Evolutionary History of the Adult β-Globin Gene in Wild Sheep: First Sequences From the Argali (Ovis ammon) and the Urial (Ovis vignei).

The β-globin gene cluster is a key model for studying molecular adaptation and gene family evolution in vertebrates, exhibiting dynamic duplication and deletion events in ruminants, particularly within the subfamily Caprinae. However, the complete nucleotide sequences of the adult β-globin gene remain unknown for several ecologically important wild sheep species, such as the Argali and the Urial, hindering robust phylogenetic and adaptive studies. Genomic DNA was extracted from wild Argali and Urial samples, and the full coding region of the adult β-globin gene was sequenced and compared against a comprehensive dataset of Bovidae and Cervidae. Sequence comparison confirmed high divergence between paralogous genes (HBBA and HBBB), and critically, revealed that Argali hosts two distinct adult β-globin haplotypes, one harboring a HBBA gene and the other a HBBB gene. Phylogenetic analysis revealed that sequences clustered consistently by paralog type (HBBA vs. HBBB) with both the Caprinae and Bovinae lineages. This pattern suggests independent evolutionary trajectories for each paralog, likely driven by concerted evolution. Molecular dating estimated the duplication event leading to the HBBA/HBBB paralogs in Caprinae at approximately 2.55 million years ago, supporting a rapid, recent diversification of the β-globin cluster in Ovis during the Pleistocene. Our analysis provides the newly characterized sequences of the Argali and Urial adult β-globin gene and detected ancestral polymorphism in Argali. The divergence time estimates and the clustering by paralog type provide a valuable temporal and evolutionary framework for understanding the complex dynamics of multigene families and offer a foundation for future studies investigating potential high-altitude adaptive selection in wild Ovis species.