[show abstract][hide abstract] ABSTRACT: E-Mails: email@example.com (P.A.K.); firstname.lastname@example.org (B.T.) Abstract: Classification of cattle breeds contributes to our understanding of the history of cattle and is essential for an effective conservation of genetic diversity. Here we review the various classifications over the last two centuries and compare the most recent classifications with genetic data. The classifications devised during the 19th to the late 20th century were in line with the Linnaean taxonomy and emphasized cranial or horn morphology. Subsequent classifications were based on coat color, geographic origin or molecular markers. Several theories were developed that linked breed characteristics either to a supposed ancestral aurochs subspecies or to a presumed ethnic origin. Most of the older classifications have now been discarded, but have introduced several Latin terms that are still in use. The most consistent classification was proposed in 1995 by Felius and emphasizes the geographic origin of breeds. This is largely in agreement with the breed clusters indicated by a biochemical and molecular genetic analysis, which reflect either groups of breeds with a common geographic origin or single breeds that have expanded by export and/or crossbreeding. We propose that this information is also relevant for managing the genetic diversity of cattle.
[show abstract][hide abstract] ABSTRACT: The introduction of livestock species in Europe has been followed by various genetic events, which created a complex spatial pattern of genetic differentiation. Spatial principal component (sPCA) analysis and spatial metric multidimensional scaling (sMDS) incorporate geography in multivariate analysis. This method was applied to three microsatellite data sets for 45 goat breeds, 46 sheep breeds, and 101 cattle breeds from Europe, Southwest Asia, and India. The first two sPCA coordinates for goat and cattle, and the first sPCA coordinate of sheep, correspond to the coordinates of ordinary PCA analysis. However, higher sPCA coordinates suggest, for all three species, additional spatial structuring. The goat is the most geographically structured species, followed by cattle. For all three species, the main genetic cline is from southeast to northwest, but other geographic patterns depend on the species. We propose sPCA and sMDS to be useful tools for describing the correlation of genetic variation with geography.
[show abstract][hide abstract] ABSTRACT: Identification of global livestock diversity hotspots and their importance in diversity maintenance is essential for making global conservation efforts. We screened 52 sheep breeds from the Eurasian subcontinent with 20 microsatellite markers. By estimating and weighting differently within- and between-breed genetic variation our aims were to identify genetic diversity hotspots and prioritize the importance of each breed for conservation, respectively. In addition we estimated how important within-species diversity hotspots are in livestock conservation.
Bayesian clustering analysis revealed three genetic clusters, termed Nordic, Composite and Fat-tailed. Southern breeds from close to the region of sheep domestication were more variable, but less genetically differentiated compared with more northern populations. Decreasing weight for within-breed diversity component led to very high representation of genetic clusters or regions containing more diverged breeds, but did not increase phenotypic diversity among the high ranked breeds. Sampling populations throughout 14 regional groups was suggested for maximized total genetic diversity.
During initial steps of establishing a livestock conservation program populations from the diversity hot-spot area are the most important ones, but for the full design our results suggested that approximately equal population presentation across environments should be considered. Even in this case, higher per population emphasis in areas of high diversity is appropriate. The analysis was based on neutral data, but we have no reason to think the general trend is limited to this type of data. However, a comprehensive valuation of populations should balance production systems, phenotypic traits and available genetic information, and include consideration of probability of success.
[show abstract][hide abstract] ABSTRACT: Maternally inherited mitochondrial DNA (mtDNA) has been used extensively to determine origin and diversity of taurine cattle (Bos taurus) but global surveys of paternally inherited Y-chromosome diversity are lacking. Here, we provide mtDNA information on previously uncharacterised Eurasian breeds and present the most comprehensive Y-chromosomal microsatellite data on domestic cattle to date. The mitochondrial haplogroup T3 was the most frequent, whereas T4 was detected only in the Yakutian cattle from Siberia. The mtDNA data indicates that the Ukrainian and Central Asian regions are zones where hybrids between taurine and zebu (B. indicus) cattle have existed. This zebu influence appears to have subsequently spread into southern and southeastern European breeds. The most common Y-chromosomal microsatellite haplotype, termed here as H11, showed an elevated frequency in the Eurasian sample set compared with that detected in Near Eastern and Anatolian breeds. The taurine Y-chromosomal microsatellite haplotypes were found to be structured in a network according to the Y-haplogroups Y1 and Y2. These data do not support the recent hypothesis on the origin of Y1 from the local European hybridization of cattle with male aurochsen. Compared with mtDNA, the intensive culling of breeding males and male-mediated crossbreeding of locally raised native breeds has accelerated loss of Y-chromosomal variation in domestic cattle, and affected the contribution of genetic drift to diversity. In conclusion, to maintain diversity, breeds showing rare Y-haplotypes should be prioritised in the conservation of cattle genetic resources.
[show abstract][hide abstract] ABSTRACT: Two Tsigai sheep populations exist in Serbia: the Old type, called Cokan, and the New type. It is assumed that the New type results from upgrading Tsigai sheep with exotic genetic material. We investigated genetic diversity and differentiation of these types by analysing 23 autosomal microsatellites. Tests for Hardy-Weinberg proportions, linkage equilibrium between genotypes across loci and the calculation of inbreeding coefficients were performed and the deficiency in the number of alleles within the Tsigai types was examined using a Wilcoxon sign-rank test. The New type displayed a higher level of genetic variability than the Cokan in terms of allele numbers, but the New Tsigai showed a pattern of heterozygosity deficiency. The positive f value for the Cokan suggests the occurrence of inbreeding in this type. The proportion of linkage disequilibrium was below that expected by chance. Exclusion of two loci in Hardy-Weinberg disequilibrium did not alter our conclusions based on the entire data set i.e. the two Tsigai types are clearly differentiated and the New Tsigai type has been influenced by crossbreeding. Therefore, the Cokan Tsigai should be considered as a distinct endangered breed in the FAO classification.
[show abstract][hide abstract] ABSTRACT: We investigated the genetic structure and variation of 21 populations of cattle (Bos taurus) in northern Eurasia and the neighbouring Near Eastern regions of the Balkan, the Caucasus and Ukraine employing 30 microsatellite markers. By analyses of population relationships, as well as by a Bayesian-based clustering approach, we identified a genetic distinctness between populations of modern commercial origin and those of native origin. Our data suggested that northern European Russia represents the most heavily colonized area by modern commercial cattle. Further genetic mixture analyses based on individual assignment tests found that native Red Steppe cattle were also employed in the historical breeding practices in Eastern Europe, most probably for incorporating their strong and extensive adaptability. In analysis of molecular variance, within-population differences accounted for approximately 90% of the genetic variation. Despite some correspondence between geographical proximity and genetic similarity, genetic differentiation was observed to be significantly associated with the difference in breeding purpose among the European populations (percentage of variance among groups and significance: 2.99%, P = 0.02). Our findings give unique genetic insight into the historical patterns of cattle breeding practices in the former Soviet Union. The results identify the neighbouring Near Eastern regions such as the Balkan, the Caucasus and Ukraine, and the isolated Far Eastern Siberia as areas of 'genetic endemism', where cattle populations should be given conservation priority. The results will also be of importance for cost-effective management of their future utilization.
[show abstract][hide abstract] ABSTRACT: Three distinct mitochondrial maternal lineages (haplotype Groups A, B, and C) have been found in the domestic sheep. Group B has been observed primarily in European domestic sheep. The European mouflon carries this haplotype group. This could suggest that European mouflon was independently domesticated in Europe, although archaeological evidence supports sheep domestication in the central part of the Fertile Crescent. To investigate this question, we sequenced a highly variable segment of mitochondrial DNA (mtDNA) in 406 unrelated animals from 48 breeds or local varieties. They originated from a wide area spanning northern Europe and the Balkans to the Altay Mountains in south Siberia. The sample included a representative cross-section of sheep breeds from areas close to the postulated Near Eastern domestication center and breeds from more distant northern areas. Four (A, B, C, and D) highly diverged sheep lineages were observed in Caucasus, 3 (A, B and C) in Central Asia, and 2 (A and B) in the eastern fringe of Europe, which included the area north and west of the Black Sea and the Ural Mountains. Only one example of Group D was detected. The other haplotype groups demonstrated signs of population expansion. Sequence variation within the lineages implied Group A to have expanded first. This group was the most frequent type only in Caucasian and Central Asian breeds. Expansion of Group C appeared most recently. The expansion of Group B involving Caucasian sheep took place at nearly the same time as the expansion of Group A. Group B expansion for the eastern European area started approximately 3,000 years after the earliest inferred expansion. An independent European domestication of sheep is unlikely. The distribution of Group A variation as well as other results are compatible with the Near East being the domestication site. Groups C and D may have been introgressed later into a domestic stock, but larger samples are needed to infer their geographical origin. The results suggest that some mitochondrial lineages arrived in northern Europe from the Near East across Russia.
Molecular Biology and Evolution 10/2006; 23(9):1776-83. · 10.35 Impact Factor
[show abstract][hide abstract] ABSTRACT: Single nucleotide polymorphisms (SNPs) in growth hormone 1 (GH1), insulin-like growth factor 1 (IGF1) and leptin (LEP), all candidates for production traits in cattle, were characterized in North Eurasian cattle breeds. Allele frequencies of IGF1 exhibited significant (P < 0.05) deviation from neutral expectation and therefore, might be associated with divergence in North Eurasian cattle because of genetic selection. Allele frequencies and lower heterozygosity of LEP may indicate a recent introduction of an alternative allele in this geographic region. Locus F(ST) estimates were highest for IGF1 (0.151, sigma = 0.042) and lowest for GH (0.062, sigma = 0.020). Our results suggest a slightly higher population differentiation across the candidate genes (FST = 0.108) than across microsatellites (FST = 0.095), possibly because of selection and stochastic effects.
[show abstract][hide abstract] ABSTRACT: Extinction of breeds threatens genetic diversity of livestock species. The need to conserve genetic diversity is widely accepted but involves in general two questions: (i) is the expected loss of diversity in a set of breeds within a defined future time horizon large enough to establish a conservation plan, and if so (ii) which breeds should be prioritised for such a conservation plan? The present study uses a marker assisted methodology to address these questions. The methodology combines core set diversity measures with a stochastic method for the estimation of expected future diversity and breed marginal diversities. The latter is defined as the change in the total diversity of all breeds caused by a one unit decrease in extinction probability of a particular breed. The stochastic method was validated by means of simulations. A large field data set consisting of 44 North Eurasian cattle breeds was analysed using simplified determined extinction probabilities. The results show that the expected loss of diversity in this set within the next 20 to 50 years is between 1 and 3% of the actual diversity, provided that the extinction probabilities which were used are approximately valid. If this loss is to be reduced, it is sufficient to include those three to five breeds with the highest marginal diversity in a conservation scheme.