To be or not be seen: the influence of substrate on anuran community coloration

Body colouration plays an important role as a defence strategy against predators. Anuran amphibians exhibit a remarkable variety of colouration patterns. Cryptic colouration, for example, is widespread among anurans due to selective pressure from high rates of predation by several groups of vertebrates and invertebrates. Body colouration in populations of some anuran species is related to the substrate. Thus, the environment could lead to phenotypic convergence in the body colouration of organisms, but studies considering several species are sparse. The objective of this study was to determine the relationship between anuran body colouration and the colouration of the substrate in which they live. The colouration of different communities and of the substrate they used during the reproductive period was measured. Different colorimetric variables (brightness, saturation, hue) were estimated using a portable spectrophotometer and used to perform statistical tests to determine the overlap between community and substrate colouration. Furthermore, a visual model for avian predators was used to determine how similar anuran colouration would be perceived relative to their background. No statistically significant difference was found between the colouration of individuals in a community and their environment; however, differences in colouration were found between areas close to forested areas and areas close to open areas. These results suggest that selective pressures, such as predation, may be important in determining the colouration of anuran communities, while specific properties of habitats lead to phenotypic convergence in the resident community.