A Critical Variable Formulation of Population Dynamics

A single—species population model which admits a more realistic and complete description of the internal structure and changes of a population as well as a more complete description of the external influences gathered about the population is presented. The basic idea is to identify the characteristics which most critically affect the population dynamics. Coupled differential equations for the total population and the means and variances of the critical variables, such as age and mass, are formulated. Thus the means and variances of the critical variables change with time. After the derivation of the equations an examples is given. The examples illustrates that the behavior of the population and its equilibrium depend on quantities which have ecological significance.