Dataset Information

A genome scan for selection signatures in pigs.

ABSTRACT: Identifying signatures of selection can provide a straightforward insight into the mechanism of artificial selection and further uncover the causal genes related to the phenotypic variation. Based on Illumina Porcine60KSNP chip data, four complementary methods, Long-Range Haplotype (LRH), Tajima's D, Cross Population Extend Haplotype Homozygosity Test (XPEHH) and FST, were implemented in this study to detect the selection signatures in the whole genome of one typical Chinese indigenous breed, Rongchang, one Chinese cultivated breed, Songliao, and two western breeds, Landrace and Yorkshire. False Discovery Rate (FDR) was implemented to control the false positive rates. In our study, a total of 159, 127, 179 and 159 candidate selection regions with average length of 0.80 Mb, 0.73 Mb, 0.78 Mb and 0.73 Mb were identified in Landrace, Rongchang, Songliao and Yorkshire, respectively, that span approximately 128.00 Mb, 92.38 Mb, 130.30 Mb and 115.40 Mb and account for approximately 3.74-5.33% of genome across all autosomes. The selection regions of 11.52 Mb shared by Landrace and Yorkshire were the longest when chosen pairs from the pool of the four breeds were examined. The overlaps between Yorkshire and Songliao, approximately 9.20 Mb, were greater than those of Yorkshire and Rongchang. Meanwhile, the overlaps between Landrace and Songliao were greater than those of Landrace and Rongchang but less than those of Songliao and Ronchang. Bioinformatics analysis showed that the genes/QTLs relevant to fertility, coat color, and ear morphology were found in candidate selection regions. Some genes, such as LEMD3, MC1R, KIT, TRHR etc. that were reported under selection, were confirmed in our study, and this analysis also demonstrated the diversity of breeds.

SUBMITTER: Ma Y

PROVIDER: S-EPMC4355907 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Publications

A genome scan for selection signatures in pigs.

Ma Yunlong Y Wei Julong J Zhang Qin Q Chen Lei L Wang Jinyong J Liu Jianfeng J Ding Xiangdong X

PloS one 20150310 3

Identifying signatures of selection can provide a straightforward insight into the mechanism of artificial selection and further uncover the causal genes related to the phenotypic variation. Based on Illumina Porcine60KSNP chip data, four complementary methods, Long-Range Haplotype (LRH), Tajima's D, Cross Population Extend Haplotype Homozygosity Test (XPEHH) and FST, were implemented in this study to detect the selection signatures in the whole genome of one typical Chinese indigenous breed, Ro ...[more]

PMID: 25756180

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Project description:BACKGROUND: Since the times of domestication, cattle have been continually shaped by the influence of humans. Relatively recent history, including breed formation and the still enduring enormous improvement of economically important traits, is expected to have left distinctive footprints of selection within the genome. The purpose of this study was to map genome-wide selection signatures in ten cattle breeds and thus improve the understanding of the genome response to strong artificial selection and support the identification of the underlying genetic variants of favoured phenotypes. We analysed 47,651 single nucleotide polymorphisms (SNP) using Cross Population Extended Haplotype Homozygosity (XP-EHH). RESULTS: We set the significance thresholds using the maximum XP-EHH values of two essentially artificially unselected breeds and found up to 229 selection signatures per breed. Through a confirmation process we verified selection for three distinct phenotypes typical for one breed (polledness in Galloway, double muscling in Blanc-Bleu Belge and red coat colour in Red Holstein cattle). Moreover, we detected six genes strongly associated with known QTL for beef or dairy traits (TG, ABCG2, DGAT1, GH1, GHR and the Casein Cluster) within selection signatures of at least one breed. A literature search for genes lying in outstanding signatures revealed further promising candidate genes. However, in concordance with previous genome-wide studies, we also detected a substantial number of signatures without any yet known gene content. CONCLUSIONS: These results show the power of XP-EHH analyses in cattle to discover promising candidate genes and raise the hope of identifying phenotypically important variants in the near future. The finding of plausible functional candidates in some short signatures supports this hope. For instance, MAP2K6 is the only annotated gene of two signatures detected in Galloway and Gelbvieh cattle and is already known to be associated with carcass weight, back fat thickness and marbling score in Korean beef cattle. Based on the confirmation process and literature search we deduce that XP-EHH is able to uncover numerous artificial selection targets in subpopulations of domesticated animals.

Project description:Yanbian cattle is inhabitant of North of China, exhibiting many phenotypic features, such as long, dense body hair, and abundant intramuscular fat, designed to combat the extreme cold climate adaption. In the current study, we studied the cold tolerance of nine Yanbian cattle by whole genome resequencing and compared with African tropical cattle, N'Dama, as a control group. Yanbian cattle was aligned to the Bos taurus reference genome (ARS-UCD1.2) yielding an average of 10.8 fold coverage. The positive selective sweep analysis for the cold adaption in Yanbian cattle were analyzed using composite likelihood ratio (CLR) and nucleotide diversity (??), resulting in 292 overlapped genes. The strongest selective signal was found on BTA16 with potential mutation in CORT gene, a regulatory gene of primary hormone in the hypothalamic-pituitary-adrenal (HPA) axis, is reported to be associated with the cold stress, representedfour missense mutations (c.269C > T, p.Lys90Ile; c.251A > G, p.Glu84Gly; c.112C > T, p.Pro38Ser; c.86G > A, p.Pro29His). Meanwhile another gene on BTA6, showed significantly higher selective sweep signals for a cold adapted trait for hair follicle and length development, FGF5 (fibroblast growth factor 5) with a missense mutation (c.191C > T, p.Ser64Phe). Moreover, cold adapted Yanbian cattle was statistically compared with the hot adapted N'Dama cattle, a taurine cattle reported to show superior heat tolerance than zebu cattle, making them better adapted to the hot regions of Africa. XP-CLR, Fst, and ?? ratio were used to compare both breeds, yielding 487, 924, and 346 genes respectively. Among the 12 overlapped genes, (CD36) (c.638A > G, p.Lys 213Arg) involved in fat digestion and absorption plays an important role in membrane transport of long-chain fatty acid and its expression could increase in cold exposure. Henceforth, our study provides a novel genetic insights into the cold climate adaptation of Yanbian cattle and identified three candidate genes (CORT, FGF5, and CD36), which can add to an understanding of the cold climate adaptation of Yanbian cattle.

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Project description:High-altitude hypoxia (reduced inspired oxygen tension due to decreased barometric pressure) exerts severe physiological stress on the human body. Two high-altitude regions where humans have lived for millennia are the Andean Altiplano and the Tibetan Plateau. Populations living in these regions exhibit unique circulatory, respiratory, and hematological adaptations to life at high altitude. Although these responses have been well characterized physiologically, their underlying genetic basis remains unknown. We performed a genome scan to identify genes showing evidence of adaptation to hypoxia. We looked across each chromosome to identify genomic regions with previously unknown function with respect to altitude phenotypes. In addition, groups of genes functioning in oxygen metabolism and sensing were examined to test the hypothesis that particular pathways have been involved in genetic adaptation to altitude. Applying four population genetic statistics commonly used for detecting signatures of natural selection, we identified selection-nominated candidate genes and gene regions in these two populations (Andeans and Tibetans) separately. The Tibetan and Andean patterns of genetic adaptation are largely distinct from one another, with both populations showing evidence of positive natural selection in different genes or gene regions. Interestingly, one gene previously known to be important in cellular oxygen sensing, EGLN1 (also known as PHD2), shows evidence of positive selection in both Tibetans and Andeans. However, the pattern of variation for this gene differs between the two populations. Our results indicate that several key HIF-regulatory and targeted genes are responsible for adaptation to high altitude in Andeans and Tibetans, and several different chromosomal regions are implicated in the putative response to selection. These data suggest a genetic role in high-altitude adaption and provide a basis for future genotype/phenotype association studies necessary to confirm the role of selection-nominated candidate genes and gene regions in adaptation to altitude.

Dataset Information

A genome scan for selection signatures in pigs.

Publications

A genome scan for selection signatures in pigs.

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