DISSERTATION RESEARCH: How life history influences host manipulation by parasites in the California fiddler crab, Uca crenulata

许多寄生虫操纵宿主的行为来增强寄生虫的传播和繁殖成功。经常？冒险？行为变得更加强烈，使中间寄主更容易受到最终寄主的捕食；这一步对完成生命周期至关重要。虽然寄生是地球上最常见的生活方式，但宿主-寄生虫关系的许多方面仍然知之甚少。首先，寄生虫在它们的操控努力中表现出相当大的差异。最近的理论模型表明，这种差异是由于寄生虫寿命的差异造成的。寿命较短的寄生虫应该比寿命较长的物种表现出更多的操纵性努力，以便在死亡之前实现传播。在寄生虫发育过程中，操控策略也可能有所不同，以将死亡率降至最低。具体地说，寄生虫应该在未成熟时抑制危险的宿主行为，并在感染最终宿主时增强它们。此外，人们对操纵性寄生虫和寄主的性信号之间的关系知之甚少。虽然寄生虫通常会降低寄主S吸引配偶和繁殖的能力，但操纵性物种可以增强性信号，使寄主对捕食者更具吸引力，同时也对潜在的配偶更具吸引力。矛盾的是，受感染的个体会经历更高的短期交配成功率，以及通过捕食而增加的死亡率。这一观点与传统模型相悖，并将揭示寄生虫在性信号进化中的新角色。这些假设将在实验室和野外使用来自南加州的自然和实验感染的招潮蟹种群进行验证。求偶和反捕食者行为将在寄生虫发育过程中进行量化，以确定寄生虫的影响如何随着时间的推移而变化。捕食试验将揭示寄生虫如何影响宿主的捕食和死亡率。这项研究将有助于我们理解寄主-寄生虫的进化动力学，以及操纵性寄生虫如何影响寄主的性信号进化。祖克和莫拉将在莫拉和自然保护区管理人员组织的公民科学活动期间，向外联组织和公众传播他们的成果。

Many parasites manipulate host behavior to enhance parasite transmission and reproductive success. Often ?risky? behaviors become intensified and make intermediate hosts more susceptible to predation by final hosts; this step is crucial for life cycle completion. While parasitism is the most common lifestyle on Earth, many aspects of host-parasite relationships remain poorly understood. First, parasites exhibit considerable variation in their manipulative effort. Recent theoretical models suggest that this variation arises from differences in parasite lifespan. Shorter-lived parasites should exhibit more manipulative effort than longer-lived species to achieve transmission before death. Manipulative strategies may also vary across parasite development to minimize mortality. Specifically, parasites should suppress risky host behaviors when immature, and enhance them once infective to final hosts. In addition, little is known about the relationship between manipulative parasites and host sexual signals. While parasites generally decrease a host?s ability to attract mates and reproduce, manipulative species could increase sexual signals to make hosts more attractive to predators, but also to potential mates. Paradoxically, infected individuals would experience higher short-term mating success, as well as increased mortality via predation. This view runs counter to conventional models, and would reveal a new role for parasites in sexual signal evolution. These hypotheses will be tested in the lab and field using naturally and experimentally infected fiddler crab populations from Southern California. Courtship and anti-predator behaviors will be quantified across parasite development to determine how parasitic effects change through time. Predation trials will reveal how parasites influence host predation and mortality. This research will contribute to our understanding of host-parasite evolutionary dynamics and how manipulative parasites influence host sexual signal evolution. Zuk and Mora will disseminate their results to outreach organizations and to the general public during citizen science events organized by Mora and nature reserve managers.