PDF(Pubmed)
Abstract：
Egg recognition and rejection are the most common and effective anti-parasitic strategies against avian brood parasitism in terms of maintaining stability over time and plasticity in response to environmental cues. Conversely, parasites have evolved multiple counter-adaptations to the anti-parasitic defenses of hosts. Among them, the crypsis hypothesis suggests that eggs that appear more cryptic in color and are closely matched to the environment are helping to counter the egg recognition strategy of the host. In this study, we investigated whether the egg recognition ability of Oriental reed warblers (Acrocephalus orientalis), a common host of common cuckoos (Cuculus canorus), changed during different reproductive stages by using model egg experiments. The effect of the crypsis hypothesis on the egg recognition ability of the hosts was also investigated by controlling the color contrast between the inside of the experimental nests and the model eggs. The results showed that the Oriental reed warbler retained strong egg recognition abilities, which were similar to the incubation stage (GLMMs: F 1,27 = 0.424, p = .521), even after entering the nestling stage and preferentially rejected model eggs with distinct contrasting colors (binomial test: Fisher\'s exact, p = .016). These results are consistent with the crypsis hypothesis. The present study suggests that the host retains a strong egg recognition ability even during the nestling stage and that cryptic-colored eggs that are closely matched with the breeding nest environment help counter the host\'s egg recognition abilities and increase the chances of successful parasitism by cuckoos. However, the effectiveness of cryptic egg may be weaker than mimic egg in countering egg recognition and rejection by hosts with open-cup nests.
摘要：
卵识别和排斥是针对禽类寄生的最常见和有效的抗寄生策略，可以维持随时间的稳定性和对环境线索的可塑性。相反，寄生虫已经对宿主的抗寄生虫防御进行了多种反适应。其中,crypsis假说表明，看起来颜色更隐秘且与环境紧密匹配的卵有助于对抗宿主的卵识别策略。在这项研究中,我们调查了东方芦苇（Acrocephalis）的卵识别能力，普通杜鹃（Cuculuscanorus）的共同宿主，通过模型卵实验在不同的生殖阶段发生了变化。还通过控制实验巢内部与模型卵之间的颜色对比度，研究了隐匿假说对宿主卵识别能力的影响。结果表明，东方芦苇莺保留了较强的卵识别能力，与孵育阶段相似(GLMMs：F1,27=0.424，p=.521)，即使在进入雏鸟阶段并优先拒绝具有明显对比颜色的模型卵(二项检验:Fisher精确,p=.016）。这些结果与隐匿假说是一致的。本研究表明，即使在雏鸟阶段，寄主仍保持较强的卵识别能力，与繁殖巢环境紧密匹配的隐色卵有助于对抗寄主的卵识别能力，并增加杜鹃成功寄生的机会。然而,隐卵的有效性可能弱于模拟卵，以对抗具有开放杯状巢的宿主对卵的识别和排斥。
