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Fundamental & Realised Niche: Fundamental & Examples

Aug 30, 2022
Dependence of niche on 
       temperature and moisture


Fundamental and Realized Niche  

The main difference- Any type of environmental condition in which a particular species can live is called a fundamental niche.  

On the other hand, the environmental condition in which the species actually live is called a realized niche. There is no competition for resources or predators in the fundamental niche, while there is competition for both resources and predators in the realized niche.

Fundamental Niche  

This can be defined as the range of environmental conditions in which a particular species can live. It means a collection of conditions and sources in which the species can survive, grow, and reproduce. Maximum advantage is taken by the organisms in the species, of both biotic and abiotic factors in the ecosystem of the fundamental niche since there is no competition for resources and predators.

Performance vs temperature for fundamental niche 

Example of Fundamental Niche  

  • In the early spring, the male red-winged blackbird has good real estate in the marshes. 
  • With the seasonal progress, however, tri-color blackbirds, which are more aggressive, move into the marshes and take over the best territory. 
  • So, before the arrival of the tri-color blackbird, the marshes are a fundamental niche for the male red-winged blackbird.

Realized Niche  

This can be defined as the range of environmental conditions in which the species actually live.  

As compared to the corresponding fundamental niche of the species, it is always smaller and is considered a subset of the fundamental niche. When the fundamental niche faces various interactions and pressure from the environment, it is forced to move into a small niche, the realized niche. 


Example Of Realized Niche  

  • Wolves roamed North America, battling with coyotes for food and territory. 
  • The hunting reduced the wolf population with the arrival of European settlers to the continent, letting coyotes enjoy a wide range of the environment.  
  • It is also considered that with the growth of the realized niche, the corresponding fundamental niche also grows accordingly.  

Similarities And Differences  

  • There are quite a few similarities and distinct differences between fundamental and realized niches. 
  • Both of these are two types of positions of the ecosystem occupied by a particular species.
Comparison between fundamental and realized niche 
  • The fundamental niche is also known as the pre-competitive niche, whereas the realized niche is known as the post-competitive niche. 
  • In the case of the niche of an organism, there are no limiting factors on the environment or resources the organism can use. It can be considered as the fundamental niche. 
  • Niche, which a viable population of a species occupies in the presence of competitor species, can be considered as the realized niche.  
  • This can be considered as the basic difference between fundamental and realized niche. 
No. of individuals vs resources for diff. niche 


  • Fundamental niche is more like a theoretical niche. 
  • A realized niche is actually the reality, i.e., where the species actually lives.  

Also called: 

  • Fundamental niche is also called pre-competitive niche. 
  • A realized niche is also called post-competitive niche.  


  • Fundamental niche is large in size. 
  • The realized niche is small in size. 
Comparison between fundamental and realized niche 

Roles of species:  

  • Various roles of a particular species are elaborated by the fundamental niche. 
  • The role that a species can actually play is elaborated by realized niche.  

Competition for resources:  

  • No competition either for resources or predators in the fundamental niche. 
  • There is competition for both resources and predators in the realized niche. 


In the fundamental niche, there is no environmental pressure. When pressure from predators or restricted resources develops, the species shifts to the realized niche. Sometimes, the fundamental niche can be of the same size as a realized niche. Depending on the rivals and predators present, the same species living in various areas may have different realized niches. Fundamental niche narrows when other organisms arrive, and there is competition for food and breeding partners or when predators start hunting in the area.  

On the other hand, the organism will survive if it adapts to the new conditions of its realized niche. Both fundamental and realized niches can be wide or narrow. The term used for organisms that live in narrow niches because they thrive only in certain environmental conditions or eat a certain food is a specialist species. 

Whereas the term used for species that occupy wider niches and make use of a variety of resources and can live in many different environmental conditions is generalist species. Example: When a tadpole, which is an herbivore, undergoes metamorphosis into a carnivorous frog.



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