Define reproductive isolation. Why it is must for speciation ?

Explanation

### Step-by-Step Solution

1. **Definition of Reproductive Isolation**:
- Reproductive isolation refers to the mechanisms that prevent different species or populations from interbreeding. This isolation can occur even if the populations are in the same geographical area. It ensures that species remain distinct and do not mix their genetic material.

2. **Mechanisms of Reproductive Isolation**:
- There are several mechanisms that can lead to reproductive isolation:
- **Geographical Isolation**: When populations are separated by physical barriers (e.g., mountains, rivers, or islands), they can evolve independently.
...