Behavioural and Evolutionary Ecology Group, Environmental Biology, Department of Biosciences, Åbo Akademi University, Turku, Finland.
Proc Biol Sci. 2013 Jul 17;280(1766):20131458. doi: 10.1098/rspb.2013.1458. Print 2013 Sep 7.
Eyespots (colour patterns consisting of concentric rings) are found in a wide range of animal taxa and are often assumed to have an anti-predator function. Previous experiments have found strong evidence for an intimidating effect of eyespots against passerine birds. Some eyespots have been suggested to increase prey survival by diverting attacks towards less vital body parts or a direction that would facilitate escape. While eyespots in aquatic environments are widespread, their function is extremely understudied. Therefore, we investigated the protective function of eyespots against attacking fish. We used artificial prey and predator-naive three-spined sticklebacks (Gasterosteus aculeatus) as predators to test both the diversion (deflection) and the intimidation hypothesis. Interestingly, our results showed that eyespots smaller than the fish' own eye very effectively draw the attacks of the fish towards them. Furthermore, our experiment also showed that this was not due to the conspicuousness of the eyespot, because attack latency did not differ between prey items with and without eyespots. We found little support for an intimidating effect by larger eyespots. Even though also other markings might misdirect attacks, we can conclude that the misdirecting function may have played an important role in the evolution of eyespots in aquatic environments.
眼斑（由同心环组成的颜色图案）存在于广泛的动物分类群中，通常被认为具有抗捕食者的功能。先前的实验为眼斑对雀形目鸟类的恐吓作用提供了强有力的证据。一些眼斑被认为可以通过将攻击转移到不太重要的身体部位或更有利于逃脱的方向来提高猎物的存活率。虽然水生环境中的眼斑很普遍，但它们的功能却极不被研究。因此，我们研究了眼斑对攻击鱼类的保护功能。我们使用了人工猎物和没有捕食经验的三刺鱼（Gasterosteus aculeatus）作为捕食者，以测试分散（转向）和恐吓假说。有趣的是，我们的结果表明，小于鱼眼的眼斑非常有效地吸引了鱼的攻击。此外，我们的实验还表明，这不是由于眼斑的显眼性所致，因为具有和不具有眼斑的猎物之间的攻击潜伏期没有差异。我们几乎没有支持较大眼斑的恐吓作用的证据。即使其他标记也可能误导攻击，我们可以得出结论，在水生环境中，眼斑的误导功能可能在其进化中发挥了重要作用。
