  Most population models assume that individuals within a given population are
identical, that is, the fundamental role of variation is ignored. Inhomogeneous
models of populations and communities allow for birth and death rates to vary
among individuals; recently, theorems of existence and asymptotic of solutions
of such models were investigated. Here we develop another approach to modeling
heterogeneous populations by reducing the model to the Cauchy problem for a
special system of ODEs. As a result, the total population size and current
distribution of the vector-parameter can be found in explicit analytical form
or computed effectively. The developed approach is extended to the models of
inhomogeneous communities.
