Final answer:
Genetic drift is the phenomenon where gene frequencies in small populations can change randomly from generation to generation, leading to the fixation of certain alleles. This effect is more significant in small populations and is distinct from changes in allele frequencies due to natural selection.
Step-by-step explanation:
When populations are small, gene frequencies can change from generation to generation and some alleles may become fixed in a population. This phenomenon is called genetic drift. Genetic drift can cause significant changes in the genome of a population particularly through random events that influence which alleles are passed to the next generation. In small populations, the impact of genetic drift is more pronounced, potentially leading to the fixation of alleles that may not confer any selective advantage or disadvantage.
Natural selection, on the other hand, tends to increase the frequency of alleles that contribute to an organism's fitness in a given environment. As beneficial alleles become more common, they can become fixed, meaning every individual in the population will carry that allele, whereas detrimental alleles can be eliminated from the gene pool.
Study of population genetics involves tracking how selective forces and genetic drift affect allele frequencies over time, thus contributing to the evolutionary process.