WHAT IS eDNA?

DNA extracted from an organism can reveal a great deal about its relatedness to other living things, both in the small-scale sense of how it compares with other populations within its species, and in the broader sense of where it fits within the tree of life.

But if it only takes a tiny sample of organic tissue – a single skin or gut cell, for example – for DNA to be extracted, then could DNAretrieval techniques be sophisticated enough for us to collect DNA that living things leave in their environments, via their shed cells, urine and faeces? The answer is yes. In a series of studies that first appeared in print during the 1990s, ecologists and geneticists worldwide have shown how the presence and identity of organisms in an area can be extracted from soil, groundwater, ice, freshwater and seawater via so-called environmental DNA or eDNA.

By collecting water from Loch Ness, scientist Prof Neil Gemmell and his team hope that they have obtained eDNA from the loch environment. They have also taken samples from nearby lochs to analyse their eDNA too. Back in the laboratory, the samples will be analysed, and any eDNA will be identified and extracted. The samples are then profiled and compared to those already in genetic databanks. Many species already known to be present in the loch will be identified in this way. The hope is that species new to the area, and perhaps even new to science, will be discovered as well.

RIGHT: Most eDNA found so far belongs to living species already known to science. However, some eDNA has been found from extinct animals, like mammoths and giant sloths. This proves that eDNA can last for thousands of years in the right conditions