Evaluation of genetic diversity and selection signals in gayal populations across four countries through whole-genome resequencing.

Gayal (Bos frontalis) an endangered bovine species inhabitingChina, India, Bangladesh, Myanmar and Bhutan, has a mysterious evolutionary origin. Shaped by natural selection, its unique traits make it a valuable genetic resource; however, its populations are rapidly declining. In this study, comprehensive whole-genome resequencing of fifty-eight samples of Gayal from China, India, Myanmar and Bangladesh was performed. We identified over 44 million SNPs across four Gayal populations. Nucleotide diversity analysis revealed variations in genetic diversity, with the lowest occurring in India and the highest occurring in China. Phylogenetic tree analysis revealed three distinct clades representing China, India and Bangladesh-Myanmar, which were further confirmed by principal component and admixture analyses. The genetic exchanges between Gayal and other bovine species indicate limited influence from domestic cattle in both the Chinese and Bangladeshi Gayal populations. Mitochondrial DNA sequences and a phylogenetic tree highlighted the unique mitochondrial genome of Gayal. Genome-wide selection signals pinpointed candidate genes linked to mitochondrial function, immunity, musculoskeletal development, reproduction and growth performance. Distinct haplotype patterns emerged for the CCDC157, KIAA0753 and MTFP1 genes in the Chinese and Bangladesh-Myanmar Gayal populations, indicating artificial selection in the Chinese population. KEGG pathway and gene ontology enrichment analyses provided insights into processes related to neurodevelopment, cardiac function, tissue growth, immunity and metabolism. In summary, our study enhances our understanding of Gayal genetics, population structure and selection signals across four countries. This knowledge is crucial for conserving this endangered species amid its rapid decline.