From environmental DNA sequences to ecological conclusions: how strong is the influence of methodological choices?

Aim: Environmental DNA (eDNA) is increasingly used for analysing and modelling all-inclusive biodiversity patterns. However, the reliability of eDNA-based diversity estimates is commonly compromised by arbitrary decisions for curating the data from molecular artefacts. Here, we test the sensitivity of common ecological analyses to these curation steps, and identify the crucial ones to draw sound ecological conclusions. Location : Valloire, French Alps. Taxon: Vascular plants and Fungi. Methods: Using soil eDNA metabarcoding data for plants and fungi from twenty plots sampled along a 1000-m elevation gradient, we tested how the conclusions from three types of ecological analyses: (i) the spatial partitioning of diversity, (ii) the diversity-environment relationship, and (iii) the distance-decay relationship, are robust to data curation steps. Since eDNA metabarcoding data also comprise erroneous sequences with low frequencies, diversity estimates were further calculated using ab...