Given below are two statements: one is labelled as Assertion (A) and the other is labelled as Reason (R).
Assertion (A): Predators in nature are said to be ‘prudent’.
Reason (R): Predators help in maintaining species diversity in a community by reducing the intensity of competition among competing prey species.
In the light of the above statements, choose the most appropriate answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Both (A) and (R) are true but (R) is not the correct explanation of (A).
Assertion (A): Predators in nature are said to be ‘prudent’. — True. A is about why predators do not wipe out their prey. If a predator is too efficient and overexploits its prey, the prey might become extinct, and then the predator too would die out for lack of food. Predators in nature therefore do not overexploit their prey; they are prudent.
Reason (R): Predators help in maintaining species diversity in a community by reducing the intensity of competition among competing prey species. — True. R is about another role of predators. When the starfish Pisaster was removed from an enclosed intertidal area, more than 10 species of invertebrates became extinct within a year because of interspecific competition among them.
Why R does not explain A? A predator is called prudent because overexploiting its prey would lead to its own extinction. R talks about how predators keep species diversity among competing prey species. Both are true, but R is a separate role of predators, not the reason why they are prudent. So R is not the correct explanation of A.
NCERT Extract:
Predation – “… Predators also help in maintaining species diversity in a community, by reducing the intensity of competition among competing prey species. In the rocky intertidal communities of the American Pacific Coast the starfish Pisaster is an important predator. In a field experiment, when all the starfish were removed from an enclosed intertidal area, more than 10 species of invertebrates became extinct within a year, because of inter-specific competition. If a predator is too efficient and overexploits its prey, then the prey might become extinct and following it, the predator will also become extinct for lack of food. This is the reason why predators in nature are ‘prudent’.”