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In population genetics, F-statistics (also known as fixation indices) describe the statistically expected level of heterozygosity in a population; more specifically the expected degree of (usually) a reduction in heterozygosity when compared to Hardy–Weinberg expectation.
Using allele frequencies, it allows for the calculation of heterozygosity, or genetic diversity, in a finite population and for the estimation of genetic distances between populations of interest. The assumptions of the ISM are that (1) there are an infinite number of sites where mutations can occur, (2) every new mutation occurs at a novel ...
Tajima's D is a population genetic test statistic created by and named after the Japanese researcher Fumio Tajima. [1] Tajima's D is computed as the difference between two measures of genetic diversity: the mean number of pairwise differences and the number of segregating sites, each scaled so that they are expected to be the same in a neutrally evolving population of constant size.
Heterozygosity values of 51 worldwide human populations. [10] Sub-Saharan Africans have the highest values in the world. In population genetics, the concept of heterozygosity is commonly extended to refer to the population as a whole, i.e., the fraction of individuals in a population that are heterozygous for a particular locus. It can also ...
The proportion of segregating sites within a gene is an important statistic in population genetics since it can be used to estimate mutation rate assuming no selection. For example it is used to calculate the Tajima's D neutral evolution statistic. A sequence alignment, produced by ClustalO, of mammalian histone proteins.
One of the most important measures of genomic health is the ratio of expected heterozygosity to measured heterozygosity. Generally, an individual or species with more heterozygous alleles have a higher chance of survival. This is known as heterosis. [4] Low levels of heterozygosity is a sign of possible concern for a species or organism.
It is usually associated with other statistical measures of population diversity, and is similar to expected heterozygosity. This statistic may be used to monitor diversity within or between ecological populations, to examine the genetic variation in crops and related species, [3] or to determine evolutionary relationships. [4]
A population bottleneck can result in a loss of heterozygosity. In this hypothetical population, an allele has become fixed after the population repeatedly dropped from 10 to 3. One of the results of population structure is a reduction in heterozygosity.