Which term describes random changes in allele frequencies in small populations?

Which term describes random changes in allele frequencies in small populations?

• A. Genetic drift
• B. Genetic equilibrium
• C. Speciation
• D. Acid rain

Answer: (A)

Random changes in allele frequencies in small populations are driven by genetic drift. In small groups, chance events—sampling the gene pool from one generation to the next—can cause allele frequencies to wander unpredictably. This can lead to one allele becoming fixed or another disappearing purely by chance, and the effect is stronger when population size is tiny. Bottlenecks (sharp reductions in population size) and founder effects (a new population started by a few individuals) are clear examples of drift in action. This process reduces genetic variation within small populations and can cause differences between populations over time, without regard to how beneficial an allele is. Genetic equilibrium describes a situation where allele frequencies stay the same over time, which is the opposite of drift. Speciation is the formation of new species and may involve many processes, including drift, but it’s not the definition of the mechanism itself. Acid rain is an environmental pollutant and not a genetic mechanism altering allele frequencies.

Random changes in allele frequencies in small populations are driven by genetic drift. In small groups, chance events—sampling the gene pool from one generation to the next—can cause allele frequencies to wander unpredictably. This can lead to one allele becoming fixed or another disappearing purely by chance, and the effect is stronger when population size is tiny. Bottlenecks (sharp reductions in population size) and founder effects (a new population started by a few individuals) are clear examples of drift in action. This process reduces genetic variation within small populations and can cause differences between populations over time, without regard to how beneficial an allele is.

Genetic equilibrium describes a situation where allele frequencies stay the same over time, which is the opposite of drift. Speciation is the formation of new species and may involve many processes, including drift, but it’s not the definition of the mechanism itself. Acid rain is an environmental pollutant and not a genetic mechanism altering allele frequencies.