Reciprocal relationships between behaviour and parasites suggest that negative feedback may drive flexibility in male reproductive behaviour

Parasites are ubiquitous components of the environment that contribute to behavioral and life-history variation among hosts. Although it’s well-known that host behavior can affect parasite infection risk and that parasites can alter host behavior, the potential for dynamic feedback between these processes is poorly characterized. Using Grant’s gazelle (Nanger granti) as a model, we tested for reciprocal effects of behavior on parasites and parasites on behavior to understand whether behavior-parasite feedback could play a role in maintaining variation in male reproductive behavior. Adult male gazelles either defend territories to attract mates or reside in bachelor groups. Territoriality is highly variable both within- and between-individuals, suggesting that territory maintenance is costly. Using a combination of longitudinal and experimental studies, we found that individual males transition frequently between territorial and bachelor reproductive status, and that elevated parasite bu...