Molecular mechanisms underlying pupal color switch in Papilio polytes butterflies

Mimicry is a survival strategy in which organisms deceive their predators by imitating other organisms or the surrounding environment. One example of this involves pupal color polymorphism, which is widely observed in butterflies and moths. It has been suggested that the pupal colors of Papilio butterflies are selected according to the tactile stimulation experienced before pupation. Specifically, larvae crawling on smooth leaves become green pupae, but those crawling on rough stems become brown pupae. These protective colors fit with the surrounding environment. However, the detailed molecular mechanisms underlying pupal polymorphism have generally remained unknown. To reveal these mechanisms, we established control over the green and brown pupal coloration in Papilio polytes under laboratory conditions. Furthermore, we analyzed the expression of coloration genes during the pre-pupal stage and at pupation in the epidermis under the green and brown conditions by RNA sequencing. This study sheds light on the evolutionary process of pupal protective colors in P. polytes.