GENETICS OF SPECIATION IN DROSOPHILA

这项拟议研究的长期目标是揭示 产生生物物种的机制。物种形成是 即使是成对的近亲物种，也很难研究，因为 它们的分歧和相互孤立限制了 它们分化的遗传基础是可以研究的。拟议中的工作 将发生在果蝇、拟黑果蝇和拟果蝇上， 三个密切相关且经常被研究的新大陆物种。它是 有可能产生这些物种的可育杂交种，所以人们可以绘制和 计算与与世隔绝相关的特征相关的基因。 研究物种差异的三种互补方法将是 参与了这项工作。一张密集的微卫星地图已经被开发出来 这些物种，以及这些标记将被用于定位负责的基因 用于隔离性状，如不育性、杂交种不生存能力和母本 歧视。(2)在这些研究进行的同时，基因组 单个微卫星座位两侧的区域将成为研究对象。 对种内和种内的DNA序列进行全面的比较研究 种间变异和种间变异。这两项研究将结合起来 显示哪些基因与那些有助于隔离的基因有关，而且它 将显示这些产品出现的分歧的历史模式 同样的地区。先前的研究表明，这些物种有一种 包括某些基因组区域的基因流动多于 其他。这意味着自然选择与基因流动背道而驰， 是它们物种形成和分化的关键部分。(3)第三项研究 也将用来测量一个物种的渗透量 对于另一个，这可能发生在每个微卫星座位上。这些 渗透实验将在实验室中进行。与之形成鲜明对比的是 隔离性状的作图，导入作图不依赖于 研究人员鉴定出了表型。该渐进映射将 评估标记的基因组区域的相对适合度，当 融入到近缘物种中。这三个组件中的每一个 借鉴了过去对这三个物种所做的类似物种形成研究 物种，虽然在拟议的工作中，测绘将在一个更精细的 使用比以前使用的标记多得多的标记进行缩放。建议数 这项工作还将允许对三种类型的 可以整合在一起的信息，以开发更全面和更多的 这些物种如何分化和遗传的综合图景 使它们保持不同的进化力量的基础。

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.