How does genetic drift primarily affect populations?

• A. It stabilizes allele frequencies in large populations
• B. It randomly changes allele frequencies
• C. It eliminates alleles completely from populations
• D. It enhances genetic variation in populations

Answer: (B)

Genetic drift primarily affects populations by randomly changing allele frequencies. This phenomenon occurs due to chance events that can disproportionately affect the alleles within a population. In small populations, genetic drift can have a more significant impact because the loss or fixation of an allele (where the allele frequency becomes either 0% or 100%) can happen quickly due to random sampling of alleles through processes like reproduction or environmental disasters.

Unlike natural selection, which is a non-random process that favors certain alleles based on their adaptive value, genetic drift does not work in a directional manner but rather through random fluctuations. For example, if a small number of individuals survive a natural disaster, the alleles present in that surviving group may not represent the original population's allele frequencies, thus shifting the overall genetic makeup of the population. Over time, this can lead to reduced genetic variation and increased divergence between separate populations.

The other options describe processes that are not characteristic of genetic drift. Stabilizing allele frequencies or enhancing genetic variation are processes more closely associated with natural selection or gene flow rather than with random changes due to genetic drift. Elimination of alleles can occur, but it is not a primary function of genetic drift, which more commonly leads to random shifts rather than a systematic