REU: Genetic Structure within Oak Populations

群体的遗传结构可以是一个大的杂交群体，遗传变异分布在整个群体中，也可以是一系列相互遗传分化的小的杂交亚群体。种群的遗传结构是基因流动、自然选择和遗传漂变相互作用的结果，也影响着这些进化力量将如何影响该种群。本研究将通过测量交配系统（即异交程度）、微生境的局部选择以及白栎和红栎两种栎树的种群遗传结构来确定自然选择是否会引起林木种群内的遗传分化。这项研究将在密苏里州中东部的橡树山核桃林中进行为期三年的研究。大部分研究将在一个4公顷的研究地块内进行，该地块包括四种类型的微生境：朝北的斜坡、朝西南的斜坡、朝西的斜坡和底地。遗传结构将用F-统计和其他适当的方法来描述，利用淀粉凝胶电泳鉴定的酶遗传标记。每个物种的交配系统每年都将使用酶遗传标记进行测量。微生境的局部选择将通过互惠移植实验进行研究。该项目解决了进化生物学家关于局部选择影响可能具有高异交率的被子植物树种种群结构的潜力的重要问题。这项研究还将为北美森林中一个具有生态和经济意义的属提供有用的遗传信息。橡树是一种有价值的木材商品，它们为野生动物提供了重要的资源。了解森林物种内遗传变异的分布将有助于确定森林管理的抽样方案。此外，这些信息将有助于我们了解日益分散的森林树木种群对自然和人为压力的反应能力。

The genetic structure of populations can range from one large interbreeding population with genetic variation distributed throughout to a series of small interbreeding subpopulations which are genetically differentiated from each other. The genetic structure of populations results from the interactions of gene flow, natural selection, and genetic drift and also influences how these evolutionary forces will affect that population. The proposed research will determine whether natural selection can cause genetic differentiation within forest tree populations by measuring mating system (i.e. the degree of outcrossing), local selection due to microhabitat, and population genetic structure of two oak species, white oak (Quercus alba) and red oak (Q. rubra). This study will be conducted over a three year period in an oak-hickory forest in central eastern Missouri. Most of the research will be conducted within a 4 ha study plot which contains four types of microhabitat: north- facing slope, southwest-facing slope, west-facing slope, and bottom land. Genetic structure will be described with F- statistics and other appropriate measures using enzyme genetic markers identified through starch gel electrophoresis. The mating system for each species will be measured each year also using enzyme genetic markers. Local selection due to microhabitat will be studied using a reciprocal transplant experiment. The project addresses significant questions for evolutionary biologists about the potential of local selection to influence population structure in angiosperm tree species which may have high outcrossing rates. This study will also provide useful genetic information on an ecologically and economically significant genus in North American forests. Oaks are a valuable commodity for lumber and they provide crucial resources for wildlife. Understanding the distribution of genetic variation within a forest species will help in determining sampling schemes for forest management. In addition, such information will help us understand the ability of increasingly fragmented forest tree populations to respond to natural and human-induced stress.