RUI: The Effects of Natural Selection on Molecular Variation in Structured Populations

在过去的十年里，人们已经清楚地认识到，自然选择对果蝇、老鼠、人类和番茄等多种生物体的整个染色体上的DNA序列变异模式具有重要影响。然而，分子变异的水平和模式在多大程度上反映了适应性达尔文进化与有害突变的净化选择仍然是一个谜。本文提出的研究将利用东南亚果蝇种群高度结构化的特性来估计有限基因流、局部适应、遗传漂动和重组对基因组结构的影响程度。一组密集的分子标记将被用于扫描基因组，以寻找在代表东南亚不同气候区域的纬度渐变种群中参与当地适应的基因。基因图谱和物理图谱将提供一种手段来检验自然选择在广泛的基因组范围内的影响。研究还将检验来自该物种祖先范围的ananassae种群样本的基因多态性模式，以估计DNA序列变异的自然选择的地理边界。这些研究探索了结构果蝇种群中形成基因组变异和多样性的基本机制，为其他具有结构种群（如人类）的生物体中形成基因组多样性的过程提供了见解。这项研究涉及美国和德国之间的国际合作，以及本科生的培训机会。

During the past decade it has become clear that natural selection has major effects on patterns of DNA sequence variation across entire chromosomes of organisms as diverse as Drosophila, mice, humans, and tomato. However, the extent to which the levels and patterns of molecular variation reflect adaptive Darwinian evolution versus purifying selection of deleterious mutations remains a mystery. The studies proposed here will take advantage of the highly structured nature of Drosophila ananassae populations in Southeast Asia to estimate the extent to which limited gene flow, local adaptation, genetic drift, and recombination influence the architecture of the genome. A dense set of molecular markers will be used to scan the genome for genes involved in local adaptation in populations along a latitudinal cline representing different climatic regions in Southeast Asia. Genetic and physical maps will provide a means to examine the effect of natural selection across broad expanses of the genome. Studies will also be performed to examine the patterns of polymorphism at genes in population samples of D. ananassae from the ancestral range of the species to estimate the geographic boundaries of natural selection on DNA sequence variation.These studies explore the fundamental mechanisms shaping genome variation and diversity in structured Drosophila populations, providing insight into the processes responsible for molding genome diversity in other organisms with structured populations such as humans. The research involves international collaborations between the United States and Germany, and training opportunities for undergraduate students.