Researchers from ETH Zurich and the Swiss Federal Institute for Forest, Snow and Landscape Research (WSL) now want to close this knowledge gap. Scientists from ETH’s Plant Ecological Genetics group are currently carrying out a pilot study on behalf of the Swiss Federal Office for the Environment (FOEN). This study aims to explore how to establish a long-term monitoring programme of the genetic diversity of selected species native to Switzerland. This pioneering study was launched in 2020 and is expected to continue until the end of 2023.
Probing five species
In their pilot study, the researchers initially restricted their investigations to five native animal and plant species: the Natterjack toad (Epidalea calamita), Yellowhammer (Emberiza citrinella), False heath fritillary (Melitaea diamina), Carthusian pink (Dianthus carthusianorum) and Hare’s tail cottongrass (Eriophorum vaginatum). These species are representative of specific habitats of conservation relevance that include dry meadows, raised bogs, amphibian habitats, agricultural landscape, and transition zones between forests and grasslands.
Having randomly selected 30 locations per species throughout Switzerland, the researchers took samples from more than 1,200 individual specimens, from which they extracted their DNA back at the lab.
While catching and sampling the Yellowhammers and Natterjacks, the researchers were assisted by specialists from the Swiss Ornithological Institute in Sempach, the Swiss coordination centre for reptile and amphibian protection (KARCH) and species specialists from three different environmental consultancies.
Using specialised analysis equipment and high-performance computer infrastructure provided by ETH Zurich, the researchers fully sequenced – in other words decoded – the organisms’ DNA one building block at a time. This generated a vast amount of data. “Printing out the genetic information contained in a single cell of a Natterjack toad would fill more than 630,000 A4 pages. That’s a stack of paper 70 metres high,” says the project’s manager, Martin C. Fischer of the Plant Ecological Genetics group at ETH Zurich.
To compare today’s genetic variability with that present around the year 1900, the researchers also looked at the DNA of samples – some of them up to 200 years old – housed at herbaria and zoological collections. In this case, they restricted their investigation to two species: the butterfly and the cottongrass.
The researchers had to examine these samples in a cleanroom laboratory to avoid contaminating what little remains of this ancient DNA. “Such museum pieces contain only fragments of DNA, similar in quality to that of a 10,000-year-old mammoth in permafrost,” Fischer says. “Analysing it was enormously time-consuming and labour-intensive.” The results of the DNA comparison are not yet in.