Sexual Conflict in the Female Reproductive Tract

Males and females each benefit from successful reproduction, but the rules do not apply equally to each sex. Males usually produce an abundance of small, motile, and metabolically cheap sperm whereas females devote more time and resources to producing each of their gametes. This differential per-gamete allocation of resources is reflective of the distinct strategies that each sex uses for reproduction. Males are often in competition with other suitors for a single female, so they leverage sperm quantity to cover their losses and may mate with more than one female to increase their odds of reproducing. Females, however, produce fewer, but more energetically costly gametes, so they are often more selective when mating. Often these conflicts between the sexes occur within the female reproductive tract of internally fertilizing species.