Rapid seasonal evolution in innate immunity of wild Drosophila melanogaster

Understanding the rate of evolutionary change and the genetic architecture that facilitates rapid adaptation is a current challenge in evolutionary biology. Comparative studies show that genes with immune function are among the most rapidly evolving genes across a range of taxa. Here, we use immune defence in natural populations of Drosophila melanogaster to understand the rate of evolution in natural populations and the genetics underlying rapid change. We probed the immune system using the natural pathogens Enterococcus faecalis and Providencia rettgeri to measure post-infection survival and bacterial load of wild D. melanogaster populations collected across seasonal time along a latitudinal transect along eastern North America (Massachusetts, Pennsylvania and Virginia). There are pronounced and repeatable changes in the immune response over the approximately 10 generations between spring and autumn collections, with a significant but less distinct difference observed among geographic...

解析演化变化速率与促成快速适应性演化的遗传架构，是演化生物学领域当前的核心挑战之一。比较研究表明，在多个类群（taxa）中，具有免疫功能的基因均属于演化速率最快的基因之列。本研究以野生黑腹果蝇（Drosophila melanogaster）自然种群的免疫防御为研究对象，旨在解析自然种群的演化速率与快速适应性变化背后的遗传机制。我们利用天然病原体粪肠球菌（Enterococcus faecalis）与雷氏普罗威登斯菌（Providencia rettgeri）侵染果蝇免疫系统，以测定采集自北美东部纬度样带的野生黑腹果蝇种群在感染后的存活率与细菌载量；这些种群按季节时序采集，采样区域覆盖马萨诸塞州、宾夕法尼亚州与弗吉尼亚州。在春季与秋季采样间隔的约10个世代内，果蝇的免疫应答呈现出显著且可重复的动态变化；不同地理种群间亦存在统计学意义显著但差异程度相对较弱的分化……