The natural selection forces which serves to eliminates the intermediate types is

Options

A. Disruptive selection
B. directional selection
C. Stabilizing selection
D. Normalizing selection

Answer

**Step-by-Step Solution:**

1. **Understanding Natural Selection Types**: Natural selection can be categorized into different types based on how they affect the population. The main types include disruptive selection, directional selection, and stabilizing selection.

2. **Defining Disruptive Selection**: Disruptive selection occurs when environmental changes create selection pressures that favor two extreme traits over intermediate traits. This means that individuals with traits at both extremes have a higher chance of survival and reproduction, while those with intermediate traits are less favored.

3. **Example of Disruptive Selection**: A classic example of disruptive selection is observed in grass plants on Welsh copper mines. In this scenario, the contaminated soil is lethal to normal grass plants, but a mutation allows some grass plants to thrive in this environment. These plants reproduce successfully in contaminated soil, while normal plants struggle and are outcompeted.

4. **Evaluating Other Selection Types**:
- **Directional Selection**: This occurs when environmental changes favor one extreme trait over others, leading to a shift in the population's traits in one direction.
- **Stabilizing Selection**: This type favors intermediate traits and reduces variation by eliminating extremes, which does not fit the question's criteria.
- **Normalizing Selection**: This is similar to stabilizing selection and focuses on reducing genetic variability by eliminating less fit individuals at both extremes.

5. **Conclusion**: Given the definitions and examples discussed, the natural selection force that eliminates intermediate types is **disruptive selection**.

**Final Answer**: The natural selection force that serves to eliminate the intermediate types is **disruptive selection**.

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