Distance-dependent camouflage components within conspicuous aposematic colour patterns. (#257)
In the study of animal defensive colouration intermediate levels of conspicuousness may appear to be counterproductive. Colour patterns are therefore often linked to physiological or environmental constraints which prevent the attainment of optimal camouflage or aposematism. Recent research is, however, increasingly suggesting that far from being a disadvantage, intermediate levels of conspicuousness may correspond to fitness peaks which balance lower predator encounter rates with salient aposematic defence. Limitations in visual acuity mean that different components of a pattern will dominate perceptual grouping mechanisms at different viewing distances, and, as high spatial frequencies will blend together to create a different hue or visual texture, a single pattern may appear radically different to observers in different locations. Patterns combining features of camouflage with conspicuous elements can be recognised as aversive at close range, but can be functionally camouflaged from greater viewing distances. Under natural variation in predation pressure these distance-dependent patterns can survive better than either parent strategy in isolation. Through a mix of controlled field and laboratory experiments, we investigate the mechanisms underlying dual-function patterns in artificial moth-like targets, and in a population of the poison frog Dendrobates tinctorius (Dendrobatidae) from French Guiana.