Developmental plasticity in sexual roles of butterfly species drives mutual sexual ornamentation

Current explanations for why sexual ornaments are found in both sexes include genetic correlation, same sex competition, andmutual mate choice. In this study, we report developmental plasticity inmating behavior as induced by temperature during development in the butterfly Bicyclus anynana. Males and females reciprocally change their sexual roles depending on their larval rearing temperatures. This switch is correlated with a change in mating benefits to females and costs to males. The discrete seasonal environments, wet season and dry season, are known to produce the two developmental forms and as a consequence impose alternating, symmetrical patterns of sexual selection, one season on male ornaments, the following season on female ornaments. Thus, reciprocal selection through time may result in mutual sexual ornamentation. Morphology and behavior can be devel-opmentally plastic and change in re-sponse to environmental variation experienced during ontology (1). Butterflies of-ten exhibit seasonal polyphenism in wing col-oration, a form of developmental plasticity triggered by certain environmental cues experienced dur-ing critical ontogenetic periods in larval and pu-pal development (2, 3). To what extent rearin