Question

Identify and define the ecological phenomenon demonstrated by this observation.

Hint:

Competitive release proves that a species' "realized niche" is often much smaller than its "fundamental niche" due to competition.

Answer 1

Step 1: Understanding the Concept:
In ecology, when two species compete for the same resource, the presence of the superior competitor limits the distribution of the inferior one.
Step 2: Detailed Explanation:
1. Identification: The observation that \textit{Chthamalus} (the smaller barnacle) expands its distribution once \textit{Balanus} (the larger, superior barnacle) is removed is a classic example of competitive release.
2. Definition: Competitive release occurs when a species whose distribution is restricted biologically because of the presence of a competitively superior species, expands its distributional range dramatically when the competing species is experimentally removed.
3. This demonstrates that \textit{Chthamalus} is capable of living in the lower intertidal zone but is normally excluded from it by the more aggressive \textit{Balanus}.
Step 3: Final Answer:
The phenomenon is Competitive Release, which is the expansion of a species' niche when a competitor is removed.