Data from: 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 burdens are a cost of territoriality. Moreover, among territorial males, parasites suppress aspects of behavior related to territory maintenance and defense. These results suggest that territorial behavior promotes the accumulation of parasites in males, and these parasites dampen the very behaviors required for territory maintenance. Our findings suggest that reciprocal feedback between host behavior and parasitism could be a mechanism maintaining variation in male reproductive behavior in the system.

寄生虫是环境中广泛存在的生物类群，可诱导宿主的行为与生活史特征产生变异。尽管学界已明确宿主行为可影响寄生虫感染风险，且寄生虫能够重塑宿主行为，但二者之间的动态反馈潜力尚未得到充分阐释。本研究以葛氏瞪羚（Nanger granti）为模型物种，通过检测宿主行为对寄生虫的作用以及寄生虫对宿主行为的双向效应，探究行为-寄生虫反馈是否在维持雄性繁殖行为变异中发挥作用。成年雄性瞪羚的生存策略分为两类：要么通过捍卫领地以吸引配偶，要么栖息于单身雄性群中。领地防御行为在个体内部与个体间均存在显著差异，这表明领地维持需付出高昂的生存代价。本研究结合纵向追踪与实验操控手段，发现雄性个体常会在领地繁殖与单身雄性群两种状态间频繁转换，且寄生虫载量升高正是领地防御行为所付出的代价之一。此外，在拥有领地的雄性瞪羚中，寄生虫会抑制其与领地维持及防御相关的行为表现。上述结果表明，领地防御行为会促进雄性个体体内寄生虫的积累，而这些寄生虫又会削弱领地维持所必需的核心行为能力。本研究结果提示，宿主行为与寄生作用之间的双向反馈，可能是维持该系统中雄性繁殖行为变异的潜在机制。