Conservation priorities and optimum allocation of conservation funds for Vietnamese local chicken breeds

The objectives of this study were to estimate conservation potential of Vietnamese local breeds and to investigate optimal allocation of conservation funds to maximize genetic diversity conserved between these breeds. Twenty-nine microsatellites were genotyped in 353 individuals from nine Vietnamese local chicken breeds and two chicken breeds of Chinese origin. The Vietnamese chicken breeds were sampled from the northern and southern parts of Vietnam while the two Chinese breeds have been kept as conservation flocks at the National Institute of Animal Sciences, Hanoi. The Weitzman approach was used to assess alternative strategies for conserving genetic diversity between breeds. Three different models, which reflect the range of possible functions in typical conservation situations, were applied. An average extinction probability of 48.5% was estimated for all Vietnamese chicken breeds. The highest conservation potential was found in the Te, Dong Tao and Ac chicken breeds, whereas the lowest corresponding values were observed in the Ri and Mia chicken breeds. The conservation funds were mainly allocated to the same three breeds (Te, Dong Tao and Ac) under all three models. This study suggests that conservation potential of the Vietnamese chicken breeds varies considerably. Population priorities for allocation of conservation funds in this study do not depend on the cost model used. The three breeds (Te, Dong Tao and Ac) with the highest conservation potential should be the prime candidates to be allocated conservation funds if the conservation budgets are limited.     

Genetic diversity of Swiss sheep breeds in the focus of conservation research

There is constant pressure to improve evaluation of animal genetic resources in order to prevent their erosion. Maintaining the integrity of livestock species as well as their genetic diversity is of paramount interest for long-term agricultural policies. One major use of DNA techniques in conservation is to reveal genetic diversity within and between populations. Forty-one microsatellites were analysed to assess genetic diversity in nine Swiss sheep breeds and to measure the loss of the overall diversity when one breed would become extinct. The expected heterozygosities varied from 0.65 to 0.74 and 10.8% of the total genetic diversity can be explained by the variation among breeds. Based on the proportion of shared alleles, each of the nine breeds were clearly defined in their own cluster in the neighbour-joining tree describing the relationships among the breeds. Bayesian clustering methods assign individuals to groups based on their genetic similarity and infer the number of populations. In STRUCTURE, this approach pooled the Valais Blacknose and the Valais Red. With BAPS method the two Valais sheep breeds could be separated. Caballero & Toro approach (2002) was used to calculate the loss or gain of genetic diversity when each of the breeds would be removed from the set. The changes in diversity based on between-breed variation ranged from −12.2% (Valais Blacknose) to 0% (Swiss Black Brown Mountain and Mirror Sheep); based on within-breed diversity the removal of a breed could also produce an increase in diversity (−0.6% to + 0.6%). Allelic richness ranged from 4.9 (Valais Red) to 6.7 (Brown Headed Meat sheep and Red Engadine Sheep). Breed conservation decisions cannot be limited to genetic diversity alone. In Switzerland, conservation goals are embedded in the desire to carry the cultural legacy over to future generations.     

How developments in cryobiology, reproductive technologies and conservation genomics could shape gene banking strategies for (farm) animals

Many local breeds are currently at risk because of replacement by a limited number of specialized commercial breeds. Concurrently, for many breeds, allelic diversity within breeds declines because of inbreeding. Gene banking of germplasm may serve to secure the breeds and the alleles for any future use, for instance to recover a lost breed, to address new breeding goals, to support breeding schemes in small populations to minimize inbreeding, and for conservation genetics and genomics research. Developments in cryobiology and reproductive technology have generated several possibilities for preserving germplasm in farm animals. Furthermore, in some mammalian and bird species, gene banking of material is difficult or impossible, requiring development of new alternative methods or improvement of existing methods. Depending on the species, there are interesting possibilities or research developments in the use of epididymal spermatozoa, oocytes and embryos, ovarian and testicular tissue, primordial germ cells, and somatic cells for the conservation of genetic diversity in farm- and other animal species. Rapid developments in genomics research also provide new opportunities to optimize conservation and sampling strategies and to characterize genome-wide genetic variation. With regard to gene banks for farm animals, collaboration between European countries is being developed through a number of organizations, aimed at sharing knowledge and expertise between national programmes. It would be useful to explore further collaboration between countries, within the framework of a European gene banking strategy that should minimize costs of conservation and maximize opportunities for exploitation and sustainable use of genetic diversity.     

Genetic diversity in native and commercial breeds of pigs in Portugal assessed by microsatellites

Population structure and genetic diversity in the Portuguese native breeds of pigs Alentejano (AL), Bísaro (BI), and Malhado de Alcoba?a (MA) and the exotic breeds Duroc (DU), Landrace (LR), Large White (LW), and Pietrain were analyzed by typing 22 microsatellite markers in 249 individuals. In general, the markers used were greatly polymorphic, with mean total and effective number of alleles per locus of 10.68 and 4.33, respectively, and an expected heterozygosity of 0.667 across loci. The effective number of alleles per locus and expected heterozygosity were greatest in BI, LR, and AL, and least in DU. Private alleles were found in 9 of the 22 markers analyzed, mostly in AL, but also in the other breeds, with the exception of LW. The proportion of loci not in Hardy-Weinberg equilibrium in each breed analyzed ranged between 0.23 (AL) and 0.41 (BI, LW, and Pietrain), mostly because of a less than expected number of heterozygotes in those loci. With the exception of MA, all breeds showed a significant deficit in heterozygosity (F(IS); P < 0.05), which was more pronounced in BI (F(IS) = 0.175) and AL (F(IS) = 0.139), suggesting that inbreeding is a major concern, especially in these breeds that have gone through a genetic bottleneck in the recent past. The analysis of relationships among breeds, assessed by different methods, indicates that DU and AL are the more distanced breeds relative to the others, with the closest relationship being observed between LR and MA. The degree of differentiation between subpopulations (F(ST)) indicates that 0.184 of the total genetic variability can be attributed to differences among breeds. The analysis of individual distances based on allele sharing indicates that animals of the same breed generally cluster together, but subdivision is observed in the BI and LR breeds. Furthermore, the analysis of population structure indicates there is very little admixture among breeds, with each one being identified with a single ancestral population. The results of this study confirm that native breeds of pigs represent a very interesting reservoir of allelic diversity, even though the current levels of inbreeding raise concerns. Therefore, appropriate conservation efforts should be undertaken, such as adopting strategies aimed at minimizing inbreeding, to avoid further losses of genetic diversity.     

An evaluation of genetic diversity indices of the Red Bororo and White Fulani cattle breeds with different molecular markers and their implications for current and future improvement options

The genetic diversity of the Red Bororo and White Fulani cattle breeds of Cameroon and Nigeria was assessed with a panel of 32 markers. Estimates for the various indices of genetic diversity, total number of alleles (TNA), mean observed number of alleles (MNA), mean effective number of alleles (MNE), observed heterozygosity (H _ob) and expected heterozygosity (H _ex), were higher at microsatellite loci than at protein loci. Mean H _ex values were above 71% at microsatellite loci in all the breeds and ranged from 37% to 41.6% at milk protein loci and from 40.9% to 45.6% at blood protein loci. The highest TNA and MNA of microsatellites were recorded for the Nigerian White Fulani. MNE of milk protein loci was highest in the Cameroonian Red Bororo, while TNA of blood protein loci was highest in the Cameroonian White Fulani. The high genetic diversity levels indicate the presence of the necessary ingredients for improvement breeding and conservation. Multi-locus estimates of within-population inbreeding (f), total inbreeding (F) and population differentiation (θ) of the breeds were significantly different from zero, except for θ of blood proteins. A high level of gene flow was found between the breeds (5.829). The phylogenetic relationship existing among the four breeds is greatly influenced by location. The high gene flow between the breeds may lead to a loss of genetic diversity through genetic uniformity and a reduction in opportunities for future breed development. We propose an improvement scheme with aims to prevent loss of genetic diversity, improve productivity and reduce uncontrolled genetic exchanges between breeds.     

Gene dropping analysis of founder contributions in a closed Japanese black cattle population

Gene dropping simulation was applied to Japanese Black cattle population in Hyogo prefecture, to examine the survivals of alleles originated from founder animals. In the analysis, unique alleles were assigned to founders, and the genotypes of all descendants along the actual pedigree were generated through Monte Carlo simulation following Mendelian segregation rules. By replicating this process 10 000 times, the distribution of frequencies of alleles from each founder was estimated. From the distribution, several quantities useful for the management of genetic diversity, such as the probability of allele extinction and the probability of alleles surviving at a critically low frequency were derived. The materials used were 68 781 animals born in 1955–1998 and their pedigree records traced back to the population in 1937 or before. The expected number of alleles retained in the population drastically decreased during the analyzed period, and reached to 57.9 in the population of 1998, which was only 3.3% of the total number of alleles assigned to founders. Detailed analysis of major founders with relatively high genetic contributions to the current population revealed that alleles from most of the major founders are now at high risk of future extinction. These results strongly suggest that for the management of genetic diversity, the genetic contributions of founders are not fully informative, and emphasize the importance of the detection of live animals having founder alleles with high extinction possibilities.     

基于全基因组SNP标记分析中国地方鸡品种的遗传多样性和种群结构

旨在对中国地方鸡品种的遗传多样性与种群结构进行分析。本研究使用Affymetrix Axiom 600K高密度鸡基因分型芯片对来自8个品种的157只地方鸡及233只商品鸡进行基因分型,以品种作为分组来计算各分组的观测杂合度、期望杂合度、次等位基因频率、近交系数及核苷酸多样性分析地方鸡群体的遗传多样性,利用进化树、主成分分析、群体结构、MDS等方法分析鸡群体的群体结构,基于状态同源(IBS)和群体分化系数(Fst)分析种群内部与种群之间的亲缘关系,利用长纯合片段(runs of homozygosity, ROH)估算得到基于ROH的近交系数。结果表明,各群体的观测杂合度均高于期望杂合度,次等位基因频率在0.175～0.236之间,近交系数在0.018～0.205之间,核苷酸多样性在0～6×10^-4之间,进化树与主成分分析表明品种间出现了明显的群体分化,地方鸡群体与商品鸡群的MDS分析发现我国地方鸡与商业肉鸡品种的遗传距离较近;IBS遗传距离在0.092 9～0.319 9之间;各品种成对Fst分析表明,群体间呈现中高分化程度(0.09～0.22);此次分析共得到了...     

Analysis of genetic diversity and the determination of relationships among western Mediterranean horse breeds using microsatellite markers

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.     

Assessment of genetic diversity and conservation priority of Omani local chickens using microsatellite markers

Designing strategies for conservation and improvement livestock should be based on assessment of genetic characteristics of populations under consideration. In Oman, conservation programs for local livestock breeds have been started. The current study assessed the genetic diversity and conservation potential of local chickens from Oman. Twenty-nine microsatellite markers were analyzed in 158 birds from six agroecological zones: Batinah, Dhofar, North Hajar, East Hajar, Musandam, and East Coast. Overall, a total of 217 alleles were observed. Across populations, the average number of alleles per locus was 7.48 and ranged from 2 (MCW98 and MCW103) to 20 (LEI094). The mean expected heterozygosity (H _E) was 0.62. Average fixation index among populations (F _ST) was 0.034, indicating low population differentiation, while the mean global deficit of heterozygotes across populations (F _IT) was 0.159. Based on Nei’s genetic distance, a neighbor-joining tree was constructed for the populations, which clearly identified the Dhofar population as the most distant one of the Omani chicken populations. The analysis of conservation priorities identified Dhofar and Musandam populations as the ones that largely contribute to the maximal genetic diversity of the Omani chicken gene pool.     

Conservation priorities for the different lines of Dutch Red and White Friesian cattle change when relationships with other breeds are taken into account

From a genetic point of view, the selection of breeds and animals within breeds for conservation in a national gene pool can be based on a maximum diversity strategy. This implies that priority is given to conservation of breeds and animals that diverge most and overlap of conserved diversity is minimized. This study investigated the genetic diversity in the Dutch Red and White Friesian (DFR) cattle breed and its contribution to the total genetic diversity in the pool of the Dutch dairy breeds. All Dutch cattle breeds are clearly distinct, except for Dutch Friesian breed (DF) and DFR and have their own specific genetic identity. DFR has a small but unique contribution to the total genetic diversity of Dutch cattle breeds and is closely related to the Dutch Friesian breed. Seven different lines are distinguished within the DFR breed and all contribute to the diversity of the DFR breed. Two lines show the largest contributions to the genetic diversity in DFR. One of these lines comprises unique diversity both within the breed and across all cattle breeds. The other line comprises unique diversity for the DFR but overlaps with the Holstein Friesian breed. There seems to be no necessity to conserve the other five lines separately, because their level of differentiation is very low. This study illustrates that, when taking conservation decisions for a breed, it is worthwhile to take into account the population structure of the breed itself and the relationships with other breeds.     

Inbreeding and genetic diversity in dogs: results from DNA analysis

This review assesses evidence from DNA analysis to determine whether there is sufficient genetic diversity within breeds to ensure that populations are sustainable in the absence of cross breeding and to determine whether genetic diversity is declining. On average, dog breeds currently retain approximately 87% of the available domestic canine genetic diversity. Requirements that breeding stock must be 'clear' for all genetic disorders may firstly place undue genetic pressure on animals tested as being 'clear' of known genetic disorders, secondly may contribute to loss of diversity and thirdly may result in the dissemination of new recessive disorders for which no genetic tests are available. Global exchange of genetic material may hasten the loss of alleles and this practice should be discussed in relation to the current effective population size of a breed and its expected future popularity. Genomic data do not always support the results from pedigree analysis and possible reasons for this are discussed.     

利用微卫星标记分析不同保种场的保种效果

分别采用23对微卫星引物分析了我国两个地方品种北京油鸡和北京鸭在不同保种场的保种效果。检测了北京油鸡和北京鸭共计240个个体的基因型,通过计算等位基因数量、遗传杂合度(H)、多态信息含量(PIC)、F统计量和Nei氏遗传距离分析了北京油鸡和北京鸭群体内与群体间的变异,比较了两个品种不同保种场的保种效果。在所检测的4个群体中,各群体均有较高的多态性,其杂合度均超过了0.5,除微卫星座位APL82(北京鸭Ⅱ)为纯合位点外,各位点等位基因数量为2~16个。结果表明,4个保种场均较好地保存了这些品种的遗传多样性,但同一品种保种场间保种群体已经发生了分化。     

浦东白猪遗传多样性及繁殖性能的变化分析

试验旨在研究浦东白猪现存群体的遗传多样性及其繁殖性能变化的原因。利用全基因组范围内的遗传标记（SNPs）,对比6个太湖流域地方品种及3个西方引进品种,对浦东白猪的遗传多样性进行了分析。同时利用落入繁殖候选基因内的SNPs,分析了群体的多样性及结构。结果显示,相较于本研究中所选择的太湖流域地方品种及西方引进品种,浦东白猪的遗传多样性较太湖流域地方品种低;除枫泾猪外,浦东白猪繁殖相关SNPs的多态性标记的比例、期望杂合度最低,等位基因丰度仅高于杜洛克猪;主成分分析（PCA）结果揭示浦东白猪繁殖相关SNPs位点仍具有其群体独特性。研究结果揭示了浦东白猪现存群体遗传多样性较低,繁殖性能的退化可能是由于一些有利等位基因的灭绝、繁殖相关基因多态性及个体杂合性的降低所致。但是浦东白猪仍然携带一定数量的有利等位基因且依旧具有其群体独特性,暗示浦东白猪仍具有较高的保种价值。本研究为浦东白猪后期的选育、保种和开发利用提供了一定的参考。     

Managing genomes of conserved livestock breeds with historical introgression to decrease genetic overlap with other breeds

Recovering the native genetic background of a breed and increasing the founder genome equivalent (FGE) that is contributed by a breed to the gene pool of the species can increase its value for conservation. The suitability of several strategies was compared, whereby a hypothetical multi‐breed population, the core set, was used to approximate the genetic diversity of the species. Twenty‐five generations of management were simulated based on genotypes of German Angler cattle. The scenarios were compared when the kinship reached 0.10. The native contribution (NC) increased in a population with 400 births per generation from 0.317 to 0.706, whereas 1,000 births enabled to reach 0.894. This scenario maximized the NC, constrained the native kinship, and the kinship of the core set so that its genetic diversity could not decrease. It increased the proportions of mainstream breeds because their genes were removed from the target breed. A substantial increase of the FGE was achieved in some other scenarios, which arose from reduced genetic overlap and from increased diversity within the breed. The latter factor is especially important for breeds with high contributions to the core set.     

Genetic Diversity and Degradation Analysis of Reproductive Performance of Pudong White Pig

This study was aimed to investigate the genetic diversity and the reason for the degradation of the reproductive performance of Pudong White pig. The genetic diversity of Pudong White pig, six Taihu pig breeds and three Western pig breeds were analyzed based on the genome-wide SNPs.The genetic diversity and population structure of these pig breeds were also explored based on the SNPs related to reproductive traits. The results showed that Pudong White pig displayed a lower level of the genetic diversity than the Taihu area pig breeds. For the reproductive-related loci, except for Fengjing pig, Pudong White pig displayed the lowest propotion of polymorphic markers, expected heterozygosities and allelic richness (excluded Duroc pig). The result of PCA showed that Pudong White pig displayed its uniqueness in the reproductive-related SNPs. With the comparsion of Taihu pigs and Western populations, Pudong White pig displayed a lower level of the genetic diversity and more homozygous reproductive-related loci. Nevertheless, a certain number of favorable alleles were still harbored in Pudong White pig, which might result high heterosis in the offsprings. In conclusion, the results of this study might provide some valuable information for the breeding, conservation and utilization of this breed.     

Analysis of genetic diversity and conservation priorities for six north Ethiopian cattle breeds

Genetic diversity and conservation potential of six indigenous cattle breeds of north Ethiopia was analysed based on 20 microsatellite markers using core set methods. Expected future diversity (assuming assigned extinction probabilities are valid for the next 20-50 years) were 0.988+/-0.011 and 0.980+/-0.010 with expected loss of diversity estimated at 0.02% and 0.74% of current level for the Maximum Variance Total (MVT) and Maximum Variance Offspring (MVO) core sets, respectively. Even though all breeds have contributed to current diversity levels, the Afar and Abergelle breeds only contributed 51% and 62% to the MVT and MVO core sets, respectively, while the Raya breed contributed only 6% and 1.5% to the MVT and MVO core set diversities, respectively. Moreover, prioritizing the six north Ethiopian cattle breeds using the conservation potential obtained from the MVT core set method seems reasonable considering the origin and migration histories of the breeds. Our results suggest that the total current genetic diversity of these breeds can be sufficiently maintained by designing a conservation strategy based on conservation potential of each breed from the MVT core set so that priority is given to lowering the extinction probabilities of breeds with high conservation potential to zero.     

应用系统进化方法评估徐海鸡遗传资源

利用简化基因组SNPs数据分析徐海鸡及周边地方鸡种遗传多样性,为徐海鸡的保护和利用提供支持.收集徐海鸡等13个地方鸡种血液样品,提取基因组DNA,应用简化基因组测序技术进行SNP分型,获取群体遗传学参数,并以邻接法、最大似然法、贝叶斯法构建系统进化树.结果显示:徐海鸡基因组SNPs观测杂合度为0.18,期望杂合度为0....     

Population genetic analysis of the Brahman cattle (Bos indicus) in Colombia with microsatellite markers

Summary The Brahman is one of the most popular breeds for meat production in the Neotropics. However, genetic studies of the breed in Latin American countries have only recently begun. In total, 178 animals of the Brahman breed from 20 Colombian provinces were genotyped at 11 microsatellite markers with the aim of studying the genetic diversity of this population and its genetic relationships with zebuine and taurine breeds. The outcomes of multivariate analyses, Bayesian inferences and inter‐individual genetic distances suggested that there is no genetic sub‐structure in the population, because of the high rate of animal migration among provinces. The population shows a high degree of heterozygosity and allelic diversity compared with other breeds, reflecting its multibreed origin. The study of the genetic relationships among the breeds reveals that the Brahman breed belongs to the zebuine group. However, it is the population nearest to taurine breeds with high frequencies of taurine alleles. Intensive artificial selection may have favoured the taurine alleles after the breed was formed. There has also been some degree of mixture with local taurine breeds while the Brahman breed has evolved in Colombia.     

利用微卫星标记分析江苏三个地方鸡品种的遗传多样性

利用30个微卫星DNA标记对3个江苏地方鸡品种进行遗传多样性分析，通过计算等位基因频率、多态信息含量、平均杂合度、有效等位基因数和遗传距离，评估各品种内遗传变异和各品种间遗传相关。结果表明：江苏的3个品种在30个微卫星上共发现196个等位基因，其中96个等位基因为三个品种共有，47个等位基因为各品种所特有；3个地方鸡品种的平均杂合度：狼山鸡为0．655，鹿苑鸡为0．681，溧阳鸡为0．687；狼山鸡与溧阳鸡的遗传距离较小，而两鸡与鹿苑鸡的遗传距离较远。     

Genetic Characterization of Mangalarga Marchador Breed Horses Based on Microsatellite Molecular Markers

The Mangalarga Marchador (MM) horse breed has expressive importance in the Brazilian economy. Thus, the aim of this study was to investigate diversity in the MM breed. A database with a total of 3,193 genotyped horses was used (MM, n = 2,829; Andalusian – AND, n = 67; Pure Blood Lusitano – LUS, n = 43; English Thoroughbred – THO, n = 54; Arabian – ARA, n = 99; Campolina – CAM, n = 61; and Mangalarga – MAN, n = 40) for 13 microsatellite. Diversity parameters were estimates, such as mean number of alleles (Nm_a) and the number of rare alleles (AR), expected heterozygosity (He), F statistics, genetic distances, Hardy-Weinberg equilibrium test (HWE), population structure, and others. The Nm_a was 10.85, the AR was prevalent in the MM, and the He was 0.7402. In MM, the values of Fis (−0.0195), Fit (0.0566), Fst (0.0748), and deviations of HWE were observed. The genetic distances of the ARA and THO breeds with the other breeds were greater than the distances between the Brazilian breeds and between these and the breeds in the Iberian Peninsula. The population structure indicated that MM was substructured, yet there were some more genetically defined breeding farms. The genetic diversity is satisfactory for MM conservation, but the population is substructure, and parameters indicate moderate gene flow and the existence, though few, of crosses with other horse breeds. Immediate implementation of a genetic breeding program is required, especially seeking to conserve the structure of the MM breed as a well-defined genetic entity.