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13. SUPPLEMENTARY MATERIALS
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F statistics
The method enables to divide the genomic variation into the interpopulational and intrapopulational
variation.
The coefficient of gene differentiation, G ST
(Eq. 13.15.13)
G ST
– the average gene diversity between subpopulations
– the gene diversity in the total population
H T
When there are two alleles at a locus, as in dominant DNA markers, this G ST
is equal to
Wright’s F ST
and it is relatively insensitive to assumptions about Hardy– Weinberg equilibrium,
heterozygosity and levels of inbreeding.
The fixation indices, F IT
, F IS
They are useful for understanding the breeding structure. They can be computed for the
group of populations and for individual alleles and then averaged for a population
(Eq. 13.15.14)
F IT
H T
– the deficiency or excess of average heterozygotes in a group of populations
– the gene diversity in the total population
(Eq. 13.15.15)
F IS
H S
– the deficiency or excess of average heterozygotes in each population
– the average gene diversity
Nei’s genetic identity and distance
Genetic distance is the extent of gene differences between populations or species. It
can be measured as the number of nucleotide substitutions per locus. It can be estimated
from polymorphism data. The principle of this method is that any difference in electrophoretic
mobility (including lack of a band) is caused by at least one nucleotide difference at the
DNA level and thus the average number of nucleotide differences per DNA fragment can be
estimated from fragment frequency data. Isoenzymes detect only about 1/4 of amino acid
substitutions in protein. Therefore to estimate the actual number of codon differences, the
genetic distance must be multiplied by 4.