Novel and known signals of selection for fat deposition in domestic sheep breeds from Africa and Eurasia

Abstract

34Genomic regions subjected to selection frequently show signatures such as within-35 population reduced nucleotide diversity and outlier values of differentiation among differentially 36 selected populations. In this study, we analyzed 50K SNP genotype data of 373 animals belonging 37 to 23 sheep breeds of different geographic origins using the Rsb and F ST statistical approaches, to 38 identify loci associated with the fat-tail phenotype. We also checked if these putative selection 39 signatures overlapped with regions of high-homozygosity (ROH). The analyses identified novel 40 signals and confirmed the presence of selection signature in genomic regions that harbor candidate 41 genes known to affect fat deposition. Several genomic regions that frequently appeared in ROH 42 were also identified within each breed, but only two ROH islands overlapped with the putative 43 selection signatures. The results reported herein provide the most complete genome-wide study of 44 selection signatures for fat-tail in African and Eurasian sheep breeds; they also contribute insights 45 into the genetic basis for the fat tail phenotype in sheep, and confirm the great complexity of the 46 mechanisms that underlie quantitative traits, such as the fat-tail. 47 48 3 51been widely applied to livestock species to achieve more desirable/profitable phenotypes [1]. For 52 instance, sheep (Ovis aries) have been selected since domestication, approximately 9,000 years ago 53 [2]. This process of selection resulted in divergent sheep breeds, reared in different geographic 54 regions due to their different adaptability. Among these, fat-tail are an important class of sheep 55 breeds and represent about 25% of the world's sheep population [3] mainly distributed in the 56 Middle East, North and East Africa and Central Asia. According to Xu et al. [4] fat tails represent 57 the energy reserve necessary to survive critical conditions such as drought seasons and food 58 shortage. This statement being emphasized by Mwacharo et al. [5] who confirmed that the fat-tails 59 are the predominant sheep across the deserts of northern Africa, and in the highlands, semi-arid and 60 arid environments of eastern and southern Africa while the thin-tails occur in Sudan and in the sub-61 humid and humid regions of West Africa. 62The unique genetic patterns inscribed in the genome of individuals by natural and/or 63 artificial selection are defined as signatures of selection, which are usually regions of the genome 64 that harbor functionally important sequence variants [6]. Although human consumption of animal 65 fat has dramatically reduced in preference of leaner meat, the investigation of the potential 66 candidate genes involved in the fat-tail might contribute to exploring the genetics of fat deposition, 67 energy storage and adaptation to climate changes [7][8][9]. With the aim to identify candidate genes 68 with a potential role in these traits, several authors performed studies targeting the fat-tail 69 phenotype contrasted with the thi...

On the origin of European sheep as revealed by the diversity of the Balkan breeds and by optimizing population-genetic analysis tools

“…Remarkably, the thin-tailed Zel sheep is found to be in the same genetic cluster as the fat-tailed Iranian sheep whereas the fat-tailed Italian Laticauda [25] is related to other breeds in central Italy. This implies that the tail phenotype is encoded by a limited number of genes [36,[68][69][70][71][72]. This is in sharp contrast to, for example, the deep-rooted split of taurine and zebu cattle.…”

Fine mapping of candidate regions associated with fat deposition in thin and fat tail sheep breeds suggests new insights into molecular aspects of fat tail selection

“…In addition, HSD15B [52], SLC35A2 [51], AR and TIMP1 [19], have been identi ed as candidate genes that affect fat tail development. Moreover, it is important to note that our regions of interest overlapped with some genes, for example BMP15, WDR13 and RBM3 that belong to the gene families that their closely related genes consisting BMP2 [21,51,[56][57][58], WDR92 [20,51] and RBM11 [5] have recently reported to be associated with fat tail formation and adipose tissue gene expression in sheep.…”

Genetics of the phenotypic evolution in sheep: a molecular look at diversity-driving genes

“…Mastrangelo et al [25] compared the genomic data of two fat-and thin-tailed sheep breeds, and again revealed previously reported genes, i.e., VRTN and BMP2, with a potential role in determining variations in the number of vertebrae and tail formation, respectively, and PDG-FRA and PDGFD, which seem to be involved in preadipocyte differentiation. Moreover, Mastrangelo et al [26] also reported a set of genes, namely, ANAPC1, MSRB3, CXXC5, PSD2, SLIT2, EPHA5, CHP1, OIP5, PCDH9, CDS2, BMP2, and OAS2, which could be associated with fat deposition in sheep breeds from Africa and Eurasia.…”