The purpose of this section is to introduce students to the factors that can limit the growth of a population. Different relationships, competition, predation, and symbiosis are defined and discussed. The central idea to this section is that an ecosystem must remain in balance, to guarantee the survival of the system. The themes that can be focused on in this section are evolution, patterns of change, and unity and diversity. The interactions that are part of these limiting factors also affect the way organisms change over time.
Organisms change and are changed by their environment.
Each time a change occurs in an ecosystem, an adjustment in the ecosystem's balance is required. The changes in the environment may be slow or rapid. They may involve individuals, species, or entire communities. But because all ecosystems are subject to the same types of change, these can be studied and sometimes controlled. All ecosystems adjust in response to change in an attempt to maintain a state of dynamic balance.