Comparative population genomic analysis uncovers novel genomic footprints and genes associated with small body size in Chinese pony

Comparative population genomics analysis for chicken body sizes using genome-wide single nucleotide polymorphisms

OBJECTIVE

This study aims to investigate the selection history, genome regions, and candidate genes associated with different chicken body sizes, thereby providing insights into the genetic basis of complex economic traits such as chicken body size and growth.

METHODS

In this study, a total of 217 individuals from eight breeds were selected. According to body size, they were divided into two groups: large chickens and bantam chickens, with four breeds in each group. Firstly, we investigate population structure by principal component analysis (PCA), phylogenetic tree, and ancestry component analysis. Next, we recognize runs of homozygosity (ROH) islands through calculating ROH. Finally, we carry out selection signatures analysis utilizing population differentiation index and nucleic acid diversity.

RESULTS

The population structure analysis show that large and bantam chickens are clearly separated. Large chickens are clustered together, the bantam chickens are relatively dispersed. The results of ROH island analysis show that 48 and 56 ROH islands were identified in large and bantam chickens respectively. Among the interesting ROH islands, a total of eight candidate genes were identified. In selection signatures analysis, a total of 322 selected genes were annotated in large chickens, such as POU1F1, BMP10, enrichment in 16 gene ontology (GO) terms. In bantam chickens, a total of 447 selected genes were annotated, such as IGF1, GRB10, enrichment in 20 GO terms and 2 Kyoto encyclopedia of genes and genomes pathways. The haplotype analysis results show that GRB10 has differences in chickens of different body sizes.

CONCLUSION

By population structure, ROH islands, and selection signatures analysis, we have identified multiple genes associated with chicken body size, growth, and development (such as BMP10, IGF1, GRB10, etc). This provides a theoretical reference for the subsequent development of molecular markers for chicken body size and the analysis of the genetic mechanism of chicken body size.

Genomic Insights into Post-Domestication Expansion and Selection of Body Size in Ponies

Horse domestication revolutionizes human civilization by transforming transportation, agriculture, and warfare patterns. Despite extensive studies on modern domestic horse origins, the intricate demographic history and genetic signatures underlying pony size remain unexplored. Here, a high-quality genome assembly of the Chinese Debao pony is presented, and 452 qualified individuals from 64 horse breeds worldwide are extensively analyzed. The authors' results reveal the conservation of ancient components in East Asian horses and close relationships between Asian horses and Western pony lineages. Genetic analyses suggest an Asian paternal origin for European pony breeds. These pony-sized horses share close genetic affinities, potentially attributed to their early expansion and adaptation to local environments. In addition, promising cis-regulatory elements influencing horse withers height by regulating genes such as RFLNA and FOXO1 are identified. Overall, this study provides insightful perspectives on the dispersal history and genetic determinants underlying body size in ponies, offering broader implications for horse population management and improvement.

Genomic insights into the genetic diversity and genetic basis of body height in endangered Chinese Ningqiang ponies

BACKGROUND

Genetic diversity in livestock and poultry is critical for adapting production systems to future challenges. However, inadequate management practices, particularly in developing countries, have led to the extinction or near extinction of several species. Understanding the genetic composition and historical background of local breeds is essential for their effective conservation and sustainable use. This study compared the genomes of 30 newly sequenced Ningqiang ponies with those of 56 other ponies and 104 horses to investigate genetic diversity, genetic differentiation, and the genetic basis of body height differences.

RESULT

Population structure and genetic diversity analyses revealed that Ningqiang ponies belong to southwestern Chinese ponies. They exhibit a moderate level of inbreeding compared to other pony and horse breeds. Mitochondrial DNA analysis indicated that Ningqiang and Debao ponies share the dominant haplogroups A and C, suggesting a likely common maternal origin. Our study identified low genetic differentiation and detectable gene flow between Ningqiang ponies and Datong horses. The study also indicated the effective population size of Ningqiang ponies showed a downward trend. These findings potentially reflect the historical formation of Ningqiang ponies and population size changes. A selection signal scan (CLR and θπ) within Ningqiang ponies detected several key genes associated with bone development (ANKRD11, OSGIN2, JUNB, and RPL13) and immune response (RIPK2). The combination of genome-wide association analysis and selective signature analysis (FST) revealed significant single nucleotide polymorphisms and selective genes associated with body height, with the most prominent finding being the TBX3 gene on equine chromosome (ECA) 8. Additionally, TBX5, ASAP1, CDK12, CA10, and CSMD1 were identified as important candidate genes for body height differences between ponies and horses.

CONCLUSION

The results of this study elucidate the genetic diversity, genetic differentiation, and effective population size of Ningqiang ponies compared to other ponies and horses, further deepen the understanding of their small stature, and provide valuable insights into the conservation and breeding of local horse breeds in China.

Milk Lipid Regulation in Dairy Goats: A Comprehensive Review

The growth, development, and milk production traits of dairy goats, which are important sources of high-quality animal protein, are significantly influenced by a combination of genetic and environmental factors. It is imperative to identify key genetic loci that govern economically valuable traits in order to enhance breeding programs. Despite advancements in genomic technologies, there are still gaps in knowledge regarding the interplay between genetic factors and environmental influences, particularly in relation to the regulation of milk production and quality. Therefore, the aim of this paper was to synthesize advancements in the genetic and environmental factors affecting milk production and quality in dairy goats and identify key regulatory mechanisms. This review summarizes the recent progress on the identification of genes associated with milk production traits using whole-genome resequencing, the use of transcriptomic profiling to identify genes linked to milk production, the exploration of regulatory mechanisms of lipid metabolism in goat mammary epithelial cells, and the evaluation of the influence of nutritional factors on milk quality. A comprehensive understanding of these interactions is essential for enhancing breeding strategies and ensuring the sustainability of dairy goat farming. Future research should incorporate multi-omics approaches to unravel the intricate regulatory processes governing milk production and adapt practices to meet global demand while upholding economic and environmental sustainability.

Structural variant landscapes reveal convergent signatures of evolution in sheep and goats

BACKGROUND

Sheep and goats have undergone domestication and improvement to produce similar phenotypes, which have been greatly impacted by structural variants (SVs). Here, we report a high-quality chromosome-level reference genome of Asiatic mouflon, and implement a comprehensive analysis of SVs in 897 genomes of worldwide wild and domestic populations of sheep and goats to reveal genetic signatures underlying convergent evolution.

RESULTS

We characterize the SV landscapes in terms of genetic diversity, chromosomal distribution and their links with genes, QTLs and transposable elements, and examine their impacts on regulatory elements. We identify several novel SVs and annotate corresponding genes (e.g., BMPR1B, BMPR2, RALYL, COL21A1, and LRP1B) associated with important production traits such as fertility, meat and milk production, and wool/hair fineness. We detect signatures of selection involving the parallel evolution of orthologous SV-associated genes during domestication, local environmental adaptation, and improvement. In particular, we find that fecundity traits experienced convergent selection targeting the gene BMPR1B, with the DEL00067921 deletion explaining ~10.4% of the phenotypic variation observed in goats.

CONCLUSIONS

Our results provide new insights into the convergent evolution of SVs and serve as a rich resource for the future improvement of sheep, goats, and related livestock.

Genomic analysis uncovers novel candidate genes related to adaptation to tropical climates and milk production traits in native goats

BACKGROUND

Since domestication, both evolutionary forces and human selection have played crucial roles in producing adaptive and economic traits, resulting in animal breeds that have been selected for specific climates and different breeding goals. Pakistani goat breeds have acquired genomic adaptations to their native climate conditions, such as tropical and hot climates. In this study, using next-generation sequencing data, we aimed to assess the signatures of positive selection in three native Pakistani goats, known as milk production breeds, that have been well adapted to their local climate.

RESULTS

To explore the genomic relationship between studied goat populations and their population structure, whole genome sequence data from native goat populations in Pakistan (n = 26) was merged with available worldwide goat genomic data (n = 184), resulting in a total dataset of 210 individuals. The results showed a high genetic correlation between Pakistani goats and samples from North-East Asia. Across all populations analyzed, a higher linkage disequilibrium (LD) level (- 0.59) was found in the Pakistani goat group at a genomic distance of 1 Kb. Our findings from admixture analysis (K = 5 and K = 6) showed no evidence of shared genomic ancestry between Pakistani goats and other goat populations from Asia. The results from genomic selection analysis revealed several candidate genes related to adaptation to tropical/hot climates (such as; KITLG, HSPB9, HSP70, HSPA12B, and HSPA12B) and milk production related-traits (such as IGFBP3, LPL, LEPR, TSHR, and ACACA) in Pakistani native goat breeds.

CONCLUSIONS

The results from this study shed light on the structural variation in the DNA of the three native Pakistani goat breeds. Several candidate genes were discovered for adaptation to tropical/hot climates, immune responses, and milk production traits. The identified genes could be exploited in goat breeding programs to select efficient breeds for tropical/hot climate regions.

A mutation in POLR2A gene associated with body size traits in Dezhou donkeys revealed with GWAS

The Dezhou donkey is a famous local donkey breed in China. The aim of the present study was to identify the genes associated with the body size traits of the Dezhou donkey and facilitate the breeding activities of the donkeys. A total of 349 donkeys from 2 generations (113 individuals in F0 and 236 in F1) were analyzed with restriction-site-associated DNA sequencing. A genome-wide association study revealed that the region between 13.7 and 15.6 Mb of chromosome 13 is significantly associated with body sizes. Candidate genes related to body size development, including POLR2A, CHRNB1, FGF11, and ZBTB4, were identified. The results of GO and KEGG analysis indicated that the genes involved in many GO terms were related to metabolic processes and developmental processes. Additionally, a T>C mutation (Chr13:14312485) was found at intron 10 of the POLR2A gene. The association analysis showed significant differences among genotypes for the size traits. The body size of the individuals with the TT genotype was significantly higher than that with the CC genotype. The results showed that the polymorphism of POLR2A has the potential to be used as a marker in the breeding programs of the Dezhou donkeys.

Comparative population genomics analysis uncovers genomic footprints and genes influencing body weight trait in Chinese indigenous chicken

Body weight of chicken is a typical quantitative trait, which shows phenotypic variations due to selective breeding. Despite some QTL loci have been obtained, the body weight of native chicken breeds in different geographic regions varies greatly, its genetic basis remains unresolved questions. To address this issue, we analyzed 117 Chinese indigenous chickens from 10 breeds (Huiyang Bearded, Xinhua, Hotan Black, Baicheng You, Liyang, Yunyang Da, Jining Bairi, Lindian, Beijing You, Tibetan). We applied fixation index (FST) analysis to find selected genomic regions and genes associated with body weight traits. Our study suggests that NELL1, XYLT1, and NCAPG/LCORL genes are strongly selected in the body weight trait of Chinese indigenous chicken breeds. In addition, the IL1RAPL1 gene was strongly selected in large body weight chickens, while the PCDH17 and CADM2 genes were strongly selected in small body weight chickens. This result suggests that the patterns of genetic variation of native chicken and commercial chicken, and/or distinct local chicken breeds may follow different evolutionary mechanisms.

Identification genetic variations in some heat shock protein genes of Tali goat breed and study their structural and functional effects on relevant proteins

BACKGROUND

Animals of different regions have adapted to adverse environmental conditions by modifying their phenotypic and genotypic characteristics in the long run.

OBJECTIVES

In this study, the effect of genetic variations of 10 heat shock protein (HSP) genes (HSP70A4, HSP70A9, HSP40C17, HSP40C27, HSP90AA1, HSP90AB1, HSPB7, HSPB11, HSPD1 and HSPE1) on the three-dimensional protein structure and function of proteins in Tali goat (a tropical breed) were studied and were compared with Saanen goat (as a sensitive breed).

METHODS

A pooled DNA of 15 samples from blood was sequenced and mapped to the goat reference sequence. The bioinformatics analysis was used to identify nsSNPs in the Tali breed and was compared with the Saanen goat. Four online bioinformatics tools (Sorting Intolerant from Tolerant, Protein Variation Effect Analyzer, Polymorphism Phenotyping version2 and Single Nucleotide Polymorphism Database and Gene Ontology) showed three deleterious missense nsSNPs and seven natural missense SNPs in these HSPs genes of Tali goat.

RESULTS

Out of 10 reported nsSNPs, 5 nsSNPs in HSP70A4, 1 nsSNP inHSP70A9, 2 nsSNPs in HSP40C17, 1 nsSNP in HSP40C27 and 1 nsSNP in HSPD1 were detected. ConSurf tools showed that the majority of the predicted nsSNPs occur in conserved sites. Moreover, several post-translational modification (PTM) predictors computed the probability of post-translation change of nsSNPs. The putative phosphorylation and glycosylation sites in HSPs proteins were substitutions rs669769139 and rs666336692 of the Tali goat breed.

CONCLUSION

These results on the effect of type of genetic variants on the function of HSP proteins will assist to predict the resistance to hard conditions in goat breeds. Considering that the identified SNPid rs669769139 (S248) which is located on the N-terminal ATPase domain of HSP70A4 is a PTM site with a highly conserved score and a natural substitution on changing the stability and benign protein that can affect the functional and structural characterization of HSPs protein for adaptation to the local climate.

Genomic adaptation to extreme climate conditions in beef cattle as a consequence of cross-breeding program

BACKGROUND

Understanding the evolutionary forces related to climate changes that have been shaped genetic variation within species has long been a fundamental pursuit in biology. In this study, we generated whole-genome sequence (WGS) data from 65 cross-bred and 45 Mongolian cattle. Together with 62 whole-genome sequences from world-wide cattle populations, we estimated the genetic diversity and population genetic structure of cattle populations. In addition, we performed comparative population genomics analyses to explore the genetic basis underlying variation in the adaptation to cold climate and immune response in cross-bred cattle located in the cold region of China. To elucidate genomic signatures that underlie adaptation to cold climate, we performed three statistical measurements, fixation index (FST), log2 nucleotide diversity (θπ ratio) and cross population composite likelihood ratio (XP-CLR), and further investigated the results to identify genomic regions under selection for cold adaptation and immune response-related traits.

RESULTS

By generating WGS data, we investigated the population genetic structure and phylogenetic relationship of studied cattle populations. The results revealed clustering of cattle groups in agreement with their geographic distribution. We detected noticeable genetic diversity between indigenous cattle ecotypes and commercial populations. Analysis of population structure demonstrated evidence of shared genetic ancestry between studied cross-bred population and both Red-Angus and Mongolian breeds. Among all studied cattle populations, the highest and lowest levels of linkage disequilibrium (LD) per Kb were detected in Holstein and Rashoki populations (ranged from ~ 0.54 to 0.73, respectively). Our search for potential genomic regions under selection in cross-bred cattle revealed several candidate genes related with immune response and cold shock protein on multiple chromosomes. We identified some adaptive introgression genes with greater than expected contributions from Mongolian ancestry into Molgolian x Red Angus composites such as TRPM8, NMUR1, PRKAA2, SMTNL2 and OXR1 that are involved in energy metabolism and metabolic homeostasis. In addition, we detected some candidate genes probably associated with immune response-related traits.

CONCLUSION

The study identified candidate genes involved in responses to cold adaptation and immune response in cross-bred cattle, including new genes or gene pathways putatively involved in these adaptations. The identification of these genes may clarify the molecular basis underlying adaptation to extreme environmental climate and as such they might be used in cattle breeding programs to select more efficient breeds for cold climate regions.

Candidate pigmentation genes related to feather color variation in an indigenous chicken breed revealed by whole genome data

Chicken plumage color is an inheritable phenotype that was naturally and artificially selected for during domestication. The Baicheng You chicken is an indigenous Chinese chicken breed presenting three main feather colors, lavender, black, and yellow plumages. To explore the genetic mechanisms underlying the pigmentation in Baicheng You chickens, we re-sequenced the whole genome of Baicheng You chicken with the three plumage colors. By analyzing the divergent regions of the genome among the chickens with different feather colors, we identified some candidate genomic regions associated with the feather colors in Baicheng You chickens. We found that EGR1, MLPH, RAB17, SOX5, and GRM5 genes were the potential genes for black, lavender, and yellow feathers. MLPH, GRM5, and SOX5 genes have been found to be related to plumage colors in birds. Our results showed that EGR1 is a most plausible candidate gene for black plumage, RAB17, MLPH, and SOX5 for lavender plumage, and GRM5 for yellow plumage in Baicheng You chicken.

Population structure and genomic footprints of selection in five major Iranian horse breeds

The genetic structure and characteristics of Iranian native breeds are yet to be comprehensibly investigated and studied. Therefore, we employed genomic information of 364 Iranian native horses representing the Asil (n = 109), Caspian (n = 40), Dareshuri (n = 44), Kurdish (n = 95), and Turkoman (n = 76) breeds to reveal the genetic structure and characteristics. For these and 19 other horse breeds, principal component analysis, Bayesian model-based, Neighbor-Net, and bootstrap-based TreeMix approaches were applied to investigate and compare their genetic structure. Additionally, three haplotype-based methods including haplotype homozygosity pooled, integrated haplotype score, and number of segregating sites by length were applied to trace genomic footprints of selection of Asil, Caspian, Dareshuri, Kurdish, and Turkoman groups. Then, the Mahalanobis distance based on the negative-log₁₀ rank-based P-values was estimated based on the haplotype homozygosity pooled, integrated haplotype score, and number of segregating sites by length values. Asil, Caspian, Dareshuri, Kurdish, and Turkoman can be categorized into five different genetic clusters. Based on the top 1% of Mahalanobis distance based on the negative-log₁₀ rank-based P-values of SNPs, we identified 24 SNPs formerly reported to be associated with different traits and >100 genes undergoing selection pressures in Asil, Caspian, Dareshuri, Kurdish, and Turkoman. The detected QTL undergoing selection pressures were associated with withers height, equine metabolic syndrome, overall body size, insect bite hypersensitivity, guttural pouch tympany, white markings, Rhodococcus equi infection, jumping test score, alternate gaits, and body weight traits. Our findings will aid to have a better perspective of the genetic characteristics and population structure of Asil, Caspian, Dareshuri, Kurdish, and Turkoman horses as Iranian native horse breeds.

Genetic diversity and signatures of selection for heat tolerance and immune response in Iranian native chickens

Background

Understanding how evolutionary forces relating to climate have shaped the patterns of genetic variation within and between species is a fundamental pursuit in biology. Iranian indigenous chickens have evolved genetic adaptations to their local environmental conditions, such as hot and arid regions. In the present study, we provide a population genome landscape of genetic variations in 72 chickens representing nine Iranian indigenous ecotypes (Creeper, Isfahan, Lari, Marand, Mashhad, Naked neck, Sari, Shiraz and Yazd) and two commercial lines (White Leghorn and Arian). We further performed comparative population genomics to evaluate the genetic basis underlying variation in the adaptation to hot climate and immune response in indigenous chicken ecotypes. To detect genomic signatures of adaptation, we applied nucleotide diversity (θπ) and F_ST statistical measurements, and further analyzed the results to find genomic regions under selection for hot adaptation and immune response-related traits.

Results

By generating whole-genome data, we assessed the relationship between the genetic diversity of indigenous chicken ecotypes and their genetic distances to two different commercial lines. The results of genetic structure analysis revealed clustering of indigenous chickens in agreement with their geographic origin. Among all studied chicken groups, the highest level of linkage disequilibrium (LD) (~ 0.70) was observed in White Leghorn group at marker pairs distance of 1 Kb. The results from admixture analysis demonstrated evidence of shared ancestry between Arian individuals and indigenous chickens, especially those from the north of the country. Our search for potential genomic regions under selection in indigenous chicken ecotypes revealed several immune response and heat shock protein-related genes, such as HSP70, HSPA9, HSPH1, HSP90AB1 and PLCB4 that have been previously unknown to be involved in environmental-adaptive traits. In addition, we found some other candidate loci on different chromosomes probably related with hot adaptation and immune response-related traits.

Conclusions

The work provides crucial insights into the structural variation in the genome of Iranian indigenous chicken ecotypes, which up to now has not been genetically investigated. Several genes were identified as candidates for drought, heat tolerance, immune response and other phenotypic traits. These candidate genes may be helpful targets for understanding of the molecular basis of adaptation to hot environmental climate and as such they should be used in chicken breeding programs to select more efficient breeds for desert climate.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12864-022-08434-7.

A single-nucleotide mutation within the TBX3 enhancer increased body size in Chinese horses

Chinese ponies are endemic to the mountainous areas of southwestern China and were first reported in the archaeological record at the Royal Tomb of Zhongshan King, Mancheng, dated to approximately ∼2,100 YBP.¹ Previous work has started uncovering the genetic basis of size variation in western ponies and horses, revealing a limited number of loci, including HMGA2,²LCORL/NCAPG,³ZFAT, and LASP1.^4,5 Whether the same genetic pathways also drive the small body size of Chinese ponies, which show striking anatomical differences to Shetland ponies,⁶ remains unclear.^2,7 To test this, we combined whole-genome sequences of 187 horses across China. Statistical analyses revealed top association between genetic variation at the T-box transcription factor 3 (TBX3) and the body size. Fine-scale analysis across an extended population of 189 ponies and 574 horses narrowed down the association to one A/G SNP at an enhancer region upstream of the TBX3 (ECA8:20,644,555, p = 2.34e−39). Luciferase assays confirmed the single-nucleotide G mutation upregulating TBX3 expression, and enhancer-knockout mice exhibited shorter limbs than wild-type littermates (p < 0.01). Re-analysis of ancient DNA data showed that the G allele, which is most frequent in modern horses, first occurred some ∼2,300 years ago and rose in frequency since. This supports selection for larger size in Asia from approximately the beginning of the Chinese Empire. Overall, this study characterized the causal regulatory mutation underlying small body size in Chinese ponies and revealed size as one of the main selection targets of past Chinese breeders.

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One single A/G SNP in TBX3 enhancer region drives size variation in Chinese horses

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The frequency of the G variant correlates positively with size in 763 horses

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Cellular and mice models confirm it affects TBX3 transcription and the limb length

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The G variant first occurred ∼2,300 years ago and rose in frequency since

Identification and in silico characterization of structural and functional impacts of genetic variants in milk protein genes in the Zebu breeds Guzerat and Gyr

Whole genome sequencing of bovine breeds has allowed identification of genetic variants in milk protein genes. However, functional repercussion of such variants at a molecular level has seldom been investigated. Here, the results of a multistep Bioinformatic analysis for functional characterization of recently identified genetic variants in Brazilian Gyr and Guzerat breeds is described, including predicted effects on the following: (i) evolutionary conserved nucleotide positions/regions; (ii) protein function, stability, and interactions; (iii) splicing, branching, and miRNA binding sites; (iv) promoters and transcription factor binding sites; and (v) collocation with QTL. Seventy-one genetic variants were identified in the caseins (CSN1S1, CSN2, CSN1S2, and CSN3), LALBA, LGB, and LTF genes. Eleven potentially regulatory variants and two missense mutations were identified. LALBA Ile60Val was predicted to affect protein stability and flexibility, by reducing the number the disulfide bonds established. LTF Thr546Asn is predicted to generate steric clashes, which could mildly affect iron coordination. In addition, LALBA Ile60Val and LTF Thr546Asn affect exonic splicing enhancers and silencers. Consequently, both mutations have the potential of affecting immune response at individual level, not only in the mammary gland. Although laborious, this multistep procedure for classifying variants allowed the identification of potentially functional variants for milk protein genes.

Integration of selection signatures and multi-trait GWAS reveals polygenic genetic architecture of carcass traits in beef cattle

Carcass merits are widely considered as economically important traits affecting beef production in the beef cattle industry. However, the genetic basis of carcass traits remains to be well understood. Here, we applied multiple methods, including the Composite of Likelihood Ratio (CLR) and Genome-wide Association Study (GWAS), to explore the selection signatures and candidate variants affecting carcass traits. We identified 11,600 selected regions overlapping with 2214 candidate genes, and most of those were enriched in binding and gene regulation. Notably, we identified 66 and 110 potential variants significantly associated with carcass traits using single-trait and multi-traits analyses, respectively. By integrating selection signatures with single and multi-traits associations, we identified 12 and 27 putative genes, respectively. Several highly conserved missense variants were identified in OR5M13D, NCAPG, and TEX2. Our study supported polygenic genetic architecture of carcass traits and provided novel insights into the genetic basis of complex traits in beef cattle.