The Evolution of Crustacean Mating Systems

A quantitative approach is described for mating system analysis that measures the source and intensity of sexual selection. Using data commonly available from ecological, life history and behavioral studies, and using crustaceans as specific examples, this chapter shows how the magnitude of the sex difference in fitness variance can be used to classify the mating systems of any sexual species. Differences between the sexes in the opportunity for selection is influenced by the spatial and temporal aggregation of matings, variation in female life history, male and female reproductive behavior, and by various forms of run-away selection processes. An empirical framework is introduced for the study of crustacean and other mating systems that emphasizes the measurement of selective forces responsible for the evolution of male-female differences. This approach is easier to test and interpret than current frameworks emphasizing optimality or parental investment theory.