Ecology of fear: ecological and evolutionary consequences of non-consumptive effects of parasites

寄生虫可能对宿主造成重大伤害，因此潜在的宿主应尽量避免接触寄生虫的感染阶段。宿主可以通过避免感染阶段、相关线索、受感染的个体或改变其栖息地的用途来避免接触感染，以避免遇到寄生虫。这些间接的非消费效应被称为“恐惧生态”。拟议的项目将在实验上回答以下问题：1)寄生虫的非消耗性效应(NCE)是否与背景和状态有关？当生物体暴露在寄生虫中时，它可能会改变它的活动、呼吸速率、取食行为、空间使用和/或时间分配给各种活动，以避免感染。个体对感知到的威胁的确切反应将取决于环境条件和自身的内部条件(年龄、性别、精力状态等)。我们将调查NCE的上下文依赖性质，以及这种影响是否会跨越发育阶段和生殖状态。2)寄生虫是否存在性状中介的间接效应？寄生虫还可以改变宿主的行为，影响其与群落中非宿主物种(例如，竞争对手、捕食者)的相互作用。对感染风险的感知可能会导致活动增加，这反过来可能会使个体处于更大的被捕食者发现的风险中。我们将调查防寄生虫和防捕食者防御之间的潜在冲突。3)寄生虫在宿主代谢环境中的NCEs是不是依赖于环境和状态？对天敌的“非打即逃”反应通常包括增加活动和呼吸。我们将测量暴露在寄生虫(没有接触)下的苍蝇在短期和长期的代谢率。众所周知，生物体的代谢率随性别、年龄、生殖状况和外部条件(如温度、拥挤)而变化。除了检查新陈代谢变化的状态依赖性质外，还测量不同条件下平均二氧化碳产生的反应标准，包括暴露时间、寄生虫线索类型和同种物质密度。我们还将测量苍蝇取食行为的相关变化。4)NCE的进化后果是什么？尽管有关恐惧生态及其健康后果的证据越来越多，但人们对非消费效应的长期进化后果仍知之甚少。我们将采用“实验室自然选择”，即改变实验室维持的种群的环境(即暴露在寄生虫中)，幸存者成为下一代的父母。将在10代后将处理种群与未改变的对照种群进行比较。虽然多种反应是可能的，但我们将重点关注新陈代谢、取食行为、体重、抗寄生虫行为(梳理、活动)和对感染的抵抗力的变化。

Parasites can cause significant harm to their hosts, hence potential hosts should try to avoid coming into contact with infectious stages of the parasite. Hosts can avoid exposure to infection by avoiding infective stages, associated cues, infected individuals, or alter their habitat use to avoid encountering parasite. These indirect non-consumptive effects are known as the "ecology of fear". The proposed project will experimentally answer the following questions: 1) Are the non-consumptive effects (NCEs) of parasites context and state-dependent? When an organism is exposed to parasites, it may change it's activity, rate of respiration, feeding behaviour, space use, and/or time allocation to various activities in order to avoid infection. Exactly how individuals respond to a perceived threat will depend on the environmental conditions and it's own internal condition (age, sex, energetic state, etc.). We will investigate the context-dependent nature of the NCE and whether the effects carry over across developmental stages and reproductive states. 2) Are there trait-mediated indirect effects of parasites? Parasites can also modify the behaviour of the host in ways that influence how it interacts with non-host species in the community (e.g., competitors, predators). The perception of infection risk could cause an increase in activity, which could in turn put an individual at greater risk of detection by predators. We will investigate the potential for conflict between anti-parasite and anti-predator defenses. 3) Are the NCEs of parasites on host metabolism context and state-dependent? The "fight or flight" response to a natural enemy often involves increased activity and respiration. We will measure the metabolic rate of flies exposed to parasites (without contact) over the short- and long-term. The metabolic rate of an organism is known to vary with sex, age, reproductive status, and external conditions (e.g., temperature, crowding). In addition to examining the state-dependent nature of the metabolic changes, measuring the reaction norm of the mean CO2 production under different conditions, including duration of exposure, types of parasite cues, and density of conspecifics. We will also measure associated changes in fly feeding behaviour. 4) What are the evolutionary consequences of NCE? Even as evidence for the ecology of fear and its fitness consequences mounts, the long-term evolutionary consequences of non-consumptive effects remains poorly understood. We will employ "laboratory natural selection" in which the environment of a laboratory-maintained population is altered (i.e., exposed to parasites) and the survivors become the parents of the next generation. The treatment populations will be compared to unaltered control populations after 10 generations. While multiple responses are possible, we will focus on changes in metabolism, feeding behaviour, body mass, anti-parasite behaviors (grooming, activity), and resistance to infection.