MOLECULAR GENETIC VARIATION IN NATURAL POPULATIONS

该项目的主要重点是调查相关的 突变、重组、遗传漂变和自然选择在 塑造在DNA水平上观察到的遗传变异水平。几 实验解决了一个基本问题：数量是多少， 分子群体遗传变异的质量？获得一个将军 回答许多位点（白色、黄色至Achete、G-6-PHD、分叉、朱红， 在果蝇自然种群中， 被调查。在这些和比较研究中的一个具体问题， 其他物种的差异是由于大量的 分子遗传变异上的交叉。的 结合理论研究的实验结果表明， 降低染色体区域的DNA序列多态性水平， 交叉减少是由“搭便车”的影响，罕见的 选择性偏好和连锁的突变体。 这个项目的一个新方面是从以前的工作中发展出来的， D. ananassae是雄性减数分裂的细胞学研究。这 物种显示规则减数分裂交换在男性，这是非典型的 其他与果蝇密切相关的物种。 本课题除了对D.阿纳纳塞马莱 减数分裂于1990年1月终止。本研究的主要方面 继续由PI和该组的其他人在他们的新研究中进行调查， 岗位这个项目是继续作为博士之间的合作。 NIEHS的兰利和贾德小组（见Z 01 ES 65037-06 LMG）。光 并对D.阿纳萨男性有 产生了一些早期前期细胞的图像。详细审查 电子显微镜照片应该能回答一些关键问题， 结构，如联会复合体。

The primary focus of this project is the investigation of the relative roles of mutation, recombination, genetic drift and natural selection in shaping the levels of genetic variation observed at the DNA level. Several experiments address the fundamental question: what is the quantity and quality of molecular population genetic variation? To obtain a general answer many loci (white, yellow to achete, g-6-phd, forked, vermilion, suppressor of forked and zeste) in natural populations of Drosophila have been surveyed. A specific question in these and comparative studies with other species is the consequence of large differences in the amounts of crossing over per kilobase on the molecular genetic variation. The experimental results in conjunction with theoretical studies suggest that reduced levels of DNA sequence polymorphism in chromosome regions where crossing over is reduced are caused by the "hitch-hiking" effect of rare selectively favored and linked mutants. A new aspect of this program that grew out of previous work examining transposons in D. ananassae is the cytological study of male meiosis. This species shows regular meiotic crossingover in males, which is atypical of other closely related Drosophila species. This project except for the cytological analysis of D. ananassae male meiosis was terminated in January 1990. Major aspects of this research continue to be investigated by the PI and others of this group in their new positions. This project is continuing as a collaboration between Dr. Langley and the Judd group at NIEHS (see Z01 ES 65037-06 LMG). The light and electron microscopic examination of meiosis in D. ananassae males has produced some figures of cells in early prophase. Detailed examination of the electron microscope pictures should answer questions about crucial structures such as the synaptonemal complex.