Figure 8.1 Life history traits. The schedule of an organism’s life begins as an embryo. It either hatches or is born at a particular size and time. During the subsequent juvenile stage the organism grows and eventually becomes a sexually mature adult. To reach this stage, many species must first pass through metamorphosis. Adults can then reproduce in one or more breeding events with a particular level of fecundity, parental investment, and longevity. At all stages, species experience a characteristic amount of growth and some probability of surviving to the next stage.