Parasite-modified behaviour in freshwater systems: Context dependence and the ecological role of signaling molecules

长期目标：提高我们对水生群落中寄生虫改变行为的生态意义的认识。许多寄生虫可以改变其宿主的行为，但对寄生虫传播和水生群落其他成员的影响往往不清楚。寄生虫介导行为的大多数例子集中在涉及营养传播的宿主-寄生虫相互作用上。然而，寄生虫的传播通常是非营养性的，涉及寄生虫阶段的传播，这些阶段是短暂的，传播能力有限。与营养传播阶段类似，改变宿主行为以增加它们在生命周期中遇到下一个宿主的可能性是有利的。然而，行为改变在非营养性寄生虫传播中的作用，以及这些变化背后的机制大多是未知的。短期目标：HQP将接受培训，整合来自野外和实验室实验的分类学、行为学和生化数据，以探索吸虫寄生虫在寄生虫介导的宿主行为中化学通讯的作用。我把重点放在淡水吸虫上，因为它们可以在人类、牲畜和野生动物中引起重大疾病。此外，吸虫在湿地中无处不在，许多种类必须在其生命周期的某一时刻感染蜗牛，后者中的许多都是通过蜗牛传播的（例如棘孔吸虫）。我的研究项目将为理解影响物种相互作用的因素做出几项重要贡献。在受控的实验室环境中确定蜗牛和寄生虫（目标1）以及植物（目标2）的行为反应将为水生群落中物种相互作用建立背景。此外，这些结果将解开寄生虫和受感染宿主对生态群落行为相互作用的影响。使用综合方法来正确识别蜗牛宿主、吸虫寄生虫和植物将解决妨碍我们理解物种相互作用的分类分歧。此外，准确识别对于吸虫生物学（例如推断宿主特异性和生命周期）、寄生虫流行病学（例如推断传播）和淡水系统软体动物保护（例如评估腹足类生物多样性和生态系统健康）的基本方面至关重要。为了探索化学通讯在物种相互作用中的机制作用，我将对蜗牛、寄生虫和植物中的氧脂素（氧化脂肪酸信号分子）进行表征（目的3）。这些数据将提示哪些氧化脂素影响物种间的相互作用。我将确定是否这些特定的分子或分子的鸡尾酒解释行为模式（目标4）。通过提高我们对宿主-寄生虫相互作用机制的认识，了解化学通讯的作用有利于寄生虫群落生态学和流行病学。

Long term goal: Advance our knowledge of the ecological significance of parasite-modified behaviour in aquatic communities. Many parasites can modify their host's behaviour, but the impacts on parasite transmission and other members of aquatic communities are often unclear. Most examples of parasite-mediated behaviour focus on host-parasite interactions that involve trophic transmission. However, parasite transmission is often non-trophic, involving transmission of parasite stages that are short-lived with limited dispersal capabilities. Similar to trophically-transmitted stages, it could be advantageous to modify host behaviour to increase their likelihood of encountering the next host in the life cycle. However, the role of altered behaviour in non-trophic parasite transmission, as well as the mechanisms underlying these changes are mostly unknown. Short-term objectives: 7 HQP will be trained to integrate taxonomic, behavioural, and biochemical data from field and lab experiments to explore the role of chemical communication in parasite-mediated host behaviour by trematode parasites. I focus on freshwater trematodes because they can cause significant disease in humans, livestock, and wildlife. Further, trematodes are ubiquitous in wetlands, many species must infect snails at one point in their life cycle, and many of the latter transmit from snail-snail (e.g. echinostome trematodes). My research program will make several important contributions to understanding factors that affect species interactions. Determining behavioural responses among snails and parasites (Objective 1), and plants (Objective 2) in a controlled lab setting will establish the contexts for species interactions in aquatic communities. Further, these results will disentangle the influence of parasites and infected hosts on behavioural interactions in ecological communities. Using an integrative approach to properly identify snail hosts, trematode parasites, and plants will resolve taxonomic disagreements that impede our ability to understand species interactions. Further, accurate identification is essential to fundamental aspects of trematode biology (e.g. inferences about host specificity and life cycles), parasite epidemiology (e.g. inferences about transmission), and mollusc conservation in freshwater systems (e.g. assessments of gastropod biodiversity and ecosystem health). To explore the mechanistic role of chemical communication in species interactions, I will characterize oxylipins (oxidized fatty acid signaling molecules) from snails, parasites, and plants (Objective 3). These data will suggest which oxylipins influence species interactions. I will determine whether some of these specific molecules or cocktails of molecules explain behavioural patterns (Objective 4). Understanding the role of chemical communication benefits parasite community ecology and epidemiology by improving our knowledge of mechanisms that mediate host-parasite interactions.