The Effect of the Gene in Body Colour Masculinization of the Damselfly

Odonata species display a remarkable diversity of colour patterns, including intrasexual polymorphisms. In the damselfly (), the expression of a sex-determining transcription factor, the () gene is reportedly associated with female colour polymorphism (CP) (gynomorph for female-specific colour and andromorph for male-mimicking colour). Here, the function of in thoracic coloration was investigated by electroporation-mediated RNA interference (RNAi). RNAi of the common region in males and andromorphic females reduced melanization and thus changed the colour pattern into that of gynomorphic females, while the gynomorphic colour pattern was not affected. By contrast, RNAi against the long isoform produced no changes, suggesting that the short isoform is important for body colour masculinization in both males and andromorphic females. When examining the expression levels of five genes with differences between sexes and female morphs, two melanin-suppressing genes, and , were expressed at higher levels in the RNAi body area than a control area. Therefore, the short isoform may induce thoracic colour differentiation by suppressing and , thereby generating female CP in These findings contribute to the understanding of the molecular and evolutionary mechanisms underlying female CP in Odonata.