Genetic drift is the random fluctuations in the frequency of the appearance of a gene in a small isolated population, presumably owing to chance rather than natural selection.
Genetic drift can result in genetic traits being lost from a population or becoming widespread in a population without respect to the survival or reproductive value of the gene pairs (alleles) involved. It is a random statistical effect. Genetic drift can occur only in small, isolated populations in which the gene pool is small enough that chance events can change its makeup substantially. In larger populations, any specific allele is carried by so many individuals that it is almost certain to be transmitted by some of them unless it is biologically unfavourable
Genetic drift has important implications for evolution and the process of speciation. When a small group of individuals becomes isolated from the majority of individuals of a species, the small group will genetically drift from the rest of the species. Because genetic drift is random and the smaller group will drift more rapidly than the larger group, it is possible that, given enough time, the small group will become different enough from the large group to become a different species.
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