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Genetic diversity is the total number of genetic characteristics in the genetic makeup of a species. It ranges widely, from the number of species to differences within species , and can be correlated to the span of survival for a species. [ 1 ]
Genetic variability is either the presence of, or the generation of, genetic differences. It is defined as "the formation of individuals differing in genotype , or the presence of genotypically different individuals, in contrast to environmentally induced differences which, as a rule, cause only temporary, nonheritable changes of the phenotype ."
Human genetic variation calculated from genetic data representing 346 microsatellite loci taken from 1484 individuals in 78 human populations. The upper graph illustrates that as populations are further from East Africa, they have declining genetic diversity as measured in average number of microsatellite repeats at each of the loci.
Genetic diversity remains lower, increasing only when gene flow from another population occurs or very slowly increasing with time as random mutations occur. [ 1 ] [ self-published source ] This results in a reduction in the robustness of the population and in its ability to adapt to and survive selecting environmental changes, such as climate ...
Genetic variation can be identified at many levels. Identifying genetic variation is possible from observations of phenotypic variation in either quantitative traits (traits that vary continuously and are coded for by many genes, e.g., leg length in dogs) or discrete traits (traits that fall into discrete categories and are coded for by one or a few genes, e.g., white, pink, or red petal color ...
Moreover, gene flow between hybrid and wild populations can result in loss of genetic diversity via genetic pollution, assortative mating and outbreeding. In human populations, genetic differentiation can also result from endogamy, due to differences in caste, ethnicity, customs and religion.
The fact that levels of genetic diversity vary much less than population sizes do is known as the "paradox of variation". [66] While high levels of genetic diversity were one of the original arguments in favor of neutral theory, the paradox of variation has been one of the strongest arguments against neutral theory.
The current distribution of genetic differences and isolation within and among populations is also influenced by genetic processes. The resulting genetic diversity within a species' distribution range is frequently unequally distributed, and significant disparities can occur when population dispersion and isolation are critical for species ...