Novel insights into sheep domestication in Southwest Asia based on genome-wide sequencing

Abstract

The origin of domestic sheep (Ovis aries) can be traced back to the Asian mouflon (Ovis gmelini), in the Near East around 10 000 years ago. Genetic divergence within mouflon populations can occur due to factors such as geographical isolation, social structures, and environmental pressures, leading to different affinities with domestic sheep. However, few studies have reported the extent to which mouflon sheep contribute to domestic sheep in different regions. Here, we implemented the demographic analyses of sheep populations across the globe based on the whole genome resequencing data of 410 samples, Y chromosome genetic variation of 417 rams, and 396 complete mitogenomes of O. aries. This revealed genetic differentiation within Iranian mouflons and a close genetic affinity between northern Iranian mouflons and worldwide domestic populations. The result illustrates that domestic sheep in our study may have derived from the same mouflon populations. Furthermore, analyses of paternal and maternal genetic diversity showed that five Y chromosome haplogroups and seven mitochondrial haplogroups were identified, of which the lineages mtF and mtG were newly found and defined. A phylogeographic interpretation of our data reveals a cline of north to south Iranian mouflons, which may be largely explained by increasing urial introgression.