THE COMPLETE MITOCHONDRIAL-DNA SEQUENCE OF THE DOMESTIC SHEEP (OVIS-ARIES) AND COMPARISON WITH THE OTHER MAJOR OVINE HAPLOTYPE

The complete mitochondrial DNA (mtDNA) molecule of the domestic sheep, Ovis aries, was sequenced, together with part of the mtDNA of a speci men representing the other major O. aries haplotype group. The length of the complete ovine mtDNA presented is 16,616 nucleotides (nt). This length is not absolute, however, due to heteroplasmy caused by the oc currence of different numbers of a 75-nt-long tandem repeat in the con trol region. The sequence data were included in analyses of intraspeci fic ovine molecular differences, molecular comparisons with bovine mtD NAs, and phylogenetic analyses based on complete mtDNAs. The compariso ns with bovine mtDNAs were based on the central domains of the ovine c ontrol regions, representing both major ovine haplotype groups, and th e corresponding domains of Bos taurus and B. indicus. The comparisons showed that the difference between the bovids was 1.4 times greater th an the intraspecific ovine difference, These findings suggest that the strains of wild sheep from which domestic sheep originated were more closely related than were the B, primigenius subspecies which gave ris e to B. indicus and B. taunts cattle. Datings based on complete mtDNAs suggest that the bovine and ovine lineages diverged about 30 million years before present. This dating is considerably earlier than that pr oposed previously.