Function of colorfulness. prey or camoflauge

Function of colorfulness. prey or camoflauge - Function of...

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Unformatted text preview: Function of being colorful in web spiders: attracting prey or camouflaging oneself? I-Min Tso, a,b Chen-Pan Liao, a Ren-Pan Huang, a and En-Cheng Yang c a Department of Life Science, Tunghai University, Taichung 407, Taiwan, b Center for Tropical Ecology and Biodiversity, Tunghai University, Taichung 407, Taiwan, and c Department of Entomology, National Chung Hsing University, Taichung, Taiwan Bright body colorations of orb-weaving spiders have been hypothesized to be attractive to insects and thus function to increase foraging success. However, the color signals of these spiders are also considered to be similar to those of the vegetation background, and thus the colorations function to camouflage the spiders. In this study, we evaluated these 2 hypotheses by field experiments and by quantifying the spiders visibility to insects. We first compared the insect interception rates of orbs constructed by the orchid spider, Leucauge magnifica , with and without the spider. Orbs with spiders intercepted significantly more insects than orbs without. Such a result supported the prey attraction but not the camouflaging hypothesis. We then tested whether bright body colorations were responsible for L. magnifica s attractiveness to insects by manipulating the spiders color signals with paint. Alteration of color signals significantly reduced L. magnifica s insect interception and consumption rates, indicating that these spiders bright body parts were attractive to insects. Congruent with the finding of field manipulations were the color contrasts of various body parts of these spiders. When viewed against the vegetation background, the green body parts were lower, but the bright parts were significantly higher than the discrimination threshold. Results of this study thus provide direct evidence that bright body colorations of orb weavers function as visual lures to attract insects. Key words: color contrast, Leucauge magnifica , orchid spider, visual ecology. [Behav Ecol 17:606613 (2006)] B rightly colored animals have fascinated many researchers and have been the subject of numerous studies. The stud- ies of animals bright coloration can be broadly categorized as intraspecific and interspecific. Studies of animal coloration in the context of intraspecific interactions have mostly focused on behavioral or morphological traits relevant to sexual selec- tion, such as species identification (Rutowski 1988), mate pre- ference (Petrie and Halliday 1994; Andersson and Amundsen 1997; Johnsen et al. 1998; Grether 2000; Rodd et al. 2002), and mate quality assessment (McGraw and Hill 2000; Doucet and Montgomerie 2003; MacDougall and Montgomerie 2003). Most studies in the context of interspecific interactions have focused on antipredation adaptations such as aposemat- ism, crypsis, or mimicry (Stuart-Fox et al. 2003; Ruxton et al....
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This note was uploaded on 01/27/2012 for the course ECOLOGY 300 taught by Professor Zumdahli during the Spring '11 term at St. Mary NE.

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Function of colorfulness. prey or camoflauge - Function of...

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