- Sexual conflict theory suggests that male and female interests often diverge, causing selection to favour sex-specific reproductive strategies that maximize the fitness of an individual at the expense of its mate. Sexually antagonistic selection can lead to conflicts over the timing and frequency of mating events, mate choice and the delivery of parental care.
- This antagonistic view of reproduction has received little attention in discussions of the evolution of mammalian mating systems. Reproduction in mammals, more than in other organisms, is characterized by asymmetry in parental investment between the sexes. This asymmetry provides opportunities for sexual conflict to manifest itself.
- We highlight the potential for sexual conflict in mammalian mating systems by exploring why males and females are selected to mate with multiple partners and by considering the shared characteristics of mammalian reproductive biology that may lead to predictable patterns of conflict over parental investment.
- The degree to which sexual conflict is realized as sexually antagonistic adaptations may vary between species, depending on the strength of selection for multiple mating, paternity assurance and the amount of parental care required.
- Empirical evidence of sexual conflict in mammalian species is needed. Available genomic and phylogenetic tools, and the identification of mating, placentation, lactation and parental care as likely sites of conflict, make mammals a natural choice for research. Understanding the factors that influence the magnitude of the conflict and the ways in which conflict shapes male and female adaptations and counter-adaptations should be priorities.
- The integration of sexual conflict theory into models of mammalian life history evolution will unify developments in behavioural ecology, physiology, genetics and genomics. This multidisciplinary approach may reveal novel ways in which sexual conflict can operate, and increase understanding of evolution.