All organisms have a position within an ecosystem. The complete set of living and nonliving factors—including food resources, climate, and terrain—that define the position of a given organism are collectively referred to as the organism’s ecological niche.

Multiple species cannot occupy the exact same niche within their habitat. If the niches of two or more species overlap to a large extent, the competitive exclusion principle dictates that one species will outcompete the other, forcing it to adapt or die out. However, flexibility in the resources an organism uses can allow similar species to coexist if they modify their realized niches to avoid competition.

Further, it appears that there is often a correlation between niche size and geographical range. Species with niches that are broader are generally found across a larger geographic area. Such larger distributions might give these species more flexibility in the realized niche, allowing them to adapt to environmental changes or the presence of competitors more easily than a species with a narrower niche and smaller geographic range.

Understanding how organisms function together in their ecosystem through their ecological niches can help guide conservation efforts for vulnerable areas and endangered species, as well as limiting the threat posed by invasive species.