Given below are two statements:
Statement I: Resources need not be limiting for competition to occur; in interference competition, the feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species, even if resources are abundant.
Statement II: A species whose distribution is restricted to a small geographical area because of the presence of a competitively superior species is found to shrink its distributional range further when the competing species is experimentally removed.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 3
The correct answer is Option (3) → Statement I is correct but Statement II is incorrect.
Competition is usually thought to happen only when two species share a resource that is limited. The book points out that this is not always so, and it gives ‘competitive release’ as evidence that competition happens in nature.
Statement I: Resources need not be limiting for competition to occur; in interference competition, the feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species, even if resources are abundant. — True. In interference competition one species gets in the way of the other. Food and space may be plentiful, yet the feeding efficiency of one species falls.
Statement II: A species whose distribution is restricted to a small geographical area because of the presence of a competitively superior species is found to shrink its distributional range further when the competing species is experimentally removed. — False. When the superior competitor is removed, the restricted species is set free and expands its distributional range dramatically. This is called competitive release. The statement says “shrink” in place of “expand”.
NCERT Extract:
Population Interactions – “… Secondly, resources need not be limiting for competition to occur; in interference competition, the feeding efficiency of one species might be reduced due to the interfering and inhibitory presence of the other species, even if resources (food and space) are abundant.”
Population Interactions – “… Another evidence for the occurrence of competition in nature comes from what is called ‘competitive release’. A species whose distribution is restricted to a small geographical area because of the presence of a competitively superior species, is found to expand its distributional range dramatically when the competing species is experimentally removed.”