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Question #46461
The Question
A population of stenothermal ectotherms is exposed to a rapid, continuous increase in environmental temperature that drastically outpaces their generation time. The population's genetic variance for thermal tolerance is nearly exhausted. According to the principles of natural selection, which of the following best describes the evolutionary trajectory of this population?
Options
- A.
The selection curve will shift in one direction, establishing a new adaptive peak for higher thermal tolerance.
- B.
The population will face extinction because the rapid environmental shift prevents evolutionary rescue due to a lack of heritable variance.
- C.
The selection curve will become narrower and taller as stabilizing selection acts on the surviving individuals.
- D.
The population will exhibit phenotypic plasticity, leading to disruptive selection and the formation of two distinct ecotypes.
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
Climate Change|Phenotypic Plasticity|Ectothermic Constraints
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Students reflexively associate 'changing environment' with 'directional selection' (e.g., industrial melanism).
The trap is failing to recognize the absolute prerequisites for natural selection: pre-existing genetic variation and sufficient generation time.
When an environmental shift outpaces generation time and variance is exhausted, the outcome is extinction, not adaptation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Evolution - Class 12 |
| Concept | Natural Selection Directionality |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |