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）指一种无害的拟态物种模仿具有更强防御性的模型物种，其涵盖的形态特征范围广泛，但二者的相似性永远无法达到完美。过往研究多采用抽象的“猎物”模型设计，证实若某些特征无法被捕食者感知或识别，则其差异对拟态而言并无实际意义。本研究在此基础上进一步拓展，通过考察人类“捕食者”对具有警戒色的黄蜂（aposematic wasps）及其食蚜蝇（hoverfly）拟态者的特征自然变异的响应，验证相关结论。我们通过构建仅保留部分可见特征的黄蜂与食蚜蝇图像，测试人类区分二者的能力，以明确这些特征在区分决策中的贡献权重。研究发现，形状是区分这两个类群（taxa）尤为实用且易于学习的特征。尽管腹部斑纹包含有效信息，但受试者并未凭借该特征成功完成区分任务。与其他特征相比，黄蜂与食蚜蝇的颜色相似性相对更高，这表明自然选择对体色的作用更为强烈。本研究结果表明，若要深入理解猎物防御机制的演化，需充分考量猎物特征的自然变异及其对捕食者的显著性。