How recombination alters drift and selection in the genome

重组如何改变基因组中的漂移和选择 我的研究计划调查遗传变异的产生和可获得性如何与漂移和选择相互作用，以影响进化。两个基本的过程产生了推动进化的变异：突变和重组。突变会产生新的变异，而重组则会将突变重新组合成新的组合。在性交过程中，重组将发生在不同个体中的有益突变聚集在一起，增加了选择的有效性。类似地，重组使附近的有益突变分离开来，否则有害突变将干扰选择来修复适应性变化的能力。有趣的是，有证据表明重组的速度在整个基因组中是不同的。这意味着在基因组区域的选择可能或多或少有效，这取决于重组的速度。令人惊讶的是，很少有关于基因组重组率变异的研究，主要是因为重组发生得如此之少，每1000万个位点中不到一次。幸运的是，基因组革命提供了在分子尺度上观察重组所需的技术。我建议研究模式藻莱茵衣藻中重组的变异及其对适应的影响。在我的提案中，我描述了三个相辅相成的短期目标： 1.我将通过对重组系的基因组进行测序，以识别数千种重组事件，来探索重组率如何以及为什么在个体之间和整个基因组中存在差异。我将研究基因组生物学的哪些方面最能预测重组率。这项工作将产生任何物种中重组率变异的最详细的特征之一。 2.我将使用重组率变异的精细图来测试重组是否减少了所选突变之间的干扰。我预计重组率高的区域将更快适应，而重组率低的区域将积累有害突变。在这个框架中，我将研究蛋白质编码突变、碱基组成和基因组大小的选择强度。 3.我将扫描自然基因组序列，寻找控制本地适应特征的基因岛。使用仔细的实验室分析，我将把使其适应当地环境的基因和特征联系起来，并量化自然界中塑造微生物种群的因素。 只有将重组和突变的直接测量结合起来，我提议的工作才能进行。这个项目将全面描述产生遗传变异的力量，促进详细了解适应如何在遗传层面上表现出来。

HOW RECOMBINATION ALTERS DRIFT AND SELECTION IN THE GENOME My research program investigates how the generation and availability of genetic variation interacts with drift and selection to influence evolution. Two fundamental processes generate the variation that fuels evolution: mutation and recombination. Mutation creates new variants, and recombination shuffles mutations into new combinations. During sex, recombination brings together beneficial mutations that have occurred in different individuals, increasing the effectiveness of selection. Similarly, recombination breaks apart nearby beneficial from harmful mutations that would otherwise interfere with the ability of selection to fix the adaptive changes. Interestingly, there is evidence that the rate of recombination varies across the genome. This means that selection in regions of the genome may be more or less effective, depending on the rate of recombination. Surprisingly, there are few studies of recombination rate variation in the genome, primarily because recombination occurs so rarely; less than once in every 10 million sites. Fortunately, the genomic revolution offers the technology needed to observe recombination at the molecular scale. I propose to investigate variation in recombination and its consequences for adaptation in the model alga Chlamydomonas reinhardtii. In my proposal I describe three complementary short-term objectives: 1. I will explore how and why the rate of recombination varies between individuals and across the genome by sequencing the genomes of recombinant lines to identify thousands of recombination events. I will examine what aspects of genome biology best predict the rate of recombination. This work will generate one of the most detailed characterizations of recombination rate variation in any species. 2. I will test whether recombination reduces interference between selected mutations using the fine-scale map of recombination rate variation. I expect that regions with high recombination will adapt more quickly, while regions with low recombination will accumulate harmful mutations. In this framework, I will examine the strength of selection on protein-coding mutations, base composition, and genome size. 3. I will scan natural genome sequences for islands of genes that control locally adapted traits. Using careful laboratory assays I will link the genes and traits that confer adaption to the local environment and quantify the factors that shape microbial populations in nature. Only by incorporating direct measurement of recombination and mutation can the work I propose be conducted. This project will provide a comprehensive description of the forces that generate genetic variation, facilitating detailed understanding of how adaptation manifests at the genetic level.