JAR_Norwegian_wild_Salmon_2022_Supplementary

<strong>Background</strong> The gut microbiota is shaped by a blend of environmental and evolutionary processes within the intestinal environment of its host. How these evolutionary processes occur in wild animals remain largely unexploited, due to the high complexity of the environment and microbial communities. Therefore, new wild model organisms with low complex microbiota and known population structures could be key to investigate co-evolution between the microbiota and their host. <strong>Results</strong> We present the first metagenomic derived genome catalogue of gut microbiota from wild Atlantic salmon (<em>Salmo salar</em>). Our data reveals a low complexity and were mainly dominated by the salmonid related <em>Mycoplasma</em>. Further, our results revealed a strong selection pressure on the gut microbiota by Atlantic salmon. Interestingly, we found a high concordance between the population structure of Atlantic salmon and the nucleotide variability of <em>Mycoplasma</em> in accordance with expectations from co-evolution between host and microbiota. <strong>Conclusion</strong> Investigations of the coevolution of host and microbiota in Atlantic salmon will lead to a higher understanding of the interactions from both actors. It is clear from our results that the microbiota from Atlantic salmon has evolved to the population structure through a close relationship between its genome and gut microbiome, showing that Atlantic salmon can be a suitable model for studying host-microbiome co-evolution.