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13. SUPPLEMENTARY MATERIALS
303
Gene diversity (heterozygosity) in a population
Gene diversity (h) was introduced by Nei (1987) as a measure of genetic variation. It is
defined unambiguously in terms of allele frequencies. The sample size effect on gene diversity
is very low, since low frequency alleles hardly contribute to this quantity. Gene diversity
can be used for any organism, whether it is haploid, diploid or polyploid and for any type
of reproductive system. In practice, however, the word heterozygosity is widely used in the
literature, so that both words can be used interchangeable. The average gene diversity (H) is
calculated over all loci and indicates:
• the average proportion of heterozygotes per locus in a randomly mating population,
• the expected proportion of heterozygous loci in a randomly chosen individual,
• the probability that two randomly chosen genes from a population are different.
Gene diversity at a locus (heterozygosity) - h
The unbiased estimate of h recommended for randomly mating populations was calculated.
(Eq. 13.15.5)
p i
m
n
population frequency of i th allele at a locus
the number of alleles
the number of individuals
Gene identity at a locus - J
J=1-h (Eq. 13.15.6)
Average gene diversity at a locus over all populations, h
(Eq. 13.15.7)
h i
n
the gene diversity at i th locus in a population
the number of populations
Average (gene diversity) heterozygosity in a population, H
(Eq. 13.15.8)
h i
r
the gene diversity at i th locus
the number of loci