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Question #46605
The Question
In a stable ecosystem, a K-selected species follows the logistic growth model dN/dt = rN[(K-N)/K]. Following severe habitat fragmentation, several key mutualistic species go extinct. According to the Rivet Popper Hypothesis, this loss of critical 'rivets' drives the surviving K-selected species towards an extinction vortex. Which of the following best explains the primary mathematical and ecological shift in the surviving species' growth model?
Options
- A.
The intrinsic rate of natural increase (r) becomes negative as the species rapidly evolves r-selected traits to survive.
- B.
The carrying capacity (K) of the habitat is fundamentally lowered, increasing environmental resistance even at reduced population densities.
- C.
The environmental resistance factor [(K-N)/K] approaches 1, indicating that the population has overcome density-dependent limiting factors.
- D.
The population shifts to an exponential growth phase (dN/dt = rN) because interspecific competition has been eliminated by the fragmentation.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Regulatory_Failure
Understand how NOT, EXCEPT, and logical constraints are used to manipulate exam results.
Concepts Behind This Question
Ecological Fitness (Darwinian Fitness)|Population Growth Model Dynamics|Rivet Popper Hypothesis
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often memorize the Rivet Popper Hypothesis purely as a metaphor for biodiversity loss without linking it to the mathematical parameters of population ecology (specifically K).
Common Misconception: Students might assume that the extinction of co-existing species frees up resources, leading to decreased environmental resistance (Option C) or exponential growth (Option D), failing to recognize that the loss of 'key' species (mutualists/keystone species) degrades the habitat's overall carrying capacity.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Organisms and Populations - Class 12 |
| Concept | Ecological Fitness (Darwinian Fitness) |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |