This book celebrates the guppy's unique contribution to evolutionary ecology. Ever since Caryl Haskins described guppy populations as a 'natural experiment' because of the way predation pressure varies over a small geographical area, generations of researchers have been drawn to Trinidad to investigate evolution in the wild. The species continues to provide classic examples of natural selection in action and elegantly illustrates how ecology, evolution, and behaviour are interlinked. Anne Magurran's account of the evolutionary ecology of the guppy integrates historical breakthroughs with new research in this fast-moving field. She reveals how guppies provided some of the first evidence of sperm competition and sexual selection, and how they continue to inform scientific thought on mating systems and cryptic choice. The consequences of variation in predation risk—as well as a host of other biotic and abiotic factors—are described and evaluated at all life stages from conception to death. The book discusses behavioural responses to ecological conditions alongside life history patterns. It examines the potential for ecological speciation and discusses new research into how reproductive isolating mechanisms become established in promiscuous mating systems. Conservation issues are also considered, both in terms of protecting the irreplaceable Trinidadian guppy system and in the context of invasion ecology. This timely synthesis of research into a species that has raised key questions in evolutionary ecology will be of great interest to graduate level students as well as professional researchers in the fields of behavioural ecology and evolutionary biology.