Costs of parasite resistance - An integrated study of underlying mechanisms

为什么有些人比其他人更容易被寄生虫感染？根据定义，寄生虫损害个体（宿主）的适应性，因此预计对宿主丰度、种群周期和防御进化具有强大的影响。这项研究将确定宿主防御的遗传变异是如何维持的，从而确定宿主如何进化以减少寄生虫的影响。这项研究使用了两种果蝇，果蝇和它们的螨虫寄生虫作为模型。研究成果将为制定改善农业环境中的害虫控制战略以及控制对人类健康和福祉具有重要意义的病媒的新方法提供信息。研究成果将被纳入涉及高中生和普通大众的教育推广计划。关于防御性状的遗传变异的维持，以及寄生的巨大进化潜力的一个主要假设，涉及抗性的代价。成本表示为在没有寄生虫的情况下，在宿主抗性和其他适应性相关特征（如生殖产出）之间的权衡。关于动物宿主-寄生虫系统的抗性成本的遗传和生理基础的数据很少，尽管它们具有广泛的重要性。研究人员将结合宿主分子、代谢组学和生理过程的研究，以及整个生物体的适应度功能，以了解寄生虫抗性成本的机制基础。利用两种自然存在的宿主-寄生虫系统，将实现三个相互关联的目标。1)检验黑腹田鼠体外寄生虫抗性进化与主要生活史性状之间的权衡关系。2)确定并比较体外寄生虫耐药性的致病分子和代谢组学因素以及两种系统的权衡。3)明确适应度成本的生理解剖机制。这些结果将是动物独有的，并将补充植物和微生物系统的研究。因此，这项研究将有助于耐药性进化统一理论的发展。

Why are some individuals more susceptible to infection by parasites than others? Parasites by definition harm the fitness of individuals (hosts), and thus are expected to have a powerful influence on host abundance, population cycles and the evolution of their defenses. This research will identify how genetic variation in host defenses is maintained and thus how hosts evolve to reduce the effects of parasites. The research uses two species of fruit flies, Drosophila species, and their mite parasites as a model. The research outcomes will inform the development of improved pest control strategies in agricultural settings, and new methods to control disease vectors that are of significance to human health and wellbeing. Research outcomes will be integrated into educational outreach programs involving high school students and the general public. A major hypothesis for the maintenance of genetic variation in defensive traits, and hence for the enormous evolutionary potential of parasitism, involves costs of resistance. Costs are expressed as trade-offs between host resistance and other fitness-related traits, such as reproductive output, in the absence of parasites. There are few data available for animal host-parasite systems on the genetic and physiological bases of costs of resistance, despite their widespread importance. The researchers will bridge studies of host molecular, metabolomic, and physiological processes, with whole-organism fitness functions, to understand the mechanistic bases of costs of parasite resistance. Using two naturally occurring host-parasite systems, three interrelated aims will be achieved. 1) Test for trade-offs between evolved ectoparasite resistance and major life-history traits in D. melanogaster. 2) Determine and compare the causal molecular and metabolomic factors of ectoparasite resistance and of trade-offs in the two systems. 3) Identify the physiological and anatomical mechanisms underlying fitness costs. The results will be unique to animals, and will complement studies in plant and microbial systems. The research will thus contribute to the development of a unified theory of resistance evolution.