Study of animal domestication processes using mitochondrial genome polymorphism (review)

Abstract

In the article it is presented the results of studies of domestication processes of the main species of agricultural animals, which were carried out with the involvement of mitochondrial genome polymorphism. Mitochondrial genome polymorphism was used in the research of domestication processes for the reason that the inclusion of mitochondrial genes in domestic animal populations occurred only as a result of domestication of females. Most often, mitochondrial DNA sequences are used to determine possible wild ancestors, the number of maternal lines and their geographic origin. Domestication can be may be considered as the final phase of intensification of relations between subpopulations of animals or plants and human societies. It consists of several degrees of intensification, which in different ways and during different periods can end with the appearance of domestic animals, plants and microorganisms formed by people. While domestication of wild animals is a form of domestication that does not entail any visible morphological changes, at least from an archeological point of view (Vigne, 2011). The emergence of agriculture in Neolithic times included the domestication of ungulates animals and was a critical moment in human development. The goat (Capra hircus) was one of the first domesticated species of ungulates animals. The main centers of domestication are believed to be the eastern half of the Iranian plateau and eastern Anatolia (Naderi et al., 2008). Sheep (Ovis aries) were domesticated in the so-called Fertile Crescent region about 9,000–8,000 years ago. Mitochondrial DNA polymorphism studies from 323 modern and 221 fossil pig bones collected throughout western Eurasia showed that domestic pigs of Near Eastern origin introduced to Europe during the Neolithic (potentially via two separate routes) reached the Paris Basin at least as early as the 4th th millennium BC. The native European wild pig had also been domesticated by that time, possibly as a direct result of the introduction of domestic pigs from the Middle East (Larson, et al. 2007). After the species of wild ancestors of domestic animals were determined, the question became of identifying molecular genetic signs of domestication. Traditionally, such research involves comparing DNA samples of wild and domestic animal populations of the same species and searching for genomic regions that demonstrate significant genetic differentiation between them. The genetic differentiation is generally based on differences in allele frequencies between populations, calculated using FST or similar statistical methods. For example, a comparison of the genomes of the Asian mouflon (Ovis orientalis), the bezoar goat (Capra hircus aegagrus), as well as domestic local breeds of sheep and goats within the geographic centers of domestication and cross-border commercial breeds, identified the regions of the genome that were subjected to the strongest selection pressure. By sequencing a library of DNA fragments 300-600 bp in size. sheep and goats, about 33 million Ovis and 23 million Capra SNPs were identified. Using haplotype differentiation as a signature (evidence) of selection, 46 and 44 regions of the domestic sheep and domestic goat genome, respectively, were found to be under selection pressure (Alberto, et al. 2018). Thus, understanding the processes of animal domestication contributes to more thoughtful breeding work to improve animal productivity, achieve desired genetic changes through targeted mutations and genomic selection. The study of the process of domestication allows us to look at the relationship between humanity and the animal world in a new way and to define new ethical standards. The review will help you form your own opinion about the process of domestication, definition of concepts and further prospects for research in this direction. Key words: domestication, DNA, mitochondrial genome, haplotype, pigs, horses, sheep, goats, cattle, neolithic.