Distinguish between gene flow and genetic drift.

Explanation

**Step-by-Step Solution:**

1. **Definition of Gene Flow:**
- Gene flow refers to the transfer of genetic material (alleles) between populations through migration. When organisms migrate from one population to another, they interbreed with the resident population, introducing new alleles into the gene pool.

2. **Mechanism of Gene Flow:**
- Migration is the primary mechanism of gene flow. When individuals move to a new location and breed with the local population, they contribute to genetic diversity. This process can occur over short distances or long distances and is often influenced by environmental factors.

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