Population Genetics. Matthew B. Hamilton

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Название Population Genetics
Автор произведения Matthew B. Hamilton
Жанр Биология
Серия
Издательство Биология
Год выпуска 0
isbn 9781118436899



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through searches in genetic genealogy databases. This approach initially utilized public databases to search for relatives and led to numerous cold cases being solved. At the same time, law enforcement and other uses of genealogical databases have generated concern over the privacy of genetic information.

      (2.24)equation

      (2.25)equation

      (2.26)equation

      With the understanding that we are considering only a single generation of mating and that the population initially had Hardy–Weinberg expected genotype frequencies, we see that the fixation index measures an excess of homozygosity exactly equal to the autozygosity. Sustained non‐random mating over multiple generations will continue to increase the homozygosity, and therefore, F will reflect the cumulative deficit of heterozygosity from all past mating among relatives. In contrast, f is defined on a per generation basis and reflects only the probability of identity by descent at mating in the most recent generation. This distinction can be observed in Figure 2.13 where F increases over time toward an equilibrium as a function of the coancestry coefficient due to each mating system.

      Returning to Figure 2.13 reinforces the relationship of the coancestry coefficient, the fixation index, and the decline in heterozygosity in several specific cases of regular consanguineous mating. Remember that in all cases in Figure 2.13, the Hardy–Weinberg expected heterozygosity is 0.5 when mating is random and f = 0.

       Phenotypic consequences of mating among relatives

      The process of consanguineous mating is associated with changes in the mean phenotype within a population. These changes arise from two general causes: changes in genotype frequencies in a population per se and fitness effects associated with changes in genotype frequencies.

Genotype Phenotype Frequency Contribution to population mean
AA +a p2 + Fpq ap2 + aFpq
Aa D