MATING SYSTEM AND SEXUAL SELECTION IN THE SCORPIONFLY PANORPA-VULGARIS (MECOPTERA, PANORPIDAE)

Scorpionflies have been a major object for the investigation of in sec t mating systems. Especially Panorpa vulgaris has become a model insec t for resting theories of sexual selection. This contribution summariz es that which has been learned in recent pears and presents new data t hat clearly show that the mating system of P. vulgaris is not simply a resource-defense polygyny, as has previously been thought. In P. vulg aris neither the pattern in food exploitation nor the ratio of varianc e in the lifetime reproductive success of the two sexes is in accordan ce with that expected in resource defense polygynous mating systems. L ifetime mating duration is the most important proximate determinant of male fitness. Males employing alternative mating tactics obtain copul ations of varying duration in relation to the Following sequence: sali va secretion > food offering > no gift. The number of salivary masses which males provide to females during their lifetime is significantly correlated with the lifetime condition index. The condition index depe nds on the fighting prowess of males and their ability to find food it ems. Thus saliva secretion of Panorpa is considered a Zahavian handica p, which can serve as an honest quality indicator used by mating femal es. Our results confirm four main predictions of the indicator model o f the theory of sexual selection: (a) the indicator signals high ecolo gical duality of its bearer. (b) the indicator value increases with ph enotypic quality, (c) the indicator value is positively correlated wit h the genetic quality affecting offspring fitness in a natural selecti on context. and (d) the quality indicator is more costly for low-than for high-quality individuals. The evolutionary consequences of the mat ing pattern and the sperm competition mechanism in P. vulgaris are dis cussed in the context the way in which sexual selection creates and ma intains sperm mixing and the evolution of a promiscuous mating system.