Fundamental & Realised Niches
Niche
- The niche of a species can be defined as follows:
The role of a species within its habitat
- A species' role takes into account
- The biotic interactions of the species, e.g. the organisms it feeds on and the organisms that feed on it
- The abiotic interactions, e.g. how much oxygen and carbon dioxide the species exchanges with the atmosphere
Fundamental vs realised niche
- The fundamental niche of a species is:
The full range of conditions and resources in which a species could survive and reproduce, based on its adaptations and tolerance limits
- The realised niche is:
The actual conditions and resources in which a species exists, due to biotic interactions
- An example of a fundamental niche compared to a realised niche can be seen in the case of the barnacle species Chthamalus dalli
- Its fundamental niche includes a wide range of rocky intertidal areas in the Pacific Northwest, where it can attach to a variety of substrates and tolerate a wide range of temperature and salinity conditions
- However, in reality, the realised niche of this species is much smaller due to competition with other barnacle species, such as Balanus glandula, for space and resources
- As a result the actual range of Chthamalus dalli is restricted to areas where Balanus glandula is absent or scarce, such as higher up on the shore, where it is exposed to air for longer periods of time and can avoid competition with Balanus glandula for space and resources
- Therefore, the realised niche of Chthamalus dallia is smaller than its fundamental niche due to the biotic interactions with other species
Fundamental niche vs realised niche table
Fundamental Niche | Realised Niche |
The niche a species would occupy if there were no limiting factors in the environment or resources the species could use | The niche that a species actually occupies, in the presence of competitor species |
The potential distribution of a species | The actual distribution of a species |
No competition for resources, no predation | Competition for resources and predation occurs |
Large in size | Small in size |
E.g. for Chthalamus: | E.g. for Chthalamus: |