eDNA: HOW IT WORKS

1 eDNA can be collected from any environmental sample, such as soil, sediment or water ( left). When working with water, samples may be collected in bags, bottles or buckets.

2 A syringe may be used to push a sample of the collected water through a filter. The filter collects the DNA, and is sent off to the lab for analysis ( left/below).

3 In the lab, the DNA is isolated using a series of steps, starting with breaking open the cells to release the DNA. At the end of the process, the DNA is in a tube on its own.

4 A single water sample can contain millions of DNA sequences. With eDNA sampling, you are usually looking for something specific. So, a relevant ‘primer’ is used to amplify the DNA in question – for instance, an amphibian primer, if looking for frogs. Eventually, you have lots of copies of the particular DNA you’re after.

5 The amplified eDNA is then sequenced and is matched with known DNA profiles from animals that are already on file.