Final answer:
The frequency of a particular allele within a population can be changed by selection, genetic drift, and gene flow, with natural selection favoring beneficial alleles and genetic drift causing random fluctuations in allele frequencies.
Step-by-step explanation:
The frequency of a particular allele within a population can be changed over time primarily by selection, genetic drift, and gene flow. Natural selection works by selecting for alleles that confer beneficial traits or behaviors, enhancing the survival and reproduction of individuals with those alleles. Over time, such beneficial alleles may become fixed in a population, meaning every individual will carry the allele. Conversely, detrimental alleles can be swiftly eliminated.
Genetic drift is the process by which chance events cause unpredictable fluctuations in allele frequencies from one generation to the next. This is especially pronounced in small populations, where the loss or gain of alleles can have a significant effect on the overall genetic makeup due to random sampling of alleles.
Gene flow, which is the transfer of alleles between populations, can introduce new genetic diversity and alter allele frequencies when individuals migrate in or out of a population. Together, these mechanisms contribute to the changing genetic landscape of populations, a primary concern of population genetics.