Collaborative Research: Organization of Nucleotide Diversity in the Inversions of Drosophila pseudoobscura

安德森9729144这个项目的研究目标是测试有关遗传力的假说，这些遗传力调节了染色体改变的变异，这种改变改变了被称为倒置的基因顺序。五十多年来，黑腹果蝇第三条染色体上的染色体倒位在进化生物学文献中占有重要地位。它们已被证明是研究地理变异、自然选择、基因流动和遗传漂移的一个非常有用的模型系统。倒置似乎代表了适应性选择的一个明显的例子，因为它们的频率随着环境的不同而变化，形成了经典的斜坡，在一些种群中，倒置频率有季节性的周期。这一建议的目的是确定选择如何作用于拟黑僵菌种群内和种群之间的倒位的遗传含量。本研究将通过分析均匀分布在假黑粉虱第三染色体上的9个PCR扩增标记的核苷酸多样性来区分不同的选择模式。这9个标记将在从四个种群中收集的假黑僵菌菌株中进行测序，这些种群跨越一个倒置频率临床。在过去的二十年里，分子进化的研究主要集中在塑造单基因多样性的遗传力上，而没有考虑选择是否保持了染色体上连锁基因的组合。基因组中特定染色体上的基因关联是由于选择还是偶然发生，这是一个悬而未决的问题。倒位是维持分布在远距离染色体上的遗传多样性之间联系的重要机制。该项目将提供关于调节自然种群中大片段基因组进化的遗传力的宝贵数据。

Anderson 9729144 The research goals of this project are to test hypotheses about the genetic forces that modulate variation of chromosomal alterations that modify gene order known as inversions. The chromosomal inversions on the third chromosome of Drosophila pseudoobscura have figured prominently in the literature of evolutionary biology for more than fifty years. They have proven to be a very useful model system for studies of geographic variation, natural selection, gene flow, and genetic drift. The inversions seem to represent a clear case of adaptive selection because they vary in frequency with the environment, form classical clines, and in some populations there are seasonal cycles of inversion frequency. The objective of this proposal is to determine how selection acts on the genetic contents of inversions within and among D. pseudoobscura populations. This research will discriminate between various models of selection by analyzing nucleotide diversity of nine PCR amplified markers uniformly distributed on the third chromosome of D. pseudoobscura. The nine markers will be sequenced in D. pseudoobscura strains collected from four populations that span an inversion frequency cline. Studies of molecular evolution over the past two decades have focussed on the genetic forces that shape diversity of single genes and have not considered if selection maintains assemblages of linked genes on chromosomes. It is an open question whether the association of genes on particular chromosomes within the genome happened due to selection or accident. Inversions provide an important mechanism to maintain the association of genetic diversity distributed across long distances of chromosomes. This project will provide valuable data on the genetic forces that modulate the evolution of large segments of the genome in natural populations.