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Question #46144
The Question
A researcher studies an isolated population of a dioecious Aschelminthes species. A sudden mutation causes the entire population to shift from obligate sexual reproduction to obligate parthenogenesis. Concurrently, an obligate symbiotic gut bacterium relies exclusively on the biochemical signals generated during the nematode's copulation to trigger its own reproduction. Assuming immigration and emigration are zero, which of the following represents the most likely immediate demographic and ecological consequences?
Options
- A.
The intrinsic rate of natural increase (r) of the nematode will initially decrease due to the absence of males, and the gut bacteria will face co-extinction.
- B.
The nematode's birth rate (B) will initially increase, elevating population density (N), while the gut bacteria will undergo co-extinction due to the absence of copulatory signals.
- C.
The nematode population density (N) will immediately crash due to a loss of genetic variation, and the gut bacteria will adapt to a free-living state.
- D.
The nematode's population density (N) will remain stable as the death rate (D) compensates for the lack of sexual reproduction, while the bacteria face co-extinction.
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
Aschelminthes Sex Differentiation|Birth/Death Rate vs Immigration/Emigration|Co-extinction Logic
Why This Question Is Tricky
Common Mistakes
Conceptual Pivot: Integrating the demographic consequences of asexual vs. sexual reproduction with the ecological concept of Co-extinction.
Common Misconception: Students often assume that losing sexual reproduction immediately decreases population growth due to a loss of genetic diversity.
However, the immediate demographic effect is a spike in the birth rate (B) because 100% of the population can now bear offspring, whereas genetic depression is a long-term consequence.
Quick Facts About This Question
Question Information
| Subject | Biology |
| Chapter | Animal Kingdom - Class 11 |
| Concept | Aschelminthes Sex Differentiation |
| Difficulty | 8 |
| Cognitive Load | 5 |
| Target Solve Time | 120 sec |
| Access | Free |