I know what you ate last summer…

That is an exaggeration of course. As I learned recently, it’s already hard to detect what an organism ate the day before. I attended the Metabarcoding of Trophic Interactions (MOTI) course organized by the Applied and Trophic Ecology group at the University of Innsbruck, Austria this September, which provided me with a nice overview on everything from experimental design to bioinformatical processing of data collected by metabarcoding.

DNA metabarcoding is becoming a more and more frequent method for food web and biodiversity analyses, which applies the principle of sequencing a target genome region that is present in all or most members of a chosen taxonomic group but different enough to distinguish them, to bulk samples, gut contents, faeces, and environmental DNA. Environmental DNA metabarcoding has become an established method for freshwater Macrozoobenthos monitoring but standardization of protocol is still outstanding. Especially the bioinformatic part can induce over- or underestimation of local biodiversity, depending on how strictly the data is cleaned. Not that it’s easy to get your data just right. Setting your thresholds too high gives you noisy and unreliable results but if you cut off too early you will lose rare and elusive species. Therefore, the quality of the final data currently relies a lot on how much knowledge the experimenters already have about their region or species of interest, that they can use to check the plausibility of the results. Based on the first reviewing round, several metabarcoding studies are now going back to the basics and trying to refine the method itself by analysing the identified problems and proposing solutions. This joint effort will help to create more reliable and comparable biodiversity data that can be used in conservation efforts.

I will do my share of work by trying to find out what dwells on the ground of the black forest and how it is affected by forest management by taking a close look at soil eDNA next summer.

by Laura-Sophia Ruppert (B4)