Sexual conflict occurs when one mating partner has an opportunity to increase its fitness at a cost to the other partner. On a genetic level, most sexual conflicts are interlocus conflicts that mainly concern the outcome of male-female interactions about the mating rate, fertility efficiency, relative parental effort, remating behavior, and female reproductive rate. In sexually antagonistic evolution, a trait that affords advantage to one sex is disadvantageous to the other. An example is the sexual arms race that evolves when resistance in one sex drives the evolution of coercive traits in the other sex. Without the restrictions of natural selection, this process may lead to a runaway amplification of male and female traits. The coevolutionary arms races between adaptations in one sex and counteradaptations in the other sex can be made visible by experimentally arresting evolution in one sex.
