Differentiate gradual speciation and abrupt speciation.

Explanation

### Step-by-Step Solution

1. **Definition of Gradual Speciation**:
- Gradual speciation refers to the process of species formation that occurs through the accumulation of small, incremental changes over a long period of time. This process is characterized by continuous and slow evolutionary changes that lead to the emergence of new species from a common ancestor.

2. **Characteristics of Gradual Speciation**:
- It involves small variations that accumulate over millions of years.
- The changes are gradual and often imperceptible over short time frames.
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