Genetic Drift 2 - Genetic Drift A common conception about...

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Genetic Drift A common conception about evolution is that the features of an organism have evolved due to random (undirected) change. Some processes in biology are random – like mutation. Natural selection is not random. Natural selection is the nonrandom preservation of random variation. Genetic drift is a random process that can be important in the evolution of some populations. One of the requirements for the maintenance of allele frequencies in populations is a very large population size. Genetic drift is the consequence of finite population size. Alleles that do not affect fitness fluctuate randomly in frequency. Random fluctuation eventually results in the loss of alleles (allelic extinction) from populations. One allele becomes fixed – the only allele in the population. Sampling error (random chance) results in some gene copies being lost and others continuing.
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Different populations will lose different alleles. The probability that a particular allele will be fixed in a population in the future equals the frequency of the allele in the population. If there are two alleles in a population, A and a , with frequencies p and q. The probability that the allele a will be lost
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