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。通常风险?行为加剧，使中间宿主更容易被最终宿主捕食；这一步对于生命周期的完成至关重要。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，寄生虫在操纵行为上表现出相当大的差异。最近的理论模型表明，这种差异源于寄生虫寿命的差异。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，以便在死亡前传播。操纵策略也可能因寄生虫发育而异，以尽量减少死亡率。具体来说，寄生虫应该在未成熟时抑制宿主的危险行为，并在感染最终宿主后增强它们。此外，人们对操纵性寄生虫和宿主性信号之间的关系知之甚少。而寄生虫通常会减少宿主？在吸引配偶和繁殖的能力方面，操纵性物种可以增加性信号，使宿主对捕食者更有吸引力，同时也对潜在的配偶更有吸引力。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背道而驰，并将揭示寄生虫在性信号进化中的新作用。这些假设将在实验室和现场使用来自南加州的自然和实验感染的招潮蟹种群进行测试。在寄生虫的发育过程中，求偶和反捕食者行为将被量化，以确定寄生效应如何随时间变化。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了解宿主-寄生虫的进化动力学以及操纵性寄生虫如何影响宿主的性信号进化。Zuk和Mora将在Mora和自然保护区管理者组织的公民科学活动中向外展组织和公众传播他们的研究结果。

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.