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Question #46467
The Question
The fossil record frequently exhibits chronological 'gaps' where new, distinct morphological phenotypes appear abruptly without transitional forms. Within the framework of population genetics, this accelerated trait fixation is most accurately attributed to:
Options
- A.
Intense directional selection acting on a large, panmictic population, leading to the gradual accumulation of micro-mutations.
- B.
Extreme genetic drift operating in a small, geographically isolated sub-population, causing rapid allele fixation and a founder effect.
- C.
Continuous gene flow between sympatric populations, which disrupts Hardy-Weinberg equilibrium and accelerates sympatric speciation.
- D.
The maintenance of Hardy-Weinberg equilibrium in a bottlenecked population, allowing rare recessive alleles to express suddenly.
Check Your Answer
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
Allele_Frequency|Bottleneck_Effect|Founder_Effect
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students often misattribute sudden fossil appearances solely to Hugo de Vries' 'Saltation' or assume 'gaps' are purely geological artifacts.
The modern synthesis explains this via the Founder Effect and Genetic Drift in small, isolated populations (allopatric speciation), where Hardy-Weinberg equilibrium is violently disrupted, leading to rapid allele fixation that outpaces the slow process of fossilization.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Evolutionary Chronology |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |