The field of developmental instability has generated a large amount of controversy recently, mostly because of fierce disagreement over the genetic basis of fluctuating asymmetry and its role in mate selection. This book is a timely and innovative synthesis of the discussion. With twenty four chapters by leading authorities, the book is an especially thorough and critical treatment of the genetic basis of fluctuating asymmetry, and of its role in animal communication, sexual selection, and plant and animal ecology and evolution. The book features an in-depth examination of the relationship between environmental stress and asymmetry, as well as a critical assessment of the value of asymmetry as a biomarker in ecotoxicology. Up-to-date information from disparate fields within the biological sciences is creatively integrated to examine the molecular and cellular origins of developmental instability and fluctuating asymmetry, and the link between asymmetry and Darwinian fitness. This comprehensive treatment also describes methodology for data analysis and optimization of experimental design, refocuses attention on key problems in the field and identifies new research directions.