signatures of selection in racing camels
Racing dromedary camels are widely distributed across the Arabian Peninsula, predominantly concentrating in its northern and southeastern regions. Phenotypically, they are differentiated from other dromedary types, characterized by their smaller body size, longer limbs, reduced hump size, and thinner chest girth. In this study, the whole genome sequences of 34 racing camels were analyzed to assess their genetic relationship with non-racing populations, estimate levels of inbreeding, assess effective population size (Ne), and identify candidate regions with signatures of positive selection. A moderate level of genomic inbreeding was estimated in both racing and non-racing camels (FROH = 0.21), with no significant genetic differentiation observed between the two groups. Ne estimations of both groups indicated a declining trend over the past 5 000 years, with recent Ne slightly lower in racing camels compared to their non-racing counterparts. Signatures of positive selection in the genomes of racing camels were identified through the application of two haplotype-based statistics, namely the integrated haplotype score (iHS) and cross-population extended haplotype homozygosity (Rsb), along with a runs of homozygosity (ROH) analysis. A total of 33 regions under selection were detected via iHS, 19 via Rsb, and 24 through ROH. Candidate regions under selection were found to overlap with genes involved in diverse biological pathways potentially linked to athletic performance, e.g., musculoskeletal development, lipid metabolism, stress response, bone integrity, and endurance. These findings provide a foundation for further exploration of the racing dromedary genome, with the goal of defining variants and haplotypes that might be associated with athletic traits. Such insights could assist the development of genetically informed breeding programmes aimed at developing specialized racing dromedary lines.