ABSTRACT
Within a biological population individuals usually exhibit differences in their population dynamical behaviour. Here we use the term behaviour to refer to those processes that have an influence upon the dynamics of the total population, as, for example, reproduction, mortality or the feeding on a limiting food resource. The differences can first of all arise from the fact that individuals occupy different positions in the space in which the population lives, and hence experience a different local environment. Another source of observed variation in behaviour is the fact that individuals are physiologically different. Finally, differences in behaviour are also observed between individuals that seem physiologically identical. In recent years developments in the field of modelling the dynamics of biological populations have been largely aimed at accounting for this variation in behaviour.
