Sociality does not predict oral microbiome composition or diversity in free-living prairie voles

Abstract

The costs and benefits of group living and sociality have received much attention. Recent studies suggest that the acquisition of a more diverse microbiome may be another benefit of sociality which could be beneficial for host health and survival. We characterized the sociality of free-living prairie voles, Microtus ochrogaster, and their oral microbiome alpha diversity and dissimilarity (beta diversity) to assess associations between sociality and microbiome diversity. Voles were born in the laboratory and then released into seminatural enclosures, representing a shift in diet and changes in social interactions. Social interactions were monitored using an automated behavioural monitoring system from which we quantified degree (the number of social connections) and association index (the strength of the social connection between two individuals). Oral microbiome samples were collected throughout the field season and then the oral microbiome was characterized using 16S rRNA gene sequencing, representing the first ever characterization of the oral microbiome in this species. Oral microbiome alpha diversity increased when voles were moved to the field from the laboratory but did not change over time in the field. It was not related to the number of social connections (unweighted degree). Oral microbiome dissimilarity (beta diversity) between two voles was not related to the strength of their social association (association index) nor was it related to whether the pair produced offspring together. The oral microbiome became more dissimilar over the field season in sibling versus nonsibling pairs. Together, our results indicate a lack of association between social interactions and oral microbiome diversity and dissimilarity and provide an important contrast as other studies on this topic are conducted mostly in primate species and mostly in the gut microbiome. This highlights the importance of investigating other areas of the microbiome besides the gut and the relationship between these variables in additional species.