Dissertation Research: Genetic Effects of Extinction and Recolonization in a Host-Parasite System

这项研究将确定若干种群水平的过程在确定自然界种群间遗传分化模式方面的作用，这些过程包括遗传漂移、迁徙、以及当地种群灭绝和重新殖民。人口统计数据将与遗传数据进行比较，以检验有关这些不同因素的影响的理论。研究动物是燕虫Oeciacus vicarius，一种内布拉斯加州悬崖燕子特有的体外寄生虫。由于悬崖燕子宿主对栖息地的短暂利用，燕子种群经历了当地种群增长和灭绝的规律周期。因此，它们非常适合于研究物种灭绝和重新定居等动态因素对种群的遗传影响。有一个长期的(10年)数据库，详细说明了悬崖燕子宿主的群体站点使用情况和迁徙模式。东部可以用来估计这些臭虫的重要种群参数，这使得在精度和广泛范围上都不寻常的种群遗传成为可能。这项研究将扩大对自然种群遗传分化基本过程的基本理解，并将针对最近提出的动态模型对种群遗传结构的经典静态(平衡)理论进行实证检验。在实践层面上，这项研究将对各种自然影响，如当地种群灭绝，在确定物种遗传多样性的整体水平方面的重要性提供一般性的见解。这些信息对于保护生物学家在制定维持野生物种遗传多样性的有效策略方面具有相当重要的指导作用。

The study will determine the roles of a number of population-level processes, including genetic drift, migration, and local population extinction and recolonization, in determining the patterns of genetic differentiation among populations in nature. Population demographic data will be compared with genetic data to test theories concerning the effects of these various factors. The study animal is the swallow bug Oeciacus vicarius an ectoparasite exclusively of cliff swallows in Nebraska. Populations of swallow bugs undergo regular cycles of local population growth and extinction due to the ephemeral use of colony sites by the cliff swallow host. They are thus ideally suited for studies of the population genetic effects of dynamic factors such as extinction and recolonization. A longterm (10-year) database is available which details colony site usage and migration patterns for the cliff swallow hosts. The east with which important population parameters for these bugs may be estimated makes possible a population genetic unusual in both its precision and broad scope. The study will expand basic understanding of the fundamental process of genetic differentiation in natural populations, and will empirically test classical static (equilibrium) theories of population genetic structure against more recently proposed dynamic models. At a practical level, the study will provide general insights into the importance of various natural effects, such as local population extinction, in determining the overall level of genetic diversity for a species. This information is of considerable importance to conservation biologists as a guide in formulating effective strategies for maintaining species genetic diversity in the wild.