Fundamental & Realised Niches (HL) (HL IB ESS OLD COURSE - IGNORE)
Revision Note
Written by: Alistair Marjot
Reviewed by: Bridgette Barrett
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
Examiner Tips and Tricks
Remember that the realised niche results from both adaptations to the environment and the pressures of competition with other species.
In exams, you might be asked to apply this concept to species not mentioned in the syllabus. Practice using the fundamental vs. realised niche framework on different species from other ecosystems.
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