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| 2. |
- McCue, Molly E., et al.
(author)
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A High Density SNP Array for the Domestic Horse and Extant Perissodactyla : Utility for Association Mapping, Genetic Diversity, and Phylogeny Studies
- 2012
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In: PLOS Genetics. - : Public Library of Science (PLoS). - 1553-7390 .- 1553-7404. ; 8:1, s. e1002451-
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Journal article (peer-reviewed)abstract
- An equine SNP genotyping array was developed and evaluated on a panel of samples representing 14 domestic horse breeds and 18 evolutionarily related species. More than 54,000 polymorphic SNPs provided an average inter-SNP spacing of similar to 43 kb. The mean minor allele frequency across domestic horse breeds was 0.23, and the number of polymorphic SNPs within breeds ranged from 43,287 to 52,085. Genome-wide linkage disequilibrium (LD) in most breeds declined rapidly over the first 50-100 kb and reached background levels within 1-2 Mb. The extent of LD and the level of inbreeding were highest in the Thoroughbred and lowest in the Mongolian and Quarter Horse. Multidimensional scaling (MDS) analyses demonstrated the tight grouping of individuals within most breeds, close proximity of related breeds, and less tight grouping in admixed breeds. The close relationship between the Przewalski's Horse and the domestic horse was demonstrated by pair-wise genetic distance and MDS. Genotyping of other Perissodactyla (zebras, asses, tapirs, and rhinoceros) was variably successful, with call rates and the number of polymorphic loci varying across taxa. Parsimony analysis placed the modern horse as sister taxa to Equus przewalski. The utility of the SNP array in genome-wide association was confirmed by mapping the known recessive chestnut coat color locus (MC1R) and defining a conserved haplotype of similar to 750 kb across all breeds. These results demonstrate the high quality of this SNP genotyping resource, its usefulness in diverse genome analyses of the horse, and potential use in related species.
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| 3. |
- Siguroardottir, Heiorun, et al.
(author)
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The genetics of gaits in Icelandic horses goes beyond DMRT3, with RELN and STAU2 identified as two new candidate genes
- 2023
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In: Genetics Selection Evolution. - : Springer Nature. - 0999-193X .- 1297-9686. ; 55:1
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Journal article (peer-reviewed)abstract
- Background: In domesticated animals, many important traits are complex and regulated by a large number of genes, genetic interactions, and environmental influences. The ability of Icelandic horses to perform the gait 'pace' is largely influenced by a single mutation in the DMRT3 gene, but genetic modifiers likely exist. The aim of this study was to identify novel genetic factors that influence pacing ability and quality of the gait through a genome-wide association study (GWAS) and correlate new findings to previously identified quantitative trait loci (QTL) and mutations.Results: Three hundred and seventy-two Icelandic horses were genotyped with the 670 K+ Axiom Equine Genotyping Array, of which 362 had gait scores from breeding field tests. A GWAS revealed several SNPs on Equus caballus chromosomes (ECA) 4, 9, and 20 that were associated (p < 1.0 x 10(-5)) with the breeding field test score for pace. The two novel QTL on ECA4 and 9 were located within the RELN and STAU2 genes, respectively, which have previously been associated with locomotor behavior in mice. Haplotypes were identified and the most frequent one for each of these two QTL had a large favorable effect on pace score. The second most frequent haplotype for the RELN gene was positively correlated with scores for tolt, trot, gallop, and canter. Similarly, the second most frequent haplotype for the STAU2 gene had favorable effects on scores for trot and gallop. Different genotype ratios of the haplotypes in the RELN and STAU2 genes were also observed in groups of horses with different levels of pacing ability. Furthermore, interactions (p < 0.05) were detected for the QTL in the RELN and STAU2 genes with the DMRT3 gene. The novel QTL on ECA4, 9, and 20, along with the effects of the DMRT3 variant, were estimated to account jointly for 27.4% of the phenotypic variance of the gait pace.Conclusions: Our findings provide valuable information about the genetic architecture of pace beyond the contribution of the DMRT3 gene and indicate genetic interactions that contribute to the complexity of this trait. Further investigation is needed to fully understand the underlying genetic factors and interactions.
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| 4. |
- Velie, Brandon, et al.
(author)
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Frequencies of polymorphisms in myostatin vary in Icelandic horses according to the use of the horses
- 2015
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In: Animal Genetics. - : Wiley. - 0268-9146 .- 1365-2052. ; 46, s. 467-468
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Journal article (peer-reviewed)abstract
- The recent association of the myostatin gene (MSTN) with best race distance has provided valuable insight into the influence of MSTN on racing performance. However, the importance of MSTN in horses is unlikely to be limited to racing performance. First described in mice, the effects of mutations in MSTN have long been associated with heavily muscled cattle. In cattle, some of the morphological variability between breeds can be attributed to MSTN and its effects on muscle fiber development. As such, it is highly probable that MSTN polymorphisms influence not only racing performance, but also the general use of a horse or breed. This variability would likely be reflected in the genotype frequencies of horses used for specific purposes, as certain genotypes would undoubtedly yield more desirable phenotypes. The aim of this study was to explore this idea by estimating the genotype frequencies of three SNPs in MSTN in the Icelandic horse breed, a breed traditionally used for both meat production and riding.
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| 5. |
- Lindgren, Gabriella
(author)
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Widespread horse-based mobility arose around 2200 bce in Eurasia
- 2024
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In: Nature. - 0028-0836 .- 1476-4687. ; 631, s. 819-825
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Journal article (peer-reviewed)abstract
- Horses revolutionized human history with fast mobility1. However, the timeline between their domestication and their widespread integration as a means of transport remains contentious2–4. Here we assemble a collection of 475 ancient horse genomes to assess the period when these animals were first reshaped by human agency in Eurasia. We find that reproductive control of the modern domestic lineage emerged around 2200 bce, through close-kin mating and shortened generation times. Reproductive control emerged following a severe domestication bottleneck starting no earlier than approximately 2700 bce, and coincided with a sudden expansion across Eurasia that ultimately resulted in the replacement of nearly every local horse lineage. This expansion marked the rise of widespread horse-based mobility in human history, which refutes the commonly held narrative of large horse herds accompanying the massive migration of steppe peoples across Europe around 3000 bce and earlier3,5. Finally, we detect significantly shortened generation times at Botai around 3500 bce, a settlement from central Asia associated with corrals and a subsistence economy centred on horses6,7. This supports local horse husbandry before the rise of modern domestic bloodlines.
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| 6. |
- Jäderkvist Fegraeus, Kim, et al.
(author)
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The DMRT3 'Gait keeper' mutation affects performance of Nordic and Standardbred trotters
- 2014
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In: Journal of Animal Science. - : Oxford University Press (OUP). - 0021-8812 .- 1525-3163. ; 92:10, s. 4279-4286
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Journal article (peer-reviewed)abstract
- In a previous study it was shown that a nonsense mutation in the DMRT3 gene alters the pattern of locomotion in horses and that this mutation has a strong positive impact on trotting performance of Standardbreds. One aim of this study was to test if racing performance and trotting technique in the Nordic (Coldblood) trotters are also influenced by the DMRT3 genotype. Another aim was to further investigate the effect of the mutation on performance in Standardbreds, by using a within-family analysis and genotype-phenotype correlations in a larger horse material than in the previous study. We genotyped 427 Nordic trotters and 621 Standardbreds for the DMRT3 nonsense mutation and a SNP in strong linkage disequilibrium with it. In Nordic trotters, we show that horses homozygous for the DMRT3 mutation (A) had significantly higher EBV for trotting performance traits than heterozygous (CA) or homozygous wild-type (CC) horses (P = 0.001). Furthermore, AA homozygotes had a higher proportion of victories and top 3 placings than horses heterozygous or homozygous wild-type, when analyzing performance data for the period 3 to 6 yr of age (P = 0.06 and P = 0.05, respectively). Another finding in the Nordic trotters was that the DMRT3 mutation influenced trotting technique (P = 2.1 x 10(-8)). Standardbred horses homozygous AA had significantly higher EBV for all traits than horses with at least 1 wild-type allele (CA and CC; P = 1.6 x 10(-16)). In a within-family analysis of Standardbreds, we found significant differences in several traits (e. g., earnings, P = 0.002; number of entered races, P = 0.004; and fraction of offspring that entered races, P = 0.002) among paternal half-sibs with genotype AA or CA sired by a CA stallion. For most traits, we found significant differences at young ages. For Nordic trotters, most of the results were significant at 3 yr of age but not for the older ages, and for the Standardbreds most of the results for the ages 3 to 5 were significant. For Nordic trotters, the proportion of victories and placings were the only traits that were significant for other ages than 3 yr.
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| 8. |
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| 9. |
- Andersson, Lisa, et al.
(author)
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Augngallar í vindóttum hrossum
- 2012
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In: Eiðfaxi, Icelandic horse Magazine. - 1023-3342. ; , s. 42-47
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Journal article (pop. science, debate, etc.)
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| 10. |
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