This book describes the sexual behavior of guppies and examines how mate choice by females leads to the evolution of the conspicuous colors and the courtship displays for which guppies are widely recognized. The author shows that female guppies prefer males with bright color patterns, especially those with orange spots, and that the mating preferences of females lead to sexual selection on both color patterns and courtship displays of males.

Abstract: Early social interactions can shape future reproductive behavior, which has been well studied in organisms with parental care (e.g., sexual imprinting in birds). Evidence suggests that socially mediated behavioral development can occur also in species without parental care or during stages following independence from parents. I discuss implications of "developmental ecology," a new conceptual framework that extends the classic imprinting paradigm to incorporate interactions among group members as being potentially important for individual behavioral ontogeny (Chapter 1). I conducted three laboratory experiments to determine whether social group composition could produce different behavioral trajectories in male guppies, Poecilia reticulata, and whether these behaviors persist with new social experience. For each experiment, males were tested in novel social environments following maturation under different rearing conditions. Maturation in all-male groups induced male-male courtship, which continued in mixed-sex groups (Chapter 2). Further, males that had already developed typical heterosexual behavior tended to increase male-directed courtship after experience in all-male groups. In order to determine whether socially inducible same-sex courtship affected reproductive competence, males reared in all-male or mixed-sex groups were given the opportunity to breed (Chapter 3). This experiment did not detect any difference between numbers of offspring produced by males that exhibited same-sex courtship in early environments compared to males that had always courted females. Thus, data did not support the hypothesis that socially mediated preference for the sex to which males direct courtship reduces mating competence later in life. More realistic, yet still biased, sex ratios promoted differences in behavioral patterns in males, which disappeared following new experience in even sex ratios (Chapter 4). This experiment suggested that maturation with other males might be beneficial for future encounters with potential mates. Overall, this project provides evidence that group composition can promote the development of different patterns of sexual behavior and that some, but not all, trajectories may be modified with new experience. Although these results were revealed under artificial conditions, they provide a starting point from which to base ecologically relevant studies, and they have implications for captive populations used in behavioral studies and conservation programs.

The Trinidadian guppy (Poecilia reticulata) is well known to biologists and home aquarium enthusiasts alike. Scientists have studied guppies for most of the twentieth century. Some of the most intensive recent research has been conducted by behavioral ecologists, who have found that the guppy mating system makes guppies especially useful in the study of sexual selection and mate choice. By observing guppy behavior in aquaria, researchers hope to obtain new insights into how selection operates in natural populations. Here Anne Houde summarizes and synthesizes the scientific work done to date, relates the empirical findings on guppies to current themes in sexual selection theory, and suggests new directions for future research. This book describes the sexual behavior of guppies and examines how mate choice by females leads to the evolution of the conspicuous colors and the courtship displays for which guppies are widely recognized. The author shows that female guppies prefer males with bright color patterns, especially those with orange spots, and that the mating preferences of females lead to sexual selection on both color patterns and courtship displays of males. Houde's work addresses a number of areas that are of interest in sexual selection, including the remarkable degree of plasticity and evolutionary lability of sexual behavior in guppies, geographic variation in mating preferences, possible mechanisms for the evolution of female mating preferences, and the role of sexual selection in speciation. In conclusion, the author explores the implications of her findings for behavioral ecologists who study sexual selection in other species.

Evidence from various fields indicates that such selectivity by females may be the norm rather than the exception. Because most postcopulatory competition among males for paternity is played out within the bodies of females, female behavior, morphology, and physiology probably often influence male success in these contests, Eberhard draws examples from a diversity of organisms, ranging from ctenophores to scorpions, nematodes to frogs, and crickets to humans.

The Trinidadian guppy represents a uniguely tractable vertebrate system, which has raised key questions in evolutionary ecology and supplied many of the answers. This work discusses this study and incorporates significant new findings and insights.