Genetic and Epigenetic Adaptation Mechanisms of Sheep Under Multi-Environmental Stress Environment

Sheep (Ovis aries), domesticated from wild Asian mouflon ~10,000 years ago, are an important livestock species adapted to various ecological environments. Recent advancements in high-throughput sequencing and global environmental databases have facilitated the exploration of genetic-environmental associations, uncovering the genetic and epigenetic mechanisms behind sheep's adaptation to multiple environments. Studies show that HIF-1α and EPAS1 enhance high-altitude adaptation via hypoxic stress regulation; UCP1 contributes to cold adaptation through non-shivering thermogenesis; SLC4A4 and GPX3 increase drought resistance by regulating renal water reabsorption; and SOCS2 likely plays a role in metabolic and stress response regulation. Additionally, sheep adapt to temperature, drought, and environmental stress through DNA methylation, transcriptional regulation (e.g., SOD1, GPX4), heat shock proteins (e.g., HSP70), and metabolic pathways (e.g., UCP1). These findings offer valuable insights for improving sheep breeding and genetic enhancement. This review summarizes the mechanisms of adaptation to high altitude, cold, heat, drought, and comprehensive climate stress.