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Question #46692
The Question
In a hypothetical scenario, a population of Periplaneta americana experiences rapid evolutionary divergence due to intense niche competition. The morphology of the asymmetrical chitinous structures surrounding the male gonopore changes drastically, while their pheromonal mate-recognition signals remain identical to the ancestral population. Assuming no geographical barriers are introduced, which of the following represents the most likely evolutionary outcome and its correct anatomical basis?
Options
- A.
Pre-zygotic mechanical isolation leading to sympatric speciation; caused by structural incompatibility between the male phallomeres and the female genital pouch.
- B.
Post-zygotic gametic isolation leading to sympatric speciation; caused by the inability of the male's anal styles to deposit spermatophores into the female's spermatheca.
- C.
Pre-zygotic behavioral isolation leading to allopatric speciation; caused by the morphological divergence of the anal cerci failing to detect mating vibrations.
- D.
Pre-zygotic mechanical isolation leading to parapatric speciation; caused by the structural mismatch between the male's mushroom gland and the female's collaterial glands.
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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
Adaptive Radiation Logic|Cockroach Reproductive Dimorphism
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating Structural Organisation in Animals (Cockroach reproductive anatomy) with Evolution (Isolating mechanisms and Speciation).
The trap relies on students confusing the functions of male-specific structures (anal styles vs. phallomeres) and failing to classify morphological genital mismatch as a pre-zygotic mechanical barrier driving sympatric speciation.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Structural Organisation in Animals - Class 11 |
| Concept | Cockroach Reproductive Dimorphism |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |