Introduction to environmental DNA (eDNA)

Abstract Chapter “Introduction to environmental DNA (eDNA)” defines the central concepts of this book. Environmental DNA (eDNA) corresponds to a mixture of genomic DNA from many different organisms found in an environmental sample such as water, soil, or feces. DNA metabarcoding can be defined as the simultaneous DNA-based identification of many taxa found in the same eDNA extract. It is usually based on the analysis of a metabarcode (i.e., a short and taxonomically informative DNA region). Metagenomics refers to the assembly and functional analysis of the different genomes found in an environmental sample, while metatranscriptomics examines gene expression and regulation at the sampling time based on the set of RNAs extracted from such a sample. Chapter also presents a brief history of eDNA, highlights the different steps of an eDNA study, and gives an overview of the different eDNA methods implemented in ecological research or biodiversity management.