Life history evolution is a fascinating topic that seeks to explain how natural selection and other evolutionary forces shape organisms to optimize their survival and reproduction in the face of ecological challenges posed by the environment. Life history traits are the major components of fitness, and since adaptation by natural selection is based on variation in Darwinian fitness among individuals, understanding life history evolution is crucial to understanding adaptation, the most fundamental issue in evolutionary biology.
Life history evolution is about understanding how evolution shapes organisms to optimize their reproductive success. Organisms differ dramatically in how they develop, the time they take to grow, when they become mature, how many offspring of a particular size they produce, and how long they live. Together, the age-, size-, or stage-specific patterns of development, growth, maturation, reproduction, survival, and lifespan define an organism’s life cycle, its life history.
Life history theory seeks to explain how natural selection and other evolutionary forces shape organisms to optimize their survival and reproduction in the face of ecological challenges posed by the environment. The theory does so by analyzing the evolution of fitness components, so-called life history traits, and how they interact: size at birth; growth pattern; age and size at maturity; number, size, and sex of offspring; age-, stage- or size-specific reproductive effort; age-, stage- or size-specific rates of survival; and lifespan.
The study of life history evolution is important because it helps us understand how organisms have evolved to optimize their reproductive success in different environments. For example, a female North Pacific Giant Octopus (Enteroctopus dofleini) lives three to four years; it lays thousands of eggs in a single bout and then dies. By contrast, a mature Coast Redwood Tree (Sequoia sempervirens) lives for many hundreds of years and produces millions of seeds each year. As these two examples illustrate, organisms differ dramatically in their life histories.
Life history evolution is a complex topic, and there is still much to learn about how natural selection shapes the life histories of different organisms. However, by studying life
Life History Diagram 7 image
