Genetic diversity

Genetic diversity is an important component of the genetic characteristics of a population, population group or species . Genetic diversity, depending on the choice of the genetic markers in question, is characterized by several measurable indicators, or parameters:

• average heterozygosity
• the number of alleles per locus ,
• genetic distance (for assessing interpopulation genetic diversity).

Average heterozygosity

This parameter of genetic diversity describes how much individuals in the population are heterozygous for the studied markers, with averaging of this parameter over the set of markers used.

The number of alleles per locus

This parameter, as a rule, is used to assess genetic diversity by markers having more than two described allelic states, for example, for microsatellite loci.

Genetic distance

The parameter describes the degree of difference and diversity between populations by the presence / absence or allele frequencies of the markers used.

For the analysis of genetic diversity, the following types of markers and the corresponding analytical methods can be used ^{[4] [5]} :

• Morphological characters ( phenes ; applicable to genetically poorly studied organisms) ^{[6] [7]} .
• Biochemical markers ( protein polymorphism determined by electrophoresis ) ^[8] .
• Immunogenetic .
• Molecular ( DNA markers ).
  • Based on DNA probes :
    • restriction fragment length polymorphism , or RFLP ,
    • minisatellites , or DNA fingerprint ( ; with a repeat length of 15-100 base pairs ),
    • ( EVE genes ).
  • Based on polymerase chain reaction (PCR):
    • polymorphism of the lengths of amplified fragments (at restriction sites ), or PDAF ( ),
    • randomly amplified polymorphic DNA ( ) ^{[9] [10]} ,
    • microsatellites ( SSR , or STR ; with a repeat length of 1-5 base pairs) ^{[11] [12]} ,
    • single nucleotide polymorphism ( SNP ) ^{[4] [5]} .

Genetic variation in a population provides the source material for the action of natural selection and genetic drift , that is, it is an essential element for microevolutionary processes. In particular, works on the inefficiency of selection in pure lines (in the absence of genetic diversity) are known. On the other hand, genetic variation in itself is a product of the action of microevolution factors.

Genetic diversity is of great importance for the ecological plasticity of populations. The presence of several alleles at allozyme loci in a population allows this population to adapt to varying conditions in which the presence of individuals of one or another allele gives an advantage. For example, two variants of the alcohol dehydrogenase gene that are widespread in Drosophila melanogaster in the homozygous state have an alternative beneficial or harmful effect, depending on the environmental temperature conditions.

Assessing genetic diversity is important when monitoring genetic variation in both wild and agricultural species and plant and animal populations; On the basis of the received genetic information, a strategy for their conservation and rational use is being developed.

Within the framework of the Food and Agriculture Organization of the United Nations (FAO) in 1983, an intergovernmental forum was formed - the Commission on Genetic Resources for Food and Agriculture , which monitors the genetic diversity of world resources ^{[2] [3]} . In order to record and monitor breeding resources, the Global Database of Domestic Animal Genetic Resources Data Bank has been created and the World Watch List for Domestic Animal Diversity ^{[13] [14] has been} published . Information on animal and bird breeds is collected for a data bank for all countries through national coordinators and voluntary professional assistants, and the World Pet Diversity Watch List has been updated three times ^{[15] [16]} .

In 1995, a working group of experts created under the auspices of the FAO proposed a plan for the Global Project for the Maintenance (or Measurement) of Domestic Animal Genetic Diversity , for short - MoDAD ) ^[14] . The project envisaged the task of quantifying genetic diversity among breeds of the main 14 species of animals bred by humans, including four bird species. For this purpose, it was proposed to genotype from 6 to 50 rocks of the same species using 30 microsatellite markers. Examples of successful testing and implementation of the recommendations of the MoDAD working group were the results of a scientific project of the European consortium AVIANDIV (to study the genetic diversity of more than 50 chicken populations) and a number of other studies ^{[4] [5] [11] [12] [14]} .

• Biodiversity
• Gene pool
• DNA marker
• Hereditary Volatility
• Polymorphism (biology)

• Altukhov Yu. P. Genetic processes in populations. - M .: IKC "Akademkniga", 2003. - 431 p.
• Johansen V. On inheritance in populations and clean lines. - M .: Selkhozgiz, 1935 .-- 57 p.