Recent selection and introgression facilitated high-altitude adaptation in cattle.

Area of Science:

• Genomics
• Evolutionary Biology
• Animal Science

Background:

• Cattle on the Qinghai-Xizang Plateau exhibit unique adaptations to high-altitude conditions (hypoxia, UV radiation, extreme cold).
• The genetic basis for these rapid adaptations in Tibetan cattle remains largely unknown.

Purpose of the Study:

• To investigate the whole-genome resequencing data of Tibetan cattle to understand their genetic adaptation mechanisms.
• To identify specific genes and introgressed segments contributing to high-altitude survival.

Main Methods:

• Whole-genome resequencing of 258 cattle, including 89 Tibetan cattle from diverse high-altitude populations.
• Phylogeographic analysis to determine ancestry.
• Identification of recent selection signals and introgression from yaks.

Main Results:

• Tibetan cattle show a phylogeographic cline from East Asian taurine to South Asian indicine ancestries.
• Recently selected genes (e.g., HMGA2, NCAPG, DUOXA2) are linked to body size and energy expenditure.
• Significant yak introgression (0.64%-3.26% genome) provided genes for hypoxia response (EGLN1), cold adaptation (LRP11), DNA repair (LATS1), and UV resistance (GNPAT).
• Yak introgressed variants in EGLN1 promoter reduced gene expression, enhancing hypoxia tolerance.

Conclusions:

• Tibetan cattle adaptation is a complex process involving both recent selection and introgression from yaks.
• These combined genetic factors facilitated rapid adaptation to the extreme high-altitude environment.