The purpose of this chapter is to place the DEB theory in a wider context and to evaluate combinations of primary processes and their consequences. The last three chapters treated them one by one, as far as possible, to reveal and explain the basic structure of the theory. Now the models for the primary processes will gain colour as the processes change together in a variable environment. Each section can be read independently, and deals with a problem that may have taxon-specific elements. Some applications aim to illustrate how particular measurements can be interpreted within the context of the DEB theory; some aim to show how mechanisms that are included can interact and explain observed phenomena; other applications are in fact extensions of the DEB theory in various directions to reveal constraints for modelling processes at a lower level of organization, and to show how such processes give some background for the assumptions on which the DEB model is based.

Although the sections cover a range of topics, many important ones are painfully lacking, which only reflects that the theory is still in a stage of development. My hope is that it is possible to reduce the dazzling amount of seemingly complex eco-physiological phenomena to a small set of simple underlying principles that can be based on lower levels of organization help to structure modelling attempts at the biochemical level.

Changing feeding conditions

Food density is never really constant, as experienced by an individual. The relative size of food particles with respect to the individual and the food density itself are important. Moreover, feeding frequently takes the form of meals.