Genetic drift is defined as a random change in allele frequencies that can reduce genetic variation.

Genetic drift is defined as a random change in allele frequencies that can reduce genetic variation.

• A. The movement of alleles between populations
• B. A random change in allele frequencies that can reduce genetic variation
• C. The formation of new species due to geographic isolation
• D. Natural selection driving adaptation

Answer: (B)

Genetic drift is random fluctuations in how common different alleles are from one generation to the next, driven by chance rather than fitness differences. In small populations, these random sampling effects can cause some alleles to become more common or disappear entirely, which often reduces overall genetic variation over time. This is different from gene flow, which changes frequencies by the movement of alleles between populations; from natural selection, which shifts frequencies because some variants improve survival or reproduction; and from geographic isolation leading to speciation, which is about populations becoming separate species. So a description of a random change in allele frequencies that can reduce genetic variation best captures what genetic drift is.

Genetic drift is random fluctuations in how common different alleles are from one generation to the next, driven by chance rather than fitness differences. In small populations, these random sampling effects can cause some alleles to become more common or disappear entirely, which often reduces overall genetic variation over time. This is different from gene flow, which changes frequencies by the movement of alleles between populations; from natural selection, which shifts frequencies because some variants improve survival or reproduction; and from geographic isolation leading to speciation, which is about populations becoming separate species. So a description of a random change in allele frequencies that can reduce genetic variation best captures what genetic drift is.