Which evolutionary mechanism involves random changes in allele frequencies that are not due to natural selection?

Which evolutionary mechanism involves random changes in allele frequencies that are not due to natural selection?

• A. Founder effect
• B. Genetic bottleneck
• C. Genetic drift
• D. Twin method

Answer: (C)

Genetic drift is the random change in allele frequencies from one generation to the next that is not caused by natural selection. It happens because the alleles passed to offspring are just a random sample of the parent gene pool, and this sampling error is especially strong in small populations. Over time, drift can cause certain alleles to become more common or disappear by chance alone, and it tends to reduce genetic variation within a population. Founding events and population bottlenecks are specific situations where drift has a strong effect because the new or surviving group is small and its allele frequencies can differ from the original population by chance. Natural selection, in contrast, changes allele frequencies based on differential reproductive success tied to traits that affect fitness. The twin method isn’t an evolutionary mechanism that changes allele frequencies; it’s a research approach used to study heredity.

Genetic drift is the random change in allele frequencies from one generation to the next that is not caused by natural selection. It happens because the alleles passed to offspring are just a random sample of the parent gene pool, and this sampling error is especially strong in small populations. Over time, drift can cause certain alleles to become more common or disappear by chance alone, and it tends to reduce genetic variation within a population. Founding events and population bottlenecks are specific situations where drift has a strong effect because the new or surviving group is small and its allele frequencies can differ from the original population by chance. Natural selection, in contrast, changes allele frequencies based on differential reproductive success tied to traits that affect fitness. The twin method isn’t an evolutionary mechanism that changes allele frequencies; it’s a research approach used to study heredity.