Flies on the move: an inherited virus mirrors Drosophila melanogaster’s elusive ecology and demography

Vertically transmitted parasites rely on their host's reproduction for their transmission, leading to the evolutionary histories of both parties being intimately entwined. Parasites can thus serve as a population genetic magnifying glass for their host's demographic history. Here, we study the fruitfly Drosophila melanogaster's vertically transmitted sigma virus DMelSV. The virus has a high mutation rate and low effective population size, allowing us to reconstruct at a fine scale how the combined forces of the movement of flies and selection on the virus have shaped its migration patterns. We found that the virus is likely to have spread to Europe from Africa, mirroring the colonization route of Drosophila. The North American DMelSV population appears to be the result of a recent single immigration from Europe, invading together with its host in the late 19th century. Across Europe, DMelSV migration rates are low and populations are highly genetically structured, likely reflecting limi...

垂直传播的寄生虫依赖宿主的繁殖完成自身传播，二者的演化历史由此紧密交织。因此，寄生虫可作为研究宿主种群演化历史的种群遗传学放大镜。本研究聚焦黑腹果蝇（Drosophila melanogaster）的垂直传播σ病毒DMelSV。该病毒具有较高的突变率与较低的有效种群大小（effective population size），使我们能够在精细尺度上重构果蝇扩散与病毒自身选择压力的共同作用如何塑造了其迁移模式。研究发现，该病毒极有可能从非洲传入欧洲，这与黑腹果蝇的殖民扩散路径相一致。北美DMelSV种群似乎源自近期一次从欧洲的单次迁入事件，与宿主一同在19世纪后期完成入侵定殖。在欧洲全域范围内，DMelSV的迁移速率较低，种群具有高度的遗传结构，这大概率反映了受限的...