Phenotypic plasticity is the ability of an organism with a given genotype to respond to changing environmental conditions by undergoing a phenotypic adaptation. The authors in this book discuss the molecular mechanisms, evolutionary significance and impact on speciation of phenotypic plasticity. Topics discussed include the role and evolution of adaptive plasticity during the colonisation of novel environments; phenotypic plasticity in functional traits of woody species in tropical dry forests; understanding the mechanisms of chemical communication and its consequences on aquatic communities using the freshwater crustacean daphnia model; and phenotypic plasticity of plants in response to environmental change.