Male wing pigmentation may affect reproductive success via female choice in a calopterygid damselfly (Zygoptera)

Male calopterygid damselflies show striking morphological and behavioural s econdary sexual traits which are known to function in intrasexual contests. The distribution of pigment in the sexually dimorphic wing 'spot' is promi nently displayed to the female during courtship, yet there is little empiri cal evidence that this trait functions in an epigamic context. Observations of marked field populations revealed (a) there was variation in wing pigme nt distribution in males, (b) the pigmentation was fixed in reproductively active males, (c) resource holding males had less heterogeneity in the dist ribution of the wing pigment than males that were never observed to hold a resource and (d) that females frequently (60.3%) rejected males after court ship. An experiment was conducted in which the frequency of key reproductiv e behaviours (female inspection flights, courtships, copulations, and ovipo sition) was measured for the same male utilising the same territory before and after treatment or control manipulation of wing pigment parameters. Inc reasing the heterogeneity (and decreasing the area) of the wing pigmentatio n by removing small areas of pigmented cuticle from their wings resulted in a decrease in the measured reproductive behaviours (control males that had non-pigmented areas removed from their wings showed no decreases). Since f emales cannot be coerced into these behaviours, the experimentally induced decrease suggests females avoided males with higher levels of wing pigment heterogeneity. The results are discussed in the context of the benefits fem ales might receive as a consequence of their reproductive decisions.