Collaborative Research: Understanding the Evolution of Diet Breadth through Ecoimmunology

人类商业和其他人为活动引起了物种地理范围的广泛变化，影响了物种在其群落内的相互作用。由于以植物为食的昆虫占地球陆地生物量的很大一部分，因此了解影响它们改变饮食的因素对于预测新组织的生态系统是否以及如何发挥作用至关重要。生态免疫学是一门新兴学科，它突出了免疫系统在物种相互作用和生活史特征进化中的作用。虽然植物-昆虫相互作用的研究很早就认识到昆虫捕食的植物物种的范围不仅由植物的特征决定，还受到捕食者和寄生虫等敌人的影响，但免疫防御在确定食物广度方面所起的作用是一个新的研究领域。这项研究探索了一种假设，即通过增强免疫力获得对病原体的抵抗力，可以影响将新植物物种纳入昆虫食草动物饮食的可能性。为了验证这一假设，研究人员将结合生态免疫学、化学生态学和微生物学的方法，使用一个由四个蝴蝶物种组成的模型系统，所有这些蝴蝶物种都将引入的植物车前草(车前科)纳入它们的饮食中。研究人员将通过量化每种蝴蝶物种不同种群中两种常见病原体的寄生率和环境水平，来评估引入植物的使用是否与疾病风险变化有关。在实验室里，这些种群的基因库将被用来比较以杉木为食的毛虫和祖先寄主植物对微生物病原体和模拟寄生的免疫反应。研究人员将通过实验研究饮食、植物化学物质的隔离和昆虫肠道中驻留的细菌之间的相互作用，方法是测量这些因素被操纵时的免疫反应。最后，他们将测试幼虫感染史是否会影响产卵雌性选择哪些植物，或者转移到杉木是否反映了天生的寄主偏好。

Human commerce and other anthropogenic activities have caused widespread changes in the geographic ranges of species, affecting how species interact within their communities. Since plant-feeding insects represent a large part of Earth's terrestrial biomass, understanding the factors that influence them to change their diets is central to predicting if and how newly organized ecosystems will function. Ecoimmunology is an emerging discipline that highlights the role of the immune system in species interactions and the evolution of life history traits. Although research in plant-insect interactions has long recognized that the range of plant species eaten by insects is shaped not only by characteristics of the plants, but also by enemies such as predators and parasites, the role played by immunological defense in determining dietary breadth is a new area of study. This research explores the hypothesis that resistance to pathogens attained via enhanced immunity can affect the likelihood of incorporating new plant species into insect herbivore diets. To test this hypothesis, researchers will combine approaches from ecoimmunology, chemical ecology and microbiology, using a model system of four butterfly species, all of which have incorporated the introduced plant, Plantago lanceolata (Plantaginaceae), into their diets. Researchers will assess whether the use of the introduced plant is associated with altered disease risk by quantifying parasitism rates and environmental levels of two common pathogens in different populations of each butterfly species that vary in their use of P. lanceolata. In the laboratory, genetic stock from these populations will be used to compare the immunological response to microbial pathogens and simulated parasitism among caterpillars feeding on P. lanceolata and ancestral host plant species. Researchers will experimentally investigate the interplay between diet, the sequestration of plant chemicals, and the bacteria residing in the insect gut by measuring the immune response when these factors have been manipulated. Finally, they will test whether larval infection history affects which plants are chosen by ovipositing females, or whether shifts to P. lanceolata reflect selection on innate host preference.