Studies on mechanism of maintenance of DNA polymorphism and statistical methods for analyzing DNA polymorphism data

自然种群在DNA水平上有大量的遗传变异。群体遗传学中最重要的问题之一是群体遗传学中有多少以及为什么会保持这样的遗传变异。提出了中性理论、轻度有害模型、搭便车模型、超显性模型和频率依赖模型等多种可能的机制。在本研究项目中，我对这一课题进行了研究，并获得了以下结果：为了理解DNA多态性的维持机制，我研究了非随机交配群体的情况，并获得了新的模型：两个亚群在t1代前部分分离，在t2代前完全分离，自然选择与种群结构的关系为：在DNA多态性的维持机制方面进行了研究。利用有限岛模型，得到了以下结果。显性对DNA多态性的影响随着迁移率的降低而降低，当迁移率极低时，显性对DNA多态性的影响消失。使用相同的模型，分子进化的速度进行了研究。结果表明，显性效应对分子演化速率的影响随迁移速率的降低而减小，但即使迁移速率很低，显性效应也不会消失。这意味着显性程度对DNA多态性数量和分子进化速率的影响不同。

Natural populations have a large amount of genetic variation at the DNA level. How much and why such genetic variation is maintained in a population is one of the most important questions in population genetics. A large number of possible mechanisms were proposed, such as neutral theory, slightly deleterious model, hitchhiking model, overdominance model and frequency dependent model. In this research project, I have worked on this subject and obtained the following results.IN order to understand the mechanism of maintenance of DNA polymorphism, I have studied the case of non-random mating population and obtained new model : two subpopulations were partially separated t1 generations ago and these two subpopulations were completely separated t2 generations ago.The relationship between natural selection and population structure were examined in terms of the mechanism of maintenance of DNA polymorphism. Using the finite island model, the following results were obtained. The effect of dominance on the amount of DNA polymorphism decreases as the migration rate decreases and the effect disappears when the migration rate is extremely low. Using the same model, the rate of molecular evolution was studied. The results indicate that the effect of dominance on the rate of molecular evolution decreases as the migration rate decreases, but the effect does not disappear even when the migration rate becomes extremely low. This means that the degree of dominance affects differently between the amount of DNA polymorphism and the rate of molecular evolution.