Tibial coloration, fluctuating asymmetry and female choice behaviour in the damselfly Platycypha caligata.

The territorial damselfly Platycypha caligata (Odontata: Chlorocyphidae) has a courtship behaviour where males wave the white anterior surface of all six laterally enlarged tibiae at females. I experimentally altered this white tibial surface using black paint to determine the effect on male behaviour of a 25% reduction in area, or an increase in asymmetry between the left and right side of the body. I collected behavioural data on courtship, mating and fighting for males already holding territories. Neither a reduction in the area nor an increase in asymmetry of tibial whiteness affected male mating rate, courtship rate or fighting behaviour. These manipulations also had no significant effect on the daily presence at the study site. Males whose tibial whiteness was experimentally removed also showed no decrease in mating rate or change in fighting behaviour while territorial. The complete removal of tibial whiteness did, however, lead to a significant reduction in daily presence, possibly due to a reduced ability to acquire or hold a territory. There was no relationship between natural levels of asymmetry in tibial whiteness and mating rate, courting rate or fighting behaviour for males with territories. However, the natural area of tibial whiteness was significantly positively related to both mean male mating rate and copulation duration for territorial males. This result suggests that a phenotypic correlate of area of tibial whiteness, probably body size, is sexually selected through female choice among males that already hold territories.Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.