Microbiome affects reproduction and investment in the uropygial gland in Great tits

Microorganisms constitute the major part of the earth biomass. The host microbiome, defined as the whole community of microorganisms in contact with an organism, includes pathogenic and commensal microorganisms that are remarkable in their diversity and ubiquity. Parasites influence allocation trade-offs between reproduction and self-maintenance, and many beneficial microorganisms are essential for instance to host digestion and nutrient synthesis. The host microbiome is thus expected to shape the evolution of host life-history traits, although experimental studies from natural systems are still lacking.