Before fascinating biologists, environmental DNA (eDNA) was initially a matter for paleontologists. When, in 2003, Danish geneticist Eske Willerslev kicked off eDNA studies, he did so by finding traces of mammoths and bison in 2 grams of Siberian permafrost. Sign of the dazzling progress of the technique, the same Eske Willerslev will direct, ten years later, a vast study retracing the evolution of Arctic vegetation – herbaceous plants, grasses or shrubs that have now disappeared – over a period spanning from – 50,000 years to the present day.
“If it is kept in the right conditions, in a cold and protected environment, it is possible to find DNA that is hundreds of thousands of years old. Even if, over time, it tends to degrade and becomes more and more complex to analyze,” explains Marie-Eve Monchamp, paleo-ecologist at McGill University in Montreal. Like many of her colleagues, the Canadian researcher has set her sights on DNA trapped in lake sediments. Although they do not allow us to go back as far in time as in the Arctic, these lake sediments are much more accessible, allowing a new generation of paleontologists to appropriate eDNA techniques at a lower cost. And, as with modern eDNA, the proliferation of studies and research teams is making it possible to gradually move away from the “simple” inventory of biodiversity.
More and more researchers are thus using ancient eDNA as a tool to answer broader questions. In August 2021, Marie-Eve Monchamp was behind the creation of an international working group bringing together more than a hundred specialists, PaleoEcoGen: “The idea was to create a network of people studying the great past ecological transitions – climate change, biological breaking points… – through ancient environmental DNA. »
Trace the story
For example, the Canadian researcher worked for a long time on the sediments of Lac de Joux, the largest in the Swiss Jura. By combining traditional methods of analysis and eDNA, the team succeeded in linking the evolution of bacterial communities and the different human occupations over the past thousand years. “In the second half of the twentiethe century, we observe in particular a sudden proliferation of cyanobacteria impacting the quality of the water, which coincides with the urbanization around the Lac de Joux and the excess of nutrients associated”describes the paleo-ecologist.
You have 29.77% of this article left to read. The following is for subscribers only.