Table 3 –

Description of α diversity indices used.

Index	Description
Observed richness	Raw number of ASVs
Chao1 richness	Estimation of the true richness by adjusting the raw number of ASVs for rare taxa
Faith’s Phylogenetic diversity index	Richness index based on phylogenetic distance between ASVs
Shannon index	Measure of heterogeneity in taxa representation (evenness × richness)
Simpson evenness index	Measure of true evenness of taxa within a sample independently of taxa richness. A value close to 0 means that the taxa are unevenly distributed in a sample.
Simpson dominance index	Measure of taxa diversity within a sample. This index is weighted towards the most abundant taxa and influenced by taxa richness. A value close to 0 means that the sample is dominated by few taxa.