| Popis: |
Background. Pressure on modern agriculture to increase production is rising with the increase in human population. To meet this demand it is important to effectively manage domesticated species. However, genetic mechanisms and genomic targets of domestication are still poorly understood. It is well known that phenotypic variability in domesticated animals is higher compared to the variability in the closest wild relatives. Indeed, there are many breeds clearly distinguishable from each other by their morphological and physiological traits. In this report we review some of available literature and present original data to define genomic targets of domestication. Results. Using both publically available data and results of our own research we demonstrate the existence of a well-defined genomic signature (also called “sub-genome”), which consists of the molecular targets of artificial selection. The genetic signatures of domestication are revealed by comparison of different mammalian species and breeds. As a result, we found that a wide repertoire of genes is involved in the domestication process. The vast majority of these genes either plays a role in the neuroendocrine regulation, immune response, or encodes the milk proteins. Comparison of cattle genome to wild relatives reveals higher degree of polymorphism within retrotransposons, enzymes of the exogenous substrate metabolism, and in the genetic elements associated with the immune system. Conclusions. Our data for first time challenges the current explanation of phenotypic variation in domesticated species as a consequence of inbreeding and concomitant increase in homozygosity. Instead, we clearly show that there is no difference in the bulk genetic variability, and other explanation for difference in phenotypic variability is needed. We discover different targets of natural and artificial selection: in the case of domesticated species systems that are responsible for exogenous substrate metabolism are the targets, while in the case of wild species, genetic systems that are responsible for energy metabolism are targeted. We further speculate that the hyperactivity of mobile genetic elements – as evident from the higher polymorphisms within retro transposons – could be the source of increased genetic variability in domesticated species. |
