title: Age-related differences in the cloacal microbiota of a wild bird species.
abstract: BACKGROUND
  Gastrointestinal bacteria play a central role in the health of animals. The bacteria that individuals acquire as they age may therefore have profound consequences for their future fitness. However, changes in microbial community structure with host age remain poorly understood. We characterised the cloacal bacteria assemblages of chicks and adults in a natural population of black-legged kittiwakes (Rissa tridactyla), using molecular methods.
  
  
  RESULTS
  We show that the kittiwake cloaca hosts a diverse assemblage of bacteria. A greater number of total bacterial OTUs (operational taxonomic units) were identified in chicks than adults, and chicks appeared to host a greater number of OTUs that were only isolated from single individuals. In contrast, the number of bacteria identified per individual was higher in adults than chicks, while older chicks hosted more OTUs than younger chicks. Finally, chicks and adults shared only seven OTUs, resulting in pronounced differences in microbial assemblages. This result is surprising given that adults regurgitate food to chicks and share the same nesting environment.
  
  
  CONCLUSIONS
  Our findings suggest that chick gastrointestinal tracts are colonised by many transient species and that bacterial assemblages gradually transition to a more stable adult state. Phenotypic differences between chicks and adults may lead to these strong differences in bacterial communities. These data provide the framework for future studies targeting the causes and consequences of variation in bacterial assemblages in wild birds.
authors.affiliation: Konrad Lorenz Institute of Ethology, Department of Integrative Biology and Evolution, University of Veterinary Medicine Vienna, Savoyenstrasse 1a, Vienna, 1160, Austria. wouter.v.dongen@gmail.com
authors.forename: Wouter F D
authors.initials: WF
authors.lastname: van Dongen
authors.forename: Joël
authors.initials: J
authors.lastname: White
authors.forename: Hanja B
authors.initials: HB
authors.lastname: Brandl
authors.forename: Yoshan
authors.initials: Y
authors.lastname: Moodley
authors.forename: Thomas
authors.initials: T
authors.lastname: Merkling
authors.forename: Sarah
authors.initials: S
authors.lastname: Leclaire
authors.forename: Pierrick
authors.initials: P
authors.lastname: Blanchard
authors.forename: Etienne
authors.initials: E
authors.lastname: Danchin
authors.forename: Scott A
authors.initials: SA
authors.lastname: Hatch
authors.forename: Richard H
authors.initials: RH
authors.lastname: Wagner
mesh_terms: D000367:Age Factors; D000818:Animals; D000835:Animals, Wild / Q000254:growth & development / Q000382:microbiology; D001419:Bacteria / Q000145:classification / Q000235:genetics / Q000302:isolation & purification*; D046091:Charadriiformes / Q000254:growth & development / Q000382:microbiology*; D002988:Cloaca / Q000382:microbiology*; D005260:Female; D008297:Male; D064307:Microbiota; D008969:Molecular Sequence Data; D010802:Phylogeny