Genome-wide landscape of runs of homozygosity and differentiation across Egyptian goat breeds

Understanding the genomic features of livestock is essential for successful breeding programs and conservation. This information is scarce for local goat breeds in Egypt. In the current study, genomic regions with selection signatures were identified as well as runs of homozygosity (ROH), genomic inbreeding coefficients (F ROH ) and fixation index (F ST ) were detected in Egyptian Nubian, Damascus, Barki and Boer goat breeds. A total of 46,268 SNP markers and 337 animals were available for the genomic analyses. On average, 145.44, 42.02, 87.90 and 126.95 ROHs were detected per individual in the autosomal genome of the respective breeds. The mean accumulative ROH lengths ranged from 46.5 Mb in Damascus to 360 Mb in Egyptian Nubian. The short ROH segments (< 2 Mb) were most frequent in all breeds, while the longest ROH segments (> 16 Mb) were exclusively found in the Egyptian Nubian. The highest average F ROH was observed in Egyptian Nubian (~ 0.12) followed by Boer (~ 0.11), while the lowest F ROH was found in Damascus (~ 0.05) and Barki breed (~ 0.03). The estimated mean F ST was 0.14 (Egyptian Nubian and Boer), 0.077 (Egyptian Nubian and Barki), 0.075 (Egyptian Nubian and Damascus), 0.071 (Barki and Boer), 0.064 (Damascus and Boer), and 0.015 (Damascus and Barki), for each pair of breeds. Interestingly, multiple SNPs that accounted for high F ST values were observed on chromosome 6 in regions harboring ALPK1 and KCNIP4 . Genomic regions overlapping both F ST and ROH harbor genes related to immunity ( IL4R, PHF23, GABARAP, GPS2 , and CD68 ), reproduction ( SPATA2L, TNFSF12, TMEM95 , and RNF17 ), embryonic development ( TCF25 and SOX15 ) and adaptation ( MC1R, KDR , and KIT ), suggesting potential genetic adaptations to local environmental conditions. Our results contribute to the understanding of the genetic architecture of different goat breeds and may provide valuable information for effective preservation and breeding programs of local goat breeds in Egypt.