Department of Animal Biology, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA
Department of Animal Biology, School of Integrative Biology, University of Illinois, Urbana-Champaign, IL 61801, USA.
Proc Biol Sci. 2018 Sep 5;285(1886):20180980. doi: 10.1098/rspb.2018.0980.
Host defences against avian brood parasites are the outcome of well-documented coevolutionary arms races, yet important questions about variation in hosts' antiparasitic response traits remain poorly understood. Why are certain defences employed by some species or individuals and not by others? Here, we propose that understanding variability in and the evolution of host defences can be facilitated by the study of the underlying physiological mechanisms. Specifically, because antiparasitic strategies involve behaviours that have been shown to be hormonally regulated in other contexts, we hypothesize that host responses to brood parasites are likely to be mediated by related endocrine mechanisms. We outline the hallmarks of the endocrine bases of parasite defence-related avian behaviours, review the current understanding of antiparasitic host tactics and propose testable hypotheses about the hormonal mechanisms that may mediate host defences. We consider these mechanisms in a life-history framework and discuss how endocrine factors may shape variation in host defences. By providing a hypothesis-driven mechanistic framework for defences against parasitism, this perspective should stimulate the study of their endocrine bases to enhance our understanding of the intricate arms races in avian host-parasite systems.
宿主防御机制是有充分文献记载的协同进化军备竞赛的结果，但宿主对抗寄生虫的反应特征的变异的一些重要问题仍未得到很好的理解。为什么某些防御机制被某些物种或个体采用，而其他物种或个体则不采用？在这里，我们提出，通过研究潜在的生理机制，可以促进对宿主防御机制的变异性和进化的理解。具体来说，由于抗寄生虫策略涉及到在其他情况下已被证明受激素调节的行为，我们假设宿主对寄生虫的反应可能是由相关的内分泌机制介导的。我们概述了与寄生虫防御相关的鸟类行为的内分泌基础的特征，回顾了目前对抗寄生虫宿主策略的理解，并提出了关于可能介导宿主防御的激素机制的可测试假设。我们在生活史框架中考虑这些机制，并讨论内分泌因素如何塑造宿主防御的变异性。通过为寄生虫防御提供一个假设驱动的机制框架，这一观点应该会激发对其内分泌基础的研究，从而增强我们对鸟类宿主-寄生虫系统中复杂军备竞赛的理解。
