Résumé
The microbiome of invasive species is increasingly seen as a potential key
factor of their ecological success, and this appears particularly true in
herbivorous invaders whose digestive abilities rely on the microbes hosted
in their gut. We characterized the gut microbiome of two invasive
herbivorous fishes (Siganus rivulatus and Siganus luridus) in their native
(Red Sea) and invaded (Levantine Sea and Northern Crete) ranges. We found
that gut bacterial communities contain a higher taxonomic and phylogenetic
diversity while becoming increasingly different from the native microbiome
as the fishes move away from the native zone. This shift resulted in the
homogenization of the microbiomes between individuals from the same
species as well as between the two species. Firmicutes and Tenericutes
reduced drastically in abundance while Proteobacteria and Bacteroidetes
became more dominant in both species. This led to a modification of the
functional potential of the gut microbiome associated with the metabolism
of short-chanin fatty acids that also became more homogeneous in the
invaded range. Altogether, our results suggest that the plasticity of the
gut microbiome in Siganidae could be a key factor underlying their
ecological success in Mediterranean ecosystems.