Fundamental & Realised Niches (HL) (HL IB Environmental Systems & Societies (ESS))

Fundamental & Realised Niches

• The fundamental niche describes:

The full range of conditions and resources in which a species could survive and reproduce if there were no limiting factors

• The realised niche describes:

The actual conditions and resources in which a species exists due to biotic interactions

or

The actual mode of existence of a species, which results from its adaptations and competition with other species

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

  • Here, 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 or 'narrower' 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

  • Here, 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