Motion dazzle and camouflage as distinct anti-predator defenses
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RESEARCH ARTICLE
Open Access
Motion dazzle and camouflage as distinct antipredator defenses Martin Stevens1*, W Tom L Searle1, Jenny E Seymour1, Kate LA Marshall1 and Graeme D Ruxton2
Abstract Background: Camouflage patterns that hinder detection and/or recognition by antagonists are widely studied in both human and animal contexts. Patterns of contrasting stripes that purportedly degrade an observer’s ability to judge the speed and direction of moving prey (’motion dazzle’) are, however, rarely investigated. This is despite motion dazzle having been fundamental to the appearance of warships in both world wars and often postulated as the selective agent leading to repeated patterns on many animals (such as zebra and many fish, snake, and invertebrate species). Such patterns often appear conspicuous, suggesting that protection while moving by motion dazzle might impair camouflage when stationary. However, the relationship between motion dazzle and camouflage is unclear because disruptive camouflage relies on high-contrast markings. In this study, we used a computer game with human subjects detecting and capturing either moving or stationary targets with different patterns, in order to provide the first empirical exploration of the interaction of these two protective coloration mechanisms. Results: Moving targets with stripes were caught significantly less often and missed more often than targets with camouflage patterns. However, when stationary, targets with camouflage markings were captured less often and caused more false detections than those with striped patterns, which were readily detected. Conclusions: Our study provides the clearest evidence to date that some patterns inhibit the capture of moving targets, but that camouflage and motion dazzle are not complementary strategies. Therefore, the specific coloration that evolves in animals will depend on how the life history and ontogeny of each species influence the trade-off between the costs and benefits of motion dazzle and camouflage.
Background Across the animal kingdom, risk of predation has led to the evolution of anti-predator defenses. Of these, defensive coloration (including camouflage, startle displays, warning signals, and mimicry) is widespread [1-3]. Recently, the study of camouflage in particular has seen a resurgence across a wide range of disciplines [3]. Recent experiments have shown that disruptive coloration, involving high-contrast markings that break up the body outline and shape, is an effective method of concealment over and above simply matching the background [4-8]. However, despite recent significant advances, two major gaps in our understanding of camouflage exist. * Correspondence: [email protected] 1 Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK Full list of author information is available at the end of the article
First, it remains controversial whether some animal markings can inhibit the predator’s judgment of the speed and trajectory of a moving prey animal and thus inhibit capture, a
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