Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia.
J Exp Biol. 2012 Apr 1;215(Pt 7):1128-36. doi: 10.1242/jeb.060558.
Sit-and-wait predators have evolved several traits that increase the probability of encountering prey, including lures that attract prey. Although most crab spiders (Thomisidae) are known by their ability to change colour in order to match the background, a few use a different strategy. They are UV-reflective, creating a colour contrast against UV-absorbing flowers that is attractive for pollinators. The nature of the relationship between colour contrast and foraging success is unknown, as is how spiders trade off the potential costs and benefits of strong colour contrast. Therefore, this study investigated the relationship between spider colouration, foraging success and background colouration in a crab spider species known to lure pollinators via UV reflectance (Thomisus spectabilis). Field data revealed that spider body condition - a proxy of past foraging success - is positively related to overall colour contrast. We experimentally tested the effect of satiation and background colour on spider colour change. Throughout the experiment, spiders changed their colour contrast regardless of their food intake, suggesting that colour contrast and the UV component contributing to overall contrast are not caused by spider condition. Although spiders responded to different backgrounds by subtly changing their body colour, this did not result in colour matching. We believe that the observed variation in colour contrast and hence conspicuousness in the field, coupled with the spiders' reaction to our manipulation, could be the result of plasticity in response to prey.
静候捕食者进化出了几种增加捕食几率的特征，包括吸引猎物的诱饵。虽然大多数蟹蛛（蟹蛛科）以变色能力而闻名，以匹配背景，但也有一些蟹蛛使用不同的策略。它们是紫外线反射的，与紫外线吸收的花朵形成颜色对比，对传粉者有吸引力。颜色对比与觅食成功率之间的关系，以及蜘蛛如何权衡强烈颜色对比的潜在成本和收益，尚不清楚。因此，本研究调查了在一种已知通过紫外线反射吸引传粉者的蟹蛛物种（Thomisus spectabilis）中，蜘蛛颜色、觅食成功率和背景颜色之间的关系。野外数据显示，蜘蛛的身体状况（过去觅食成功率的代表）与整体颜色对比呈正相关。我们通过实验测试了饱食和背景颜色对蜘蛛颜色变化的影响。在整个实验过程中，蜘蛛无论食物摄入量如何，都会改变颜色对比，这表明颜色对比和导致整体对比的紫外线成分不是由蜘蛛的状况引起的。尽管蜘蛛会根据不同的背景微妙地改变身体颜色，但这并没有导致颜色匹配。我们认为，在野外观察到的颜色对比变化和因此而变得明显，再加上蜘蛛对我们操纵的反应，可能是对猎物反应的可塑性的结果。
