9419823 REZNICK One example of a prediction from life history theory is that high adult mortality rates will select for individuals that mature and reproduce earlier in change will carry costs, such as reduced life span or reduced reproduction late in life. This cost is offset by an increase in the probability of successful reproduction early in life, since the odds of living to an advanced age in the face of a high mortality rate are poor. The theory of life history evolution thus also makes predictions about the evolution of aging and life span. Because the properties and assumptions that underlie the theory are very general, the predictions are also general and will apply to a diversity of organisms, including humans. They also provide important insight in areas such as fisheries management, since a consequence of such resource exploitation is an increase in mortality rates. Such increases will inevitably select for undesirable features in exploited populations, such as earlier maturity at a smaller size. Dr. Reznick has shown that fish from high predation localities have mortality rates that are twice as great. They also mature at an earlier age, smaller size, and produce more offspring than those from low predation localities. These results are all consistent with theoretical predictions. Four experiments in progress are evaluating these traits by either adding predators to low predation sites or introducing prey from high predation sites to low predation sites that previously lacked them. Progress to date indicates that these traits are as predicted. When combined with other data, such as estimates of generation time and the heritability of these traits, it is also possible to evaluate the potential rate of change in nature. It is clearly far greater than previously thought, in large part because such prior inferences were based primarily on the fossil record.
