Genetic basis of breed variation: Genome wide selection signature of neighboring sheep breeds

Within species diversity is essential for the population extant and sustainable livestock production under different feed regimes and climate changes scenarios. Here we report geographical distribution, reproductive performance, body morphometry and genome wide variations among two sheep populations evolved in adjacent terrains. Mazai sheep are kept in large flocks with restricted breeding, whereas Waziri sheep are bred continuously with 13.4% ewes lambing twice a year. Waziri sheep lamb at an earlier age (16.6 ± 0.2 months) than Mazai (17.4 ± 0.3 months). The body size of Mazai sheep is larger and heavier compared to Waziri sheep. The whole genome sequencing revealed a total of 20058 protein coding genes with 5.765 and 5.758 million variants in Mazai and Waziri sheep, respectively, compared to the reference genome. A significant number of unique variants were found in both of the genomes with 7135 genes showing differential non-synonymous variants among the two sheep breeds. These genes were involved in different biological processes, molecular functions, cellular components synthesis, and disease progression. Selective sweep analysis revealed three genes in Mazai (SGO1, GYS2, and VPS13B) and three genes in Waziri sheep (WDPCP, FAM227B, and OR8U1) under selection pressure. These genes might be associated with the differences in body size, milk production, and reproductive behavior among the two sheep breeds. Phylogenetic analysis revealed greater genetic divergence of Mazai sheep from Waziri and other regional sheep breeds. These results are important for genetic architecture of breed development, adaptation, conservation, and selection strategies.