Fidelity in protein synthesis

predicts that unresolvable sexual arms races may be infrequent, and that it is more usual for one sex or the other to gain an evolutionary advantage, halting antagonistic co-evolution, even though the underlying conflict may not be resolved, or that a balance in 'arms levels' results. Exceptions may be common at the molecular level — for example, involving seminal proteins and receptors — where costs of escalation are probably relatively low. What's the big deal? Sexual conflict has been implicated as the driving force behind many important biological phenomena, including the rapid molecular evolution of reproductive genes and proteins, genome evolution and genomic imprinting. Conflict over reproductive investment may even explain the evolution of the sexes: proto-males may have parasitized the larger gametes of proto-females. Recently, sexual conflict has been implicated in speciation. In any evolutionary arms race between the sexes, there are potentially many different ways individuals of either sex could evolve to enhance their fitness. Any adaptation then counter-selects on the opposite sex, which again has many ways it could counter-adapt, and so on. In any sexual arms race, it is genes involved in reproduction that are the focus of conflict, and molecular evidence suggests that many reproductive genes evolve extremely rapidly. As a result, populations can, in principle, evolve differences in almost any reproductive trait extremely rapidly through sexual conflict, and it is largely this feature that has prompted the promotion of sexual conflict as a speciation agent. It is important to note, however, that more traditional mechanisms of sexual selection can also generate rapid evolution of reproductive characters, and that distinguishing between the different selection pressures that can potentially lead to reproductive isolation is likely to be difficult. Sexual conflict, sexual selection, what's the difference? The two concepts are intimately related. Sexual selection, selection in exclusive relation to securing matings (more strictly fertilizations), inherently generates sexual conflict because, for example, females will mate with some males, but not with others. Additionally, sexual conflict can be thought of as a sexual selection mechanism, as adaptation to win sexual conflicts can increase variance in reproductive success. Traditionally, sexual selection via female choice was seen to be generated by either direct or indirect benefits to females. In contrast, recent formulations of sexual selection generated by sexual conflict give primacy to direct costs, and female mating decisions are viewed as an attempt to minimise costs rather than maximise benefits. The …