Population genetics · USMLE Step 1

Which factor is most likely to increase genetic variation within a population?

  1. Genetic drift acting on allele frequencies
  2. Inbreeding within the population
  3. Mutation introducing new alleles
  4. Stabilizing selection on the phenotype
Show answer and explanation

Correct answer: Mutation introducing new alleles

Mutation introduces new alleles and is the ultimate source of genetic variation. Drift and inbreeding tend to reduce variation, and stabilizing selection removes phenotypic extremes, lowering diversity.

Difficulty: Medium Question 12 of 20

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