Adam Łomnicki

Individual-based models and the individual-based approach to population ecology

This paper discusses some general problems in applying individual-based models in ecology. The reasons why classical ecology did not use an individual-based approach are presented, as are theoretical and technical difficulties related to this approach. It is then considered as a consequence of recent progress in evolutionary ecology. The need for clear distinctions between individual variation, skewness, asymmetric competition and monopolization of resources is discussed, since these concepts are fundamental to understanding population stability. A brief critical evaluation of the importance of chaotic population dynamics is also given. A criticism of individual-based configuration models is presented, with suggestions concerning the further progress of the individual-based approach.

Do individual differences in resource intakes without monopolization cause population stability and persistence

A theoretical model of population dynamics in discrete time units is investigated with the following assumptions: (1) resource partitioning among individuals is unequal, with different degrees of inequality, and (2) scramble competition without a monopolization of resources by stronger individuals occurs. To describe unequal resource partitioning the simpleest possible linear function is assumed, with a parameter describing inequality in resource partitioning. The model of population dynamics in which this parameter is allowed to vary shows that while an increase of inequality has some effect on the population stability and persistence, this effect is a minor one when compared with contest competition (with monopolization). The latter phenomenon always brings about both population stability and persistence.