Archaeogenomics illuminates 4000 years of Northern European Short Tailed Sheep in the Baltic Sea region

Abstract: Sheep were domesticated ~10 000 years ago from Asiatic Mouflon. They then spread to Europe via the migration of farming human populations and had reached Scandinavia by ~6000 years ago. Another migration of humans stemming from the Pontic-Caspian steppe reached Scandinavia around ~5000 years ago, possibly with new types of sheep. Ancient sheep have mostly been studied using mitochondrial DNA. The few examples to date that have applied genome wide sequencing have shown that modern northern European sheep are most closely related to ~9000-year-old Anatolian sheep. Northern European Short Tailed sheep are a group known for their “rustic” phenotype. Their visual appearance together with mitochondrial DNA studies has led to the hypothesis that these sheep are a relict of early migrations. In this study I present five new ancient domestic sheep genomes, from the islands Gotland and Åland in the Baltic Sea, covering the timespan ~4000-500 years ago. Most samples show exceptionally good preservation, with four having over 1x nuclear coverage, ranging up to 11.6x. I use these genomes together with two large panels of Eurasian genome wide SNPs, which includes the three Norther European Short Tailed breeds from these islands, Gotland- Gute-, and Åland sheep. I study how these ancient sheep relate to modern populations. I also evaluate their wool phenotype based on two genetic markers and find that these ancient sheep probably had medium-coarse wool fiber thickness. The results also show that sheep in the Baltic Sea area show a remarkable degree of continuity between 4000 and 500 years ago, and that these ancient sheep are closely related to modern breeds from the area, Åland sheep being the closest extant population.