Data from: Which traits do observers use to distinguish Batesian mimics from their models?

Batesian mimicry, in which a harmless mimic resembles a more aversive model, can encompass a wide range of morphological traits, but the resemblance is never perfect. Previous studies have used abstract “prey” designs to show that differences in certain traits may not be relevant to mimicry if they are not perceived or recognized by a predator. Here, we extend these results by examining how human “predators” respond to realistic variation in traits of aposematic wasps and their hoverfly mimics. We measured the ability of humans to discriminate between images of wasps and hoverflies in which only certain traits were visible, to determine the contributions of those traits to discrimination decisions. We found that shape is a particularly useful and easily learnt trait for separating the two taxa. Subjects did not successfully discriminate on the basis of abdominal patterns, despite those containing useful information. Color similarity between wasps and hoverflies is relatively high in comparison with other traits, suggesting that selection has acted more strongly on color. Our findings demonstrate the importance of consideration of natural variation in the traits of prey and their salience to predators for understanding the evolution of prey defenses.贝茨拟态（Batesian mimicry）指无害的拟态类群模仿具有更强厌恶性的模型物种，其涉及的形态性状范围广泛，但拟态的相似度永远无法达到完美。既往研究多采用抽象的"猎物"实验设计，证实若捕食者无法感知或识别特定性状差异，则这些差异与拟态过程无关。本研究通过考察人类"捕食者"对警戒态黄蜂（aposematic wasps）及其食蚜蝇拟态者的性状自然变异的响应，拓展了前述研究结论。我们测量了人类区分仅特定性状可见的黄蜂与食蚜蝇图像的能力，以此明确各性状对区分决策的贡献程度。研究结果显示，形状是区分这两个类群尤为实用且易于学习的关键性状。尽管腹部图案包含有效区分信息，但受试者无法仅凭该图案成功完成区分任务。相较于其他性状，黄蜂与食蚜蝇的颜色相似度相对更高，这表明自然选择对颜色性状的作用强度更强。本研究结果表明，若要深入理解猎物防御策略的演化机制，需同时考虑猎物性状的自然变异及其对捕食者的感知显著性。