Paired and complex copulatory organs: do they really impede flexible use?

Abstract

AbstractAnimals with internal fertilization possess complex male genitalia that are characterized by rapid and divergent evolution. Such complexity and divergence renders male genitalia highly species specific. Furthermore, in species with paired genitalia in males and females as is typically the case in spiders, the genital complexity is considered to restrict usage of each male intromittent organ (pedipalp) to a specific genital opening of the female genitalia. Here, we report cases of flexible pedipalp insertion (16%) in the dwarf spider Oedothorax retusus – a species with complex pedipalps. A flexible insertion mode allows males of this species to react to the mating history of the female by circumventing the highly effective mating plugs and mating into the unused side. Our findings disagree with the species isolating lock‐and‐key hypothesis for explaining divergence in genital morphology as the ‘key’ can be applied to the mirror‐inversed female ‘lock’ in the spider species O. retusus. Rather, our data suggest that sexual selection is an important underlying selective regime for the evolution of highly complex and diverse genitalia.