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eDNA - DNA Metabarcoding output files

The section below describes two common files derived from DNA metabarcoding studies. Along with the metadata, these files can be used as inputs for data analysis, statistics, and for constructing figures.

ASV Table

Data are in a human readable format that can be used to construct a species list, create figures, and run statistical analyses. A commonly used format for processed data is an ASV table. An ASV table is essentially a spreadsheet where each row is an eDNA sample, each column is a different ASV, and the numbers in each cell are the number of copies of each ASV detected in each sample.

The ASV table provides a way to view the processed data. In this table each row is a sample with a unique identifier that matches samples in the metadata file. Each column represents a unique DNA sequence, and the numbers within the cells represent the quantity of each sequence detected in each sample. Each ASV corresponds to a species detected in the survey.

Taxonomy Table

The ASV table is accompanied by a Taxonomy Table that provides the inferred species of origin for each ASV sequence. Note that it is often not possible to know the exact species of origin in an eDNA metabarcoding study, and some ASVs will only be assigned to a genus, family or order. It is also likely that species will have multiple different ASVs, which represents within-species genetic variation.

The taxonomy table is where species names are assigned to each DNA sequence. In this table, each row is a different sequence, and the cells contain the taxonomic information at the phylum, class, order, family, genus, and species level.