Department of Botany and Zoology, Faculty of Science, Masaryk University, Kotlářská 2, 611 37 Brno, Czech Republic.
Am Nat. 2011 Jul;178(1):124-34. doi: 10.1086/660287.
Several hypotheses have been put forward to explain the evolution of inaccurate mimicry. Here we investigated the novel hypothesis that inaccurate mimicry (in color and shape) is maintained by opposing selective pressures from a suite of different predators: model-aversive visually oriented predators and model- and mimic-specialized predators indifferent to mimetic cues. We hypothesize that spiders resembling ants in color and shape escape predators that typically avoid ants but fall prey to ant-eating predators. We tested whether inaccurate myrmecomorphic spiders are perceived as their models by two types of predators and whether they can escape from these predators. We found that model-specialized (ant-eating) predators captured mimics significantly less frequently than their ant models, because mimics changed their behavior by fleeing predatory attacks. The fastest escape was found in less accurate mimics, indicating a negative association between visual resemblance and effectiveness of defenses. In trials with spider-eating predators, mimics were not captured more frequently than their models. The quality of defensive mechanisms appears to result from opposing selection forces exerted by the predator complex: mimics are more accurate (in color and shape) in microhabitats dominated by model-aversive predators and less accurate in microhabitats with model- and mimic-specialized predators.
已经提出了几种假说来解释不准确模仿的进化。在这里，我们研究了一个新的假说，即不准确的模仿（在颜色和形状上）是由一系列不同捕食者的相反选择压力维持的：对模型有厌恶感的视觉导向捕食者和对模仿线索漠不关心的模型和模仿物专门捕食者。我们假设颜色和形状上类似蚂蚁的蜘蛛可以逃避那些通常回避蚂蚁但却捕食蚂蚁的捕食者。我们测试了颜色和形状不准确的拟态蜘蛛是否被两种类型的捕食者视为其模型，以及它们是否可以逃避这些捕食者。我们发现，专门针对模型的（食蚁）捕食者捕获的模仿者明显少于它们的蚂蚁模型，因为模仿者通过逃避捕食攻击而改变了它们的行为。最快的逃跑发生在不太准确的模仿者身上，这表明视觉相似性与防御效果之间存在负相关。在与蜘蛛捕食者的试验中，模仿者的被捕食频率并不高于它们的模型。防御机制的质量似乎来自于捕食者复合体施加的相反选择力：在以模型回避捕食者为主的微生境中，模仿者的颜色和形状更准确，而在有模型和模仿物专门捕食者的微生境中，模仿者的颜色和形状则不准确。
