DNA Variability and Genetic Hitchhiking in Mus

9306493纳赫曼种群遗传学的一个中心目标是了解影响生物自然种群遗传变异的过程。一种重要的现象被称为基因搭便车，涉及自然选择和基因重组(基因的两个副本之间的基因混合)的相互作用。当一种特定的DNA突变受到自然选择的青睐时，它可能会在种群中变得更加常见，因为带有该突变的个体将取代没有该突变的个体。然而，当自然选择倾向于某个特定的DNA位点时，它也会影响到附近不在选择中的DNA位点。通常，基因搭便车会导致这些附近位置的DNA变异性降低。减少的数量取决于重组的速度。这种关系很重要，因为它允许我们通过比较具有不同重组率的基因的DNA可变性水平来寻找自然选择的证据。最近对果蝇(果蝇)的研究表明，基因搭便车可能会影响很大一部分基因组。这对基因组进化具有广泛的意义，包括自然选择可能相当频繁地发挥作用。%为了了解这些发现是否代表了分子进化的一般方面，这项研究将寻找家鼠的遗传搭便车的证据。这将通过比较X染色体上四个重要基因之间的DNA序列变异水平来实现：两个重组率较高(PIP和AMG)，两个重组率较低(HPRT和G6PD)。如果基因搭便车是常见的，那么重组率高的两个基因应该比重组率低的两个基因表现出更大的DNA序列变异性。小鼠的这四个基因中有三个是人类遗传病的重要模型(HPRT：Lesch-Nyhan综合征；G6PD：溶血性贫血：PLP：P elizaeus-Merzbacher病)。

9306493 Nachman A central goal of population genetics is to understand the process that shape genetic variation in natural populations of organisms. An important phenomenon, knows as genetic hitchhiking, involves the interaction of natural selection and genetic recombination (genetic mixing between the two copies of a gene). When a particular DNA mutation is favored by natural selection, it may become more common in a population since individuals with the mutation will replace individuals without it. However, when natural selection favors a particular DNA site, it will also affect nearby DNA sites which are not themselves under selection. Typically, genetic hitchhiking will cause a reduction in DNA variability at these nearby sites. The amount of reduction depends on the rate of recombination. This relationship is important because it allows us to look for evidence of natural selection by comparing levels of DNA variability in genes with different recombination rates. Recent studies on fruit flies (Drosophila) have demonstrated that genetic hitchhiking may affect a large portion of the genome. This has broad significance for genome evolution, including the implication that natural selection may be acting quite frequently.%%% To learn if these findings represent a general aspect of molecular evolution, this study will look for evidence of genetic hitchhiking in the house mouse, Mus domesticus. This will be achieved by comparing levels of DNA sequence variation among four important genes on the X-chromosome: two with high recombination rates (Pip and Amg), and two with lower recombination rates (Hprt and G6pd). If genetic hitchhiking is common, then the two genes with a high recombination rate should show a greater amount of DNA sequence variability than the two genes with a low recombination rate. Three of these four genes in mice serve as important models for human genetic diseases (Hprt: Lesch-Nyhan syndrome; G6pd: hemolytic anemia: Plp: P elizaeus-Merzbacher disease).