Macroevolution in a Model Ecosystem

A greatly oversimplified model of the evolution of energy flow in a single population or a simple ecosystem is presented. In all cases treated, once the effect of the initial size of the ecosystem is lost, the total energy content of the ecosystem increases linearly with time. A constant fraction of the cumulative energy inflow remains in the system at any given time. This fraction is smaller the more unpredictable is the environment and is greater the more trophic levels are present. In simple cases the trophic pyramid converges to a geometric shape which does not lengthen during evolution. A somewhat arbitrary measure of the information content of a population per unit energy content is proportional to the logarithm of time. Aside from many other limitations, the model does not allow for evolution of the efficiency of energy intake. This might have a dramatic effect on the conclusions.