Ecological and behavioural systems exist within an evolutionary framework and can only be understood within this context. This subject combines the areas of evolutionary biology, ecology and behaviour and explores the methods used to examine ecological and behavioural systems within an evolutionary framework. There is a strong emphasis on understanding how to derive and test adaptationist hypotheses, through a series of case studies that include: the evolution and maintenance of sex; the use of phylogenies in comparative analysis; the organisation of complex systems; the evolution of eusociality; sexual selection and mate choice.