ABSTRACT
This chapter reviews the importance of sexual selection in the elaboration of fins and courtship behavior in male fishes. Male secondary sexual traits, such as elaborate fins, courtship, and aggressive behavior are metabolically costly and affect all aspects of swimming performance. Elaborate fins are likely to reflect a compromise between sexual selection for showy courtship displays and natural selection for other aspects of swimming performance, such as metabolic cost and predator avoidance. Predation is a strong selective pressure influencing the evolution and expression of secondary sexual traits. Multiple selective pressures affect swimming performance of fish. Among these are abiotic conditions of the physical environment, such as temperature, salinity, and flow velocity, and biotic interactions, such as competition, predation, and parasitism. Most of the information about ways that elaborate sexually-selected traits affect swimming performance comes from studies of a very limited and biased sample, mostly poeciliids.
