Expósito-Granados Mónica, Parejo Deseada, Martínez Juan Gabriel, Sánchez-Tójar Alfredo, Precioso Marta, Molina-Morales Mercedes, Avilés Jesús M
Department of Functional and Evolutionary Ecology, EEZA-CSIC, Almería, Spain.
Department of Zoology, University of Extremadura, Badajoz, Spain.
PLoS One. 2017 Jun 28;12(6):e0179206. doi: 10.1371/journal.pone.0179206. eCollection 2017.
Hosts can counteract parasites through defences based on resistance and/or tolerance. The mechanistic basis of tolerance, which involve defensive mechanisms minimizing parasite damage after a successful parasitic attack, remains poorly explored in the study of cuckoo-host interactions. Here, we experimentally explore the possibility that the risk of great spotted cuckoo Clamator glandarius parasitism may induce tolerance defences in magpie Pica pica hosts through plasticity in life-history traits. We predict that magpies exposed to auditory cues indicating high parasitism risk will more likely exhibit resistance and/or modify their life-history traits to minimize parasitism costs (i.e. tolerance) compared to magpies under low parasitism risk. We found that manipulating the perceived parasitism risk did not affect host resistance (i.e. rejection of parasitic eggs) nor host life-history traits. Unexpectedly, host's egg volume increased over the season in nests exposed to auditory cues of control non-harmful hoopoes Upupa epops. Our results do not provide support for inducible defences (either based on resistance or tolerance) in response to risk of parasitism in magpie hosts. Even so, we encourage studying plastic expression of breeding strategies in response to risk of cuckoo parasitism to achieve a better understanding of the mechanistic basis of tolerance defences.
宿主可以通过基于抗性和/或耐受性的防御来对抗寄生虫。耐受性的机制基础，即涉及在寄生虫成功攻击后将寄生虫损害降至最低的防御机制，在杜鹃-宿主相互作用的研究中仍未得到充分探索。在这里，我们通过实验探讨了大斑杜鹃（Clamator glandarius）寄生风险可能通过生活史特征的可塑性诱导喜鹊（Pica pica）宿主产生耐受性防御的可能性。我们预测，与处于低寄生风险下的喜鹊相比，暴露于表明高寄生风险的听觉线索的喜鹊更有可能表现出抗性和/或改变其生活史特征，以将寄生成本降至最低（即耐受性）。我们发现，操纵感知到的寄生风险既不影响宿主的抗性（即拒绝寄生卵），也不影响宿主的生活史特征。出乎意料的是，在暴露于对照无害戴胜（Upupa epops）听觉线索的巢穴中，宿主的卵体积在整个季节中都有所增加。我们的结果不支持喜鹊宿主对寄生风险产生诱导性防御（基于抗性或耐受性）。即便如此，我们鼓励研究应对杜鹃寄生风险的繁殖策略的可塑性表达，以更好地理解耐受性防御的机制基础。
