Walton Olivia C, Stevens Martin
Centre for Ecology & Conservation, College of Life & Environmental Sciences, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
Commun Biol. 2018 Aug 17;1:118. doi: 10.1038/s42003-018-0126-3. eCollection 2018.
Animal defensive coloration has long provided many important examples of evolution and adaptation. Of these, industrial melanism in the peppered moth is the classic textbook example of evolution in action, whereby dark and pale morphs suffer differential predation in polluted and unpolluted woodland based on their camouflage. Despite extensive work, a striking gap remains in that no study has ever objectively quantified their camouflage or related this directly to predation risk. Here we use image analysis and avian vision models to show that pale individuals more closely match lichen backgrounds than dark morphs. Artificial predation experiments in unpolluted woodland show 21% higher survival rates of pale than melanic individuals. Overall, we provide the strongest direct evidence to date that peppered moth morph frequencies stem from differential camouflage and avian predation, providing key support for this iconic example of natural selection.
长期以来，动物的防御性色彩为进化和适应提供了许多重要例证。其中，桦尺蛾的工业黑化现象是进化实际发生的经典教科书案例，在这个案例中，深色和浅色形态的桦尺蛾因其伪装效果，在污染和未污染的林地中遭受不同程度的捕食。尽管已有大量研究，但仍存在一个显著差距，即从未有研究客观量化过它们的伪装，也未将其与捕食风险直接关联起来。在此，我们运用图像分析和鸟类视觉模型表明，浅色个体比深色形态更能与地衣背景相匹配。在未污染林地进行的人工捕食实验显示，浅色个体的存活率比黑色个体高21%。总体而言，我们提供了迄今为止最有力的直接证据，证明桦尺蛾形态频率源于不同的伪装和鸟类捕食，为这一自然选择的标志性案例提供了关键支持。
