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Ecoevolutionary dynamics of the gut microbiota at the macroscale level,
that is, in across-species comparisons, are largely driven by ecological
variables and host genotype. The repeated explosive radiations of African
cichlid fishes in distinct lakes, following a dietary diversification in a
context of reduced genetic diversity, provide a natural setup to explore
convergence, divergence and repeatability in patterns of microbiota
dynamics as a function of the host diet, phylogeny and environment. Here
we characterized by 16S rRNA amplicon sequencing the gut microbiota of 29
cichlid species from two distinct lakes/radiations (Tanganyika and Barombi
Mbo) and across a broad dietary and phylogenetic range. Within each lake,
a significant deviation between a carnivorous and herbivorous lifestyle
was found. Herbivore species were characterized by an increased bacterial
taxonomic and functional diversity and converged in key compositional and
functional community aspects. Despite a significant lake effect on the
microbiota structure, this process has occurred with remarkable parallels
in the two lakes. A metabolic signature most likely explains this trend,
as indicated by a significant enrichment in herbivores/omnivores of
bacterial taxa and functions associated with fiber degradation and
detoxification of plant chemical compounds. Overall, compositional and
functional aspects of the gut microbiota individually and altogether
validate and predict main cichlid dietary habits, suggesting a fundamental
role of gut bacteria in cichlid niche expansion and adaptation.
247 views reported since publication in 2018.