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Population Genetical Studies on Molecular Evolution and Polymorphism of DNA Sites Linked to Selected Sites

分子进化和与选定位点相关的 DNA 位点多态性的群体遗传学研究

基本信息

批准号：
06640800
负责人：
IIZUKA Masaru
金额：
$ 1.34万
依托单位：
Kyushu Dental College
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1994
资助国家：
日本
起止时间：
1994 至 1995
项目状态：
已结题

项目摘要

In this research project, I studied the following two problems.(1)A stochastic model for molecular evolution by compensatory interaction. In this study, I considered two loci where mutation occurs irreversibly from the wild type allele to a mutant allele in both loci. Genetic combinations with single mutant are deleterious. The double mutant, however, compensates the harmful effect of single mutants. For this model, the average time until fixation of the double mutant was investigated to see a possibility that the compensatory interaction is a common mechanism for molecular evolution. I showed that the linkage between the loci is an important factor and the compensatory interaction can be a mechanism for molecular evolution when the loci are linked strongly or moderately. One remarkable finding was that deleterious mutation can accelerate the speed of fixation of the double mutant. In other words, the average time until fixation of the double mutant is shorter under the existence of appropriate deleterious intermediate states.(2)The effect of autocorrelated stochastic selection on neutral polymorphism. In this study, I considered a neutral locus with 2 alleles linked to a selected locus with 2 alleles. An autocorrelated stochastic selection is operating on the selected locus. I investigated how genetic variability of the neutral locus is effected by the existence of the selected locus. I found that this effect is an inceasing function of the intensity of selection and the population size and there is an optimal mean persistent time for environmental change of the autocorrelated stochastic selection.

在这个研究项目中，我研究了以下两个问题。(1)A补偿作用下分子进化随机模型在这项研究中，我考虑了两个基因座，其中突变发生不可逆的野生型等位基因的突变等位基因在这两个基因座。单一突变体的遗传组合是有害的。然而，双突变体弥补了单突变体的有害影响。对于这个模型，直到固定的双突变体的平均时间进行了研究，看看补偿相互作用是一种常见的分子进化机制的可能性。我表明，基因座之间的连锁是一个重要的因素，当基因座之间的连锁强或适度时，补偿相互作用可以是分子进化的一种机制。一个值得注意的发现是，有害突变可以加速双突变体的固定速度。换句话说，在存在适当的有害中间状态的情况下，双突变体固定的平均时间更短。（2）自相关随机选择对中性多态性的影响。在这项研究中，我考虑了一个中性基因座与一个选定的基因座与2个等位基因。自相关随机选择作用于所选的位点。我研究了中性位点的遗传变异性是如何受到所选位点的影响的。发现这种效应是选择强度和种群规模的递增函数，并且存在一个最优的自相关随机选择环境变化的平均持续时间。