Evidence for Balancing Selection at Immunity Genes in Drosophila

该项目的目标是深入了解寄生虫感染的先天免疫反应中涉及的基因的进化。我们利用来自祖先（非洲）和衍生（欧洲）人口的下一代序列数据来检测证据，以平衡选择沿着果蝇基因组。平衡选择是维持群体中有利遗传变异的重要生物学力量。然而，介导不同的群体遗传原因，如遗传机制（如杂合子优势），人口结构和/或复杂的时间人口过程，这种形式的选择是相当困难的研究。因此，它在大多数物种基因组中的流行率、模式和目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性的长期过程。我们使用特定的群体遗传学方法来识别平衡选择的靶基因，在短到很长的进化时间尺度上寻找指示平衡选择的基因组签名。然后，我们分析的免疫基因，显示最有力的证据，平衡选择，研究这种类型的选择的潜在机制。

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.