Which of the following factors has not aided in the high species diversity of tropics

Options

A. Less seasonal variation promoting niche specialisation
B. Availability of more solar energy
C. More pest pressure
D. Less migration

Answer

To determine which factor has not aided in the high species diversity of the tropics, we will analyze each option provided in the question.

### Step-by-Step Solution:

1. **Understanding Species Diversity in Tropics**:
- The tropics are known for their high species diversity due to various ecological factors. We need to identify which of the given options does not contribute to this diversity.

2. **Analyzing Option 1: Less Seasonal Variation**:
- Less seasonal variation in the tropics allows for stable environments, which promotes niche specialization. This stability supports a greater number of species. Therefore, this factor aids in high species diversity.

**Hint**: Consider how stable environments can lead to more specialized niches.

3. **Analyzing Option 2: More Solar Energy**:
- The tropics receive more solar energy due to direct sunlight throughout the year. This abundant energy supports a wide range of plant and animal life, contributing to high species diversity. Thus, this factor also aids in diversity.

**Hint**: Think about how energy availability impacts the growth of ecosystems.

4. **Analyzing Option 3: More Pest Pressure**:
- High pest pressure can lead to increased competition among species, which may drive some species to adapt or become extinct. However, it can also create a dynamic ecosystem where species evolve in response to pest pressures. This factor can be complex, but generally, it does not directly aid in increasing species diversity.

**Hint**: Reflect on how competition and predation can influence species survival and diversity.

5. **Analyzing Option 4: Less Migration**:
- Migration is essential for maintaining genetic diversity and introducing new species into an ecosystem. Less migration can lead to isolation of species, reducing genetic diversity and overall species diversity. Therefore, this factor does not aid in high species diversity.

**Hint**: Consider how the movement of species affects genetic variation and ecosystem dynamics.

### Conclusion:
Based on the analysis, the factor that has not aided in the high species diversity of the tropics is **Option 4: Less Migration**.

### Final Answer:
**Option 4: Less Migration** is the correct answer as it does not contribute to high species diversity in the tropics.