REU: Genetic Structure within Oak Populations

种群的遗传结构可以从一个遗传变异分布在各处的大型杂交种群到一系列相互遗传分化的小型杂交亚种群。种群的遗传结构是基因流、自然选择和遗传漂移相互作用的结果，也影响着这些进化力量将如何影响该种群。拟议的研究将通过测量交配系统(即异交度)、微生境的局部选择以及两个橡树物种--白栎树(Quercus Alba)和红栎树(Q.rubra)的种群遗传结构，来确定自然选择是否会导致林木种群内的遗传分化。这项研究将在密苏里州中东部的一片橡树山核桃林中进行，为期三年。大部分研究将在一个4公顷的研究样地内进行，该样地包含四种类型的微生境：北向坡、西南向坡、西向坡和底地。遗传结构将用F统计量和其他适当的措施来描述，使用通过淀粉凝胶电泳法鉴定的酶遗传标记。每年还将使用酶遗传标记来测量每个物种的交配系统。将通过相互移植实验来研究由于微生境而进行的局部选择。该项目向进化生物学家提出了一些重要问题，即局部选择可能影响被子植物树种的种群结构，因为被子植物树种的异交率可能很高。这项研究还将提供有关北美森林中一个具有生态和经济意义的属的有用遗传信息。橡树是木材的宝贵商品，它们为野生动物提供了至关重要的资源。了解遗传变异在森林物种中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林木种群对自然和人类诱导的胁迫做出反应的能力。

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.