Bacterial Communities Associated with Junco Preen Glands: Preliminary Ramifications for Chemical Signaling
Intraspecific chemical communication may play a significant role in avian behavior. Preen oil secreted by the uropygial gland emits volatile compounds that vary with many aspects of bird biology and may figure prominently in mate choice. Many of these compounds are known end products of bacterial metabolism in other environments. The fermentation hypothesis for chemical recognition suggests that symbiotic bacteria in mammalian scent glands produce volatile odorants that are used as recognition cues by the host animals and that variation in these bacterial communities contributes to variation in the animal scents. We preliminarily evaluated whether this hypothesis could apply to birds by sampling and sequencing bacterial communities associated with the preen gland of adult breeding dark-eyed juncos (Junco hyemalis). The most common operational taxonomic units (OTUs), defined by the V4 region of the 16S rRNA gene, belonged to the phyla Actinobacteria, Firmicutes, and Proteobacteria. Most of the identified bacterial genera contain species that are known odor producers. Most notably, Burkholderia and Pseudomonas species consistently produce 9 of the 17 volatile compounds whose production is either upregulated during the breeding season or differs between the sexes in juncos. Other genera have documented antifungal or antibacterial properties and may provide other valuable services to the birds. We found no effect of host sex on bacterial community composition or structure. Instead, paired males and females clustered together, suggesting that individuals that have frequent contact may develop similar microbial communities quickly. Our study suggests that the fermentation hypothesis for chemical recognition, originally formulated for mammals, may apply to birds as well, opening new pathways for avian-microbial research.
KeywordsBacterial Community Zebra Finch Bacterial Community Composition Symbiotic Bacterium Methyl Ketone
This work was supported by the BEACON Center for the Study of Evolution in Action (NSF Cooperative Agreement DBI-0939454). Fieldwork was supported by a Mountain Lake Biological Station Early Career Fellowship to DJW. All work was conducted in compliance with the Bloomington Institutional Animal Care and Use Committee guidelines (BIACUC protocol 09-037) and with permission from the US Department of Fish and Wildlife, the Virginia Department of Game and Inland Fisheries, and the US Forest Service. We thank Mountain Lake Biological Station, University of Virginia, as well as Mountain Lake Hotel and the Dolinger family for allowing research on their grounds. We thank Nicole Gerlach, Abby Kimmitt, Dustin Reichard, Samuel Slowinski, Sarah Wanamaker, and Joseph Welklin for assistance in the field, John Dover and Arvind Venkataraman for assistance with DNA extraction and sequence processing, and Ellen Ketterson for helpful discussion.
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