Which concept describes how allele frequencies are influenced by random fluctuations?

The concept that describes how allele frequencies are influenced by random fluctuations is genetic drift. Genetic drift refers to the random changes in allele frequencies that can occur in a population, especially in small populations. These fluctuations in allele frequencies are due to chance events rather than natural selection or environmental pressures.

For example, if a natural disaster randomly eliminates a portion of a population, the alleles that are present in the surviving individuals may differ significantly from those in the original population. Over time, this can lead to a reduction in genetic variation and potentially result in alleles becoming fixed or lost entirely, depending on the random sampling of alleles in successive generations.

This phenomenon is particularly important in small populations because the effects of random sampling are more pronounced; even small changes can significantly alter allele frequencies. In contrast, concepts like natural selection involve non-random processes that favor certain alleles over others based on their advantages in survival and reproduction. Assortative mating affects allele frequencies through mate selection but does not involve randomness in the same way as genetic drift. Gene flow refers to the transfer of alleles from one population to another, which is a more structured process involving migration rather than random fluctuations.