Simply stated, a niche is the location where a species can be found based on its physical features. A niche can also describe the organism’s functional role in the environment (Ecological Society of America 1991). Hutchinson quantified this concept by stating that if an environmental variable could be sorted on a high/low scale, then a species niche could partially be defined by the upper and lower bounds where is can survive and reproduce (Hutchinson 1957). The sums of these ranges are the fundamental niche, all of the area that a species could occupy (Hutchinson 1957). A species will rarely inhabit its entire fundamental niche however because of competitive exclusion principal. This states that two species cannot have the same fundamental niche indefinitely. Their niches may overlap, but the more they overlap, the more competition that exists between the species (Cain et. al 2011).This leads to the realized niche, where the organism actually exists. This depends on competition between species and which one is more fit for the specific environment.
This is an important concept in invasion ecology. When an introduced species occupies a similar niche as a native species, the competitive exclusion principal states that only one species should subsist. Many invasive species have traits that make them better competitors than the natives, causing native populations to decline. Understanding the niche that invasive species occupies is important to understand their effect on the ecosystem.
Cain, M. L. (2011). Ecology (2nd ed.). Sunderland, Mass: Sinauer Associates.
Ecological Society of America. (1991). Foundations of ecology: classic papers with commentaries. Chicago: University of Chicago Press.
Hutchinson, G. E. (1957). Concluding Remarks. Cold Spring Harbor Symposia on Quantitative Biology, 22(0), 415–427.