Conservation & local programs

Genome-wide identification of heterozygosity-rich regions in the native Saryarka sheep breed of Kazakhstan

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Abstract

Abstract: Heterozygosity-rich regions (HRRs) are genomic segments with a high proportion of heterozygous SNPs and may harbor loci under balancing selection that contribute to fitness and environmental resilience. From a biological and evolutionary perspective, the persistence of heterozygosity in HRRs may be associated with mechanisms such as overdominance or locally reduced recombination, which can facilitate the maintenance of adaptive variation. This study aimed to identify genome-wide HRRs in the native Saryarka sheep breed of Kazakhstan and to investigate their potential role in adaptation to arid steppe environments. Genomic data from 282 Saryarka lambs, obtained by the Illumina OvineSNP50 BeadChip v3, were used. After filtering the dataset for sample and SNP call rate, minor allele frequency, and deviation from Hardy-Weinberg equilibrium, HRRs were detected using the sliding window approach implemented in the detectRUNS R package. Genes harbored by HRR islands, defined as those present in more than 30% of the population, were functionally annotated using the g:Profiler database. A total of 24,116 HRR segments were detected, with a mean length of 824.8 kb (SD = 308.9 kb) and 14 SNPs per segment on average. The mean number of segments per individual was 86 (SD = 9), ranging from 61 to 120. There was a linear relationship between chromosome length and the number of detected HRR segments. A total of 10 heterozygosity-rich regions (HRR islands) were identified across the Saryarka sheep genome. These HRR islands were distributed over 8 chromosomes (OAR1, OAR2, OAR3, OAR5, OAR8, OAR10, OAR17 and OAR22) with the longest region detected on OAR8 (approximately 24.6 Mb, from 39.6 to 64.2 Mb). Functional enrichment revealed that the genes harbored within the islands are significantly involved in trace-amine receptor activity (GO:0001594, adjusted p = 4.22 à— 10⁻²⁶) and G protein-coupled amine receptor activity (GO:0008227, adjusted p = 5.62 à— 10⁻¹⁸) molecular functions, and Neuroactive ligand-receptor interaction (KEGG:04080, p = 3.14 à— 10⁻⁷) and Pantothenate and CoA biosynthesis (KEGG:00770, p = 0.0015) pathways, suggesting roles in sensory perception, neuroendocrine regulation, and metabolic responses to environmental stress. These results provide a genomic framework for identifying candidate regions involved in environmental adaptation and can be used to support conservation strategies and the sustainable management of locally adapted sheep populations.

Keywords: 2026

How to Cite:

Bakhtybekkyzy, S., Orazymbetova, Z., Mussayeva, A. & Baneh, H., (2026) “Genome-wide identification of heterozygosity-rich regions in the native Saryarka sheep breed of Kazakhstan”, World Congress on Genetics Applied to Livestock Production Digital Archive 2026(1): 2284500. doi: https://doi.org/10.31274/wcgalp.23571

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