Parasitism in early life: environmental conditions shape intra-brood variation in responses to infection

Parasites play key ecological and evolutionary roles through the costs they impose on their host. In wild populations, the effect of parasitism is likely to vary considerably with environmental conditions, which may affect the availability of resources to hosts for defense. However, the interaction between parasitism and prevailing conditions is rarely quantified. In addition to environmental variation acting on hosts, individuals are likely to vary in their response to parasitism, and the combined effect of both may increase heterogeneity in host responses. Offspring hierarchies, established by parents in response to uncertain rearing conditions, may be an important source of variation between individuals. Here, we use experimental antiparasite treatment across 5 years of variable conditions to test how annual population productivity (a proxy for environmental conditions) and parasitism interact to affect growth and survival of different brood members in juvenile European shags (Phalac...寄生虫通过对宿主施加生存代价，在生态与进化过程中发挥关键作用。在野生种群中，寄生作用的影响很可能随环境条件发生显著变化，而环境条件会影响宿主用于防御的资源可获得性。然而，寄生作用与当前环境条件之间的交互效应却鲜有量化研究。除了作用于宿主的环境变异之外，不同个体对寄生作用的响应也可能存在差异，二者的联合效应可能会加剧宿主响应的异质性。亲代为应对不确定的育幼环境而建立的后代等级制度，可能是个体间表型差异的重要来源。本研究通过在5年可变环境条件下开展抗寄生虫实验处理，检验种群年度生产力（作为环境条件的替代指标）与寄生作用的交互效应，如何影响幼年欧洲鸬鹚（Phalac...）不同窝雏鸟的生长与存活情况。