Genetic variation occurs because beneficial traits exist in a collection of genes, and gene flow makes these traits more prevalent in populations.
Further explanation
Genetic diversity is a level of biodiversity that refers to the total amount of genetic variation in the whole species that inhabits some or all of the earth's surface that can be inhabited.
Genetic diversity uses several simple measurements:
Gene diversity is the proportion of polymorphic loci throughout the genome.
Heterozygosity is the average number of individuals with polymorphic loci.
Alleles per locus, also used to demonstrate variability.
