GENETICS OF SPECIATION IN DROSOPHILA

拟议研究的长期目标是揭示进化 生物物种的形成机制。物种形成是 很难研究，即使是对密切相关的物种，因为 它们之间的分歧和孤立限制了 可以研究它们分歧的遗传基础。拟议工作 拟暗果蝇D. p. bogotana和D. persimilis， 三个密切相关且经常被研究的新世界物种。是 可能产生这些物种的可育杂交种，因此人们可以绘制地图， 计算与隔离相关的基因。 研究物种差异的三种互补方法将是 参加了这项工作。已绘制了密集的微卫星图， 这些物种，这些标记将用于定位基因负责 分离性状，如不育性，杂种无活力，和材料， 歧视(2)在这些研究进行的同时，基因组 各个微卫星基因座侧翼的区域将是研究对象， 一个彻底的比较DNA序列研究的种内和 种间和种间变异。这两项研究将 显示哪些基因与那些导致隔离的基因有关， 将展示这些国家的历史分化模式 相同的区域。先前的研究表明，这些物种有一个 历史上，包括更多的基因流的一些基因组区域比 他人这意味着自然选择，对基因流的作用， 是它们物种形成和分化的关键部分。(3)第三项研究 也将被用来测量一个物种的基因渗入量， 每个微卫星位点都可能发生的变化。这些 将在实验室中进行渐渗实验。相比 隔离性状的作图，渐渗作图不依赖于 研究者确定的表型。基因渗入作图将 评估标记的基因组区域的相对适合度，当 渗入到近缘物种中。这三个组成部分中的每一个 借鉴了过去对这三个物种进行的类似物种形成研究， 物种，虽然在拟议的工作中，映射将在一个更精细的 使用比以前更多的标记。拟议 工作还将允许对这三种类型进行全新的比较 这些信息可以汇集在一起，以制定一个更全面， 这些物种是如何分化的， 使它们保持独特的进化力量的基础。

The long term goal of the proposed research is to reveal the evolutionary mechanisms that have given rise to biological species. Speciation is difficult to study, even with pairs of closely related species, because their divergence and isolation from each other limits the degree to which the genetic basis of their divergence can be studied. The proposed work will be on Drosophila pseudoobscura, D. p. bogotana and D. persimilis, three closely related and frequently studied new world species. It is possible to generate fertile hybrids of these species, so one can map and count genes that are responsible for the traits associated with isolation. Three complementary approaches to the study of species differences will be joined in this work. A dense microsattelite map has been developed for these species, and these markers will be use for mapping genes responsible for isolation traits, such as sterility, hybrid inviability, and mater discrimination. (2) At the same time as these studies proceed, the genomic regions that flank the individual microsattelite loci will be the subject of a thorough comparative DNA sequence study of intraspecific and interspecific and interspecific variation. Together these two studies will show which genes are linked to those that contribute to isolation, and it will show the historical pattern of divergence that has occurred for these same regions. Previous research has shown that these species have a history that includes more gene flow for some genomic regions than for others. This means that natural selection, acting against gene flow, has been a critical part of their speciation and divergence. (3) A third study will also be done to measure the amount of introgression, from one species to another, that can occur for each microsatellite locus. These introgression experiments will be done in the laboratory. In contrast to the mapping of isolation traits, the introgression mapping does not rely on investigator identified phenotypes. The introgression mapping will assess the relative fitness of the marked genomic regions, when introgressed into closely related species. Each of these three components draws on similar speciation research done in the past on these three species, though in the proposed work, the mapping will be on a much finer scale with many more markers than has been used previously. The proposed work will also permit entirely novel comparisons of the three types of information which can be brought together to develop a fuller and more integrated picture of how these species came to diverge and the genetic basis of the evolutionary forces that have kept them distinct.