Which phenomenon explains why certain alleles are more frequent in specific geographic areas?

The founder effect is a phenomenon that occurs when a small group of individuals becomes isolated from a larger population and establishes a new population. This new group may possess a limited genetic diversity compared to the original population. As a result, certain alleles may become more frequent in this newly founded population due to the limited genetic variation inherited from the initial individuals.

This happens because the reproductive success of the founders influences which alleles are passed on to future generations. If the founding population has a higher frequency of certain alleles, these alleles can become prevalent in subsequent generations, particularly if the population remains isolated. Thus, the geographic distribution of certain alleles can be attributed to the founder effect, especially in cases where populations are established by a small number of individuals in a new environment.

In contrast, the bottleneck effect refers to a drastic reduction in population size due to environmental events, which also affects allele frequencies but in a different context. Genetic drift refers to random changes in allele frequencies within a population, which can occur in any size population but does not necessarily explain geographic variations specifically. Natural selection involves differential survival and reproduction of individuals based on advantageous traits, contributing to allele frequency changes as well, but its focus is more on adaptive traits rather than geographic distribution alone