Can social partnerships influence the microbiome? insights from ant farmers and their trophobiont mutualists.

Mutualistic interactions with microbes have played a crucial role in the evolution and ecology of animal hosts. However, it is unclear what factors are most important in influencing particular host-microbe associations. While closely related animal species may have more similar microbiota than distantly related ones due to phylogenetic contingencies, social partnerships with other organisms, such as those in which one animal farms another, may also influence an organism’s symbiotic microbiome. We studied a mutualistic network of Brachymyrmex and Lasius ants farming several honeydew-producing Prociphilus aphids and Rhizoecus mealybugs to test whether the mutualistic microbiomes of these interacting insects are primarily correlated with their phylogeny or with their shared social partnerships. Our results confirm a phylogenetic signal in the microbiomes of aphid and mealybug trophobionts, with each species harboring species-specific endosymbiont strains of Buchnera (aphids), Tremblaya and...