Ecology: Ecosystem
The competitive exclusion principle is related to the niche concept.
A niche is the particular set of environmental conditions that an organism requires to live, including conditions such as temperature and humidity, but also resources such as food and territory. The niche is also modified by the interaction with other organisms in the same space.
Here is where the competitive exclusion principle comes into play. This principle means that a niche can only be occupied by one species, and if two species occupy the same niche, that would be just for a short period of time, where they will compete for the resources until one of them is displaced. This displacement can mean that they use the resources at different times of the day or that, for example, one species feeds at the base of the tree and the other at the top of the tree.