Inducible defences are phenotypic shifts in prey activated by biological agents ranging from predators to pathogens. They are widespread in the natural world, and the authors of this book bring together leading researchers from all fields to review common themes and explore emerging ideas. The topics examined include unicellular algae and higher vertebrates, considering defences that range from immune systems to protective changes in morphology, behaviour, chemistry and life history. Case studies and theoretical studies pinpoint unifying factors favouring the evolution of inducible defences. Throughout, the volume emphasizes a multidisciplinary approach, integrating applied and theoretical ecology, evolution, genetics and chemistry.