ANALYSIS OF MITOCHONDRIAL-DNA INDICATES THAT DOMESTIC SHEEP ARE DERIVED FROM 2 DIFFERENT ANCESTRAL MATERNAL SOURCES - NO EVIDENCE FOR CONTRIBUTIONS FROM URIAL AND ARGALI SHEEP

To investigate the origins and phylogenetic relationships of domestic sheep, mitochondrial DNA (mtDNA) from 243 sheep of five European, one African, and four Asian breeds and several mouflon (Ovis musimon), uri al (O. vignei bochariensis), and argali (O. ammon nigrimontana, O. a c ollium) were assayed for restriction fragment length polymorphisms (RF LP), Twenty haplotypes were identified which occurred in three major p hylogenetic groups: urial/argali, mouflon/domestic, and domestic sheep . From the branches that contain mouflon and domestic sheep, two major domestic sheep lineages are apparent. One lineage, termed European li neage, contains the majority of haplotypes detected among European dom estic sheep. These mtDNAs resemble mouflon haplotypes, The other linea ge, termed Asian lineage, consists of haplotypes found in central Asia n and some European domestic sheep. The mean sequence difference betwe en these two lineages (0.72%) is of similar magnitude as that between two argali subspecies. To accurately estimate sequence differences bet ween the European and Asian mtDNA types, the mitochondrial control reg ion of one animal from each lineage and of one mouflon and urial were completely sequenced. Sequence comparisons show that Asian and Europea n domestic sheep lineages differ by 4.43%. The mouflon sequence diverg es from the Asian type by 4.52%, but by only 1.36% from the European t ype. Our data supports the hypothesis that some modern domestic sheep and European mouflon derive from a common ancestor and provide evidenc e of an additional wild ancestor, other than the urial and argali grou ps, which has yet to be identified.