CONSTRAINTS ON MOLECULAR VARIATION AND EVOLUTION

这项建议的目的是研究遗传基因施加的限制 位置和交配系统对分子进化和变异的影响。 这应该可以解释变异和进化的基本机制。 对这些问题的认识对于人类认识和理解人类具有重要意义。 遗传病。 第一个项目将确定X-的相对进化率 果蝇的染色体和常染色体基因座。理论与间接 经验证据表明，适应性评估的比率可能是 X连锁基因比可比常染色体基因更快。理论 表明中性进化对于这两个类是相同的，但是 轻微有害等位基因的替代速度应该较慢。 用于X连锁基因座。这些预测将通过比较利率进行检验。 同义和非同义核苷酸替换在适当的位置 果蝇种中常染色体携带这些基因的基因座 已经被转移到X染色体上，在物种中的比率 这些基因座是常染色体。 在第二个项目中，育种系统对肉鸡生产水平的影响 分子变异将通过检测DNA序列变异来研究 在十字花科植物物种中，其中一些高度自交 而另一些则完全是异种杂交。理论预测 高度自交应该会导致几乎完全丧失多样性 中性站点将通过比较同义词的模式进行测试 这两类物种的变异。可能采取的行动 保持变异的选择将通过比较同义词进行测试 对比两种类型物种内部和之间的非同义词差异。

The aim of this proposal is to study the constraints imposed by genetic location and by the mating system on molecular evolution and variation. This should illuminate basic mechanisms of variation and evolution. Knowledge of these is of significance for the understanding of human genetic disease. The first project will determine the relative rates of evolution of X- chromosomal and autosomal loci in Drosophila. Theory and indirect empirical evidence suggest that the rate of adaptive evaluate may be faster for X-linked genes than for comparable autosomal genes. Theory shows that the of neutral evolution is the same for the two classes, but the rate of substitution of slightly deleterious alleles should be slower for X-linked loci. These predictions will be tested by comparing rates of synonymous and non-synonymous nucleotide substitutions at suitable loci in a species of Drosophila in which autosome carrying these loci have been translocated onto the X-chromosome with rates in species in which the loci are autosomal. In the second project, the effect of breeding system on the level of molecular variation will be studied by examining DNA sequence variation in species of Brassicaceous plants, some of which highly self-fertilizing and others of which are completely outcrossing. Theoretical predictions the high selfing should lead to an almost complete loss of diversity at neutral sites will be tested by comparing patterns of synonymous variation in the two classes of species. The possible action of selection in maintaining variation will be tested by comparing synonymous versus non-synonym variation within and between the two types of species.