Schaefer H Martin, Stobbe Nina
Institute of Biology 1, University of Freiburg, Hauptstrasse 1, 79104 Freiburg, Germany.
Proc Biol Sci. 2006 Oct 7;273(1600):2427-32. doi: 10.1098/rspb.2006.3615.
Natural selection shapes the evolution of anti-predator defences, such as camouflage. It is currently contentious whether crypsis and disruptive coloration are alternative mechanisms of camouflage or whether they are interrelated anti-predator defences. Disruptively coloured prey is characterized by highly contrasting patterns to conceal the body shape, whereas cryptic prey minimizes the contrasts to background. Determining bird predation of artificial moths, we found that moths which were dissimilar from the background but sported disruptive patterns on the edge of their wings survived better in heterogeneous habitats than did moths with the same patterns inside of the wings and better than cryptic moths. Despite lower contrasts to background, crypsis did not provide fitness benefits over disruptive coloration on the body outline. We conclude that disruptive coloration on the edge camouflages its bearer independent of background matching. We suggest that this result is explainable because disruptive coloration is effective by exploiting predators' cognitive mechanisms of prey recognition and not their sensory mechanisms of signal detection. Relative to disruptive patterns on the body outline, disruptive markings on the body interior are less effective. Camouflage owing to disruptive coloration on the body interior is background-specific and is as effective as crypsis in heterogeneous habitats. Hence, we hypothesize that two proximate mechanisms explain the diversity of visual anti-predator defences. First, disruptive coloration on the body outline provides camouflage independent of the background. Second, background matching and disruptive coloration on the body interior provide camouflage, but their protection is background-specific.
自然选择塑造了诸如伪装等反捕食防御机制的进化。目前存在争议的是，拟态和扰乱色是伪装的替代机制，还是相互关联的反捕食防御机制。具有扰乱色的猎物的特征是拥有高对比度的图案以隐藏身体形状，而拟态猎物则将与背景的对比度降至最低。通过确定鸟类对人工蛾的捕食情况，我们发现，与背景不同但翅膀边缘有扰乱图案的蛾在异质栖息地中的生存情况优于翅膀内部有相同图案的蛾，也优于拟态蛾。尽管与背景的对比度较低，但在身体轮廓上，拟态并没有比扰乱色带来更大的适应性优势。我们得出结论，边缘的扰乱色能独立于背景匹配对其拥有者起到伪装作用。我们认为这一结果是可以解释的，因为扰乱色通过利用捕食者识别猎物的认知机制而非信号检测的感官机制而有效。相对于身体轮廓上的扰乱图案，身体内部的扰乱斑纹效果较差。身体内部因扰乱色而产生的伪装是特定于背景的，并且在异质栖息地中与拟态一样有效。因此，我们假设两种直接机制解释了视觉反捕食防御的多样性。第一，身体轮廓上的扰乱色能独立于背景提供伪装。第二，身体内部的背景匹配和扰乱色提供伪装，但其保护作用是特定于背景的。
