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Question #45602
The Question
In a large, randomly mating population, a specific gene locus exhibits co-dominance, maintaining a high degree of allelic diversity. A small group of individuals from this population colonizes a newly formed archipelago with diverse, extreme ecological niches, subsequently undergoing adaptive radiation. Which of the following best describes the most likely evolutionary fate of these co-dominant alleles in the newly specialized descendant populations?
Options
- A.
The alleles will be maintained at a stable 1:2:1 genotypic ratio across all niches because co-dominance inherently prevents allelic fixation.
- B.
Strong directional selection in specific niches, combined with the founder effect, will likely lead to the fixation of one allele, overriding the maintenance of heterozygosity.
- C.
The alleles will spontaneously mutate into recessive forms to allow for rapid phenotypic specialization in the new environments.
- D.
Disruptive selection will universally eliminate the co-dominant heterozygotes, immediately establishing Hardy-Weinberg equilibrium in the new niches.
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Correct Answer
Step-by-Step Solution
Explanation
How the Examiner Thinks
Evolutionary_Exception
Tackle problems where standard rules evolve or change based on specific environmental constraints.
Concepts Behind This Question
Population_Genetics|Speciation|Selection_Pressure
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students frequently confuse Mendelian allelic expression (co-dominance) with population genetics dynamics.
A common misconception is that co-dominant alleles are inherently immune to fixation because both are expressed.
This question requires synthesizing the disruption of Hardy-Weinberg equilibrium via the founder effect (genetic drift) and directional selection during adaptive radiation, demonstrating that ecological pressures can eliminate heterozygosity despite the alleles being co-dominant.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Principles of Inheritance and Variation - Class 12 |
| Concept | Co-dominance Allelic Interaction |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |