Data from: Antagonistic coevolution accelerates the evolution of reproductive isolation in Tribolium castaneum

The evolution of reproductive isolation among populations is often the result of selective forces. Among those, parasites exert strong selection on host populations and can thus also potentially drive reproductive isolation. This hypothesis has yet to be explicitly tested and, here, we set up a multigenerational coevolution experiment to explore this possibility. Five lines of Tribolium castaneum were allowed to coevolve with their natural parasite, Nosema whitei; five paired lines of identical origin were maintained in the absence of parasites. After 17 generations, we measured resistance within and reproductive isolation between all lines. Host lines from the coevolution treatment had considerable higher levels of resistance against N. whitei than their paired host lines which were maintained in the absence of parasites. Reproductive isolation was greater in the coevolved selection regime and correlated with phenotypic differentiation in parasite resistance between coevolved host lines. This suggests the presence of a selection-driven genetic correlation between offspring number and resistance. Our results show that parasites can be a driving force in the evolution of reproductive isolation, and thus potentially speciation.

种群间生殖隔离（reproductive isolation）的演化通常是选择压力作用的结果。在各类选择压力中，寄生虫对宿主种群施加强烈的选择压，因此也有可能推动生殖隔离的形成。该假说尚未得到明确验证，因此本研究设计了一项多代协同进化实验以探究该可能性。将5株赤拟谷盗（Tribolium castaneum）与其天然寄生虫白氏微孢子虫（Nosema whitei）进行协同培养；同时设置5个起源相同的配对株系，在无寄生虫的环境下维持培养。经过17代培养后，我们测定了所有株系的抗性水平以及株系间的生殖隔离程度。经协同进化处理的宿主株系，其对白氏微孢子虫的抗性水平显著高于无寄生虫环境下维持的配对株系。协同进化选择体系下的生殖隔离程度更高，且与协同进化宿主株系间的寄生虫抗性表型分化呈显著相关。这提示子代数量与抗性之间存在由选择驱动的遗传相关性。本研究结果表明，寄生虫可作为生殖隔离演化的驱动因素，进而潜在推动物种形成。