Understanding the diversity of anti-predator defence

简介：走进大多数加拿大人的后院，你可能会看到许多保护性色彩图案的例子：与背景相似的飞蛾，警示色的瓢虫，以及无害的悬停苍蝇，它们像螫人的黄蜂或蜜蜂一样获得保护。在过去的一个世纪里，研究人员已经准确地理解了这些防御特征是如何保护生物免受捕食者的侵害的。然而，在单独对待每一种防御性适应时，更基本的问题被忽视了。特别是，为什么有些物种进化出一种防御方式，而其他物种进化出另一种防御方式？同样，为什么一些模仿物种进化得与它们的厌恶模型几乎完全相似，而另一些物种进化得只有粗略的相似？在这个研究项目的过程中，我建议测试一系列关键的假设，这些假设将帮助我们理解为什么物种进化出它们所做的防御。这些假设中的每一个都直接源于一种认识，即反捕食者防御是捕食者和猎物共同进化的结果，因此不仅依赖于对猎物生活史的基本理解，而且依赖于对捕食者认知的基本理解。目标：我有三个目标。首先，我将在系统发育框架内描述观察到的防御变异，从毛虫的眼斑到悬停蝇的模仿。从这里开始，我将测试进化的防御模式与其他属性（如体型和物候）之间的预测关联。许多预测的关联直接来自于未经验证的假设，即捕食者如何应对给定的防御。因此，我的第二个目标将是测试关于捕食者行为如何影响观察到的猎物防御变化的特定假设。第三，在为观察到的捕食者行为寻找基本解释的过程中，我将开发和评估迄今为止主要在近似水平上考虑的已建立的心理现象的适应性解释。**方法：我将利用过去事件的系统发育重建来阐明进化模式，并描述不同防御策略之间的转变，例如黄蜂模仿进化成蜜蜂模仿所必需的特征变化。我将通过调查产生这种多样性的捕食者行为的本质来支持这些分析。例如，我将使用实地试验，通过监测不同大小的人工毛虫的存活率来量化不同类型毛虫的眼点的选择优势，我将评估野生鸟类在区分美味和不美味的猎物时如何以及为什么倾向于忽视潜在的信息特征。为了补充这项工作，我将开发原始的优化模型来评估是否可以从自适应的角度理解任何观察到的行为（例如对新线索的恐惧和使用一组有限的判别特征）。意义：捕食是最普遍和最重要的选择行为之一，在自然界中产生了一系列令人眼花缭乱的特征。在这里，我们将测试关于为什么不同物种进化出不同的反捕食者防御的明确假设，并检查捕食者认知在形成这些防御中的作用。经过几十年的研究，伪装，警告信号和模仿是独立的，在这里，我们采用了一个更广泛的视角，旨在了解适应性捕食者行为和认知如何塑造猎物的反捕食者特征的多样性。

INTRODUCTION: Go into most Canadian backyards and you are likely to see numerous examples of protective colour patterns: moths that resemble their backgrounds, warningly-coloured ladybugs, and harmless hover flies that gain protection by resembling stinging wasps or bees. Over the last century, researchers have come to understand precisely how these defensive traits serve to protect organisms from predators. However, in treating each of these defensive adaptations independently, more fundamental questions have been overlooked. In particular, why have some species evolved one form of defence, while other species have evolved another? Likewise, why have some mimetic species evolved an almost perfect resemblance to their aversive models, while other species have evolved only a crude similarity? Over the course of this research program, I propose to test a series of key hypotheses which will help us understand why species evolve the defences that they do. Each of these hypotheses arises directly from an appreciation that anti-predator defences are the outcome of co-evolution between predators and prey, and therefore depend on a fundamental understanding of not just prey life history, but also predator cognition. **OBJECTIVES: I have three objectives. First, I shall characterize observed variation in defences, ranging from eyespots in caterpillars to mimicry in hover flies, within a phylogenetic framework. From here, I will test for predicted associations between the evolved mode of defence and other attributes such as body size, and phenology. Many of the predicted associations arise directly from untested assumptions as to how predators would react to a given defence. Therefore, my second objective will be to test specific hypotheses as to how predator behaviour shapes the observed variation in prey defence. Third, in seeking fundamental explanations for the observed predator behaviours, I will develop and evaluate adaptive explanations for established psychological phenomena that have hitherto been considered primarily at the proximate level.**METHODS: I will utilise phylogenetic reconstruction of past events to elucidate evolutionary patterns, and to characterise transitions between different defensive strategies, such as the trait changes necessary for wasp mimicry to evolve into bee mimicry. I will support these analyses by investigating the nature of predator behaviour proposed to generate this diversity. For example, I will use field trials to quantify the selective advantage of eyespots in different types of caterpillar by monitoring the survivorship of artificial caterpillars of different size, and I will evaluate how and why wild birds tend to overlook potentially informative features when discriminating palatable from unpalatable prey. To complement this work, I will develop original optimization models to evaluate whether any of the observed behaviours (such as a fear of novel cues and the use of a restricted set of discriminative features) can be understood from an adaptive perspective.**SIGNIFICANCE: Predation is one of the most universal and important agents of selection, responsible for a bewildering array of traits in the natural world. Here we will test clear hypotheses as to why different species have evolved different anti-predator defences, and examine the role of predator cognition in shaping these defences. After decades of research in which camouflage, warning signals and mimicry were viewed independently, here we adopt a far broader perspective aimed at understanding how adaptive predator behaviour and cognition shape the diversity of anti-predator traits in prey.