Fitness, Uncertainty, and the Role of Diversification in Evolution and Behavior

Abstract

I have shown how a maximum principle for evolutionary processes based solely upon mean fitness of behaviors may, under certain circumstances, be misrepresentative and misleading in the analysis of biological systems. Many of the misrepresentations can be corrected by including variance of fitness associated with environmental uncertainty and variability in the structure of the maximum principle. There are many ways of incorporating this variance into a mathematical model. I have chosen to depict the modified maximum principle as a discounted function of expected fitness, where the discount is a function of the variance in fitness between behaviors. Such a function under no uncertainty reverts to the simpler mean maxim. Including uncertainty generally results in evolutionary strategies consisting of sets of diverse behaviors whose resulting fitness show negative covariance. Under certainty organisms can specialize, showing only single types of behavior. Supporting evidence has been gathered from different areas of ecology and evolutionary biology. The model appears to be consistent with what I believe to be the consequences of uncertainty in sexual processes, herbivory and pollination systems. Future research will, hopefully, demonstrate the general applicability of this approach.