Study of polymorphism and divergence of genomic DNA at the species and population levels (using DNA of domestic sheep and wild rams as an example)

: Genetic divergence in repetitive sequences of nuclear DNA of wild and domestic sheep was studied by general restriction endonuclease mapping (i.e., the taxonoprint method). The PCR RAPD method with one and two arbitrary primers was also used to analyze the nuclear DNA polymorphism in some other regions. The taxonoprint method, performed using six endonucleases, showed specificity and virtually complete similarity in the patterns of repetitive DNA sequences of two wild forms, argali and mouflon, and five domestic sheep breeds. Central Asian breeds, Kazakh fine-fleeced, karakul, ghissar, and eadeelbay, and an English breed, Lincoln, were examined. The results confirm the opinion that wild and domestic sheep may be considered one polytypic species. The PCR-RAPD method, both with one and two arbitrary primers, revealed a closer similarity of all the sheep breeds examined when argali, rather than with mouflon, was used. These results indicate that the domestication area of sheep was much broader than was earlier presumed. Otherwise, hybridizations of domestic and wild forms could occasionally occur in the area of their coexistence. The amplification patterns of PCR-RAPD products are the most promising population genetic markers.