Evolution of Animal Mating Systems

Animal mating systems are fascinating and diverse, and their evolution is central to evolutionary biology. A mating system describes patterns and processes of how females and males mate and reproduce successfully, and how this relates to their reproductive ecologies, including demographic and environmental factors. One of the more stimulating challenges in biology is to provide a comprehensive explanation for the evolution of mating adaptations among animals. In the course of sexual reproduction, animals engage in a dizzying array of traits, behaviors, and strategies. Such diversity simultaneously requires and eludes categorization: it is required for a general understanding, but at once confounds any rigorous classification because an almost inexhaustible supply of animal examples disrupt otherwise neatly ordered systems (see Classifications of Animal Mating Systems). Historically, mating with a single partner was thought to be a common mating system among animals. However, increasing observations of multiple mating by both sexes, supported by genomic evidence of mixed parentage within families, has since revealed that strict genetic monogamy is rare. In this bibliography, the selected literature highlights a compelling diversity and flexibility among animal mating systems, and sexual selection emerges both as a contributing cause and consequence of this variation. Sexual selection plays a central role in animal mating system evolution, and key references provide insights into its operation before and after mating, and describe how it leads to the expression of secondary sexual traits and sexual conflicts. Efforts to explain diversity in animal mating systems have often focused on how acquiring mates or matings relates to variance in reproductive success. This variation and diversity can be approached at the level of an individual, among individuals in a population, or between species. However, a preoccupation with the mean or average pattern often leads to generalizations that obscure important diversity crucial to evolutionary understanding. To avoid unnecessary categorization, the presentation here focus`es on variation in mating patterns and contrasts multiple mating with mating with a single partner. Furthermore, it considers the wider effects of animal mating systems, and includes associations with patterns of parental care. The aim with this bibliography is to provide key citations demonstrating that animal mating systems evolve from diverse, interactive, complex and dynamic processes resulting in a variety of adaptive mating strategies in females and males. A grateful acknowledgment is given to C. Kvarnemo and D. Gwynne for insightful comments.