從視覺生態角度探討蜘蛛捕食者與昆蟲獵物間之行為互動 (3/3)(國科會 96-2311-B-029-001)

Abstract

When animals forage or court they do not always act out their full capacity to obtain maximum reward because from time to time they are constrained by factors such as predation risk. Animals with high mobility usually exhibit behavioral plasticity to trade off opposing pressures. However, animals with foraging or courtship tightly linked to morphology cannot make quick behavioral adjustments when encountering a dilemma. In this study, we investigate how opposing pressures of maximizing prey intake and minimizing predation risk shape the morphology-associated foraging traits of a sit-and-wait predator. Recently, the conspicuous body colorations of certain orb weaving spiders have been demonstrated to be attractive to both insect prey and predators. In this study, we performed field manipulations to assess how visual luring signals of such predators trade off opposing pressures of feeding and surviving. Dummies made of cardboard were used to test how changing signal intensity affected attractiveness to prey and predators. Dummies mimicking the coloration pattern and chromatic properties of N. pilipes were attractive to prey and predators as were real spiders. Dummies with greatly enhanced conspicuous signal intensity attracted significantly more prey than those with standard coloration pattern of N. pilipes. However, such dummies also attracted far more hymenopteran predators. Our findings indicate that the morphology-associated foraging traits of certain animals do not necessarily provide the best feeding performance but reflect a compromise between opposing pressures. However, when simultaneously considering hunting efficiency and predation risk, the current signal design seems to be most optimal.

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Updated: Jan-24-2014 11:34:24 (Taiwan, GMT+08:00).