Introduction
This chapter demonstrates how investigating patterns of survival, reproduction, growth and development – life histories – can improve understanding and prediction in diverse areas of ecology ranging from microevolution and population dynamics of individual species, to ecosystem function and biogeochemistry.
To make sense of the huge diversity of life history in nature, a first step is to derive a common set of traits, such as age and size at first reproduction, number and size of offspring, inter-clutch interval, and juvenile and adult survival. The effects of changes in the magnitude of each of these traits on the others (e.g. increased offspring size may be traded off against a reduction in offspring number), and their relationship to fitness or population growth under particular environmental conditions, can then be analyzed.
This chapter initially outlines how this process, life-history analysis, is used in adaptive evolutionary models that predict adult and offspring size within species. As there are numerous reviews that introduce life-history analysis (e.g. Lessells, 1991; Roff, 1992; Stearns, 1992; Daan & Tinbergen, 1997; Stearns, 2000; Roff, 2002; Begon, Townsend & Harper, 2006), this chapter outlines only the salient features. While some applications of life-history analysis are beyond the scope of this chapter (e.g. elasticity analysis; Benton & Grant, 1999), here we will evaluate the importance of life-history analysis in understanding and predicting body-size variation and the scaling of many traits with body size, at various levels of ecological organization ranging from within-genotype variation (phenotypic plasticity and changes during ontogeny) to differences among ecological functional groups that affect ecosystem function and biogeochemistry.