Landscape genomics reveals adaptive divergence of indigenous sheep in different ecological environments of Xinjiang, China

Abstract

Sheep are important livestock animals that have evolved under various ecological pressures. Xinjiang is a region with diverse and harsh environments that have shaped many local sheep breeds with unique characteristics and environmental adaptability. However, these breeds are losing ecological flexibility due to the promotion of intensive farming practices. Here we sequenced 14 local sheep breeds from Xinjiang and analyzed their genetic structure and gene flow with other sheep breeds from neighboring regions. The Tibetan Plateau was the geographic origin of Xinjiang native sheep evolution. We performed genome-environment association analysis and identified Bio9: Mean Temperature of Driest Quarter and Bio15: Precipitation Seasonality as the key environmental factors affecting Xinjiang local sheep and the key genes involved in their survival and adaptation. We classified Xinjiang native sheep breeds into six groups based on their differential genes by pairwise selective sweep analysis and Community Network Analysis. We analyzed transcriptome expression data of 832 sheep tissues and detected tissue-specific enrichment of six group-specific genes in different biological systems. Our results revealed the genetic basis of year-round estrus, drought tolerance, hypoxia resistance, and cold tolerance traits of Xinjiang sheep breeds. Moreover, we proposed conservation strategies for Xinjiang local sheep breeds and provided theoretical guidance for breeding new sheep breeds under global extreme environments.