Tracking earthworm communities from soil DNA

Earthworms are known for their important role within the functioning of an ecosystem, and their diversity can be used as an indicator of ecosystem health. To date, earthworm diversity has been investigated through conventional extraction methods such as handsorting, soil washing or the application of a mustard solution. Such techniques are time-consuming and often difficult to apply. We showed that combining DNA metabarcoding and next generation sequencing facilitates the identification of earthworm species from soil samples. The first step of our experiments was to create a reference database of mitochondrial DNA (mtDNA) 16S gene for 14 earthworm species found in the French Alps. Using this database, we designed two new primer pairs targeting very short and informative DNA sequences (about 30 bp and 70 bp) that allow unambiguous species identification. Finally, we analyzed extracellular DNA taken from soil samples in two localities (two plots per locality, eight samples per plot). The ...