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

摘要

Male calopterygid damselflies show striking morphological and behavioural secondary sexual traits which are known to function in intrasexual contests. The distribution of pigment in the sexually dimorphic wing 'spot' is prominently displayed to the female during courtship, yet there is little empirical evidence that this trait functions in an epigamic context. Observations of marked field populations revealed (a) there was variation in wing pigment distribution in males, (b) the pigmentation was fixed in reproductively active males, (c) resource holding males had less heterogeneity in the distribution of the wing pigment than males that were never observed to hold a resource and (d) that females frequently (60.3%) rejected males after courtship. An experiment was conducted in which the frequency of key reproductive behaviours (female inspection flights, courtships, copulations, and oviposition) was measured for the same male utilising the same territory before and after treatment or control manipulation of wing pigment parameters. Increasing the heterogeneity (and decreasing the area) of the wing pigmentation 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 females 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 females might receive as a consequence of their reproductive decisions.