For each index (A. Jaccard, B. Unweighted UniFrac, C. Bray, D. Weighted UniFrac), the first two axes of the principal coordinates analysis (PCoA) are represented. The two first indices represent a qualitative measure (absence or presence of bacterial taxa) while the two last are quantitative (adjusted with taxa abundance). The matrices on the right side of each index showed the significance level of the Permanova test (differences between populations) and the β dispersion test (homogeneity of variance between populations). All four indices showed that water microbiome was different from snail hemolymph microbiomes, that the two species of snail (B. glabrata and B. alexandrina) can be differentiated on quantitative and qualitative approaches, and that B. glabrata populations were differentiated based on rare taxa (qualitative aspect) and this differentiation could be linked to their geographic origin. The ellipse represents the multivariate normal distribution.