Behaviour 2019
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Male reproductive behavior shapes gut microbiota responses to infection   
Kate A. Sabey, Vanessa O. Ezenwa. University of Georgia, Athens, GA, United States

The immunocompetence handicap hypothesis suggests that testosterone enhances male sexual traits while compromising immunity and influencing infection rates. One way testosterone might affect immunity and infection is via effects on the gut microbiota. To test this, we assessed whether reproductive behavior, testosterone levels, and parasite loads are associated with the gut microbiota of wild male Grant’s gazelles (Nanger granti), which switch between territorial and non-territorial states. Differences in gut microbiota composition between these types of males were, in part, explained by their distinct patterns of habitat use, suggesting an indirect effect of testosterone via changes in behavior. Testosterone levels were also directly and negatively correlated with the abundance of microbes enriched in non-territorial males, including anti-inflammatory Verrucomicrobia. Interestingly, we found that microbial differences between territorial and non-territorial males were related to parasite loads, though patterns varied among parasite types. This suggests that reproductive behavior can shape the gut microbiota, with potential consequences for immunity and responses to infection.