Department of Biology, Carleton University, Ottawa, Ontario K1S 5B6, Canada. tom_sherratt@.carleton.ca
Evolution. 2011 Jul;65(7):2014-25. doi: 10.1111/j.1558-5646.2011.01274.x. Epub 2011 Mar 29.
Precisely how predators solve the problem of sampling unfamiliar prey types is central to our understanding of the evolution of a variety of antipredator defenses, ranging from Müllerian mimicry to polymorphism. When predators encounter a novel prey item then they must decide whether to take a risk and attack it, thereby gaining a potential meal and valuable information, or avoid such prey altogether. Moreover, if predators initially attack the unfamiliar prey, then at some point(s) they should decide to cease sampling if evidence mounts that the type is on average unprofitable to attack. Here, I cast this problem as a "two-armed bandit," the standard metaphor for exploration-exploitation trade-offs. I assume that as predators encounter and attack unfamiliar prey they use Bayesian inference to update both their beliefs as to the likelihood that individuals of this type are chemically defended, and the probability of seeing the prey type in the future. I concurrently use dynamic programming to identify the critical informational states at which predator should cease sampling. The model explains why predators sample more unprofitable prey before complete rejection when the prey type is common and explains why predators exhibit neophobia when the unfamiliar prey type is perceived to be rare.
捕食者究竟如何解决对不熟悉猎物类型进行抽样的问题,这是我们理解各种抗捕食防御进化的核心问题,从缪勒拟态到多态性。当捕食者遇到一个新的猎物时,它们必须决定是否冒险攻击它,从而获得潜在的食物和有价值的信息,或者完全避免这种猎物。此外,如果捕食者最初攻击不熟悉的猎物,那么在某个时候,它们应该决定停止采样,如果有证据表明这种类型的猎物平均攻击无利可图。在这里,我将这个问题描述为一个“双臂强盗”,这是探索-开发权衡的标准隐喻。我假设,随着捕食者遇到并攻击不熟悉的猎物,它们会使用贝叶斯推理来更新它们对这种类型的个体是否具有化学防御的可能性的信念,以及未来看到猎物类型的概率。我同时使用动态规划来确定捕食者应该停止采样的关键信息状态。该模型解释了为什么当猎物类型常见时,捕食者在完全拒绝之前会对不那么有利可图的猎物进行更多的抽样,以及为什么当捕食者认为不熟悉的猎物类型稀少时,它们会表现出新奇恐惧症。