engleski

Identification of selection signatures on X chromosome in East Adriatic sheep metapopulation

The sheep is the most important domestic animal in the region East Adriatic. Since strict selection is not practiced, much of the genetic value depends on adaptation to the environment. Therefore, the main objective of this study was to identify genomic regions showing signals of a positive selection signature. Our analysis was based on 200 individuals (males and females) from eighth indigenous breeds (Istrian Sheep, Dalmatian Pramenka ; Dubrovnik Ruda Sheep, Istrian and Pag Island sheep), all representing East Adriatic or the Balkan sheep cluster (by extension meaning) as a single metapopulation, using the Ovine Infinium® HD SNP BeadChip. Our analysis was limited to the X chromosome only (21, 748 SNPs), as such specific studies are rarely performed. Two different methods were used: identification of extremely frequent SNPs in ROHs (eROHi) and Integrated Haplotype Score (iHS). Using iHS, we detected a weak selection signal in a narrow region at position 25.6 Mb, whereas using eROHi (1 Mb), we identified strong selection signals in a large region extending from position 69.9 to 74.6 Mb, with a large number of potential gene candidates, some of which were previously identified in several Chinese and European breeds. Significant gene regions with positive selection signals, most likely related to environmental adaptation, were identified. We have also shown that genotyped rams can contribute to the identification of positive selection signals on the X chromosome.

X chromosome, East Adriatic sheep, selection signatures, female individuals

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