How does genetic drift typically affect small populations?

Genetic drift is a mechanism of evolution that refers to random changes in allele frequencies within a population, particularly impacting small populations. In these smaller groups, chance events can have a more pronounced effect on which alleles are passed on to the next generation. When the population size is limited, certain alleles can become more or less common simply due to random sampling, rather than environmental pressures or natural selection influencing which individuals reproduce.

This randomness means that specific alleles can be lost entirely from the gene pool, leading to decreased genetic diversity over time. Since small populations are more susceptible to these fluctuations, it is more likely that significant shifts in allele frequencies occur without any adaptive advantage playing a role. This differentiates the effect of genetic drift in small populations from larger ones, where the sheer size helps buffer against random changes, allowing for a more stable genetic structure influenced more by natural selection.

The other options do not accurately describe the impact of genetic drift in small populations. While genetic drift does not typically enhance genetic variation, it often leads to a loss of genetic diversity, and it does not stabilize allele frequencies over time or prevent the loss of rare alleles. Instead, it is more likely to result in the ultimate fixation or loss of alleles purely by chance.