IndexIntroductionEffects of genetic driftChange in allele frequencyLoss of genetic variationLoss of allelic diversityFounder EffectsFounder Effect (i) genetic bottleneckCase study: Greater Prairie ChickensFounder Effect (ii)Fitness Effect of Drift geneticsEffective population sizeGenetic drift and natural selectionCorrelation between fitness and genetic diversityConclusionReferencesGenetic drift in natural populationsIntroductionIf you flip a coin 500 times, a roll of 300 heads and 200 tails might make you suspicious of that coin. But you wouldn't be surprised if you flipped a coin 10 times and the result was 8 heads and 2 tails. The fewer coin flips, the greater the probability that chance alone will cause a deviation from the expected outcome (Campbell & Reece 2008). In this case, the prediction is an equal number of heads and tails. Allele frequencies fluctuate unpredictably due to random events, from one generation to the next, especially in small populations. Genetic drift is an overall change in allele distribution, especially in a small population, due to random variation in an individual's allele frequencies. Genetic drift (also known as random drift) occurs mostly in small populations due to a severe reduction in population size called bottlenecks and founder events where a new population starts from a small number of individuals. Genetic drift is an example of a stochastic process in which the actual outcome cannot be predicted because it is influenced by chance (Allendorf & Luikart 2007). Population genetic theory predicts that when populations are finite and random genetic drift occurs, it increases the population... middle of paper... gene heterozygosity in natural populations. II. Amount of variation and degree of heterozygosity in natural populations of Drosophila pseudoobscura. Genetics 54:595-609. Luikart, G., J. M. Cornuet. 1998. Empirical evaluation of a test for identifying recently bottlenecked populations from allele frequency data. Conservation Biology 12:228-237.Méndez, M., J. L. Tella, and J. A. Godoy. 2011. Restricted gene flow and genetic drift in the recently fragmented population of an endangered steppe bird. Journal of Biological Conservation 144:2615-2622.Reed, D.H. and R. Frankham. 2003. Correlation between fitness and genetic diversity. Journal of Conservation Biology 17:230-237. Robert CL, 1987. Loss of genetic diversity from managed populations: interacting effects of drift, mutation, immigration, selection, and population subdivision. Conservation biology 2:143-158.