Interactions Between Two Species

Populations of two different species that coexist within the same geographic area may be viewed as two separate population systems, which interact with each other through their common environment. In this way, the numbers of one population modify the favorability of the environment for the other (Figure 4.1). This interaction creates an additional feedback loop, shown as a bold line in the figure, which passes through both population systems. This loop may be positive or negative depending on the signs of the interspecific interactions.