The Ecological and Evolutionary Importance of Variation in Life History Reaction Norms

This chapter argues that integrative studies are needed to dissect the precise environmental drivers of life history plasticity and the genetic and physiological control mechanisms that may underpin individual variation in plasticity, and long-term field studies, to relate ecologically-realistic reaction norms to demographic rates and thus natural selection and population dynamics. It begins by re-introducing the very general reaction norm framework and the idea of individual by environment interactions. The chapter then discusses the relative merits and limitations of laboratory and field studies of life history plasticity, and goes on to illustrate progress being made from both field and laboratory studies of the phenology of small hole-nesting passerine birds. Finally, it considers the many challenges ahead if we are to forge a cohesive understanding of the physiological, ecological and evolutionary causes and consequences of variation in life history plasticity.