerous occasions to replace the air filters, each time marking a step further into their investigation.
“We saw relatively few animals in the short time we spent in the forest when we changed the air filters. A squirrel, the sound of a woodpecker, a pheasant squawking, and a white-tailed eagle flying above us one day,” said Christina Lynggaard. However, the richness of the biodiversity they discovered in the air starkly contrasted the lack of visible activity.
Which animals were detected?
By sequencing the airborne DNA particles collected on the filters, the team discovered a surprising number of forest inhabitants. The “vacuuming” process, executed over three days in an area of the forest roughly equivalent to a football field, unveiled DNA traces from 64 animal species.
They detected the DNA of animals including domestic species like cows, pigs, sheep, chickens, and dogs, and even exotic pets like parakeets and peacocks. Yet, the real surprise was the detection of roughly 50 terrestrial wild animals.
The DNA revealed the presence of small to large wild animals with varied lifestyles – red deer, roe deer, Eurasian badger, white-tailed eagle, red fox, different vole species, robin, Eurasian red squirrel, common toad, smooth newt, great crested newt, crane, great spotted woodpecker, nuthatch, grey heron, marsh tit, woodcock, and several more.
In a stunningly short time, the researchers uncovered nearly a quarter of the land-living animals previously recorded in and around the area.
“It’s absolutely crazy! Although we have worked hard to optimise the method, we did not dare to hope for such good results. We didn’t think we would succeed so well in the very first attempt in nature,” said Professor Kristine Bohmann.
The DNA that was collected from the air is referred to as environmental DNA. “Animals secrete DNA into their surrounding environment all the time. It could be in the form of fragments of hair, feathers, and skin cells. If they are airborne, we can vacuum them and use DNA analyses to find out which animals they came from,” explained Lynggaard.
This innovative approach of “vacuuming” DNA from air builds upon a previous study by the same team that explored the presence of animal DNA in the air at a zoo and mapped the presence of many of its inhabitants.
However, there’s a big difference between a zoo and nature, as Bohmann explained: “In a zoo, the animals are present in large numbers in a relatively small area, while in nature they are much less concentrated. Therefore, we were unsure how well we could make the method work in nature. And that is where we have to get it to work if we want to use it to monitor biodiversity.”
The trial in the Danish forest has proven that airborne environmental DNA could become a valuable tool in biodiversity monitoring.
“We are in a biodiversity crisis, and tools are needed to understand how ecosystems change as a result of human impacts, to guide management strategies and to assess the risk of the spread of diseases in areas where animals can come into contact with people,” said Lynggaard.
Despite dealing with tiny amounts of airborne environmental DNA, the researchers went to great lengths to verify their findings. When they first detected DNA from peacocks, they feared it might be an error. But upon further investigation, they found local residents who confirmed occasional peacock sightings during their walks.
The initial results suggest that this method could be effective in mapping the presence of wild animals. The study inspires optimism, even though the technique needs further refinement and testing. “It demonstrates a sensitive method for mapping the presence of animals without having to see or disturb them,” said Professor Bohmann.
More about DNA air sampling
DNA air sampling, also referred to as environmental DNA (eDNA) air sampling, is a revolutionary scientific technique for collecting and analyzing DNA present in airborne particles.
This approach represents a breakthrough in ecological and biological research. It opens new and exciting opportunities to study species distribution, disease surveillance, and biodiversity.
In DNA air sampling, scientists actively capture and analyze the genetic material from air samples. Airborne DNA, often associated with microscopic particles such as dust, pollen, or skin cells, provides an environmental snapshot of the biological entities present in a particular location.
The process involves the use of specially designed air filters or samplers, which collect airborne particles from the surrounding environment. The air filters trap DNA-carrying particulates, which researchers then extract and purify in a lab.
Following extraction, scientists apply a technique called polymerase chain reaction (PCR) to replicate the collected DNA sequences. The replication allows for easier detection and analysis of the genetic material. Next, they sequence the DNA to identify the species of organisms present in the sample.
The application of high-throughput sequencing technologies, also known as next-generation sequencing, has significantly improved the detection accuracy and identification capacity of this technique.
Applications for DNA air sampling
The use of DNA air sampling extends to various domains. In ecology, it provides a non-invasive tool to study species distribution and diversity. It enables scientists to monitor the presence or absence of specific species, including endangered, invasive, or disease-causing organisms.
In public health, the technique has enormous potential in disease surveillance. By detecting airborne pathogens or allergens, scientists can monitor the prevalence of diseases, thereby aiding in early warning systems.
In forensics, DNA air sampling might prove instrumental in crime scene investigations. It could potentially detect the presence of a suspect through skin cells or other biological traces left in the air.
Limitations and future directions
While DNA air sampling holds promise, it is not without its limitations. Issues such as potential contamination, the uneven distribution of airborne DNA, and the need for comprehensive reference databases for accurate species identification can pose challenges.
Further refinement and testing of the technique are needed. However, the potential of DNA air sampling is vast, and ongoing research continues to expand its applications. As the methodology improves, it will likely become an increasingly important tool for biodiversity monitoring and ecological research.
In summary, DNA air sampling is a promising technique that leverages the ubiquity of airborne DNA. It offers a non-invasive means of studying and monitoring the biodiversity of an environment, tracking diseases, and potentially aiding in forensic investigations. Despite its limitations, the technique holds immense potential and represents an exciting frontier in biological and ecological research.
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