Genetic diversity of eleven European pig breeds

A set of eleven pig breeds originating from six European countries, and including a small sample of wild pigs, was chosen for this study of genetic diversity. Diversity was evaluated on the basis of 18 microsatellite markers typed over a total of 483 DNA samples collected. Average breed heterozygosity varied from 0.35 to 0.60. Genotypic frequencies generally agreed with Hardy-Weinberg expectations, apart from the German Landrace and Schwäbisch-Hällisches breeds, which showed significantly reduced heterozygosity. Breed differentiation was significant as shown by the high among-breed fixation index (overall F_ST = 0.27), and confirmed by the clustering based on the genetic distances between individuals, which grouped essentially all individuals in 11 clusters corresponding to the 11 breeds. The genetic distances between breeds were first used to construct phylogenetic trees. The trees indicated that a genetic drift model might explain the divergence of the two German breeds, but no reliable phylogeny could be inferred among the remaining breeds. The same distances were also used to measure the global diversity of the set of breeds considered, and to evaluate the marginal loss of diversity attached to each breed. In that respect, the French Basque breed appeared to be the most "unique" in the set considered. This study, which remains to be extended to a larger set of European breeds, indicates that using genetic distances between breeds of farm animals in a classical taxonomic approach may not give clear resolution, but points to their usefulness in a prospective evaluation of diversity.     

Microsatellite and Mitochondrial Diversity Analysis of Native Pigs of Indo-Burma Biodiversity Hotspot

Assessment of genetic diversity in indigenous animals is an important and essential task for animal genetic improvement studies as well as conservation decision-making. The genetic diversity and evolutionary relationships among geographically and phenotypically distinct three pig breeds/types native to Indo-Burma and Eastern Himalayan global biodiversity hotspots were determined by genotyping with a panel of 22 ISAG recommended microsatellite loci as well as sequencing partial MTRNR1gene. The mean number of alleles per locus, effective number of alleles and observed heterozygosity were found to be 11.27 ± 0.85, 5.29 ± 0.34, and 0.795 ± 0.01, respectively. The moderate F_ST value (0.115 ± 0.01) indicated a fair degree of genetic differentiation among the native breeds. The Nei’s unbiased genetic identity estimates indicated less genetic distance (0.2909) between Niang Megha and Tenyi Vo pigs than the both individually with Ghoongroo breed. The divergence time was also estimated from the microsatellite analysis. Analysis of MTRNR1gene revealed distinct clustering of native Indian pigs with Chinese pigs over European pigs. The study revealed the abundance of genetic variation within native Indian pigs and their relationships as well as genetic distances.     

Assessment of genetic diversity of Korean native pig (Sus scrofa) using AFLP markers

In order to assess the genetic diversity and genetic relationships among the six commercial pig breeds including the Korean native pig, we performed an amplified fragment length polymorphism (AFLP) analysis. Applying the three EcoRI/TagI primer combinations to 54 individual pig samples out of six breeds, a total of 186 AFLP bands were generated, 67 (36%) of which were identified as polymorphic bands. From these polymorphic bands, the three estimates (percentage of polymorphic loci, Neis heterozygosity and Shannon index) of genetic diversity, G(ST) estimates, Neis unbiased genetic distance and two indices of genetic similarity were calculated. From all the calculations of genetic diversity, the lowest genetic diversity was exhibited in the Korean native pig, and the highest in the Chinese Yanbian pig. Given the mean G(ST) value (G(ST) = 0.390) across all pigs examined, levels of apparent breed subdivision were considerable. A UPGMA tree of individuals based on Jaccards similarity index showed that the Korean native pig formed a distinct cluster from the other five pigs. In addition, the tree displayed that all the individuals except for six individuals were grouped into their breeds. Principal component analysis based on the binary data matrix of either presence or absence confirmed the distinctness of the Korean native pig from the other pigs. Our results indicate that the Korean native pig has a low level of genetic diversity and is distinct from the five pig breeds, confirming the results from previous microsatellite data. The findings also suggest that AFLP analysis may be a valuable tool for revealing genetic relationships and genetic diversity among different pig breeds.     

Genetic diversity in the Churra tensina and Churra lebrijana endangered Spanish sheep breeds and relationship with other Churra group breeds and Spanish mouflon

The aim of the present study was to estimate the genetic intra-breed variability of Churra tensina and Churra lebrijana endangered breeds and to establish genetic relationships with Churra, Latxa and Merino breeds, as well as Spanish mouflon, by using 28 microsatellite markers, to provide useful information for their conservation. Allele frequencies and heterozygosity revealed high genetic variation in the two endangered breeds despite their small population size. Estimates of inbreeding coefficient (F_IS) were significant for all breeds studied, except for Churra lebrijana breed. The highest inbreeding coefficient (F_IS = 0.143) was found in the Spanish mouflon. Genetic differentiation tests (F_ST = 0.121) and assignment of individuals to populations indicated the existence of defined breed populations, and low genetic flow between these breeds. The highest pairwise Reynolds distance (D_R) values were observed between Mouflon and the domestic sheep breeds. Considering only domestic sheep breeds, the Churra lebrijana breed showed the highest pairwise D_R values_. The lowest values were found between Latxa and the other domestic sheep, except for Churra lebrijana. Results of pairwise D_R values, as well as phylogenetic tree and bottleneck analysis showed an important genetic isolation of the Churra lebrijana breed from the other Churra types, and genetic signatures of a demographic bottleneck. Finally, structure analysis of populations detected a population subdivision in the Latxa sheep breed. In conclusion, this study presents valuable insight into the existing genetic variability of two Spanish endangered breeds, as well as the first study in Spanish mouflon based on microsatellite analysis. The high degree of variability demonstrated in Churra tensina and Churra lebrijana implies that these populations are rich reservoirs of genetic diversity.     

Genetic relationships among twelve Chinese indigenous goat populations based on microsatellite analysis

Twelve Chinese indigenous goat populations were genotyped for twenty-six microsatellite markers recommended by the EU Sheep and Goat Biodiversity Project. A total of 452 goats were tested. Seventeen of the 26 microsatellite markers used in this analysis had four or more alleles. The mean expected heterozygosity and the mean observed heterozygosity for the population varied from 0.611 to 0.784 and 0.602 to 0.783 respectively. The mean F_ST (0.105) demonstrated that about 89.5% of the total genetic variation was due to the genetic differentiation within each population. A phylogenetic tree based on the Nei (1978) standard genetic distance displayed a remarkable degree of consistency with their different geographical origins and their presumed migration throughout China. The correspondence analysis did not only distinguish population groups, but also confirmed the above results, classifying the important populations contributing to diversity. Additionally, some specific alleles were shown to be important in the construction of the population structure. The study analyzed the recent origins of these populations and contributed to the knowledge and genetic characterization of Chinese indigenous goat populations. In addition, the seventeen microsatellites recommended by the EU Sheep and Goat Biodiversity Project proved to be useful for the biodiversity studies in goat breeds.     

Evaluation of genetic diversity in Chinese indigenous chicken breeds using microsatellite markers

China is rich in chicken genetic resources, and many indigenous breeds can be found throughout the country. Due to poor productive ability, some of them are threatened by the commercial varieties from domestic and foreign breeding companies. In a large-scale investigation into the current status of Chinese poultry genetic resources, 78 indigenous chicken breeds were surveyed and their blood samples collected. The genomes of these chickens were screened using microsatellite analysis. A total of 2740 individuals were genotyped for 27 microsatellite markers on 13 chromosomes. The number of alleles of the 27 markers ranged from 6 to 51 per locus with a mean of 18.74. Heterozygosity (H) values of the 78 chicken breeds were all more than 0.5. The average H value (0.622) and polymorphism information content (PIC, 0.573) of these breeds suggested that the Chinese indigenous chickens possessed more genetic diversity than that reported in many other countries. The fixation coefficients of subpopulations within the total population (F _ST) for the 27 loci varied from 0.065 (LEI0166) to 0.209 (MCW0078), with a mean of 0.106. For all detected microsatellite loci, only one (LEI0194) deviated from Hardy-Weinberg equilibrium (HWE) across all the populations. As genetic drift or non-random mating can occur in small populations, breeds kept on conservation farms such as Langshan chicken generally had lower H values, while those kept on large populations within conservation regions possessed higher polymorphisms. The high genetic diversity in Chinese indigenous breeds is in agreement with great phenotypic variation of these breeds. Using Nei’s genetic distance and the Neighbor-Joining method, the indigenous Chinese chickens were classified into six categories that were generally consistent with their geographic distributions. The molecular information of genetic diversity will play an important role in conservation, supervision, and utilization of the chicken resources.     

Evaluation of genetic diversity in Chinese indigenous chicken breeds using microsatellite markers

China is regarded as one of the domestication cen-ters for chickens and archaeological studies provided evidence of chicken domestication in northern Chinaas early as 6000 BC[1]. At present, China has the larg-est chicken population in the world, represen…     

Genetic diversity and population structure of 10 Chinese indigenous egg-type duck breeds assessed by microsatellite polymorphism

The genetic structure and diversity of 10 Chinese indigenous egg-type duck breeds were investigated using 29 microsatellite markers. The total number of animals examined were 569, on average 57 animals per breed were selected. The microsatellite marker set analysed provided 177 alleles (mean 6.1 alleles per locus, ranging from 3 to 10). All populations showed high levels of heterozygosity with the lowest estimate of 0.539 for the Jinding ducks, and the highest 0.609 observed for Jingjiang partridge ducks. The global heterozygote deficit across all populations (F _IT) amounted to −0.363. About 10% of the total genetic variability originated from differences among breeds, with all loci contributing significantly. An unrooted consensus tree was constructed using the NeighborNet tree based on the Reynold’s genetic distance. The structure software was used to assess genetic clustering of these egg-type duck breeds. Clustering analysis provided an accurate representation of the current genetic relations among the breeds. An integrated analysis was undertaken to obtain information on the population dynamics in Chinese indigenous egg-type duck breeds, and to better determine the conservation priorities.     

Assessing genetic diversity and differentiation in Portuguese coarse-wool sheep breeds with microsatellite markers

Population structure and genetic diversity in the Portuguese native breeds of sheep Algarvia (AL), Badana (BA), Galega Bragançana (GB), Galega Mirandesa (GM), Mondegueira (MO) and Churra da Terra Quente (TQ), as well as the exotic Assaf (AS), were analyzed by typing 25 microsatellite markers in 210 individuals. The markers used exhibited high levels of polymorphism, with means for total and effective number of alleles per locus of 13.0 and 4.2, respectively, and an expected heterozygosity of 0.72 across loci. The mean number of alleles per locus and expected heterozygosity were highest in GM and GB, and lowest in AS. Exclusive alleles were found in 10 of the 25 markers analysed, mostly in the AS breed. The proportion of loci which were not in Hardy–Weinberg equilibrium in each breed ranged between 0.12 (GB) and 0.40 (AL and GM), mostly due to a lower than expected number of heterozygotes in those loci. All breeds showed a significant deficit in heterozygosity, which was more pronounced in GM (F_IS = 0.113) and BA (F_IS = 0.103), suggesting that inbreeding might be a major concern in these breeds. The analysis of relationships among breeds, assessed by different methods, indicates that AS and AL are the more distanced breeds relative to the others, while the closest relationships were observed between TQ with MO and GM with GB. The estimated F_ST indicates that only 0.049 of the total genetic variability can be attributed to differences among breeds, and this ratio dropped to 0.029 when only the native breeds were considered. The analysis of individual distances based on allele-sharing indicates that only AS and AL had a tendency for animals of the same breed to cluster together, while for the other breeds there was overlapping among breeds. The results of this study confirm that native breeds of sheep represent an important reservoir of genetic diversity, even though the level of differentiation among closely located breeds tends to be rather small. For several of the breeds analyzed, the levels of inbreeding currently observed cause some apprehension, and recommend the establishment of appropriate conservation strategies, aimed at minimizing inbreeding to avoid further losses of genetic diversity.     

Inference of population structure of purebred dairy and beef cattle using high-density genotype data

Information on the genetic diversity and population structure of cattle breeds is useful when deciding the most optimal, for example, crossbreeding strategies to improve phenotypic performance by exploiting heterosis. The present study investigated the genetic diversity and population structure of the most prominent dairy and beef breeds used in Ireland. Illumina high-density genotypes (777 962 single nucleotide polymorphisms; SNPs) were available on 4623 purebred bulls from nine breeds; Angus (n=430), Belgian Blue (n=298), Charolais (n=893), Hereford (n=327), Holstein-Friesian (n=1261), Jersey (n=75), Limousin (n=943), Montbéliarde (n=33) and Simmental (n=363). Principal component analysis revealed that Angus, Hereford, and Jersey formed non-overlapping clusters, representing distinct populations. In contrast, overlapping clusters suggested geographical proximity of origin and genetic similarity between Limousin, Simmental and Montbéliarde and to a lesser extent between Holstein, Friesian and Belgian Blue. The observed SNP heterozygosity averaged across all loci was 0.379. The Belgian Blue had the greatest mean observed heterozygosity (H_O=0.389) among individuals within breed while the Holstein-Friesian and Jersey populations had the lowest mean heterozygosity (H_O=0.370 and 0.376, respectively). The correlation between the genomic-based and pedigree-based inbreeding coefficients was weak (r=0.171; P<0.001). Mean genomic inbreeding estimates were greatest for Jersey (0.173) and least for Hereford (0.051). The pair-wise breed fixation index (F_st) ranged from 0.049 (Limousin and Charolais) to 0.165 (Hereford and Jersey). In conclusion, substantial genetic variation exists among breeds commercially used in Ireland. Thus custom-mating strategies would be successful in maximising the exploitation of heterosis in crossbreeding strategies.     

Multilocus genotypic data reveal high genetic diversity and low population genetic structure of Iranian indigenous sheep

Iranian livestock diversity is still largely unexplored, in spite of the interest in the populations historically reared in this country located near the Fertile Crescent, a major livestock domestication centre. In this investigation, the genetic diversity and differentiation of 10 Iranian indigenous fat‐tailed sheep breeds were investigated using 18 microsatellite markers. Iranian breeds were found to host a high level of diversity. This conclusion is substantiated by the large number of alleles observed across loci (average 13.83, range 7–22) and by the high within‐breed expected heterozygosity (average 0.75, range 0.72–0.76). Iranian sheep have a low level of genetic differentiation, as indicated by the analysis of molecular variance, which allocated a very small proportion (1.67%) of total variation to the between‐population component, and by the small fixation index (F_ST = 0.02). Both Bayesian clustering and principal coordinates analysis revealed the absence of a detectable genetic structure. Also, no isolation by distance was observed through comparison of genetic and geographical distances. In spite of high within‐breed variation, signatures of inbreeding were detected by the F_IS indices, which were positive in all and statistically significant in three breeds. Possible factors explaining the patterns observed, such as considerable gene flow and inbreeding probably due to anthropogenic activities in the light of population management and conservation programmes, are discussed.     

Genetic diversity of Chinese indigenous sheep breeds inferred from microsatellite markers

To determine the genetic diversity and phylogenetic relationships among Chinese sheep, 10 indigenous breeds and one introduced breed were genotyped for 19 microsatellite loci. The mean number of alleles per breed ranged from 5.44 (Guide Black Fur sheep) to 9.13 (Ujumqin sheep and Hulunbeier sheep), the expected heterozygosity varied from 0.623 (Guide Black Fur sheep) to 0.737 (Zhaotong sheep), and the allelic richness ranged from 5.169 (Guide Black Fur sheep) to 7.610 (Zhaotong sheep). The deviation from Hardy–Weinberg equilibrium (HWE) was statistically significant (P < 0.05) at three loci (SRCRSP5, OarAE129 and DYMS1) in most of the breeds. Chinese sheep breeds had maintained a high level of within-population genetic differentiation (95.23%), with the remainder explained by differentiation among populations (4.77%). The genetic differentiation pattern and genetic relationships among Chinese sheep breeds displayed a high consistency with the traditional classification. Both the Bayesian cluster and principal component analyses showed a reliable clustering pattern, which revealed three major clusters in Chinese indigenous sheep (Mongolian sheep, Kazakh sheep and Tibetan sheep), except Zhaotong and Guide Black Fur sheep. There were probably caused by different breeding history, geography isolation and different levels of inbreeding. This study will help to interpret the genetic characters of Chinese indigenous sheep and benefit to the future conservation programs.     

Genetic analysis, breed assignment and conservation priorities of three native Danish horse breeds

A genetic analysis was performed on three indigenous Danish horse breeds using 12 microsatellite markers from a standard kit for parental testing. These three breeds are all considered endangered based on their small population sizes. Genetic variation in these three breeds was comparable to other horse breeds in Europe, and they do not seem to be at immediate danger of extinction caused by genetic deterioration. The Knabstrupper breed had more genetic variation, as measured by expected heterozygosity and allelic richness, than the other two breeds (Frederiksborg and Jutland). F(ST) statistics and population assignments confirmed population differentiation into three distinct breeds. The Frederiksborg and Knabstrupper breeds were closer to each other than to the Jutland breed. When establishing conservation priorities for the breeds, the priorities will depend on the conservation goals. Different methods for establishing conservation priorities are also discussed.     

中国部分地方黄牛品种线粒体D-loop区的遗传变异与进化分析

测定了13个黄牛品种125个个体的线粒体D-loop区段的全序列,包括12个中国地方黄牛品种的123个个体和德国黄牛2个个体,并进行了分析。结果显示,共检测到93个变异位点,57个单倍型,平均核苷酸差异(average number ofnucleotide differences,k)为22.708,核苷酸多样度(nucleotide diversity,π)为0.0251±0.00479,单倍型多样度(haplotypediversity,Hd)为0.888±0.026,表明我国黄牛品种遗传多样性非常丰富。构建的Neighbor-Joining进化树显示这13个品种主要分成两大类型:普通牛和瘤牛;新发现的特殊类型Ⅲ只有一个西藏阿沛甲咂牛的个体,它与牦牛D-loop序列最相近,证明西藏地区的黄牛与牦牛之间存在基因渗入现象。普通牛和瘤牛在日喀则驼峰牛中占的比例分别是64.3%和35.7%,在阿沛甲咂牛中占的比例分别是50.0%和50.0%,证明了西藏的黄牛也有瘤牛类型。云南牛品种的单倍型非常丰富证明了云南在中国黄牛起源上的重要地位;在27个中国黄牛品种中(本研究11个品种以及GenBank上的16个品种)找到了中国瘤牛的核心单倍型i1,并且对它进行了讨论。同时证明了西藏瘤牛独立于中国瘤牛核心类群的特殊性。     

Genetic diversity and population structure of Sicilian sheep breeds using microsatellite markers

Genetic diversity studies in domestic animals aim at evaluating genetic variation within and across breeds mainly for conservation purposes. In Sicily, dairy sheep production represents an important resource for hilly and mountain areas economy. Their milk is used for the production of traditional raw milk cheeses, sometimes protected designation of origin (PDO) cheeses. In some cases, the quality of these products is linked to a specific breed, i.e. mono-breed labelled cheeses and it is therefore important to be able to distinguish the milk of a breed from that of others, in order to guarantee both the consumer and the breed itself. In order to investigate the genetic structure and to perform an assignment test, a total of 331 individuals (Barbaresca, BAR n = 57, Comisana, COM n = 65, Pinzirita, PIN n = 75, Sarda, SAR n = 64, and Valle del Belice, VDB n = 70) were analysed using a panel of 20 microsatellite markers. A total of 259 alleles were observed with average polymorphic information content equal to 0.76, showing that the microsatellites panel used was highly informative. Estimates of observed heterozygosity ranged from 0.65 in the BAR breed to 0.75 in the COM breed. The low value of genetic differentiation among breeds (F_st = 0.049) may indicate that these breeds are little differentiated probably due to common history and breeding practices. The low F_is and F_it values indicated low level of inbreeding within and among breeds. The unrooted neighbor-joining dendrogram obtained from the Reynold's genetic distances, and factorial correspondence analysis revealed a separation between BAR and the other sheep breeds. Recent migration rates were estimated, showing that four out of the five breeds have not received a significant proportion of migrants. Only for the PIN breed a recent introgression rate from the VDB breed (7.2%) was observed. The Bayesian assignment test showed that BAR and SAR breeds had a more definite genetic structure (proportion of assignment of 92% and 86.6%, respectively), whereas the lowest assignment value was found in the PIN breed (67.1%). Our results indicated high genetic variability, low inbreeding and low genetic differentiation, except for BAR breed, and were in accordance with geographical location, history, and breeding practices. The low robustness of the assignment test makes it unfeasible for traceability purposes, due to the high level of admixture, in particular for COM, PIN and VDB.     

Assessing genetic diversity in indigenous Veneto chicken breeds using AFLP markers

Genetic variation in four indigenous chicken breeds from the Veneto region of Italy was assessed using amplified fragment length polymorphism (AFLP) markers. A total of 99 individuals were analysed using three AFLP primer combinations that produced 70 polymorphisms. Four indigenous Veneto chicken breeds (Ermellinata, Padovana, Pépoi and Robusta) and a reference broiler line were included in the analysis. Breed-specific markers were identified in each breed. The expected heterozygosity did not differ significantly among the indigenous Veneto chicken breeds and the broiler line. The coefficient of gene variation (Gst) value across loci indicated that almost half of the total variability was observed among breeds. Nei's standard genetic distance between pairs of breeds showed that the distance between the broiler line and the Pépoi breed was greater than the distances between the broiler line and the other three chicken breeds. Cluster analysis based on standard genetic distances between breeds indicated that the Padovana and Pépoi breeds were closely related. Factorial analysis based on a binary matrix of the AFLP data showed a clear distinction of all breeds.     

Evaluation of the genetic diversity of Laiwu pigs using twenty-seven microsatellite markers

The Laiwu pig, an indigenous pig breed known for extremely high intramuscular fat content, is a well-preserved ancient breed due to long-term natural and artificial selections. In this study, using 27 microsatellite markers jointly recommended by the International Society of Animal Genetics (ISAG) and the Food and Agriculture Organization (FAO), we investigated the genetic diversity of the Laiwu pig breed. The genetic diversity of Laiwu pigs is dramatically low, with the observed heterozygosity ranging from 0.067 to 0.767. Among the 27 microsatellite markers, 10 were high polymorphic loci, 10 were moderate polymorphic loci, six were low polymorphic loci, and no polymorphism was detected at one locus (IGFI). Further analyses with the 10 high polymorphic loci and five moderate polymorphic loci revealed that the Laiwu pig breed was inbred and heterozygous deficient to some extent, but not severely, and that the Laiwu pigs were relatively pure, with almost no hybridization with other breeds. Two subgroups of the current 13 Laiwu pig pedigrees were identified. These results suggest that the Laiwu pig breed has a low diversity and a conservation program must be developed to preserve the “Laiwu pig” gene pool.     

Genetic relationships between Spanish Assaf (Assaf.E) and Spanish native dairy sheep breeds

At present, the Assaf is the main dairy sheep in Spain. The Spanish Assaf (Assaf.E) was formed by male-mediated absorption of native Spanish sheep. Here we assess the genetic relationships among the Assaf.E and major native Spanish dairy breeds using microsatellites to contribute to the knowledge of the formation and within-population genetic variability of the breed. Blood samples from 44 unrelated Assaf.E individuals from 23 different Assaf.E flocks spread throughout 6 different Spanish provinces were obtained and genotyped using 14 microsatellites. Up to 312 additional samples belonging to the Awassi and Milchschaf sheep breeds and to six native Spanish dairy sheep breeds (Castellana, Churra, Latxa, Manchega, and Rubia de El Molar) as well as samples from Merino individuals to be used as the outgroup were also analysed observed (H_o) and expected (H_e) heterozygosity, rarefacted number of alleles per locus and distances based on molecular coancestry information were computed. Probabilities of assignment of the Assaf.E individuals to native Spanish dairy sheep breeds and cryptic genetic structure in the whole dataset were also assessed. It can be concluded that the Assaf.E breed has low genetic variability and high genetic distance with respect native Spanish dairy sheep breeds. From our results, the formation of the Assaf.E breed basically occurred via the absorption of individuals belonging to the Entrefino type, particularly to the Castellana and Manchega populations. Furthermore, Churra individuals may have participated in the formation of the Assaf.E breed at an early moment of the introduction of the breed into Spain.     

Genetic characterization of Uruguayan Pampa Rocha pigs with microsatellite markers

In this study, we genetically characterized the Uruguayan pig breed Pampa Rocha. Genetic variability was assessed by analyzing a panel of 25 microsatellite markers from a sample of 39 individuals. Pampa Rocha pigs showed high genetic variability with observed and expected heterozygosities of 0.583 and 0.603, respectively. The mean number of alleles was 5.72. Twenty-four markers were polymorphic, with 95.8% of them in Hardy Weinberg equilibrium. The level of endogamy was low (F_IS = 0.0475). A factorial analysis of correspondence was used to assess the genetic differences between Pampa Rocha and other pig breeds; genetic distances were calculated, and a tree was designed to reflect the distance matrix. Individuals were also allocated into clusters. This analysis showed that the Pampa Rocha breed was separated from the other breeds along the first and second axes. The neighbour-joining tree generated by the genetic distances D_A showed clustering of Pampa Rocha with the Meishan breed. The allocation of individuals to clusters showed a clear separation of Pampa Rocha pigs. These results provide insights into the genetic variability of Pampa Rocha pigs and indicate that this breed is a well-defined genetic entity.     

Genetic diversity in Spanish donkey breeds using microsatellite DNA markers

Genetic diversity at 13 equine microsatellite loci was compared in five endangered Spanish donkey breeds: Andaluza, Catalana, Mallorquina, Encartaciones and Zamorano-Leonesa. All of the equine microsatellites used in this study were amplified and were polymorphic in the domestic donkey breeds with the exception of HMS1, which was monomorphic, and ASB2, which failed to amplify. Allele number, frequency distributions and mean heterozygosities were very similar among the Spanish donkey breeds. The unbiased expected heterozygosity (H_E) over all the populations varied between 0.637 and 0.684 in this study. The low G_ST value showed that only 3.6% of the diversity was between breeds (P < 0.01). Significant deviations from Hardy-Weinberg equilibrium were shown for a number of locus-population combinations, except HMS5 that showed agreement in all analysed populations. The cumulative exclusion probability (PE) was 0.999 in each breed, suggesting that the loci would be suitable for donkey parentage testing. The constructed dendrogram from the D_A distance matrix showed little differentiation between Spanish breeds, but great differentiation between them and the Moroccan ass and also with the horse, used as an outgroup. These results confirm the potential use of equine microsatellite loci as a tool for genetic studies in domestic donkey populations, which could also be useful for conservation plans.