Molecular Evolution of Drosophila Y Chromosome

描述(申请人提供)：Y染色体提供了一种不同寻常的 研究种群遗传过程的机会，如搭便车和 背景选择，因为它与其他 染色体，其有效的单倍体传递，以及它对 男性。果蝇Y染色体群体遗传学研究进展 被我们对蛋白质编码基因和单拷贝的无知所阻碍 序列。通过使用与正常方法相反的BLAST，我们已经 成功鉴定出猪Y染色体上的8个新的蛋白质编码基因 D.黑腹蛇。我们现在能够提供一个彻底的量化 在Y染色体上的变异模式，并定位于 这在与相关物种的种间序列分歧的背景下。 四个相互竞争的模型，并不都是相互排斥的，做出了关于 Y染色体上的变异水平。它们是穆勒的棘轮，背景 选择、希尔-罗伯逊效应和搭便车。这四个都通向 关于Y的标准变异水平应该被压低的预测 与常染色体相比，但他们对频率的说法不同 等位基因的谱、种群细分程度和年龄分布。我们 建议将这些参数化为参数并定量衡量这些优点 通过以下三个目标相互竞争的假设：第一，我们将量化 并建立了Y染色体上蛋白质编码基因的种内多态模型 DHPLC和直接测序相结合的黑腹水母染色体研究 96个Y染色体置换系中Y连锁蛋白编码基因的研究 在全球范围内发行。其次，我们将从一个 一系列相关物种，以确定分歧率和 描述内含子Y异染色质的分子进化。最后，我们 将检验分离Y变异和精子变异之间的关系 通过精子运动学分析和精子竞争性试验实现的功能 才能。这些研究将使黑腹毛虫成为一项关键的实验。 Y染色体多态和分子进化分析系统。

DESCRIPTION (provided by applicant): The Y chromosome provides an unusual opportunity to examine population genetic processes like hitchhiking and background selection because of its recombinational isolation from other chromosomes, its effectively haploid transmission, and its restriction to males. Progress in studying Y chromosome population genetics of Drosophila has been held back by our ignorance of protein-coding genes and single-copy sequence. By using BLAST in the reverse of the normal approach, we have successfully identified eight new protein-coding genes on the Y chromosome of D. melanogaster. We are now in a position to provide a thorough quantification of patterns of variation on the Y chromosome of D. melanogaster, and to place this in the context of interspecific sequence divergence with related species. Four competing models, not all mutually exclusive, make predictions about levels of variation on a Y chromosome. They are Muller's ratchet, background selection, the Hill-Robertson effect, and hitchhiking. All four lead to the prediction that standing levels of variation on the Y ought to be depressed compared to autosomes, but they make different claims about the frequency spectrum, degree of population subdivision, and age distribution of alleles. We propose to parameterize and to quantitatively weigh the merits of these competing hypotheses through the following three aims: First, we will quantify and model intraspecific polymorphism in protein-coding genes on the Y chromosome of D. melanogaster by a combination of dHPLC and direct sequencing of Y-linked protein-coding genes in a set of 96 Y chromosome replacement lines of global distribution. Second, we will obtain corresponding sequences from a series of related species, in order to determine divergence rates and to characterize the molecular evolution of intronic Y heterochromatin. Finally, we will test associations between segregating Y variation and variation in sperm function through sperm kinematics assays and tests of sperm competitive ability. These studies will establish D. melanogaster as a key experimental system for analysis of Y chromosome polymorphism and molecular evolution.