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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.
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.
The best-known example of disassortative mating in humans is preference for genes in the major histocompatibility complex (MHC) region on chromosome 6. Individuals feel more attracted to odors of individuals who are genetically different in this region. [7] This promotes MHC heterozygosity in the children, making them less vulnerable to pathogens.
Population structure (also called genetic structure and population stratification) is the presence of a systematic difference in allele frequencies between subpopulations. In a randomly mating (or panmictic) population, allele frequencies are expected to be roughly similar between groups. However, mating tends to be non-random to some degree ...
In population genetics, the Wahlund effect is a reduction of heterozygosity (that is when an organism has two different alleles at a locus) in a population caused by subpopulation structure. Namely, if two or more subpopulations are in a Hardy–Weinberg equilibrium but have different allele frequencies , the overall heterozygosity is reduced ...
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.
For the more general case of dioecious diploids [organisms are either male or female] that reproduce by random mating of individuals, it is necessary to calculate the genotype frequencies from the nine possible matings between each parental genotype (AA, Aa, and aa) in either sex, weighted by the expected genotype contributions of each such ...
Genetic diversity is a measure of the number of different alleles or combinations of alleles present in a population. This may be measured by the amount of heterozygosity measured compared to the expected amount of heterozygosity predicted by Hardy-Weinberg Equilibrium. Evaluating genetic diversity in the genomes of populations can inform us ...