Despite much attention on the history of goat evolution, information on origin, demographic history, and expansion route remains controversial. To address these questions, we collected 4,189 published goat DNA sequences including 1,228 sequences from 57 breeds in China and 2,961 sequences including 193 goat breeds from 71 other countries and carried out an integrated analysis. We found goat breeds from South China had the highest genetic diversity of lineage B, and subclades B2 only were found in Southwest China, suggesting that lineage B (particularly, subclade B2) probably originated from Southwest China and its surrounding areas. In addition, in this study, we found that lineage A from South China also presented higher genetic diversity and earlier expansion time (10, 606 years ago), even earlier than breeds from the Middle East. Hence, we speculated that South China and surrounding areas were the origin of lineage B and also the transportation hub for lineage A spreading to North China and Southwest Asia. Furthermore, according to the analysis of correlation between genetic differentiation value λ1 and λ2 and geographical distance, we further confirmed two phases of migration in goat breeds of North China. These results will contribute to a better understanding of the origin and migration history of domestic goat.

Altay is a typical fat-tailed sheep breed displaying the unique ability to rapidly mobilize fat, which is vital for maintaining a normal metabolism that facilitates its survival in lengthy winter conditions. However, the physiological, biochemical, and molecular mechanisms underlying fat mobilization remain to be elucidated. In this study, the monitoring of rump fat adipocyte sizes disclosed a positive correlation between cell size and fat deposition ability. In addition, we subjected sheep to persistent starvation to imitate the conditions that trigger rump fat mobilization and screened 112 differentially expressed proteins using the isobaric peptide labeling approach. Notably, increased secretion of leptin and adiponectin activated the key fat mobilization signaling pathways under persistent starvation conditions. Furthermore, the upregulation of resistin (RETN), heat-shock protein 72 (HSP72), and complement factor D (CFD) promoted lipolysis, whereas the downregulation of cell death-inducing DFFA-like effector C (CIDEC) inhibited lipid droplet fusion, and the increase in HSP72 and apolipoprotein AI (Apo-AI) levels activated the body’s stress mechanisms. The synergistic actions of the above hormones, genes, and signaling pathways form a molecular network that functions in improving the adaptability of Altay sheep to extreme environments. Our findings provide a reference for elucidating the complex molecular mechanisms underlying rump fat mobilization.

Introduction: In the evolutionary context of sheep, the development of fat tails represents an adaptive survival mechanism in response to varying food availability. Despite food resource instability, sheep store energy by accumulating tail fat to survive periods of famine. This energy storage function remains present in domesticated sheep, serving as a key evolutionary reason for the formation of sheep tail fat.Methods: Here, we conducted whole-genome resequencing of 555 sheep samples (30 samples were newly sequenced and 525 were retrieved from published data) globally to investigate selection signatures associated with fat-tailed traits using Fixation Index (F_ST), Nucleotide diversity (π), cross-population composite likelihood ratio (XP-CLR), and runs of homozygosity (ROH) methods.Result and discussion: Our examination of selection signatures in Fat-tailed and Thin-tailed Sheep Populations identified 32 candidate genes, with 6 genes (PDGFD, BMP2, GLIS1, LIPE, MSRB3, and TBX15) implicated in fat accumulation and lipid metabolism. Notably, 8 significant Gene Ontology terms (mesenchymal cell differentiation, positive regulation of ERK1 and ERK2 cascades, hormone metabolic process, nucleocytoplasmic transport, regulation of hormone levels, response to growth factor, regulation of canonical Wnt signaling pathway, and tissue morphogenesis) may play a role in fat deposition and tail fat development. These results will provide molecular targets for low-fat sheep breeding and enhance economic returns in sheep farming.Conclusion: This study will play a crucial role in environmental adaptation and product development, comprehensively driving the development of the sheep farming industry and enhancing economic benefits.

Background: Sheep (Ovis aries) tail fat serves as a crucial energy reserve for adapting to harsh environments. However, excessive deposition can reduce farming efficiency and product quality. Elucidating the regulatory mechanisms of tail fat deposition is of great significance for genetic improvement in sheep. Methods: In this study, transcriptome sequencing was conducted on tail fat tissues from fat-tailed Kazakh sheep (KAZ), thin-tailed Suffolk sheep (SFK), and their F2 hybrid sheep (CSH) (3 individuals per group). Subsequently, qRT-PCR validation, Enrichr, and KEGG database analyses were performed to investigate the molecular pathways involved in tail fat deposition. Results: High-quality clean reads were obtained from sequencing, with a genome alignment rate ranging from 76.15% to 79.43% and good data reproducibility. Differential expression analysis revealed multiple differentially expressed genes (DEGs) between KAZ and CSH groups, KAZ and SFK groups, as well as SFK and CSH groups. Five core candidate genes (BDH1, EPHX1, BCAT2, FASN, ACACA) were identified, all enriched in the fatty acid synthesis pathway and highly expressed in fat-tailed sheep, which was confirmed by qRT-PCR. Additionally, 189 lncRNAs were identified to collectively regulate target genes (e.g., FABP family, AGPAT2), along with three common differentially expressed miRNAs (novel_120, novel_171, novel_440) targeting genes enriched in lipid transport and lipid droplet formation pathways. Conclusions: This study confirms that the lncRNA-mRNA-miRNA regulatory axis is a key pathway in tail fat formation, providing important theoretical support and molecular targets for genetic improvement of ovine tail fat deposition traits.