Review Paper: Evolutionary Outcome of Sexual Conflict

The determining factors that influence the evolutionary outcome of sexual conflict are the benefits of manipulation and resistance, the costs of manipulation and resistance, and the feasibility of manipulation (Lessells 2006). Intralocus conflict leads to each sex impeding adaptive evolution in the other sex. By contrast, interlocus conflicts occur when there is conflict over the outcome of male–female interactions, so that the optimal outcome is different for the two sexes. These types of conflicts can occur over mating frequency, fertilization, relative parental effort, female remating behaviour, female reproductive rate, and clutch size. Both sexes are expected to evolve suites of sexually antagonistic adaptations that bias the outcome towards their own interests (Chapman et al. 2003). However, the two major forms of sexual conflict relate to mating/fertilization and parental investment (PI). For instance, some species of insects produce seminal toxins that reduce female receptivity or enhance oviposition, or insert plugs after mating that prevent females from mating with another male (Parker 2006).
Sexual conflict over mating has been studied from the regarding female choice by resistance, in which a females’ probability of mating is directly correlated to the males 'harm level'. This showed that a wide range of conditions could generate costly female choice and exaggerated harmful male traits, leading to a stable equilibrium (Parker 2006). Sexual conflict over mating tends to emphasize the lack of long-term stable evolutionary outcomes and the widespread occurrence of harmful behaviour. Mating may be costly because it has an effect on the female's survival or future fecundity (Lessells 2006).
Sexual conflict over parental investment are not as strongly associated with harmful behaviours and rapid evolutionary change, as is the case in conflicts over mating. Parental investment conflicts rely heavily on game theory models that seek evolutionarily stable