Countering counteradaptations: males hijack control of female kicking behavior

Abstract

Adaptations and counteradaptations are central to sexually antagonistic coevolution and understanding how males and females respond to the selection imposed by the other. Although adaptations such as seminal fluid components can be subtle, female seed beetles, Callosobruchus maculatus, have a conspicuous pericopulatory kicking behavior thought to have evolved to shorten copula duration and reduce the damage from male genital spines. Our observations suggested, however, that the violent kicking may itself cause damage and negatively impact female fitness; therefore, we investigated the adaptive significance of kicking for both sexes. We show that females allowed to kick for longer die sooner and gain no benefit in lifetime reproductive success despite an elevated sur vival of fertilized eggs. The idea that kicking shortens copula was not upheld; when rival males were present during copulation, kicking duration doubled but copula duration remained unchanged. Furthermore, we found that males, not females, control the duration of kicking, indeed the duration of all copulation components, whereas females did not show any capacity to control mating behavior in this situation. These findings support the notion that males have hijacked control of female kicking to serve their own evolutionary interests.