TEST OF NEUTRAL MOLECULAR EVOLUTION IN DROSOPHILA

这项拟议中的研究旨在测试自然选择是否有助于 维持物种内的多态性和遗传分化 物种之间，如果选择是操作，以区分 不同种类的选择。 该分析共同依赖于一个强大的 一种新的策略，用于确定同一基因的许多等位基因的DNA序列， 基因和一套新的统计测试区分进化 力. 通过比较物种内的核苷酸多态性和分歧 在物种之间，统计测试允许遗传漂变，阳性 选择（自适应变化），负选择（自适应约束）和 平衡选择（杂合子优势），以区别于 另 这些测试还将解决是否氨基酸取代， 蛋白质进化是由遗传漂变或正选择控制的。 这项研究的目的是了解进化的原因， 两种主要的蛋白质变异模式：无多态性的基因座和 中间频率等位基因。 核苷酸多态性水平将 在三个相关的果蝇中的每一个中确定六个基因位点 物种 基因座已经被选择，以便可以进行具体的预测。 关于影响它们进化的选择模式。 自然界中蛋白质遗传变异的种类 人口，和选择的力量对他们的运作是直接的 对遗传疾病和变异问题的兴趣 环境条件。

The proposed research tests whether natural selection contributes to the maintenance of polymorphism within species and to genetic divergence between species, and if selection is operating to distinguish between different kinds of selection. The analysis relies jointly on a powerful new strategy for determining the DNA sequences of many alleles of the same gene and on a new set of statistical tests for distinguishing evolutionary forces. By comparing nucleotide polymorphism within species to divergence between species the statistical tests allow genetic drift, positive selection (adaptive change), negative selection (adaptive constraint) and balancing selection (heterozygote advantage) to be distinguished one from another. The tests will also address whether amino acid substitutions in protein evolution are governed by genetic drift or by positive selection. The goal of the study is to understand the evolutionary cause of two major patterns of protein variation: loci with no polymorphism and loci with Intermediate frequency alleles. Nucleotide polymorphism levels will be determined for six gene loci in each of three related Drosophila species. The loci have been chosen so that specific predictions can be made about the mode of selection affecting their evolution. The kinds of genetic variation in proteins in natural populations, and the forces of selection operating on them is of direct interest to problems of genetic disease and to variation In response to conditions of the environment.