Dissertation Research: Genetic Differentiation Among Populations Of Euphydryas Editha

这项工作是对加州红杉国家森林中的Euphydryas editha蝴蝶种群的长期研究的延续。 先前的研究表明，伐木影响了蝴蝶饮食的进化。 它们在已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，但昆虫从这些斑块中迁移的比例不成比例，部分原因是它们保留了对传统栖息地和寄主植物的偏好。 拟议的工作将研究遗传分化，无论是在这个受干扰的系统，这个系统和其他人口之间的同一物种在50公里的距离。 研究人员将在约塞米蒂国家公园及其周边地区的一个未伐木系统上进行一项等效的研究。 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。这项工作还将研究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，以及昆虫对特定宿主植物物种的适应。人类对景观的干预以戏剧性的方式影响了食草昆虫。 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土植物的相对质量。 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，但偶然地通过提高本地植物物种的质量（从昆虫的角度来看）提供了一种新的宿主。 昆虫环境的变化会影响它们在栖息地之间的运动模式，以及它们在运动时成功繁殖的可能性。 这些对运动的影响反过来又会影响种群在遗传上彼此不同的趋势。 种群之间的遗传分化是拟议工作的重点，它将阐明存在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.