Give three hypotheses for explaining why tropics show greatest levels of species richness.

Explanation

### Step-by-Step Solution:

1. **Understanding Species Richness**:
- Species richness refers to the number of different species present in a particular area. In the context of biodiversity, it indicates the variety of flora and fauna in a region.

2. **Identifying the Latitudinal Gradient**:
- Biodiversity is not uniformly distributed across the globe. The latitudinal gradient indicates that species richness is highest in the tropical regions near the equator and decreases as one moves toward the poles.

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