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1.
In this study we examined the genetic diversity of yak populations in the northernmost part of their current global distribution. Five Mongolian and one Russian yak populations as well as one Chinese yak population from the Qinghai–Tibetan Plateau, the putative centre of yak domestication, were analysed with 15 microsatellite loci to determine the level of genetic variation within populations as well as the genetic differentiation and relationship between populations. A total of 116 microsatellite alleles were identified. The mean number of alleles per locus (MNA) across populations was 7.73 ± 1.98 and the mean expected heterozygosity (HE) was 0.696 ± 0.026. The relative magnitude of gene differentiation (FST) among populations was 4.1%, and all genetic differentiations (FST) between populations were significant (p < 0.001). A significant inbreeding effect (FIS) was detected in the Hovsgol yak (p < 0.01). There was no indication of a recent bottleneck in any of the populations studied. The results showed that yak populations in Mongolia and Russia have maintained high genetic diversity within populations and a low, although significant, genetic differentiation between populations. Both phylogenetic and principal component analyses support a close genetic relationship between the Gobi Altai, south Gobi and north Hangai populations, and between the Hovsgol and Buryatia populations respectively. Our results indicate that these yak populations should be considered as distinct genetic entities in respect of conservation and breeding programmes.  相似文献   

2.
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.  相似文献   

3.
The genetic variation at four milk protein loci αs1‐casein (CSN1S1), β‐casein (CSN2), κ‐casein (CSN3) and β‐lactoglobulin (LGB) was investigated in 358 animals belonging to seven populations well adapted to hot climatic conditions, reared in Africa and Italy. Bos taurus (Somba, Lagune and Modicana), Bos indicus (Sudanese Zebu Peul, Azaouak and Adamawa), and B. taurus × B. indicus (Borgou) were studied by adapting different molecular methodologies to evaluate their genetic variability. All loci were polymorphic and a new CSN2 synonymous variant, named A2′, was detected and characterized. Noteworthy differences in the distribution of alleles and haplotypes were observed between zebuine and taurine cattle showing that milk protein polymorphism is suited for discriminating B. taurus from B. indicus efficiently, and also taurine breeds. Milk protein loci, being positively selected loci, can also provide information about the occurrence of germplasm particularly useful for breeding strategies and production improvement.  相似文献   

4.
Carnivores as top predators are commonly found in relatively low densities even in optimal habitats. Despite a lack of empirical studies, it could be suspected that long‐term low density could result in genetic depletion. The genetic structure of European polecat Mustela putorius natural populations was investigated by allozyme electrophoresis in five distinct areas. Density estimates significantly differed among sites from 0.17 to 0.83 individuals/km2 with an average of 0.56 individuals per km2, resulting in a scattered distribution. Genetic structure varied among distinct populations both in number of polymorphic loci and heterozygosity. Polecats from Brittany revealed a very low observed heterozygosity (HO = 0.028) whereas mean heterozygosity reached HO = 0.072 in Brière. That the lowest heterozygosity levels and highest inbreeding coefficient FIS were significantly associated with the lowest densities suggests that low densities may affect populations of carnivores. Both the loss of polymorphic loci and the reduction in heterozygosity rates suggest a density‐dependent effect and population density can be arguably regarded as a factor affecting genetic diversity in top carnivores.  相似文献   

5.
In the current study, milk protein variation was examined in cattle (Bos indicus), mithun (Bos frontalis), yak (Bos grunniens) and their hybrid populations in Bhutan to estimate genetic variability, conduct genetic characterization and assess the possibility of gene flow between mithun and cattle. Isoelectric focusing of 372 milk samples from 11 populations detected four molecular types of β‐lactoglobulin (A, B, E and M), five molecular types of αS1‐casein (A, B, C, E and X) and three molecular types of k‐casein (A, B and X). Mithun and yak shared alleles but were found to exhibit different allele frequencies for the proteins studied. The degree of genetic variability within populations was measured by average heterozygosity and ranged from 24–40% in cattle, 26% for yak and 33% for mithun. We also resolved the traditional mithun and cattle hybridization system via principal component analysis. Our results suggested secondary introgression of mithun genes to the village Thrabum population, and a close genetic relationship between Bhutanese indigenous cattle and Indian cattle.  相似文献   

6.
Eighteen microsatellites were used to investigate the genetic diversity and differentiation of eight Chinese indigenous goat breeds. The results indicated that there is a significant difference of genetic diversity between different loci. Chinese indigenous goat breeds have similar genetic diversity to other Asian goats, but with lower Fst. The clustering of individuals and populations showed that Chinese indigenous goat breeds might have originated from two ancestral populations. The genetic differentiation between populations is consistent with the results of archaeology, mtDNA and RAPD.  相似文献   

7.
The patterns of isolation by distance (IBD) entailing increased genetic differentiation among populations have aroused extensive concerns for evolutionary biologists. Although the IBD may act on spatial processes contributing to the genetic differentiation among populations in anuran species, the factors shaping the IBD of frogs among populations in natural systems are largely unknown. Here, we studied the genetic differentiation among six populations with 24 individuals of the spotted-leg treefrog along a latitudinal gradient (1860.31 km) based on 1020 single nucleotide polymorphisms from restriction site-associated DNA sequencing. The results showed that the genetic diversity differed significantly among populations and that the insular populations had higher genetic diversity than the mainland populations. Furthermore, we also found a significant genetic differentiation among populations (FST = 0.277) and no sign of inbreeding (FUNI = −0.145). The IBD was detected for all populations, and a higher degree of the IBD was indicated when controlling for the effects of the isolation between Hainan and mainland populations caused by the Qiongzhou Strait. Our findings suggest that the form of the Qiongzhou Strait plays a key role in shaping the genetic diversity and population differentiation in treefrogs.  相似文献   

8.
The genetic population structure of red snapper Lutjanus malabaricus and orange‐spotted grouper Epinephelus coiodes in Brunei and Sabah was investigated using allozyme electrophoresis. Samples were collected from three sites in Brunei for E. coiodes and from three sites in Brunei and Sabah for L. malabaricus. A total of 22 loci and 16 loci were scored, respectively. The index of fixation (FST) for the E. coiodes population was 0.176 but, in general, it lacked within‐population structuring. The FST was particularly high between Brunei Bay/Jerudong and Brunei Bay/ Kuala Belait, suggesting genetic subdivision on a small spatial scale. Isolation of Brunei Bay from the South China Sea may constrain the movement of adult fishes and larval dispersal, thereby reducing homogeneity among subpopulations. All variable loci for E. coiodes were in Hardy‐Weinberg equilibrium except for MDH* and GTDHP* (P < 0.01), in which two subpopulations showed an excess of heterozygotes (P < 0.01). The study on the L. malabaricus population showed a heterozygote deficit of approximately 60% in variable loci (FST genetic variation within population = 0.45; P < 0.05); however, the mean observed heterozygosity for the population far exceeded L. malabaricus populations in Australia and Indonesia. A FST value of 0.076 revealed moderate genetic differentiation among subpopulations of L. malabaricus. The genotypes were likely to be drawn from the same distribution in Jerudong and Kuala Belait. This study infers that sustainable management of snapper and grouper resources in Brunei waters must take into account the presence of a single stock and two stocks, respectively.  相似文献   

9.
Level of genetic differentiation, gene flow and genetic structuring of nine Bos indicus and three Bos taurus cattle breeds in Cameroon and Nigeria were estimated using the genetic information from 16 microsatellite, five blood protein and seven milk protein markers. The global heterozygote deficit across all populations (Fit) amounted to 11.7% (p < 0.001). The overall significant (p < 0.001) deficit of heterozygotes because of inbreeding within breeds (Fis) amounted to 6.1%. The breeds were moderately differentiated (Fst = 6%, p < 0.001) with all loci except CSN1S2 contributing significantly to the Fst value. The 12 populations belong to two genetic clusters, a zebu and a taurine cluster. While inferred sub‐clusters within the taurine group corresponded extremely well to predefined breed categorizations, no real sub‐clusters, corresponding to predefined breeds, existed within the zebu cluster. With the application of prior population information, cluster analysis achieved posterior probabilities from 0.962 to 0.994 of correctly assigning individuals to their rightful populations. High gene flow was evident between the zebu populations. Positive and negative implications of the observed genetic structure of the breeds on their development, improvement and conservation are discussed. The study shows that the breeds are threatened by uncontrolled breeding and therefore are at risk to become genetically uniform in the future. This situation can be avoided by putting in place effective breeding and management measures aimed at limiting uncontrolled mating between the breeds and to preserve special characteristics, genetic as well as breed biodiversity. The first step towards realizing these goals might be to geographically demarcate the breeds.  相似文献   

10.

Ethiopia is home to a diverse gene pool of indigenous sheep populations. Therefore, a better understanding of genetic variation holds the key to future utilization through conservation. Three of these breeds, Afar, Blackhead Somali, and Hararghe Highland, are found in eastern Ethiopia where they contribute significantly to the livelihood of most pastoralist, agro-pastoralist, and smallholder farmers. These indigenous sheep are recognized on the basis of morphotype and their genetic distinction remains unknown. Here, to assess genetic variation, and matrilineal genetic origin and relationship of fat-rumed sheep found in eastern Ethiopia, 300 individuals from the three breeds were genotyped for 22 microsatellite markers and sequenced for the mitochondrial DNA displacement loop (mtDNA d-loop) region. The overall HO and HE were 0.57 and 0.75, respectively. Differentiation statistics revealed that a high proportion (97%) of the total genetic variation was explained by differences between individuals within populations. Genotype assignment independent of the population of origin showed K?=?2 to be the optimum number of genetic backgrounds present in the dataset. This result was further confirmed by mtDNA D-loop sequences comparison in which the matrilineal genetic origin of eastern Ethiopia sheep is from two haplotype groups (types A and B) among the five haplotypes globally observed. Taken together, our findings suggest that the sheep populations from three breeds originated from two ancestral genetic backgrounds that may have diverged prior to their introduction to Ethiopia. However, to obtain a complete picture of the evolutionary dynamics of Ethiopian indigenous sheep, more samples and populations from within and outside of the country will need to be analyzed.

  相似文献   

11.
Polymorphisms for seven microsatellite loci in three red deer subspecies (9 populations) found in XinJiang were detected by polymerase chain reaction (PCR), 12% nondenaturation polyacrylamide gel electrophoresis and the Sanguinetti silver staining method. Numbers of alleles, average effective numbers of alleles (E) and the average rate of homozygosity, allelic frequencies of seven microsatellite loci, polymorphism information content (PIC), mean heterozygosity (H) and genetic distances among the populations were calculated for each population. Dendrograms were constructed based on genetic distances by the neighbor‐joining method (NJ), utilizing molecular evolutionary genetics analysis software PHYLIP (3.6). The phylogenetic tree was constructed based on allelic frequencies using maximum likelihood (ML); the bootstrap value was estimated by bootstrap test in the tree. Lastly, phylogenesis was analyzed. The results showed that four of the seven microsatellite loci were highly polymorphic, but BMS2508 and Celjp0023 showed no polymorphism and BM5004 was a neutral polymorphism. It is our conclusion that the four microsatellite loci are effective DNA markers for the analysis of genetic diversity and phylogenetic relationships among the three red deer subspecies. The mean PIC, H and E‐values across the microsatellite loci were 0.5393, 0.5736 and 2.64, which showed that these microsatellite loci are effective DNA markers for the genetic analysis of red deer. C.e. songaricus populations from Regiment 104, 151 and Hami are clustered together. C.e. yarkandensis populations from Regiment 35, Xaya and Alaer are clustered together. These two clusters also cluster together. Lastly, C.e. sibiricus populations from Burqin, Regiment 188 and the first two clusters were clustered together. The phylogenetic relationship among different red deer populations is consistent with the known origin, history of breeding and geographic distributions of populations.  相似文献   

12.
Preservation of rare genetic stocks requires continual monitoring of populations to avoid losses of genetic variability. Genetic variability can be described using genealogical and molecular parameters characterizing variation in allelic frequencies over time and providing interesting information on differentiation that occurred after the foundation of a conservation program. Here we analyze the pedigree of the rare Xalda sheep breed (1851 individuals) and the polymorphism of 14 microsatellites in 239 Xalda individuals. Individuals were assigned to a base population (BP) or 4 different cohorts (from C1 to C4) according to their pedigree information. Genetic parameters were computed at a genealogical and molecular level, namely inbreeding (F), observed (Ho) and expected (He) heterozygosity, individual coancestry coefficients (f and fm), average relatedness (AR), mean molecular kinship (Mk), average number of allele per locus (A), effective number of ancestors (fa), effective population size (Ne and Ne(m)) and founder genome equivalents (Ng and Ng(m)). In general, the computed parameters increased with pedigree depth from BP to C4, especially for the genealogical information and molecular coancestry-based parameters (fm, Mk and Ng(m)). However, Ho and He showed the highest values for C1 and the molecular heterozygote deficiency within population (FIS(m)) showed the lowest value for C1, thus indicating that loss of genetic variability occurs very soon after the implementation of conservation strategies. Although no genealogical or molecular parameters are sufficient by themselves for monitoring populations at the beginning of a conservation program, our data suggests that coancestry-based parameters may be better criteria than those of inbreeding or homozygosity because of the rapid and strong correlation established between f and f(m). However, the obtaining of molecular information in well-established conservation programs could not be justified, at least in economic terms.  相似文献   

13.
The Cape river crab, Potamonautes perlatus, is widely distributed in streams and rivers of the Western Cape where it exhibits considerable morphological variation. Recent genetic work on populations in the Olifants River system has demonstrated the existence of a new cryptic species of river crab, while populations of P. perlatus in the nearby Berg River system remained uninvestigated. Six populations of P. perlatus were collected from along the length of the Berg River system (125 km) and the genetic structure was investigated using allozyme electrophoresis. Results from 14 allozyme loci showed that the populations were genetically invariant across the river system. It is suggested that gene flow may be responsible for the poor genetic differentiation amongst populations in the Berg River system. The implication for future management of the system is briefly discussed.  相似文献   

14.
Despite the wide range of observed phenotypic diversities and adaptation to different ecological conditions, little has been studied regarding the genetics of adaptation in the genome of indigenous cattle breeds of developing countries. Here, we investigated the linkage disequilibrium (LD) and identified the subset of outlier loci that are highly differentiated among cattle populations adapted to different ecological conditions in Ethiopia. Specifically, we genotyped 47 unrelated animals sampled from high‐ versus low‐altitude environments using a Bovine 50K SNP BeadChip. Linkage disequilibrium was assessed using both D′ and r2 between adjacent SNPs. We calculated FST and heterozygosity at different significance levels as measures of genetic differentiation for each locus between high‐ and low‐altitude populations following the hierarchical island model approach. We identified 816 loci (p < 0.01) showing selection signals and are associated with genes that might have roles in local adaptation. Some of them are associated with candidate genes that are involved in metabolism (ATP2A3, CA2, MYO18B, SIK3, INPP4A, and IREB2), hypoxia response (BDNF, TFRC, and PML) and heat stress (PRKDC, CDK1, and TFDC). Average r2 and D′ values were 0.14 ± 0.21 and 0.57 ± 0.34, respectively, for a minor allele frequency (MAF) ≥ 0.05 and were found to increase with increasing MAF value. The outlier loci identified in the studied Ethiopian cattle populations indicate the presence of genetic variation produced/shaped by adaptation to different environmental conditions and provide a basis for further validation and functional analysis using a reasonable sample size and high‐density markers.  相似文献   

15.
The genetic structure of three Indian sheep breeds from two different geographical locations (Nali, Chokla from north‐western arid and semi‐arid region; Garole from eastern saline marshy region) of India was investigated by means of 11 ovine‐specific microsatellite markers as proposed in FAOs MoDAD programme. Microsatellite analysis revealed high allelic and gene diversity in all the three breeds. Nali sheep showed higher mean number of alleles and gene diversity (6.27 and 0.65) than Chokla (5.63 and 0.64) and Garole (5.63 and 0.59). High within population inbreeding estimates observed in the three breeds (FIS, Chokla = 0.286, Nali = 0.284, Garole = 0.227) reflected deficit of heterozygotes. The overall estimates for F‐statistics were significantly (p < 0.05) different from zero. High values of FST (0.183) across all the loci revealed substantial degree of breed differentiation. Based on pair wise FST and Nm between different breeds, Nali and Chokla (FST = 6.62% and Nm = 4.80) were observed to be the closest followed by Garole and Nali (FST = 20.9% and Nm = 1.80), and Garole and Chokla (FST = 21.4% and Nm = 1.71). In addition, genetic distance estimates, phylogeny analysis and individual assignment test used to evaluate interbreed genetic proximity and population structure also revealed substantial genetic differentiation between Garole and the other two Rajasthani (Nali and Chokla) sheep. This divergent status of Garole sheep indicated genetic uniqueness of this breed suggesting higher priority for its conservation.  相似文献   

16.
Massive actions have been and are being taken into protecting the world's primates from extinction, while the study of the properties of genetic diversity, demographic history, and ecological relationships will benefit the understanding of the long-term survival of a species. The Taihangshan macaque (Macaca mulatta tcheliensis), a subspecies of rhesus macaque (Macaca mulatta), is endemic to China and currently restricted to southern Mt. Taihangshan area. Herein, we evaluated the genetic diversity, population structure, and demographic history of this subspecies using mitochondrial (Cytb and high variable region I: HVR I) and nuclear markers (microsatellite loci) of 131 individuals collected from 9 localities covering the distribution range of this subspecies. Both phylogenetic analyses and genetic assignment revealed that the wild populations of Taihangshan macaques could be divided into 2 major highly divergent clades, THS-east and THS-west. Low genetic diversity (π: 0.00266 ± 0.00016) but high haplotype diversity (Hd: 0.80352 ± 0.015) were detected in the Taihangshan macaques, particularly in THS-east. Analyses of demographic history suggested that the Taihangshan macaques experienced first a stable historical population size from Holocene to early 19th century but a subtle decline and then slight growth in the recent 200 years. We suggest that bridging the neighbor populations (i.e. setting corridors) would facilitate the male-mediated gene flow and subsequently increase the genetic diversity of the Taihangshan macaque populations.  相似文献   

17.
Three Meriones species inhabit Tunisia, namely M. shawi, M. libycus and M. crassus, but little genetic data exist on these gerbils. We collected Meriones from eight localities in Tunisia, and obtained mitochondrial (cytochrome b) and nuclear (IRBP) gene sequence data for 37 and 13 specimens, respectively, belonging to two species: M. shawi and M. libycus. We also optimised three microsatellite markers previously described in M. unguiculatus to obtain a finer analysis of their genetic diversity and geographic structure, given their wide distribution. Phylogenetic inferences of cyt b and IRBP data for these species, in the context of other gerbillin data, corroborate their taxonomic affinities reported by previous studies. High cyt b haplotype diversity was observed in both species (25 haplotypes in 29 and 27 sequences for M. shawi and M. libycus, respectively) with little geographical structure for M. shawi but three divergent groups in M. libycus. The average microsatellite diversity within each population was high (HO ≥ 0.6, HE ≥ 0.8) with M. libycus populations attaining the highest values. Population differentiation was moderate for several population pairs (Fst ≥ 0.1), the highest being between M. shawi populations. However, genetic distance among populations was not significantly correlated with geographic distance in either M. shawi or M. libycus. Our results contribute to a better characterisation of Tunisian Meriones species, suggesting high geographic structure in mtDNA of M. libycus populations within North Africa.  相似文献   

18.
A herd of 15 Chinese elephants attracted international attention during their 2021 northward trek, motivating the government to propose establishment of an Asian elephant national park. However, planning is hampered by a lack of genetic information on the remaining populations in China. We collected DNA from 497 dung samples from all 5 populations encompassing the entire range of elephants in China and used mitochondrial and microsatellite markers to investigate their genetic and demographic structure. We identified 237 unique genotypes (153 females, 84 males), representing 81% of the known population. However, the effective population size was small (28, range 25–32). Historic demographic contraction appeared to account for low haplotype diversity (Hd = 0.235), but moderate nucleotide and nuclear diversity (π = 0.6%, He = 0.55) was attributable to post-bottleneck recovery involving recent population expansion plus historical gene exchange with elephants in Myanmar, Lao PDR, and Vietnam. The 5 populations fell into 3 clusters, with Nangunhe elephants differing consistently from the other 4 populations (FST = 0.23); elephants from Mengyang, Simao, and Jiangcheng belonged to a single population (henceforth, MSJ), and differed from the Shangyong population (FST = 0.11). Interpopulation genetic variation reflected isolation by distance and female-biased dispersal. Chinese elephants should be managed as 2 distinct units: Nangunhe and another combining Shangyong and MSJ; their long-term viability will require restoring gene flow between Shangyong and MSJ, and between elephants in China and neighboring countries. Our results have the potential to inform conservation planning for an iconic megafaunal species.  相似文献   

19.
利用8对微卫星标记对江苏省野生及家养中华蜜蜂群体遗传多样性进行分析,评估群体内的遗传变异和群体间的遗传分化,结果表明,共检测到31个等位基因,每个位点的等位基因数从1~7不等,平均等位基因数为3.875;所有位点平均的期望杂合度和PIC值分别为0.4424和0.4054。野生及家养中华蜜蜂群体8个微卫星位点平均有效等位基因数分别为3.83和4.17,平均基因杂合度为0.0778和0.0993,两个群体均表现出较低的群体杂合度和遗传多样性。群体分化系数为4.9%(P<0.001),两个群体的Reynolds’遗传距离和Nm值分别为0.05024和4.852。江苏省野生及家养中华蜜蜂群体均表现出较低的群体杂合度和遗传多样性水平,且有相互交流的迹象。  相似文献   

20.
为了解中国双峰驼群体的遗传多样性及不同种群间的遗传进化关系,本研究采用微卫星标记技术,对中国阿拉善驼、青海驼、南疆驼、北疆驼、肃北驼、苏尼特驼6个双峰驼群体进行了遗传多样性分析。通过计算杂合度(H)、多态信息含量(PIC)、有效等位基因(Ne)、Shannon信息指数等分析群体内遗传变异,通过计算F-统计量、基因流、遗传分化系数、遗传距离等分析群体间遗传进化关系。结果显示,10个微卫星位点共检测到了89个等位基因,平均每个位点检测到8.9个等位基因;所有位点均属中高度多态位点(YWLL08除外),平均PIC值在0.488~0.752之间;6个群体观测杂合度值(0.355~0.448)都低于期望杂合度值(0.643~0.703);几乎所有位点的Shannon指数都>1,且处于哈代-温伯格不平衡状态(P< 0.05)。群体间遗传分化系数Fst值为0.059,处于较低程度的中等分化状态; 6个双峰驼群体的平均Fis值均为正值,说明6个双峰驼群体都存在不同程度的近交。基于标准遗传距离DS和遗传距离DA进行聚类分析,南疆驼和北疆驼聚为一支,阿拉善驼、青海驼、肃北驼、苏尼特驼4个群体聚为一支。研究表明,中国双峰驼遗传多样性丰富,群体内遗传变异较大,存在一定近交现象;群体间存在着一定的基因流动,群体间的分化主要由群体内的遗传变异造成;6个群体分为2个类群。  相似文献   

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