Evidence for Balancing Selection at Immunity Genes in Drosophila

该项目的目标是深入了解涉及寄生虫感染的先天免疫反应的基因的进化。我们利用来自祖先(非洲)和派生(欧洲)种群的下一代序列数据来检测沿着黑腹果蝇基因组平衡选择的证据。平衡选择是维持种群有利遗传变异的重要生物学力量。然而，由于受到多种群体遗传因素的调节，如遗传机制(如杂合子优势)、群体结构和/或复杂的时间群体过程，这种形式的选择很难研究。因此，它在大多数物种基因组中的流行情况、模式和靶标在很大程度上是未知的。在共同进化的宿主-寄生虫系统中，它可能发生在非常不同的时间尺度上，从最近的选择性事件到导致跨物种多态的长期过程。我们使用特定的群体遗传学方法来识别平衡选择的目标基因，寻找表明在短到很长的进化时间尺度上平衡选择的基因组特征。然后，我们分析证明平衡选择的最有力证据的免疫基因，以研究这种类型选择的潜在机制。

The goal of this project ist o gain insights into the evolution of genes involved in the innate immunity response to parasite infection. We utilize next-generation sequence data from an ancestral (African) and a derived (European) population to detect evidence for balancing selection along the genome of Drosophila melanogaster. Balancing selection is an important biological force for maintaining advantageous genetic variation in populations. However, being mediated by diverse population genetic causes, such as genetic mechanisms (e.g. heterozygote advantage), population structure and/or complex temporal population processes, this form of selection is rather hard to study. Hence, its prevalence, patterns and targets in the genomes of most species are largely unknown. In coevolutionary host-parasite systems, it may occur on very different time scales, from very recent selective episodes to long-term processes causing trans-species polymorphism. We use specific population genetics methods to identify the target genes of balancing selection, searching for genomic signatures indicating balancing selection on short to very long evolutionary time scales. Then we analyze the immunity genes that show the strongest evidence for balancing selection to study the underlying mechanisms of this type of selection.