Optimal camouflage can, in principle, be relatively easily achieved in simple, homogeneous, environments where backgrounds always have the same colour, brightness and patterning. Natural environments are, however, rarely homogenous, and species often find themselves viewed against varied backgrounds where the task of concealment is more challenging. One result of variable backgrounds is the evolution of intraspecific phenotypic variation which may either be generalized, with multiple similarly cryptic patterns, or specialized, with each discrete colour form maximizing concealment against a single component of the background. We investigated the role of phenotypic variation in a highly variable population of the Neotropical toad Rhinella margaritifera using visual modelling and a computer-based detection task. We found that phenotypic variation was not divided into discrete colour morphs, and all toads were well camouflaged against the forest floor. However, although the whole population may appear to consist of random samples from the background, the toads were a particularly close match to the leaf litter, suggesting that they masquerade as dead leaves, which are themselves variable. Furthermore, rather than each colour form being equally effective against a single background, each toad was specialized towards its own particular local surroundings, as suggested by a specialist strategy. Taken together, these data highlight the importance of background matching to a nominally masquerading species, as well as how habitat heterogeneity at multiple spatial scales may affect the evolution of camouflage and phenotypic variation.

中文翻译：

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颜色图案的变化形成了模仿叶子的蟾蜍的局部背景匹配伪装。

原则上，在背景始终具有相同颜色、亮度和图案的简单、均匀的环境中，可以相对容易地实现最佳伪装。然而，自然环境很少是同质的，物种经常发现自己在不同的背景下被观察，隐藏的任务更具挑战性。可变背景的一个结果是种内表型变异的演变，这可能是概括的，具有多个类似的隐秘模式，或者是专门的，每个离散的颜色形式最大限度地隐藏对背景的单个组成部分。我们使用视觉建模和基于计算机的检测任务研究了表型变异在新热带蟾蜍 Rhinella margaritifera 高度可变的种群中的作用。我们发现表型变异没有分为离散的颜色变形，所有蟾蜍都很好地伪装在森林地面上。然而，尽管整个种群似乎由背景中的随机样本组成，但蟾蜍与落叶特别接近，这表明它们伪装成枯叶，而枯叶本身是可变的。此外，正如专家策略所建议的，不是每种颜色形式在单一背景下都同样有效，而是每个蟾蜍都专门针对自己特定的当地环境。总之，这些数据强调了背景匹配与名义上的伪装物种的重要性，以及多个空间尺度的栖息地异质性如何影响伪装和表型变异的进化。