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Question #46622
The Question
In a grassland ecosystem, a newly introduced predator selectively hunts only the pre-reproductive individuals (juveniles) of a specific mammalian prey population. Assuming this intense stage-selective predation pressure is sustained, which of the following best describes the long-term impact on the prey's age pyramid and its population dynamics?
Options
- A.
The age pyramid will transition to an urn shape, and the population's intrinsic rate of natural increase (r) will become negative due to truncated reproductive potential.
- B.
The age pyramid will become bell-shaped, stabilizing the population size by optimizing the Darwinian fitness of the surviving reproductive adults.
- C.
The base of the age pyramid will expand, as the reproductive cohort increases its breeding frequency to compensate for the high juvenile mortality.
- D.
The age pyramid will become inverted with a broad apex, leading to an immediate increase in r due to reduced resource competition among juveniles.
Check Your Answer
Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Comparative_Analysis
Sharpen your ability to evaluate multiple scenarios and distinguish between competing potential answers.
Concepts Behind This Question
Predator-Prey Oscillations|Diversity-Stability Relationship|Rivet Popper Hypothesis
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the NCERT line that 'predators keep prey populations under control' and might incorrectly assume this leads to a 'stable' (bell-shaped) population.
However, they fail to distinguish between general predation and stage-selective predation.
Targeting the pre-reproductive cohort specifically destroys the population's future reproductive value (Darwinian fitness), shifting the pyramid to a declining (urn) shape and driving the intrinsic rate of natural increase (r) negative.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Organisms and Populations - Class 12 |
| Concept | Predator-Prey Oscillations |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |