Evolution, Ecology and Genetics, Research School of Biology, The Australian National University, Canberra, Australia.
Biol Rev Camb Philos Soc. 2016 Aug;91(3):569-77. doi: 10.1111/brv.12181. Epub 2015 Mar 12.
Avian brood parasites lay their eggs in the nests of their hosts, which rear the parasite's progeny. The costs of parasitism have selected for the evolution of defence strategies in many host species. Most research has focused on resistance strategies, where hosts minimize the number of successful parasitism events using defences such as mobbing of adult brood parasites or rejection of parasite eggs. However, many hosts do not exhibit resistance. Here we explore why some hosts accept parasite eggs in their nests and how this is related to the virulence of the parasite. We also explore the extent to which acceptance of parasites can be explained by the evolution of tolerance; a strategy in which the host accepts the parasite but adjusts its life history or other traits to minimize the costs of parasitism. We review examples of tolerance in hosts of brood parasites (such as modifications to clutch size and multi-broodedness), and utilize the literature on host-pathogen interactions and plant herbivory to analyse the prevalence of each type of defence (tolerance or resistance) and their evolution. We conclude that (i) the interactions between brood parasites and their hosts provide a highly tractable system for studying the evolution of tolerance, (ii) studies of host defences against brood parasites should investigate both resistance and tolerance, and (iii) tolerance and resistance can lead to contrasting evolutionary scenarios.
鸟类巢寄生者将它们的卵产在宿主的巢中，由宿主来养育寄生者的后代。寄生的代价促使许多宿主物种进化出防御策略。大多数研究都集中在宿主的抵抗策略上，即通过驱赶成年巢寄生者或拒绝寄生卵等防御措施，尽量减少成功寄生的次数。然而，许多宿主并没有表现出抵抗能力。在这里，我们探讨了为什么有些宿主在巢中接受寄生虫卵，以及这与寄生虫的毒力有何关系。我们还探讨了宿主接受寄生虫的程度可以在多大程度上通过容忍的进化来解释；这种策略是指宿主接受寄生虫，但会调整其生活史或其他特征，以最小化寄生的代价。我们回顾了巢寄生者宿主中的容忍实例（例如对卵数和多窝产卵的修改），并利用宿主-病原体相互作用和植物食草的文献，分析了每种防御类型（容忍或抵抗）及其进化的流行程度。我们得出结论：（i）巢寄生者与其宿主之间的相互作用为研究容忍的进化提供了一个高度可行的系统；（ii）对宿主防御巢寄生者的研究应该同时调查抵抗和容忍；（iii）容忍和抵抗可以导致截然不同的进化情景。
