Institute of Integrative Biology, Experimental Ecology, Eidgenössische Technische Hochschule Zürich Universitätstrasse 16, CHN K 12.2, 8092 Zürich, Switzerland.
Am Nat. 2012 Oct;180(4):520-8. doi: 10.1086/667589. Epub 2012 Aug 20.
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 considerably 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.
种群间生殖隔离的进化通常是选择压力的结果。在这些因素中，寄生虫对宿主种群施加了强大的选择压力，因此也可能潜在地推动生殖隔离。这一假设尚未被明确验证，在这里，我们建立了一个多代共同进化实验来探索这种可能性。我们允许五种赤拟谷盗（Tribolium castaneum）与它们的天然寄生虫——白僵菌（Nosema whitei）共同进化；同时，保持五个配对的具有相同起源的线系在没有寄生虫的情况下生存。经过 17 代后，我们测量了所有线系的内部抗性和生殖隔离。与在没有寄生虫的情况下保持配对的宿主线系相比，来自共同进化处理的宿主线系对 N. whitei 的抗性水平要高得多。在共同进化的选择体系中，生殖隔离更大，并且与共同进化的宿主线系之间对寄生虫抗性的表型分化相关。这表明在后代数量和抗性之间存在由选择驱动的遗传相关性。我们的结果表明，寄生虫可能是生殖隔离进化的驱动力，从而可能导致物种形成。
