Coevolution in simple and complex host-parasite systems. CLUSTER: "Evolutionary genetics of three-spined stickleback - parasite interactions"

该项目是第一阶段项目(Bakker BA2885/3-1：简单和复杂寄主-寄生虫系统中的共同进化)成果的扩展和基础，在该阶段中，利用微卫星对三刺刺鱼及其直接生活史的一种寄生虫--体外寄生单殖吸虫和一种生活史复杂的吸虫--双口吸虫进行了系统地理分析。它以鸟类为最终宿主，表演了苏格兰外赫布里底群岛北乌伊斯特岛上无数孤立的湖泊。使用繁殖有色较好的种群之一的鱼，采用全同胞/半同胞育种设计，在实验室进行实验感染。对雄性繁殖颜色和繁殖行为进行了量化。该数据集将提供有关寄主抗性的进化性和性选择在寄主抗性进化中的作用的信息。在第二阶段项目中，重点将放在宿主-大型寄生虫在该系统中相互作用的生态学以及寄生虫传染性的变化上。北乌里斯特的湖泊有两种不同的栖息地类型：岛的东部和中部的湖泊是茶色的酸性湖泊，而西部的湖泊是清澈的碱性湖泊。生态对寄主-大型寄生虫相互作用的影响将在三个不同的水平上进行研究。首先，第一阶段项目的刺鱼及其脊椎动物和双口寄生虫的系统地理数据集将得到扩展，并与水质(PH值、能见度)和鱼类种群数量等生态变量相关，作为遗传变异性的替代指标。这一分析将深入了解宿主-寄生虫共同进化的生态制约因素。其次，实验室饲养的全同胞/半同胞后代的实验感染来自一个几乎没有发育的、单调繁殖色彩的种群，与第一阶段项目中彩色雄性的类似实验相比，说明了性别选择在宿主抗性进化中的作用的生态限制。第三，实验室饲养的其中一个刺鱼种群的后代将使用当地湖泊特有的水接触来自不同湖泊的寄生虫，以建立寄生虫传染性的种群间变异。这项实验将在回龙身上进行，当能在湖中收集到足够多的能够剥离囊虫的蜗牛时，也将与双口螺一起进行。感染力的变化将与生态因素有关，如水质(PH值、能见度)、鱼类种群数量以及雄性繁殖色彩的阐述。总之，这三种不同的方法将增加我们对生态学在宿主-寄生虫相互作用进化中的作用的理解。

This project extends and builds upon the results of the phase I project (Bakker BA2885/3-1: Coevolution in simple and complex host-parasite systems), in which a phylogeographic analysis using microsatellites of three-spined sticklebacks, Gasterosteus aculeatus, and one of its parasites with a direct life cycle, the ectoparasitic monogenean Gyrodactylus spp., and one with a complex life cycle, the digenean trematode Diplostomum spp. that uses birds as final hosts, of numerous isolated lakes on the island of North Uist, Outer Hebrides, Scotland was performed. Using fish from one of the populations with well-developed breeding coloration, experimental infections in the laboratory using a full-sib/half-sib breeding design were done. Male breeding coloration and reproductive behaviour were quantified. This dataset will give information about the evolvability of host resistance and the role of sexual selection in the evolution of host resistance. In the phase II project the emphasis will lie on the ecology of host-macroparasite interactions in this system and variation in parasite infectivity. The lakes on North Uist are of two distinguished habitat types: on the east and central parts of the island the lakes are tea-stained and acid while on the west part the lakes are clear and alkaline. Ecological influences on host-macroparasite interactions will be studied on three different levels. First, the phylogeographic dataset of sticklebacks and their Gyrodactylus and Diplostomum parasites of the phase I project will be extended and related to ecological variables like water quality (pH, visibility) and fish population size as a proxy for genetic variability. This analysis will give insights into ecological constraints on host-parasite coevolution. Second, experimental infections of lab-reared full-sib/half-sib progeny from a population with hardly developed, drab breeding coloration will, compared to similar experiments with colourful males in the phase I project, illustrate ecological constraints in the role of sexual selection in the evolution of host resistance. Third, lab-reared progeny of one of the stickleback populations will be exposed to parasites from different lochs using local, loch-specific water in order to establish interpopulational variation in parasite infectivity. This experiment will be done with Gyrodactylus and, when enough snails that shed metacercariae can be collected in the lochs, also with Diplostomum. Variation in infectivity will be related to ecological factors like water quality (pH, visibility), fish population size, and the elaboration of male breeding coloration. Together, the three different approaches will increase our understanding of the role of ecology in the evolution of host-parasite interactions.