With some exceptions (e.g., Leslie matrix
models), macro population models often assume that the carrying capacity of the species
forms the base of the food chain or food web (e.g., Schaefer 1954; Clark 1985, 1990). The
carrying capacity is believed to change with the environment and the abundance of predators,
parasites, and competitors (Hart & Reynolds 2002); however, the carrying capacity
parameter is just a result of a particular assumption about density dependence and has
nothing explicitly to do with the environment (Pastor 2008). The complicated models of
species interaction and food webs simply pushed the environment problem that is constraining
species interaction down to the lowest species in the food web or community
(Pastor 2008). Macro population models also ignore variability between individuals in a
population. In addition, these models ignore the transactions of individual organisms and
do not answer the question of how the interaction of individual organisms translates into
population changes (Eichner & Pethig 2006).