Genetic Diversity
 
Genetic diversity is the biological diversity that is present in the genetic material or information. Genetic diversity may be represented at the DNA level, at the level, at the chromosomal level, at the level, and at other higher levels, such as gene interaction.
 Heterozygosity is the general measure of the genetic variation per locus in a given population. Suppose that a population contains n alleles at a locus, designated 1, 2, 3,¼n and with respective frequencies p₁, p₂, p₃ ,¼, pn. Designating the frequency of the i-th allele by pi, the heterozygosity is then defined as H= 1-Ʃ P²i  . When we are interested in many loci, the average heterozygosity (H( can be computed as an unweighted average of heterozygosities over various loci. Thus, the average heterozygosity is a simple and good measure for the genetic diversity of a population (1).
 For DNA sequences, the average number of nucleotide substitutions between all possible pairs of alleles sampled in the population can be measured to evaluate the genetic diversity at the DNA level. This quantity is called the “nucleotide diversity” (1). These quantities are useful for measuring the genetic diversity within a population.
References
“Genetic Diversity” in , Vol. 2, p. 1000, by T. Gojobori; “Genetic Diversity” in  (online), posting date: January 15, 2002, by T. Gojobori, National Institute of Genetics, Shizuoka, Japan. 1. M. Nei (1987). "Molecular Evolutionary Genetics". Columbia University Press, New York.