Host life-history and host-parasite syntopy predict behavioral resistance and tolerance of parasites

There is growing interest in the role that life-history traits of hosts, such as their “pace-of-life”, play in the evolution of resistance and tolerance to parasites. Theory suggests that, relative to host species that have high syntopy (local spatial and temporal overlap) with parasites, host species with low syntopy should have lower selection pressures for more constitutive (always present) and costly defenses, such as tolerance, and greater reliance on more inducible and cheaper defenses, such as behavior. Consequently, we postulated that the degree of host-parasite syntopy, which is negatively correlated with host pace-of-life (an axis reflecting the developmental rate of tadpoles and the inverse of their size at metamorphosis) in our tadpole-parasitic cercarial (trematode) system, would be a negative and positive predictor of behavioral resistance and tolerance, respectively. To test these hypotheses, we exposed seven tadpole species to a range of parasite (cercarial) doses crosse...宿主的生活史特征（life-history traits）——例如其“生活节奏（pace-of-life）”——在宿主对寄生虫的抗性与耐受性演化过程中所发挥的作用，日益受到学界关注。现有理论指出，相较于与寄生虫呈现高同域共存（syntopy，即本地时空重叠）的宿主物种，同域共存程度较低的宿主物种，其针对组成型（始终存在且成本高昂）防御策略（如耐受性）的选择压力更低，而更依赖诱导型且成本较低的防御策略（如行为防御）。据此，我们提出假设：在本研究的蝌蚪-寄生尾蚴（吸虫纲，trematode）系统中，宿主与寄生虫的同域共存程度与宿主生活节奏呈负相关（生活节奏轴反映蝌蚪的发育速率，以及其变态时体型大小的倒数），且该同域共存程度分别可作为行为抗性与耐受性的负向、正向预测因子。为验证上述假设，我们将7种蝌蚪暴露于不同梯度的寄生虫（尾蚴，cercarial）感染剂量下，……