Population structure of Kyrgyz Mountain Merino sheep: Analysis of nuclear locus variability

The relevance of the study is determined by the need to preserve local, unique and highly adapted breeds of farm animals in the context of global climate change and a reduction in the number of breeding stock. The Kyrgyz Mountain Merino is a valuable genetic resource, highly adaptable to mountain conditions, with high-quality wool and efficient use of scarce feed. However, a limited gene pool and increasing inbreeding pose risks to the breed’s productivity and adaptability. The aim of the study was to analyse the population structure of the Kyrgyz Mountain Merino based on an assessment of nuclear locus variability. To achieve this goal, sheep were genotyped using a panel of highly polymorphic microsatellite markers (SSR) recommended by the International Society for Animal Genetics (ISAG). Allele diversity indices, observed and expected heterozygosity, F_IS fixation coefficients, Nei genetic distances were calculated, and population structure analysis was performed using cluster analysis, PCA and STRUCTURE model methods. The results of the study showed a high level of allelic diversity at most loci (number of alleles per locus 6-14, effective number of alleles Ne 3.41-6.21, PIC > 0.69). The observed heterozygosity (Ho = 0.68-0.73) practically corresponded to the expected (He = 0.70-0.74), and the F_IS coefficients remained low (0.012-0.028), indicating the absence of pronounced inbreeding. Genetic differentiation between groups was weak (F_ST = 0.018-0.032), Nei’s genetic distances were minimal (0.038-0.051), and STRUCTURE analysis revealed two conditional genetic clusters with uniform distribution across groups, confirming the integrity of the population. The practical value of the study lies in identifying the current state of the Kyrgyz Mountain Merino gene pool, which allows for the development of recommendations for controlled selection work, the preservation of unique alleles, and the maintenance of genetic diversity of the breed, ensuring its resistance to adverse environmental conditions