Female genital mutilation as a novel mating strategy in spiders: conflict or cooperation?

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Reproductive interests between males and females do not fully coincide since the reproductive success of males is generally limited by the number of mating partners that can be gained whereas the reproductive success of females is limited by the number of eggs that can be produced over a lifetime. Sexual selection theory concludes that the diversity of sexually selected traits has evolved due to competition among males over access to females and due to female choice of mating partners. The theory of antagonistic coevolution on the other hand posits that the diversity of sexual traits has evolved due to male manipulations and female counter-adaptations in the race over control of fertilization. As a consequence, females are not selected to prefer specific male traits but to reduce fitness costs that result from male manipulations. Harm inflicted on the female during mating is considered a paradigm example of antagonistic coevolution. In this project we will investigate the as yet unnoticed phenomenon of external genital mutilation of female genitalia. A literature search and query among taxonomists revealed that the phenomenon is not a singular one but wide spread at least among spiders. We will investigate the mechanism of genital mutilation, the consequences of mutilation on the remating probability of female as well as the effects of mutilation on life expectancy and reproductive success of both sexes. We will analyse to what extend this type of mating system is shaped by antagonistic coevolution or by selective cooperation of the female (classical female choice). The mechanisms and adaptive values of genital mutilation will be elucidated in three selected orb-web spider species of the genus Larinia. Finally, the data will be incorporated into a mathematical model on the evolution of this novel phenomenon.