Does wing shape of andromorph females of Calopteryx splendens (Harris, 1780) resemble that of males?

Abstract

Female limited polymorphism consists in the coexistence of two or more female morphs in the same population and is widespread among odonates. Generally, one female morph, the andromorph, resembles males in colour or, sometimes, also in morphology and behaviour, while one or more other morphs, gynomorphs, differ from males. This phenomenon is probably promoted by advantages to females which arise from reduced sexual harassment. Andromorph females of Calopteryx splendens keep wing spots, like males (although these ornaments do not match exactly male wing spot colour), while gynomorphs have hyaline wings. Males and gynomorphs show a marked sexual dimorphism in wing shape, and this determines flight patterns which differ between sexes. If andromorphs mimic male wing spots to avoid harassment, they may also benefit from mimicking the male flight morphology, and consequently the male flight pattern. In this case wing shape of andromorph and gynomorph females would differ, as the wing shape of andromorphs resembles that of males. In this study we compared the wing morphology of males and of the two female morphs of C. splendens using geometric morphometrics. Our results revealed that andromorphs and gynomorphs of this species share the same wing shape, size, and static allometry, and this suggests that flight patterns should also be shared by the two morphs. Thus, females might avoid male harassment by mimicking exclusively male wing pigmentation (male mimicry hypothesis), or confound males through an uncommon appearance (learned mate recognition hypothesis).

Keywords: Odonata, dragonfly, Calopteryx, geometric morphometrics, andromorph, gynomorph, polymorphism

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