Evolutionary and ecological forces underlying ontogenetic loss of decoy coloration

Abstract

Abstract Predator-based selection has resulted in the repeated evolution of a variety of antipredator traits. Despite the effectiveness of these traits, some species experience shifts or even complete loss of antipredator traits during development. The evolutionary forces that favour such a transition are poorly understood. We sought to comprehend the role of predator-based selection and organismal factors underlying developmental loss of antipredator traits by focusing on decoy coloration in skink lizards. To this end, we studied the ontogenetic loss of decoy tail coloration in three Nearctic skink species. We performed natural history collection surveys and clay-model studies on predation to determine the organismal determinants of decoy coloration (body size and energy content of the tail) and predation based upon size and decoy coloration. We found that decoy coloration was lost during development at a similar size in all three species. Although predation rates on juvenile models were similar for both uniform brown and decoy models, predation rates on adult models with decoy coloration were much higher than those on non-decoy adult models. Overall, our results suggest that predator-based selection is an important factor driving the ontogenetic loss of decoy coloration at similar sizes across these species and might be generalizable to other antipredator traits.