Tullberg Birgitta S, Merilaita Sami, Wiklund Christer
Department of Zoology, University of Stockholm, 10691 Stockholm, Sweden.
Proc Biol Sci. 2005 Jul 7;272(1570):1315-21. doi: 10.1098/rspb.2005.3079.
The idea that an aposematic prey combines crypsis at a distance with conspicuousness close up was tested in an experiment using human subjects. We estimated detectability of the aposematic larva of the swallowtail butterfly, Papilio machaon, in two habitats, by presenting, on a touch screen, photographs taken at four different distances and measuring the time elapsed to discovery. The detectability of larvae in these images was compared with images that were manipulated, using existing colours either to increase or decrease conspicuousness. Detection time increased with distance for all colourations. However, at the closest distance, detection time was longer for the larvae manipulated to be more cryptic than for the natural and more conspicuous forms. This indicates that the natural colouration is not maximally cryptic at a short distance. Further, smaller increments in distance were needed to increase detection time for the natural than for the conspicuous larva. This indicates that the natural colouration is not maximally conspicuous at longer distances. Taken together, we present the first empirical support for the idea that some colour patterns may combine warning colouration at a close range with crypsis at a longer range. The implications of this result for the evolution of aposematism are discussed.
在一项以人类为实验对象的实验中，对警戒色猎物在远处具有隐蔽性而在近处具有醒目性这一观点进行了测试。我们通过在触摸屏上展示在燕尾蝶（金凤蝶，Papilio machaon）的两个栖息地中，在四个不同距离拍摄的警戒色幼虫照片，并测量发现幼虫所用的时间，来估计其可探测性。将这些图像中幼虫的可探测性与经过处理的图像进行比较，处理方式是利用现有的颜色来增加或降低醒目性。对于所有颜色的幼虫，探测时间都随着距离的增加而增加。然而，在最近的距离处，经过处理使其更具隐蔽性的幼虫的探测时间比自然形态且更醒目的幼虫更长。这表明自然颜色在短距离内并非最大限度地具有隐蔽性。此外，与醒目幼虫相比，自然形态的幼虫需要更小的距离增量来增加探测时间。这表明自然颜色在较长距离内并非最大限度地醒目。综合来看，我们首次通过实证支持了这样一种观点，即某些颜色模式可能在近距离结合了警戒色，在远距离结合了隐蔽性。文中还讨论了这一结果对警戒色进化的影响。
