Ecology and evolution of host/parasite interactions

寄生是地球上最常见的生活方式。这一现象的一个特点是宿主和寄生虫之间存在着复杂而密切的相互作用，以满足它们的生存和繁殖需要。尽管结果往往涉及敌对双方之间的冲突，但许多结果可以被解释为满足双方截然不同的目标的妥协。我们通常不知道特定的宿主-寄生虫相互作用在这个连续体中的位置，这使得很难解释“新的”宿主/寄生虫组合将如何进行进化，而这些组合通常主宰着我们的人类栖息地。我结合了实验室操作、系统发育分析、野外工作和现代分子工具来研究宿主和寄生虫之间的相互作用。在我们的主要模型系统中，我们使用普通的小鱼和它们的脑环吸虫来评估宿主的反应策略，以及寄生虫的利用策略。这些蠕虫在大脑组织中有一个专性的进食阶段，这会降低宿主的生理和行为表现。我们现在正在结合系统发育比较和实验暴露来跟踪幼虫摄食阶段的进化，并测试与生命周期其他阶段的生活史权衡。在同一系统内，我们将结合实验室和现场实验，以评估宿主通过完全避免感染阶段而使感染成本最小化的程度。在这里，我们询问鱼类是否可以检测到与感染相关的“恐惧因素”，然后学会通过抗寄生虫行为来降低风险。除了利用宿主资源外，许多寄生虫还利用宿主行为来满足其传播需要。我们对潜在的机制知之甚少。一个引人注目的例子是，一种感染蚂蚁大脑的吸虫的幼虫阶段，导致它们在一天中寒冷的时候爬上植被并紧紧抓住。我们将使用涉及寄生虫和宿主组织的现代蛋白质组学工具来揭示导致“僵尸蚂蚁”行为改变的机制。

Parasitism is the most common lifestyle on earth. One hallmark of the phenomenon is the complex and intimate interplay that exists between host and parasite to meet their survival and reproduction needs. Although the outcome often involves conflict between two antagonists, many outcomes can be interpreted as a compromise that meet the contrasting aims of the two partners. We often do not know where particular host-parasite interactions fit on this continuum, making it difficult to interpret how evolution will proceed in 'new' host/parasite combinations that so often dominate our anthropogenic habitats. I use a combination of laboratory manipulations, phylogenetic analyses, field work, and modern molecular tools to study the interplay between hosts and parasites. In our main model system, we use common minnows and their brain-encysting flukes to evaluate host response strategies on the one hand, and parasite exploitation strategies on the other. These worms have an obligate feeding phase within brain tissue that reduce the hosts' physiological and behavioural performance. We are now combining phylogenetic comparisons and experimental exposures to track the evolution of the larval feeding stage and testing for life-history trade-offs with other stages in the life-cycle. Within this same system, we will combine laboratory and field experiments to assess the extent to which hosts can minimize the costs of infection by avoiding infective stages all-together. Here, we ask whether fish can detect 'fear factor' associated with infection and then learn to respond via anti-parasite behaviours that reduce risk. In addition to exploiting host resources, many parasites exploit host behaviours to meet their transmission needs. We have a poor understanding of underlying mechanisms. One spectacular example involves the larval stages of a fluke that infects the brains of ants, causing them to ascend vegetation and clamp-on during cold hours of the day. We will use modern proteomics tools involving both parasite and host tissue to uncover the mechanisms leading to the altered behaviours of the 'zombie ants'.