Assessing the Genomics Structure of Dorper and White Dorper Variants, and Dorper Populations in South Africa and Hungary

Abstract

Dorper sheep was developed for meat production in arid and semi-arid regions under extensive production systems in South Africa. Two variants with distinct head and neck colors were bred during their development process. White Dorper have a white coat while Dorper have a black head and neck. Both variants have grown in popularity around the world. Therefore, understanding the genomic architecture between South African Dorpers and Dorper populations adapted to other climatic regions, as well as genomic differences between Dorper and White Dorper variants is vital for their molecular management. Using the ovine 50K SNP chip, this study compared the genetic architecture of Dorper variants between populations from South Africa and Hungary. The Dorper populations in both countries had high genetic diversity levels, although Dorper in Hungary showed high levels of inbreeding. White Dorpers from both countries were genetically closely related, while Dorpers were distantly related according to principal component analysis and neighbor-joining tree. Additionally, whereas all groups displayed unique selection signatures for local adaptation, Dorpers from Hungary had a similar linkage disequilibrium decay. Environmental differences and color may have influenced the genetic differentiation between the Dorpers. For their molecular management and prospective genomic selection, it is crucial to understand the Dorper sheep's genomic architecture, and the results of this study can be interpreted as a step in this direction.

Keywords: adaptation; dorper; genetic diversity; linkage disequilibrium; management best practices; population structure.

Figure 1

Population clustering by PCA and neighbor-joining tree. (A) Principal component for global sheep populations. (B) Principal component plot for the Dorpers and Racka breeds. (C) Neighbor-joining tree for Dorpers and Racka sheep breeds.

Figure 2

Genome-wide distribution of iHS values for (A)—HUDOR, (B)—HUWDOR, (C)—SADOR, (D)—SAWDOR, and (E)—HORAC sheep breeds. x-axis of Manhattan plots represents Autosome chromosome numbers, The red line represents the top 0.001 percentile distribution of iHS values, while the blue line represents the top 0.01 percentile, SNPs are annotated at p value of 0.00001. (F) Genome-wide linkage disequilibrium decay against marker distance in each population.