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Question #45204
The Question
A mammalian species in a continuous sub-arctic habitat exhibits short extremities, adhering to Allen's Rule. Severe anthropogenic activities cause extensive habitat fragmentation, isolating the species into very small, disconnected patches. After several generations, biologists note that some isolated subpopulations now possess significantly longer ears and limbs, despite the climate remaining freezing. Which of the following best explains this morphological deviation?
Options
- A.
Increased gene flow between the fragmented patches has introduced alleles for longer extremities.
- B.
Genetic drift has overridden natural selection, fixing non-adaptive alleles in the small populations.
- C.
The edge effect of fragmented habitats has induced a high rate of directed mutations for longer limbs.
- D.
Disruptive selection has favored extreme phenotypes to minimize intraspecific competition in limited spaces.
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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
Detritus Food Chain|Enzymatic Kinetics|Q10 Effect
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often assume Natural Selection is an absolute force that always optimizes a species to its environment (e.g., maintaining Allen's Rule).
The trap lies in failing to recognize that population size dictates the dominant evolutionary force.
In small populations (induced by habitat fragmentation), Genetic Drift overpowers Natural Selection, allowing maladaptive traits to become fixed by chance.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Organisms and Populations - Class 12 |
| Concept | Allen’s Rule and Surface-to-Volume Ratio |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |