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Overview Edit

Population bottleneck

Genetic drift model showing initial, 5th, and 10th generation frequency distribution.

Genetic drift is characterized by random changes in the numbers of gene variants in a population. This occurs mainly when variants in the forms of alleles increase and decrease by chance overtime. Genetic Drift variations are measured in terms of changes in allele frequencies. The phenomenon is mainly seen in small populations. This is because the gene pool must be small enough for chance events to change an organisms genetic make up substantially. In a large population such as humans, a specific allele will be carried by a high number of individuals that it will almost certainty be passed to future generations in the population. The only exception can be if a certain allele is biologically unfavorable.

Effects on organisms Edit

In small populations, infrequently occurring alleles face a greater chance of being lost due to genetic drift. Once started, this process will continue until either the involved allele is lost or until it is the only allele present in a population at a certain locus. Regardless, a population experiencing genetic drift will see a decrease in its genetic diversity. Genetic drift is most notable after an event that causes a certain species to bottleneck. An event will occur to decrease the number of members in a population and as a result, rare alleles will be lost and the size of the gene pool becomes smaller. This removal of rare or under expressed genes from a group of organisms is believed to be a driving source in modern day evolution.

Resources Edit

1.The Editors of Encyclopædia Britannica. "Genetic Drift." Encyclopedia Britannica Online. Encyclopedia Britannica, n.d. Web. 01 Sept. 2014. http://www.britannica.com/EBchecked/topic/228886/genetic-drift

2. Pray, Leslie A. "Genetic Drift: Bottleneck Effect and the Case of the Bearded Vulture." Nature.com. Nature Publishing Group, n.d. Web. 02 Sept. 2014. http://www.nature.com/scitable/definition/random-genetic-drift-genetic-drift-201

3."Genetic Drift." Wikipedia. Wikimedia Foundation, 09 Jan. 2014. Web. 02 Sept. 2014. [[1]]