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1.
Abstract

Young horse performance test data from two warmblood riding horse populations, Norwegian warmblood (NWB) and Swedish warmblood (SWB), were analysed to examine whether including information from a related studbook would increase the accuracy of the genetic evaluations within a population. Ten conformation and performance traits from 31,588 horses, 774 NWB and 30,814 SWB were analysed separately and jointly using single trait animal models. Heritabilities were moderate to high, and varied from 0.15 (conformation, joint data) to 0.74 (jumping technique, NWB data). The genetic similarity (GS) between populations was 31%, with the SWB, as expected given the size of the populations, contributing most to the GS (98%). Genetic correlations between the same traits in the two populations were 0.43–0.90 but with large standard errors (0.2–0.3). Including information from the other population increased the average accuracy of estimated breeding values for common stallions, on average 4% for SWB and 110% for NWB.  相似文献   

2.
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3.
The distribution of genetic diversity and the genetic relationships among western Mediterranean horse breeds were investigated using microsatellite markers. The examined sample included seven Spanish and three Italian local horse breeds and populations, plus a Spanish Thoroughbred outgroup. The total number of animals examined was 682 (on average 62 animals per breed; range 20–122). The microsatellite marker set analysed provided 128 alleles (10.7 alleles per locus). Within‐breed genetic diversity was always high (>0.70), with breeds contributing about 8% of the total genetic variability. The mean molecular coancestry of the entire population examined was 0.205, Losino being the breed that contributed most. In addition to Nei's standard and Reynolds’ genetic distances, pair‐wise kinship distance and molecular coancestry were estimated. Remarkably similar breed rankings were obtained with all methods. Clustering analysis provided an accurate representation of the current genetic relationships among the breeds. Determining coancestry is useful for analysing genetic diversity distribution between and within breeds and provides a good framework for jointly analysing molecular markers and pedigree information. An integrated analysis was undertaken to obtain information on the population dynamics in western Mediterranean native horse populations, and to better determine conservation priorities.  相似文献   

4.
旨在揭示康西草原马匹的品种来源以及群体遗传结构。本研究采集了当地60匹健康状况良好、体重适中、3～6岁之间不区分公母马的血液样品,试验分为6个种群并以纯血马等4个国外马品种、1个我国地方马品种作为对照， 通过设计引物并提取基因组DNA结合微卫星扩增法对染色体上12个微卫星位点的等位基因进行检测，并对各种群遗传多样性参数、群体分化指数、瓶颈效应以及群体结构进行分析。试验按照群体个数为依据分为6组，每组1个重复，每个重复以该组样本量为标准。分析6个种群马的遗传参数结果表明，其中共检测到221个等位基因,平均Shannon指数为1.691；有效等位基因数(Ne)为3.649～5.397；期望杂合度(He)为0.681～0.798；观测杂合度(Ho)为0.632～0.780；平均多态信息含量(PIC)为0.643～0.772。这些结果表明，6个群体都具有很高的遗传多样性。通过微卫星DNA位点的连锁不平衡及哈迪-温伯格平衡分析发现， 大多数位点的P值都大于校正值(P=0.006 5)，表示较多位点都处于哈迪-温伯格及连锁平衡状态。各群体间群体分化系数(Fst)表明，群体间分化程度较低(Fst<0.15)。基于Nei’s遗传距离与地理距离之间Mantel相关性检验显示二者之间呈现正相关性(R=0.502)，但未达到显著水平(P=0.310)；各马匹种群瓶颈效应分析表明，P值极显著(P(IAM)<0.01)说明该地区的马群体受到过瓶颈效应的影响且该马群体历史上数量有大规模的减少。通过 FCA因子分析、基于Nei’s标准遗传距离UPGMA树状图以及Structure贝叶斯聚类分析发现，该地区马种群与纯血马和温血马聚为一类，说明该种群最有可能主要来源于温血马和纯血马。这些结果揭示，康西草原地区马匹具有较高的遗传多样性，该地马群体的血统与纯血马和温血马相近，这为当地马遗传资源评估以及开发利用打下了坚实的基础。  相似文献   

5.
We have evaluated the use of genomic coancestry coefficients based on shared segments for the maintenance of genetic diversity through optimal contributions methodology for populations of three different Austrian cattle breeds. This coancestry measure has been compared with the genomic coancestry coefficient calculated on a SNP‐by‐SNP basis and with pedigree‐based coancestry. The regressions of the shared segments coancestry on the other two coefficients suggest that the former mainly reflect Identity By Descent but with the advantage over pedigree‐based coancestry of providing the realized Identity By Descent rather than an expectation. The effective population size estimated from the rate of coancestry based on shared segments was very similar to those obtained with the other coefficients and of small magnitude (from 26.24 to 111.90). This result highlights the importance of implementing active management strategies to control the increase of inbreeding and the loss of genetic diversity in livestock breeds, even when the population size is reasonably large. One problem for the implementation of coancestry based on shared segments is the need of estimating the gametic phases of the SNPs which, given the techniques used to obtain the genotypes, are a priori unknown. This study shows, through computer simulations, that using estimates of gametic phases for computing coancestry based on shared segments does not lead to a significant loss in the diversity maintained. This has been shown to be true even when the size of the population is very small as it is usually the case in populations subjected to conservation programmes.  相似文献   

6.
ABSTRACT

The Norwegian coastal goat is a national and endangered breed. Coastal goat populations are mainly divided with a large mainland and two small island populations. The objective of this study is to describe genetic diversity in the feral Skorpa island population and its relationship to the mainland coastal goat population (Selje) using the Norwegian milk goat population as a reference. Analyses were based on 96 samples genotyped by the CaprineSNP50 Beadchip from three populations; 7 Skorpa (SK), 37 Selje (SE) and 52 Norwegian milk goats (MG). The SK population had significantly less genetic variation and higher levels of inbreeding than the two other populations. It was more distant from the two mainland populations than they were from each other. The marginal contribution of the SK population to genetic diversity was small. Means of introducing genetic diversity into the SK population should be considered if the population is prioritized for conservation.  相似文献   

7.
Genetic structure of Norwegian horse breeds   总被引：1，自引：0，他引：1  
The evaluation of the genetic structure of four native Norwegian horse breeds was investigated using 35 genetic markers including nine biochemical loci and 26 microsatellites. The proportion of genetic variation measured as heterozygosity and the number of alleles indicated high variation in Fjord Horse and Coldblooded Trotter, but somewhat reduced variation in Døle Horse. No clear signs of bottleneck effects were found in either of the breeds, but significant inbreeding estimates in Nordland/Lyngen Horse may indicate subdivision of this breed. Significant population differentiation was detected between all breeds, also between the recently diverged Døle Horse and Coldblooded Trotter. The principal component analysis supports the close genetic relationship between these two breeds.  相似文献   

8.
Reasons for performing study: Warmblood horse studbooks aim to breed horses with a conformation that will enable elite future performance, but reduce the risk of injuries and lameness. Negative conformational traits, such as asymmetrical or ‘uneven’ forefeet would possibly diminish performance. Objectives: To assess the prevalence and heritability of uneven feet and its genetic relationship to other conformation traits as well as to sporting performance later in life in Warmblood riding horses. Methods: The databases of the Royal Dutch Warmblood Studbook (KWPN, n = 44,840 horses) and Royal Dutch Equestrian Sports Federation (KNHS, n = 33,459 horses in dressage and n = 30,474 horses in showjumping) were linked through the unique number of each registered horse. Therefore, heritabilities and genetic and phenotypic correlations could be estimated from the scores of the jury at studbook admission and the sports performance of that population in dressage and jumping over the period 1990–2002. Results: The prevalence of uneven feet was 5.3% on average, and increased from under 4.5% during the first 3 years of recording to over 8% in the years from 2000 onwards. Heritability estimates of foot conformation traits were moderate and ranged from 0.16 for heel height to 0.27 for hoof shape. The genetic correlation between the trait of uneven feet and performance in competition was negative but weak: ?0.09 with dressage and ?0.12 with showjumping. Conclusions: Predisposition to uneven feet can be reduced by selection. Because of weak genetic correlations, the increased prevalence is not directly associated with selection for better sports performance or higher conformation grade. If the trait ‘uneven feet’ arises from a disproportionate relationship between height at the withers and neck length, then selection on conformation grade might result in development of uneven feet. In general, limb conformation has a moderate genetic relationship to conformation grade and foot conformation traits have a genetic relationship to sporting performance. Reducing occurrence of uneven feet by selection is possible, without limiting progress in sport performance.  相似文献   

9.
Criollo horse populations descend from horses brought from the Iberian Peninsula over the period of colonization (15th to 17th century). They are spread throughout the Americas and have potentially undergone genetic hybridization with other breeds in the recent past. In this study, 25 autosomal microsatellites were genotyped in 50 horse breeds representing Criollo populations from 12 American countries (27 breeds), breeds from the Iberian Peninsula (19), one breed each from France and Morocco and two cosmopolitan horse breeds (Thoroughbred and Arabian). The genetic relationships among breeds identified five clusters: Celtic; Iberian; North American with Thoroughbred influence; most Colombian breeds; and nearly all other Criollo breeds. The group of “all other Criollo breeds” had the closest genetic relationship with breeds originating from the Iberian Peninsula, specifically with the Celtic group. For the whole set of Criollo breeds analysed, the estimated genetic contribution from other breeds was approximately 50%, 30% and 20% for the Celtic, Iberian and Arab-Thoroughbred groups, respectively. The spatial distribution of genetic diversity indicates that hotspots of genetic diversity are observed in populations from Colombia, Ecuador, Brazil, Paraguay and western United States, possibly indicating points of arrival and dispersion of Criollo horses in the American continent. These results indicate that Criollo breeds share a common ancestry, but that each breed has its own identity.  相似文献   

10.
The Carthusian horse is a Pura Raza Español (PRE) strain (CS), bred as a closed population since its creation more than 500 years ago. The aim of this study was to analyse for the first time its population structure and situation of variability combining both genealogical (GEL) and genomic (GEN) data. The GEL data comprised 348,429 pedigree records (56,105 CS horses), while the GEN analysis included the high-density genotypes (670,804 SNPs) of 287 horses. Pedigree completeness demonstrated its accuracy, showing a good correlation of GEL (F) and GEN (FROH) inbreeding coefficient in the case of PRE subpopulations partially related and non-related to Carthusian strain (0.68) but a lower value in the 100% Carthusian horses (0.42), due to the high weight of founders not detected by GEL analysis. GEN (PCA, AMOVA, and Admixture) and GEL analysis showed a good differentiation of subpopulations, but also a high level of introgression of the CS in the breed during past decades. A recent change in this trend was noteworthy, with a considerable reduction in CS variability and a genetic bottleneck (effective population sizes of 31.57 and 30.20 in GEL and GEN analysis, respectively, in last generation). The PRE has maintained its variability, and a considerable difference in estimated Ne by GEL (60.77) and GEN (188.0) data was observed. Using two sources of complementary information, it was found the existence of an ancient PRE strain with a unique genetic landmark, practically free from the influence of other equine populations.  相似文献   

11.
Abstract

A simulation study relevant for the Norwegian horse populations (D?le, Fjord and Nordland/Lyngen), compared with how the effective population size per generation is affected by: the population size, the proportion of offspring from three-year-old sires, performing phenotypic selection of sires at three years of age and random selection amongst these at four years of age (mating for 4 years). The distribution of family size (number of mated mares per sire) was as observed in the D?le. The population size had the largest effect on the effective population size per generation, and therefore at least 200 foals should be born and registered per year. The second most limiting factor was the proportion of young sires, where higher effective population size could be obtained by having more offspring from three-year-old sires (allowing more sires selected). Omitting selection only had a minor effect on the effective size.  相似文献   

12.
Effective population size is a key parameter in conservation genetics. In the management of conservation programs using pedigree information, there is a consensus that the optimal method for maximizing effective population size is to calculate the contribution of each potential parent (the number of offspring that each individual leaves to the next generation) by minimizing the global pedigree-based coancestry between potential parents weighted by their contributions. When using molecular data, the optimal method for managing genetic diversity will remain the same but now the molecular coancestry calculated from markers will replace the pedigree-based coancestry. However, in this situation, the concept of effective population size loses its meaning because with optimal molecular management, genetic diversity increases in early generations and therefore effective population size takes negative values. Furthermore, in the long term, the molecular effective population size does not attain an asymptotic value but it shows an unpredictable behaviour.  相似文献   

13.
ABSTRACT

The aim of this study was to evaluate genetic diversity within and between lines at the Norwegian live poultry gene bank as well as assessing the conservation value in an international context. Eight lines including the national breed, Jærhøns, were genotyped with the 600K Affymetrix® Axiom® Chicken Genotyping Array. The white egg layers were generally more inbred than the brown layers. Comparative analyses were carried out with 72 international populations of different origins. The lines that were last bred for commercial production in Norway, Norbrid, are clearly separated from the rest of the international set and more closely related to the current commercial lines. The brown egg layer Norbrid 7 has the highest relative contribution to genetic diversity. The Norwegian genebank lines are of conservation value in a national and international perspective, as they all add genetic diversity to the global set.  相似文献   

14.
试验旨在以线粒体DNA(mitochondrial DNA,mtDNA)为切入点,研究建昌马的母系遗传多样性与系统进化。从建昌马(n=39)血液中提取基因组DNA,用PCR方法扩增mtDNA D-loop区并直接测序,分析其高变区247 bp序列信息,统计mtDNA D-loop区的单倍型及变异位点,计算单倍型多样性(haplotype diversity,Hd)、核苷酸多样性(nucleotide diversity,Pi)和平均核苷酸变异数(average number of nucleotide differences,K)。构建包括建昌马在内的19个品种马的NJ系统进化树,计算各品种间的遗传距离。结果显示,试验获得了清晰的PCR扩增产物,并通过直接测序方法获得了约1200 bp的序列。39匹建昌马mtDNA D-loop区247 bp序列(其中1个样品缺失1 bp)的AT碱基含量为61.45%,属AT碱基对富集区,检测到33个多态性位点,共显示26种单倍型,其中4种为共享单倍型,且Hap7和Hap1为优势单倍型,单倍型多样性为0.947,核苷酸多样性为0.02399,平均核苷酸变异数为5.901,显示丰富的母系遗传多样性;NJ系统进化树显示,建昌马分布在A、C、D、E、F、G共6个支系中,约50%的样品分布在A支系,显示出复杂的母系起源;建昌马与关中马的遗传距离最小(0.021),其次是三河马、文山马、韩国车巨马(0.024),与韩国济州岛马遗传距离最大(0.032)。本研究结果表明,建昌马的mtDNA D-loop高变区遗传多样性丰富,具有多个母系起源,且A支系占有明显优势,与关中马、文山马可能有共同的母系起源。  相似文献   

15.
The content of cadmium and selenium in horse kidneys from Jutland , Denmark, in relation to age, local geographical variation and possible relationship between the two elements has been investigated. During the winter of 1982-1983 kidneys from 50 horses were sampled and analysed for cadmium and selenium. The cadmium content of the horse kidneys was recorded in connection with the age of the horses. The cadmium level increases until the animal has reached approximately 7 years of age. At this age the cadmium concentration levels off. A significant regional difference was shown. The cadmium content is higher in horse kidneys from South and Central Jutland than in kidneys from North Jutland (Fig. 2). This geographic pattern is consistent with the one for atmospheric deposition of cadmium and cadmium content in Danish cattle kidneys from Jutland . The cadmium level in kidneys from Danish horses is considerably lower than the level in Norwegian and Swedish horse kidneys. Differences in water hardness and atmospheric deposition may explain some of this difference within Scandinavian countries. The selenium concentration shows no relationship with neither age, cadmium content nor place of rearing. So, the study did not reveal any relationship between the cadmium and selenium concentrations in horse kidneys. The high level of cadmium found in Danish horse kidneys emphasizes the importance of a prohibition against the use of the kidneys in animal and human nutrition, as proposed by others.  相似文献   

16.
In this study it was investigated whether the "Einsiedler" warmblood horse, a historically old horse population from central Switzerland (Abbey of Einsiedeln), is distinguishable from micellaneous horse breeds, using molecular genetic techniques. The breeding history of Einsiedler horses is characterised by systematic line breeding through the dams. Therefore, two Einsiedler dam lines (N = 28), going back to the middle of the 19th century according to pedigree entries, were the focus of the survey. Random samples of diverse warmblood horse populations, but also samples from more distinct types of horse breeds, served as comparison populations (N = 52).Variation in the mitochondrial genome appeared to be only partially informative to demarcate the studied horses, as horses of distinct breeds may share identical mtDNA sequence fragments. Both dam lines revealed haplotypes commonly found in Iberian horse breeds. This is to take as an indication on the genetic origin of Einsiedler horses. Furthermore, the Klima dam line held a homologous mtDNA sequence fragment with E. ferus przewalskii. Therefore, this seems to be a phylogenetically old haplotype. The analysis of microsatellite loci revealed that horses from the two Einsiedler dam lines were in fact distinguishable from more distinct types of horses, but not from closely related European warmblood horse breeds and English thoroughbred.  相似文献   

17.
In this study, genetic analyses of diversity and differentiation were performed on five horse breeds raised in Algeria (Barb, Arab‐Barb, Arabian, Thoroughbred and French Trotter). All microsatellite markers were highly polymorphic in all the breeds. A total of 123 alleles from 14 microsatellite loci were detected in 201 horses. The average number of alleles per locus was the highest in the Arab‐Barb horses (7.86) and lowest in the thoroughbred breed (5.71), whereas the observed and expected heterozygosities per breed ranged from 0.71 (Thoroughbred) to 0.752 (Barb) and 0.71 (Thoroughbred) to 0.77 (Arab‐Barb), respectively. The genetic differentiation between the breeds was significant (p < 0.01) based on the infinitesimal model (FST). Three different approaches for evaluating the genetic relationships were applied. Genetic distances, the factorial correspondence analysis and structure analysis showed that a significant amount of genetic variation is maintained in the native horse populations and the other breeds. The Barb and Arab‐Barb breeds seem to be the most genetically related and support the decision to consider the breeds as same population.  相似文献   

18.
The primary objective of most horse breeding operations was to maximize reproductive efficiency and minimize the cost of producing live foals. Here, we compared individual horses from the Thoroughbred population (n = 17), known as a horse breed with poor reproductive performance, with other six horse populations (n = 28), to detect genomic signatures of positive selection underlying of reproductive traits. A number of protein-coding genes with significant (p-value <.01) higher FST values (616 genes) and a lower value for nucleotide diversity (π) (310 genes) were identified. The results of our study revealed some candidate genes such as IGFBP2, IGFBP5, GDF9, BRINP3 and GRID1 are possibly associated with functions influencing reproductive traits. These genes may have been under selection due to their essential roles in reproduction performance in horses. The candidate selected genes identified in this work should be of great interest for future research into genetic architecture of traits relevant to horse breeding programmes.  相似文献   

19.
The pedigree of the current Austrian Noriker draught horse population comprising 2808 horses was traced back to the animals considered as founders of this breed. In total, the number of founders was 1991, the maximum pedigree length was 31 generations, with an average of 12.3 complete generations. Population structure in this autochthonous Austrian draught horse breed is defined by seven breeding regions (Carinthia, Lower Austria, Salzburg, Styria, Tyrol, Upper Austria and Vorarlberg) or through six coat colour groups (Bay, Black, Chestnut, Roan, Leopard, Tobiano). Average inbreeding coefficients within the breeding regions ranged from 4.5% to 5.5%; for the colour groups, the coefficients varied from 3.5% to 5.9%. Other measures of genetic variability like the effective number of founders, ancestors and founder genomes revealed a slightly different genetic background of the subpopulations. Average coancestries between and within breeding areas showed that the Salzburg population may be considered as the nucleus or original stock whereas all other subpopulations showed high relationship to horses from Salzburg. The target of draught horse breeding in the 21st century does not meet the breeding concept of maximizing genetic gains any more. Stabilizing selection takes place. In this study, we show that demographic factors as well as structure given by different coat colours helped to maintain genetic diversity in this endangered horse breed.  相似文献   

20.
利用微卫星标记对宁强矮马和蒙古马遗传多样性的研究   总被引：2，自引：0，他引：2  
通过8个微卫星位点的多态性检测对宁强矮马和蒙古马共83个个体进行了遗传多样性分析。计算各微卫星位点的等位基因频率、有效等位基因数(Ne)、多态信息含量(PIC)、杂合度(H)和F统计量。结果表明:8个微卫星座位中HMS2变异最大,HTG6变异最小;蒙古马的Ne、PIC、H的平均值均高于宁强马;总群体的平均遗传分化系数Fst为0.017(P<0.01),群体内近交系数Fis为0.171(P<0.01)。说明蒙古马和宁强矮马虽外形和性能上有很大差异,但在品种形成和进化上有着较近的遗传关系。  相似文献   

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