Dissertation Research: Genetic Differentiation Among Populations Of Euphydryas Editha

这项提议的工作是长期研究伐木对加州红杉国家森林中ephydryas editha蝴蝶种群影响的续集。先前的研究表明，伐木影响了蝴蝶饮食的进化。它们在被砍伐的栖息地斑块中获得了一种新的寄主植物，但在未受干扰的斑块中保留了它们的传统饮食。在受干扰的斑块中，种群增长更快，但昆虫的迁移不成比例，部分原因是它们保留了对传统栖息地和寄主植物的偏好。这项工作将研究这个受干扰系统内的遗传分化，以及这个系统与50公里范围内的同一物种的其他种群之间的遗传分化。调查人员将对约塞米蒂国家公园及其周边地区的一个未被记录的系统进行类似的研究。这两项研究将探讨这种蝴蝶种群之间自然存在的遗传分化以及人类活动如何影响它。这项工作还将检查种群之间的遗传分化与栖息地之间的距离、中间地形的景观性质以及昆虫对特定寄主植物物种的适应有多大关系。人类对景观的干预以戏剧性的方式影响着食草昆虫。外来植物的引进改变了可作为食物的植物种类的范围。牧场和伐木技术也改变了现有本地植物的相对质量。例如，在目前的研究系统中，伐木除去了昆虫的主要寄主植物，但偶然地通过提高（从昆虫的角度）本地植物物种的质量提供了一个新的寄主。昆虫环境的变化会影响它们在栖息地之间的移动模式，以及它们在移动时成功繁殖的可能性。这些对迁徙的影响反过来又会影响种群之间基因差异的趋势。这种种群间的遗传差异是拟议工作的重点，它将阐明现存的自然模式和人类活动对这些模式的影响。

The proposed work is a sequel to a long-term study of the influence of logging on populations of Euphydryas editha butterfly in Sequoia National Forest, California. Prior work showed that logging influenced the evolution of diet in the butterflies. They acquired a novel hostplant in habitat patches that had been logged, but retained their traditional diet in undisturbed patches. Population growth was faster in the disturbed patches, but insects emigrated disproportionately from those patches, partly because they retained a preference for their traditional habitat and hostplant. The proposed work will examine genetic differentiation both within this disturbed system and between this system and other populations of the same species within a distance of 50 km. The investigators will conduct an equivalent study on an unlogged system in Yosemite National Park and environs. These two studies will ask what genetic differentiation naturally existed among populations of this butterfly and how human activities might be affecting it. The work will also examine how much genetic differentiation among populations is associated with the distance between habitats, the nature of the landscape in the intervening terrain, and the adaptations of the insects to particular host plant species.Human intervention in the landscape affects herbivorous insects in dramatic ways. Introduction of exotic plants alters the range of plant species available as food. Ranching and logging techniques also change the relative qualities of existing native plants. For example, in the current study system logging removed the insects' principal hostplant but incidentally provided a novel host by improving the quality (from the insects' perspective) of a native plant species. Changes in the insects' environment influence their patterns of movement among habitats and their likelihoods of successfully reproducing when they do move. These effects on movement will in turn affect the tendency for populations to differ from each other genetically. This genetic differentiation among populations is the focus of the proposed work, which will illuminate both the natural patterns that exist and the influence that human activities are having upon those patterns.