Experimental elimination of parasites in nature leads to the evolution of increased resistance in hosts
Experimental elimination of parasites in nature leads to the evolution of increased resistance in hosts
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DOI：
10.1098/rspb.2013.2371
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发表时间：
2013-12-22
影响因子：
4.7
通讯作者：
Fussmann, Gregor F.
中科院分区：
文献类型：
--
作者：
Dargent, Felipe;Scott, Marilyn E.;Fussmann, Gregor F.
预期选择强度的降低会导致性状表达降低的进化。因此，消灭一种寄生虫应该会导致对这种寄生虫的抗性降低。为了测试这一预测在自然界中，我们研究了第四代和第八代的后代孔雀鱼（孔雀鱼）引入到四个自然流实验消除常见的和有害的寄生虫（Gyrodactylus属）。经过两代的实验室饲养，以控制可塑性和母体的影响，我们感染个别鱼，以评估其抵抗寄生虫。与理论预期相反，引入的孔雀鱼种群迅速且可重复地进化出对现在不存在的寄生虫的抵抗力。这种演变不是由于抗性-耐受性的权衡，也不是由于站点之间生产力的差异。相反，一个领先的候选人的假设是，快速的生活史进化典型的引进多效性增加寄生虫的抵抗力。我们的研究为当代野外进化的证据增加了一个新的维度，也指出了重新考虑宿主-寄生虫理论的简单期望的必要性。特别是，我们的研究结果强调了在自然环境中研究进化时，需要更多地考虑选择和多效性的多种来源。
A reduction in the strength of selection is expected to cause the evolution of reduced trait expression. Elimination of a parasite should thus cause the evolution of reduced resistance to that parasite. To test this prediction in nature, we studied the fourth-and eighth-generation descendants of guppies (Poecilia reticulata) introduced into four natural streams following experimental elimination of a common and deleterious parasite (Gyrodactylus spp.). After two generations of laboratory rearing to control for plasticity and maternal effects, we infected individual fish to assess their resistance to the parasite. Contrary to theoretical expectations, the introduced guppy populations had rapidly and repeatably evolved increased resistance to the now-absent parasite. This evolution was not owing to a resistance-tolerance trade-off, nor to differences in productivity among the sites. Instead, a leading candidate hypothesis is that the rapid life-history evolution typical in such introductions pleiotropically increases parasite resistance. Our study adds a new dimension to the growing evidence for contemporary evolution in the wild, and also points to the need for a re-consideration of simple expectations from host-parasite theory. In particular, our results highlight the need for increased consideration of multiple sources of selection and pleiotropy when studying evolution in natural contexts.