Realised hypothetical phenotypes and the adaptive value of Batesian mimicry

许多动物，如毒蛇或刺黄蜂，通过展示明亮，大胆的颜色图案来向潜在的捕食者宣传它们很好地防御。其他动物，被称为“模仿者”，已经进化到通过展示与危险的“模型”相似的图案来欺骗捕食者，尽管它们是无害的。研究拟态的进化有可能告诉我们很多关于自然选择如何导致野生动物适应的问题。在拟态动物中，我们看到了许多进化可以产生极端适应的突出而美丽的例子。然而，一些模仿者，包括许多模仿黄蜂的食蚜蝇，只是近似地类似于它们的模型。我们期望自然选择会偏爱最有说服力的模仿者，因为不太好的模仿者应该被捕食者识别并挑选出来：那么为什么有些模仿者不准确呢？也许捕食者（如鸟类）并不注意猎物外表的各个方面，所以模仿者不必在每一个方面都很准确。鸟类可能会避开所有与特别令人讨厌的模型大致相似的猎物，因此超过一定程度，进一步的准确性是不必要的。或者，最好的生存机会可能是由近似于几个讨厌的模式物种的模仿者获得的，而不是那些完美模仿一个特定模式的模仿者。为了测试这些想法，我们不仅需要知道现有的模仿方法有多成功，还需要知道具有与现有方法不同的特征组合的替代模仿方法的性能。一个更准确的模仿者会生存得更好吗？如果它除了颜色之外是完美的呢？这是进化生物学中一个更普遍的问题的例子，预测不存在的，但理论上合理的生物体与我们在自然界中观察到的生物体相比可能会表现得如何。为了探索拟态的进化潜力，我们的项目以生物学家从未利用过的方式汇集了最近开发的技术。首先，我们将从多个角度拍摄食蚜蝇和黄蜂，并组装3D数字表示。然后，我们将创建新的“变形”的形象，似是而非，但想象，中间的食蚜蝇和黄蜂之间的变化相似的黄蜂。第三，我们将使用3D打印来创建这些中间体（以及“真实的”昆虫）的模型，这些模型在大小、颜色、图案和形状方面都是逼真的。最后，我们将在各种实验中测量这些3D模型的“生存”。我们将通过训练鸟类“攻击”食蚜蝇模型，但避开黄蜂模型，以获得食物奖励，来测试捕食者的反应。在了解了这一区别之后，这些鸟将被测试它们对中间外观的3D模型的行为。鸟类在攻击前犹豫的时间越长，模仿的效果就越好，因为在野外，这种拖延会给昆虫一个逃跑的机会。我们将研究捕食者在野外的行为，在野外，具有不同经验水平的鸟类自然群落正在觅食，在实验室中，我们可以控制每个个体的经验并观察它们如何学习。我们还将用螳螂代替鸟类重复实验，以调查昆虫捕食者是否对模仿有不同的判断。我们的项目解决了一个关于不准确模仿进化的长期存在的生物学问题，但也将为进化过程提供更广泛的见解。现存的物种是什么意思，当其他物种没有生存下来，或者从来没有进化的时候，它们生存了下来？这反过来又使我们能够理解进化如何产生现有物种特征的组合，并预测未来进化可能采取的方向。我们的新方法将为其他进化生物学家提供一个框架，以探索各种不同生物体中的类似问题。

Many animals, such as venomous snakes or stinging wasps, advertise to potential predators that they are well defended by displaying bright, bold colour patterns. Other animals, known as "mimics", have evolved to deceive predators by displaying patterns similar to the dangerous "models", despite being harmless. Studying the evolution of mimicry has the potential to tell us much about how natural selection leads to adaptation in wild animals.Among mimics, we see many prominent and beautiful examples of the extreme adaptations that evolution can produce. However, some mimics, including many hoverflies that mimic wasps, only approximately resemble their model. We expect natural selection to favour the most convincing mimics, because less good ones ought to be recognised and picked off by predators: so why are some mimics inaccurate? Perhaps predators (such as birds) do not pay attention to all aspects of the prey's appearance, so the mimic does not have to be accurate in every way. Birds might avoid all prey that are roughly similar to a particularly nasty model, so beyond a certain point, further accuracy is unnecessary. Alternatively, the best chances of survival may gained by mimics which approximately resemble several nasty model species, rather than those which are perfect mimics of one particular model. To test these ideas, we need to know not only how successful existing mimics are, but also the performance of alternative mimics with different combinations of features to the existing ones. Would a more accurate mimic survive better? What if it were perfect except for its colour? This is an example of a more general problem in evolutionary biology, of predicting how non-existent, but theoretically plausible, organisms might perform in comparison to those that we observe in nature. To explore the evolutionary potential of mimics, our project brings together recently-developed technologies in a way never exploited before by biologists. First, we will photograph hoverflies and wasps from multiple angles and assemble 3D digital representations. We will then create new "morphed" images of plausible, but imaginary, intermediates between hoverflies and wasps which vary in similarity to the wasps. Thirdly, we will use 3D printing to create models of these intermediates (as well as the "real" insects) that are realistic in terms of their size, colour, pattern and shape. Lastly, we will measure the "survival" of these 3D models in a variety of experiments.We will test the response of predators by training birds to "attack" models of hoverflies, but avoid those of wasps, in order to gain food rewards. Having learnt that distinction, the birds will then be tested for how they behave towards 3D models of intermediate appearance. The longer the birds hesitate before attacking, the more effective is the mimicry, because in the wild such delays would give the insect an opportunity to escape. We will look at predator behaviour both in the wild, where natural communities of birds with varying levels of experience are foraging for food, and in the laboratory, where we can control the experiences of each individual and watch how they learn. We will also repeat the experiments using praying mantises in place of birds, to investigate whether insect predators judge mimicry differently. Our project addresses a long-standing biological question about the evolution of inaccurate mimicry, but will also provide broader insights into evolutionary processes. What is it about existing species that mean they survived when others either did not survive, or never evolved in the first place? This in turn allows us to understand how evolution produced the combinations of characteristics of existing species, and to predict the direction that evolution might take in the future. Our novel method will provide a framework for other evolutionary biologists to explore similar questions in a wide range of different organisms.