Size and contrast increase the divertive effect of eyespots

Recent studies have shown that some eyespots of prey divert the strikes of predators, increasing the likelihood of prey escape. However, little is known about what makes eyespots effective divertive (deflective) prey marks. The size of eyespots varies much both between and even within taxa. Yet, whether size is important for the divertive function of eyespots is unknown. Furthermore, eyespots have often been described as highly contrasting, but the effects of contrast on the divertive function of eyespots has never been tested experimentally. Using artificial prey and the three-spined stickleback (Gasterosteus aculeatus) as a model for predator cognition and behaviour, we tested the importance of size as well as internal contrast for the divertive effect of eyespots. We independently increased the internal contrast and size of eyespots and found that both increased the divertive effect. The effect of size was significant over all four subsequent prey presentations, whereas the effect of...已有研究表明，部分猎物的眼斑（eyespots）可偏转捕食者的攻击，提升猎物逃脱的概率。然而，目前学界对何种特性可使眼斑成为有效的偏转（或偏转性）猎物标记仍知之甚少。眼斑的大小在不同类群间甚至类群内部均存在显著差异，但尚不明确大小是否会影响眼斑的偏转功能。此外，眼斑常被描述为具有极高对比度，但对比度对眼斑偏转功能的影响尚未经实验验证。本研究以人工猎物和作为捕食者认知与行为模型的三刺鱼（Gasterosteus aculeatus）为实验对象，探究了眼斑大小以及内部对比度对其偏转效应的影响。我们通过独立操控眼斑的内部对比度与大小，发现二者均可提升眼斑的偏转效应。大小的效应在后续四次猎物呈现实验中均显著，而对比度的效应则……