Life-History Patterns

Life-history theory attempts to explain intra- and interspecific variation in the survival, growth, and reproductive traits of organisms. Because these variables affect both individual fitness and population dynamics, life-history patterns naturally fall at the intersection of evolution and ecology. Life-history theory is based on the premise that organisms face trade-offs arising from energetic, physiological, developmental, or genetic constraints and that these trade-offs affect the patterns we observe in nature. Optimality theory has been used extensively to understand questions such as the timing and frequency of reproduction, the trade-off between offspring size and number, and allocation between current and future reproduction. Quantitative genetics is another powerful approach that has been used extensively to examine phenotypic plasticity and the relative effect of environmental and genetic variation on individual traits. In general, classic life-history theory makes many predictions that have been widely documented empirically and explores the effect of environmental conditions, ecological interactions, and evolutionary dynamics on intra- and interspecific variation in growth, survival, and reproduction. Recent developments in the field include the application of life-history theory to fisheries management, research on species' responses to environmental change, and a greater understanding of the mechanisms that determine senescence and longevity.