Camouflage and the light environment

被捕食者发现可能意味着动物的末日。因此，露营对许多物种的生存至关重要，也是自然界中最常见的反捕食者策略之一。动物的伪装通常依赖于与周围环境的颜色和图案相匹配，但是当光照条件不断改变背景的外观时，它是如何做到这一点的呢？场景中的植被和纹理会创建复杂的阴影和图案，当云经过并漫射照明时，这些阴影和图案会迅速消失。同样，场景中的颜色取决于大气条件;在晴朗的日子里，阴影是蓝色的，当阴天时，照明颜色变得均匀。因此，光照条件和三维栖息地结构之间的相互作用可能是动物伪装成功的关键，并影响其生存。已经确定了一些伪装策略，帮助动物保持隐形，它们通常取决于特定的光照条件。例如，反阴影是在许多背部黑色和腹部苍白的物种中发现的一种策略。这种颜色有助于抵消动物下侧的阴影，使其不太容易识别。在许多物种中也发现了创造虚假纹理和深度线索的颜色;模仿阳光直射照明的策略。背景模式匹配可以保护动物免受捕食者的伤害，但背景模式会在一天中发生变化。因此，这些战略在弥漫、多云的条件下可能变得无效，甚至适得其反。除了基本的颜色差异，这些伪装策略在不同的光环境和栖息地结构中如何表现仍然是未知的;理解这种相互作用-这可能会影响任何视觉狩猎物种的生存-将是我拟议的研究重点。我计划使用一系列创新的实验来调查三维栖息地结构，颜色和照明条件对伪装的重要性。首先，我将确定苇莺是否可以选择巢址的照明条件，优化其蛋的伪装，并测试是否蛋的颜色和照明之间的不匹配增加被捕食者发现的可能性。接下来，我将在野外建立人工巢穴，测试不同的伪装策略如何在捕食时的栖息地结构和光照条件下发挥作用。最后，我将使用一个在线进化游戏，它允许计算机生成的“鸡蛋”在不同的照明条件和不同的背景下进化。我预测，最佳的伪装策略应该根据光线与场景三维结构的相互作用而改变。平坦的栖息地应该有利于创造虚假纹理和深度线索的策略，直接照明应该促进反阴影和红绿色的颜色匹配而不是蓝黄色。我的研究将为照明条件和栖息地形状对个体动物生存的重要性提供基本见解。这些发现将对保护项目具有直接价值，以制定土地利用战略和耕作方法，帮助保护脆弱物种免受捕食。由于气候变化，人类正在改变世界各地栖息地的照明条件，这可能会改变在不同照明制度下进化的伪装策略的功效。因此，我的研究有可能在伪装，环境变化和保护方面开辟新的研究领域。

Being spotted by a predator can spell the end for an animal. Camouflage is therefore critical to the survival of many species and is one of the most common anti-predator strategies in nature. An animal's camouflage often depends on matching the colours and patterns of its surroundings, but how can it achieve this when the lighting conditions continually alter the background's appearance? The vegetation and textures in a scene create complex shadows and patterns that rapidly disappear when a cloud passes over and diffuses the lighting. Likewise the colours in a scene depend on atmospheric conditions; on a clear day shadows are blue-tinted, and when overcast the lighting colour becomes uniform. Interactions between lighting conditions and three-dimensional habitat structure could therefore be essential for the success of an animal's camouflage and affect its very survival.A number of camouflage strategies have been identified that help animals stay unseen, and they often depend on specific lighting conditions. For example, counter-shading is a strategy found in many species that have dark backs and pale underbellies. This coloration helps to cancel out the shadows on the animal's underside, making its tell-tale shape less easily recognised. Coloration that creates false textures and depth cues is also found in many species; tactics that mimic illumination by direct sunlight. Background pattern matching can protect animals from predators, but the background patterns will shift and change throughout the day. It is therefore possible that these strategies become ineffective or even counterproductive under diffuse, overcast conditions. Beyond basic colour differences it remains unknown how these camouflage strategies perform in different light environments and habitat structures; understanding this interaction - which could affect the survival of any visually hunted species - will be the focus of my proposed research.I plan to use an innovative range of experiments to investigate the importance of three-dimensional habitat structure, colour and lighting conditions on camouflage. First, I will determine whether reed warblers can select nest sites with lighting conditions that optimise the camouflage of their eggs, and test whether a mismatch between egg coloration and lighting increases their likelihood of being spotted by predators. Next, I will create artificial nests in the wild, testing how different camouflage strategies perform given the habitat structure and lighting conditions at the time of predation. Finally, I will use an online evolution game that allows computer-generated 'eggs' to evolve under different lighting conditions and against different backgrounds. I predict that the optimal camouflage strategy should switch depending on how light interacts with the three-dimensional structure of a scene. Flat habitats should favour strategies that create false textures and depth cues, and direct lighting should promote counter-shading and red-green colour matching over blue-yellow.My research will provide fundamental insights into the importance of lighting conditions and the shape of a habitat on the survival of individual animals. These findings would be of immediate value to conservation projects to develop land-use strategies and farming practices that help protect vulnerable species from predation. Humans are changing the lighting conditions of habitats across the world as a consequence of climate change, potentially altering the efficacy of camouflage strategies that had evolved under different lighting regimes. My research therefore has the potential to open up new areas of research in camouflage, environmental change and conservation.