List any four techniques where the principle of ex-situ conversion of biodiversity has been employed.

Explanation

### Step-by-Step Solution:

1. **Understanding Ex-situ Conservation**:
- Ex-situ conservation refers to the practice of conserving biodiversity by removing plants and animals from their natural habitats and placing them in controlled environments. This is done to protect endangered species from extinction.

2. **Identifying Techniques**:
- There are several techniques employed for ex-situ conservation. Here, we will list four significant ones.

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