Genome-wide assessment of genetic diversity, population structure and selection signatures in Polish mountain sheep breeds using SNP microarrays*

The study aimed to characterize the genetic structure with the use of SNP microarrays of three mountain sheep breeds: the Podhale Zackel (PZ), the Polish Mountain Sheep (PMS) and the Polish Colored Mountain Sheep (CMS), including the assessment of the size, nature and biological significance of genetic differences between them and to assess the usefulness of the obtained data in the implementation of conservation programs for populations at risk. The analyses were based on the data from OvineSNP50 BeadChip microarray (Illumina). The level of heterozygosity was similar for all analyzed breeds, and the value of the inbreeding coefficient of the studied populations was low. Comparing the genetic distances based on FST between the studied breeds, the highest values were noted between the PMS and CMS, and the lowest between the PZ and the PMS. Detailed studies of the genetic differentiation across the genome revealed the presence of differential selection signals. In addition, a common genome region located on chromosome 4 under selective pressure was detected, in which two genes were found ( ISPD – a gene associated with the development of the nervous system, and SOSTDC1 – a gene associated with the morphogenesis of hair follicles). The possibility of obtaining comprehensive information on the genetic diversity of the studied populations indicates the usefulness of SNP microarrays in determining the genetic variability of native sheep breeds.