DNA fishing reveals wildlife

This red deer leaves DNA traces in the river water, which indicate its presence in the ecosystem. (Photo: UMass Amherst / Joseph Drake)

They are shy, inconspicuous or very rare – which animal species occur in a habitat can often only be proven by elaborate methods or lengthy observation. But researchers have now shown the potential of a comparatively straightforward method for identifying entire communities of mammals in ecosystems: the detection of environmental DNA in river water can reveal which species live in the catchment area of ​​a body of water.

The world is changing – many of the world’s ecosystems are changing significantly as a result of human intervention and climatic changes: As a result, certain species disappear from their habitats – others, on the other hand, spread invasively. In order to be able to record these processes and to check whether protective measures are successful, an exact assessment of the population and the spread of animals is very important.

New methods are required

However, it is known that some species are difficult to record – this is particularly true for mammals. “Various methods are therefore used to detect and monitor them, such as searching for signs such as footprints or feces or using camera traps,” says co-author Allan McDevitt from the University of Salford. As he emphasizes, these methods are comparatively complex and expensive. In addition, these traditional survey methods are often tailored to a certain type and are therefore not suitable for an overall view of the types of an ecosystem. “We are therefore looking for ways to improve biodiversity assessment and monitoring that can be applied universally and cost-effectively,” said McDevitt.

This gave the researchers the idea of ​​applying the metabarcoding method to their area of ​​application. In marine and freshwater ecosystems, this environmental DNA detection technology has already revolutionized the monitoring of the biodiversity of entire habitats. The concept is based on the detection of small amounts of genetic material that animals such as fish or amphibians release into the water via the faeces, for example. The extent to which terrestrial animals living in the catchment area of ​​a body of water can also be demonstrated by their washed-in genetic traces in the water has so far been unclear.

Animal communities reflected in their environmental DNA

To explore this possibility, McDevitt and his colleagues collected water and sediments from streams and rivers in Scotland and England and subjected them to genetic tests in the laboratory. As they report, they successfully demonstrated the potential of the method: they identified the DNA of over 20 wild mammals in the river water. The results represented the entire community: from vole, badger and fox to red deer. The results coincided with the data from inventory surveys in the respective areas by tracks, faecal samples or by surveillance cameras.

“These elaborate methods may soon no longer be absolutely necessary: ​​Now we may just have to collect a few bottles of water, take them to the laboratory and analyze the DNA that we find in the samples,” says McDevitt. He concludes: “We have shown that environmental DNA collected from water can provide us with information about the presence or absence of mammals with nature conservation concerns. This method could now be used extensively to monitor the decline or recovery of populations or for the early detection of invasive species, ”says the scientist.

Source: University of Massachusetts Amherst, technical article: Journal of Applied Ecology, doi: 10.1111 / 1365-2664.13592

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