ABSTRACT
Many authors have noticed the hierarchical organization of many systems in very different scopes and many models of hierarchical systems have been proposed. This chapter refers to several of the past two decades works. One distinguishes the following levels: particles, atoms, molecules, macromolecules, organelles, cells, organs and organisms. In ecology, one considers grossly the individual level, the population level, and the ecosystem level. Groups of cells constitute organs, groups of organs are organisms, groups of animals are populations, and groups of populations are ecosystems. The animals have many different activities all day long whose sequences can vary with seasons or else environmental changes such as pollution or climate changes. As a consequence, when one considers competition in links with activity sequences, one must consider that the animals may strongly compete for some food sources and weakly compete or even be in symbiosis for food sources. In this chapter, the author describes the influence of individual behavior on competition models.
