The microbiota has a broad range of impacts on host physiology and behaviour, pointing out the need to improve our comprehension of the drivers of host microbiota composition. Of particular interest is whether the microbiota is acquired passively, or whether and to what extent hosts themselves shape the acquisition and maintenance of their microbiota. In birds, the uropygial gland produces oily secretions used to coat feathers that have been suggested to act as an antimicrobial defence mechanism regulating body feather microbiota. However, comprehension of this process is still limited. In this study, the authors coupled high-throughput sequencing of the microbiota of both body feathers and the direct environment (i.e. the nest) in great tits with chemical analyses of the composition of uropygial gland secretions to examine whether host chemicals have either specific effects on some bacteria or non-specific broad-spectrum effects on the body feather microbiota. Using a network approach investigating the patterns of co-occurrence or co-exclusions between chemicals and bacteria within the body feather microbiota, we found no evidence for specific pro or anti-microbial effects of uropygial gland chemicals. However, it was found that one group of chemicals was negatively correlated to bacterial richness on body feathers, and a higher production of these chemicals was associated with a poorer body feather bacterial richness compared to the nest microbiota. The study provides evidence that chemicals produced by the host might function as a non-specific broad-spectrum antimicrobial defence mechanism limiting colonisation and/or maintenance of bacteria on body feathers, providing new insight about the divers of the host’s microbiota composition in wild organisms.
Authors: Jacob S, Sallé L, Zinger L, Chaine AS, Ducamp C, Boutault L, Russell AF, Heeb P. ; Full Source: Molecular Ecology. 2018 Mar 13. doi: 10.1111/mec.14551. [Epub ahead of print]