Identification of an ancestral haplotype in the mitochondrial phylogeny of the ovine haplogroup B

Background. European mouflon (Ovis orientalis musimon) has been reintroduced in mainland Europe since the 18th-century sourcing from the Sardinian and Corsican autochthonous mouflon populations. The European mouflon is currently considered the feral descendent of the Asian mouflon (O. orientalis), and the result of first wave of sheep domestication occurred 11,000 years ago in the Fertile Crescent, and brought to Corsica and Sardinia ca. 6,000 years ago, where they still live as autochthonous populations. However, this phylogeny is based on mitogenome sequences of European mouflon individuals exclusively. Methods. We sequenced the first complete mtDNA of the long-time isolated Sardinian mouflon and compared it with several ovine homologous sequences, including mouflon from mainland Europe and samples representative of the five known mitochondrial domestic sheep haplogroups. We applied Bayesian inference, Maximum Likelihood and Integer Neighbour-Joining network methods and provided a robust, fully-resolved phylogeny with strong statistical support for all nodes. Results. We identified an early split (110,000 years ago) of the Sardinian mouflon haplotype from both sheep and mainland European mouflon belonging to haplogroup B, the latter two sharing a more recent common ancestor (80,000 years ago). Further, the Sardinian mouflon sequence we generated had the largest genetic distance from domestic sheep haplogroups (0.0136 ± 0.004) among mouflon species. Our results suggest the Sardinian mouflon haplotype as the most ancestral in the HPG-B lineage, hence partially redrawing the known phylogeny of the genus Ovis.