Uropygial gland size and composition varies according to experimentally modified microbiome in Great tits.

Staffan Jacob,Nathalie Parthuisot,Sarah Leclaire,Christine Ducamp,Philipp Heeb,Gilles Espinasse,Anika Immer

doi:10.1186/1471-2148-14-134

Abstract

BackgroundParasites exert important selective pressures on host life history traits. In birds, feathers are inhabited by numerous microorganisms, some of them being able to degrade feathers or lead to infections. Preening feathers with secretions of the uropygial gland has been found to act as an antimicrobial defence mechanism, expected to regulate feather microbial communities and thus limit feather abrasion and infections. Here, we used an experimental approach to test whether Great tits (Parus major) modify their investment in the uropygial gland in response to differences in environmental microorganisms.ResultsWe found that males, but not females, modified the size of their gland when exposed to higher bacterial densities on feathers. We also identified 16 wax esters in the uropygial gland secretions. The relative abundance of some of these esters changed in males and females, while the relative abundance of others changed only in females when exposed to greater bacterial loads on feathers.ConclusionBirds live in a bacterial world composed of commensal and pathogenic microorganisms. This study provides the first experimental evidence for modifications of investment in the defensive trait that is the uropygial gland in response to environmental microorganisms in a wild bird.

Highlights

Parasites exert important selective pressures on host life history traits
Bacterial communities in nests and feathers From the 52 nest samples analyzed for bacterial community composition, we identified 180 operational taxonomic unit (OTU), whereas feather bacterial communities appeared less diverse with 138 OTUs extracted from the 94 feather samples
We found a significant effect of the treatments on nest total and keratinolytic bacterial densities

Summary

Introduction

Parasites exert important selective pressures on host life history traits. In birds, feathers are inhabited by numerous microorganisms, some of them being able to degrade feathers or lead to infections. Preening feathers with secretions of the uropygial gland has been found to act as an antimicrobial defence mechanism, expected to regulate feather microbial communities and limit feather abrasion and infections. We used an experimental approach to test whether Great tits (Parus major) modify their investment in the uropygial gland in response to differences in environmental microorganisms. Given the importance of avoiding pathogen infections and maintaining good plumage integrity, birds are expected to have evolved means to regulate the microorganisms on their feathers [17]. Preening feathers with uropygial gland secretions might act as an antimicrobial defence mechanism to regulate microorganisms on feathers [20,21,25,26]

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