Turnover of strain-level diversity modulates functional traits in the honeybee gut microbiome between nurses and foragers

Strain-level diversity is widespread among bacterial species and can expand the functional potential of natural microbial communities. However, to what extent communities undergo consistent shifts in strain composition in response to environmental/host changes is less well understood. Here, we used shotgun metagenomics to compare the gut microbiota of two behavioral states of the Western honeybee ( Apis mellifera ), namely nurse and forager bees. While their gut microbiota is composed of the same bacterial species, we detected consistent changes in strain-level composition between nurses and foragers. Single nucleotide variant profiles of predominant bacterial species clustered by behavioral state. Moreover, we identified strain-specific gene content related to nutrient utilization, vitamin biosynthesis, and cell-cell interactions specifically associated with the two behavioral states. Our findings show that strain-level diversity in host-associated communities can undergo consistent changes in response to host behavioral changes modulating the functional potential of the community.