Drift, genetic

Genetic drift is alteration of allele frequencies in small populations by chance events. During times when large populations are reduced to small numbers of individuals, genetic variation is likely to be lost by chance. Genetic drift also occurs when a small number of individuals colonize a new region. The pioneers are unlikely to have all the alleles found in the source population and the frequencies of the ones they do have are likely to differ from those in the source population. 

Reuter, G., Pankovics, P., and Szucs, G. (2008). Genetic drift of norovirus genotype GII-4 in seven consecutive epidemic seasons in Hungary. /. Clin. Virol. 42,135-140. 

Darwin was a pluralist. He was very careful to state that natural selection is not the only motor of evolutionary change. He invented the concept of sexual selection, the only addition to natural selection which evolutionary psychology theorists are prepared to include in their pantheon. We need not be Lamarckian to accept that other processes are at work. The existence of neutral mutations, founder effects, genetic drift, exaptations and adoptations (Dover, 2000) all enrich the picture. 

Some of the mathematical basis for the equations is due to the geneticist Moto Kimura, who is considered a resolute proponent of the neutral theory of evolution , which states that statistical, chance fluctuations are more important in the formation of new species than is Darwinian natural selection. Evolution via such chance fluctuations is referred to as genetic drift . Dyson considers that both forms of evolution are important (Dyson, 1999). 

Dyson s model has been the subject of careful criticism as well as well-meaning agreement. Shneior Lifson (1997) found fault in particular with Dyson s assumption that metabolism (and other properties) could have developed without natural selection. In his third assumption, Dyson postulates that There is no Darwinian selection. Evolution of a molecule population occurs via genetic drift (Dyson, 1999). Lifson (1997) points out that, while Dyson stresses the role of primitive metabolism, its adaptability, error tolerance etc., he himself considers that such properties can only evolve via natural selection. 

Genetic variants that do not affect protein structure, function, or synthesis could have attained polymorphic frequency by chance propagation (genetic drift) aided by a genetic bottleneck in which the population size was reduced. 

Procedure for the Chinese Hamster V79/Hgprt Assay. The assay usually comprises three test concentrations, each in duplicate, and four vehicle control replicates. Suitable positive controls are ethylmethane sulphonate (—S9) and dimethyl benzanthracene (+S9). V79 cells with a low nominal passage number should be used from frozen stocks to help minimize genetic drift. The procedure described includes a reseeding step for mutation expression. 

Genetic drift can change allele frequencies in small populations by chance... 

The African American population is large and consequently would not be expected to have experienced elevated levels of genetic drift (choice B). 

Genetic drift can be rapid due to changes in gene frequency caused by selection, random drift and mutation... 

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