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1.
利用微卫星标记对文蛤4个壳色花纹品系的遗传分析   总被引：3，自引：1，他引：2  
利用9个微卫星位点对文蛤红壳(RS)、黑斑(BS)、细纹(TC)、暗纹(DF)4个壳色花纹品系共120个个体进行遗传差异分析。结果共检测到105个等位基因,每个位点平均观察等位基因数为11.7个,其中WG07位点等位基因数最多(21个),WG11位点最少(7个)。每个品系均具有特异等位基因类型,不同品系中相同微卫星位点的等位基因分布规律不同。4个文蛤品系的观测杂合度、期望杂合度和多态信息含量变异范围分别为0.110～1.000、0.486～0.867、0.433～0.834,均属高度多态性位点。Hardy-Weinberg平衡的卡方检测发现,大多数位点偏离平衡状态;聚类分析表明,4个品系间存在较明显的遗传差异,TC品系与其它品系的遗传距离最大,DF品系和RS品系的遗传距离相对较小。  相似文献   

2.
An allozyme survey was conducted in three naturalized populations of rainbow trout, Oncorhynchus mykiss (Walbaum), from rivers in two Andean lakes of southern Chile. The analysis was based on 32 presumed loci, 10 of which were variable, and revealed that the mean percentage of polymorphic loci (P= 21.8%; range = 15.6-28.1%), the mean number of alleles per locus (n=1.26; range = 1.2-1.3) and the mean observed heterozygosity (HO=7.0%; range = 6.0-8.2%) are high, although within the range reported for rainbow trout. Although the mean genetic distance between the samples was low (D = 0.003), and only 5.2% of the total observed genetic variation can be accounted by interpopulation differences (FST= 0.052), eight out of 10 polymorphic loci exhibited significant allelic heterogeneity. Some loci, notably EST-1*, IDHP-3,4*, MEP-1* and PGM-1*, showed considerable discriminatory capacity among the samples. Rainbow trout has a longer history in Chilean waters since salmonid introduction started earlier this century. Under current intensive farming practices, the preliminary information provided in the present paper is likely to be helpful in setting up a baseline for further characterization and/or monitoring of naturalized populations.  相似文献   

3.
The genetic composition of consecutive year classes of two farmed rainbow trout, Oncorhynchus mykiss (Walbaum), strains was assessed, using starch gel electrophoresis of 11 enzymes encoded by a minimum of 23 loci, many of which have been shown to be polymorphic in previous studies. Angle frequencies at the majority of polymorphic loci varied significantly between year classes of each strain. Several alleles which were present at low frequency in the 1900 year classes, were absent in the samples from the 1991 cohorts. However, mean heterozygosity per locus (H) did not differ significantly between year classes of either strain, illustrating that allelic diversity is a more sensitive indicator of loss of genetic variability than mean heterozygosity. This heterogeneity between cohorts is probably due either to broodstock maintenance practices such as the use of insufficient numbers of spawners, or, in the case of one strain, to bottlenecking caused by selection for late maturation and increased growth rate. Genetic monitoring of all year classes of reared strains is suggested, if insufficient breeding and distribution records are available from egg producers. Such records are often unavailable in commercial situations.  相似文献   

4.
Coho salmon, Oncorhynchus kisutch (Walbaum), is intensively cultured in Chile. An increasing proportion of the eggs necessary to sustain the culture are locally produced by some hatcheries. However, there is no information about the origin or the genetic variability in these strains. The present study analysed allozymic variability and its distribution within and between some commercial strains of coho salmon in southern Chile. The genetic variability was estimated using horizontal starch gel electrophoresis. Samples of coho salmon were obtained randomly from four Chilean hatcheries. Twenty‐five enzymatic systems were examined, representing 51 enzymatic loci. Eight loci showed variability in at least one strain, which represented a total polymorphism (P) of 15.7%. Only the PGM‐1* locus was variable in all strains. The remaining loci were fixed in at least one strain. Total heterozygosity (HT) and within population heterozygosity (HS) were 0.35% and 0.36% respectively. The index of genetic diversity (GST) was 1.5%. The results confirm previous reports of low genetic variability in cultured strains of coho salmon in Chile, below that observed in their native range, which suggests loss of the genetic variability caused by genetic drift or other causes in these strains.  相似文献   

5.
The Korean rockfish, Sebastes schlegeli, is a valuable and intensively exploited species in Korea. We discuss the genetic diversity and genetic structure of four Korean rockfish populations using eight microsatellite loci. In total, 161 different alleles from 138 individuals were observed. Average allele number per locus ranged from 2.5 to 23 and allelic richness varied from 13.38 to 14.63 within a population. Despite a long history of stocking practices, we found very high levels of polymorphism (mean heterozygosity = 0.810), which is comparable to other congeneric species. No significant difference in genetic diversity and molecular genetic variance (FST and RST) was observed among four local samples (P > 0.1). Little indication of contemporary inbreeding (FIS= 0.051) or population structure (K = 1) was detected. This absence of differentiation may reflect high levels of gene flow along the coast of Korea. Our study demonstrates that rockfish in Korea should be managed as a single unit. Currently, the species does not appear to be genetically threatened, but the potential for a rapid loss of genetic diversity remains. This information on the genetic characteristics of Korean rockfish populations has important implications for fisheries management and conservation efforts, and will aid in the sustainable exploitation of the fishing resources and the preservation of biodiversity.  相似文献   

6.
The genetic diversity and differentiation of sea trout were studied in three river basins in Lithuania: Akmena-Dane, Bartuva, and Nemunas. A total of 282 individuals were genotyped at eight microsatellite loci. A similar level of genetic diversity was found in all of the populations studied: mean allelic richness ranged from 3.64 to 5.03, and average expected heterozygosity ranged from 0.588 to 0.721. Significant genetic divergence was observed among the different river basins as well as between populations within the drainages. All pairwise F ST values were highly significant, ranging from 0.027 to 0.197. The analysis of molecular variance showed rather weak hierarchical population structuring within the Nemunas basin, which may be explained by extensive gene flow among different river basins or, alternatively, reflect the influence of artificial breeding. Information on genetic diversity and differentiation of the Lithuanian sea trout populations will be useful for future management decisions.  相似文献   

7.
采用微卫星标记技术分析不同世代三疣梭子蟹选育家系的遗传结构。利用16个多态性微卫星位点分析了三疣梭子蟹家系F1到F4 4个选育家系的遗传结构与遗传多样性变化情况。结果显示,随着选育的进行,4个世代家系遗传多样性指标值逐渐下降,F1到F4 16个微卫星位点的平均多态信息含量从0.675 3下降到0.406 1,平均等位基因数从3.500 0下降到2.133 3,平均观测杂合度从0.643 5下降到0.4774,平均等位基因纯合率从0.566 9下降到0.402 4。对各个位点进行H-W检验,每个世代出现不同程度的平衡偏离。对各家系进行F-检验,结果表明,各家系存在不同程度的遗传分化,19.07%的遗传分化来自群体间,80.93%的遗传分化来自群体内。另外,对FIS值的计算显示,4个家系在整体上均表现为一定程度的杂合子缺失,其中F4有12个位点、F3有6个位点、F2有3个位点、F1有8个位点处于杂合子缺失状态。遗传距离逐渐增加,相邻世代间的遗传相似性逐步升高。经过连续4代的选育,选育群体的遗传基础逐步得到纯化,基因型逐渐趋向纯合、稳定,经进一步的选育可望获得较稳定的品系。  相似文献   

8.
Genetic diversity is vital for the maintenance of genetic pool in cultured shrimps. In order to estimate the current status of genetic diversity in Litopenaeus vannamei shrimp in Iran, as an exotic species, a total of 45 individuals from Amiri and Gorgeaj farms in Jask port of Hormozgan province and one hatchery in Gomishan city of Golestan province, were detected using four microsatellite loci. The number of alleles per locus was 5–10, and the mean effective number of alleles (N e) across populations and loci ranged from 4.834 to 5.148. The overall mean observed heterozygosity (H o) ranged from 0.450 to 0.479, which was lower than the expected one (0.789–0.794). There was nothing remarkable about any of the allele frequencies across populations or loci. The mean inbreeding coefficient (F IS) and pairwise genetic differentiation (F ST) among populations were 41.6 % and 0.133, respectively. The three studied populations departed from Hardy–Weinberg equilibrium (HWE). Analysis of molecular variance revealed 14 % variability among and 86 % within populations. However, considering departing from HWE and the high F IS and F, the moderate pairwise F ST values, importance of introducing genetically diverse broodstock and monitoring to control inbreeding is discussed.  相似文献   

9.
为改良马氏珠母贝养殖群体性状,2010年4月,从马氏珠母贝选育系F3选择性腺成熟个体为亲本,建立了36个家系,按照常规技术进行幼体培育和海区养成.2010年11月,从36个家系中随机选取4个家系,每个家系取样30个个体,利用13对微卫星引物进行家系遗传结构和系谱鉴别分析.结果显示,(1) 13个微卫星引物在4个家系中共检测到39个等位基因,每个位点的等位基因数为2～5,4个家系的平均观测杂合度(Ho)为0.531 ～0.597,平均期望杂合度(He)为0.474 ～0.507;(2)根据子代基因型成功地推断出4个家系的亲本基因型,据此鉴别各个家系;用UPGMA法对120个样本进行聚类分析,98.3％的同一家系的子代个体能够聚到一起,分类结果与系谱来源基本一致.结果说明,这4个家系具有较高的遗传多样性和家系间具有明显的遗传分化;微卫星标记能有效地为马氏珠母贝群体的系谱分析提供技术支持.  相似文献   

10.
Ten populations of Penaeus kerathurus (Forskäl), a prawn of high commercial value, were sampled from the eastern and western Mediterranean coastal waters of Tunisia and screened electrophoretically for genetic variation at 13 allozyme loci. Four among the six polymorphic loci were out of Hardy–Weinberg equilibrium (H–WE) in at least one population. In the same way, the multilocus test showed deviation from H–WE in six populations. These populations showed heterozygote deficiency whereas the average heterozygosity for the four remaining ones is quite similar to the expected levels. Genetic variability was low. The number of alleles per locus ranged from 1.2 to 1.5 (average=1.3), and the observed heterozygosity varied between 0.010 and 0.048 (average=0.021). Significant population differentiation (FST=0.076, P<0.05) in the total data set reflected the differentiation of the two populations, which were at the margins of the range sampled, from all the others (Pairwise FST values ranged from 0.035 to 0.208). Although there was no significant differentiation among the other populations (pairwise FST values ranged from ?0.006 to 0.201, P>0.05). Our data suggest a population structure consistent with separation by Mediterranean Sea basins that might reflect different local biogeographical zones.  相似文献   

11.
The genetic diversity and structure of nine domesticated strains of red sea bream used in a private hatchery were studied and compared to a wild population. A total of 313 individuals were genotyped at eight microsatellite loci. Average number of alleles per locus ranged from 5.5 to 9.4 in domesticated strains, but that of the wild population was 28.4. Heterozygosity of domesticated strains (ranged 0.697–0.804) was also lower compared to the wild population (0.952). Estimated Ne also decreased in all domesticated strains (ranged 10.3–126.0) compared to the wild population (1422.5). The UPGMA tree and 3‐D FCA showed that there were two main clusters containing domesticated strains, and the wild population was at the middle of both of the domesticated clusters. The STRUCTURE analysis also supported the phylogenetic analysis, and revealed three sub‐clusters in the domesticated strains. Pairwise FST revealed that all domesticated strains were statistically different from the wild population, and also the differentiation between domesticated strains was all statistically significant. Information on genetic diversity and structure of domesticated strains of red sea bream obtained in this study will be useful for future broodstock management and selective breeding programmes.  相似文献   

12.
Abstract – Local genetic differentiation may potentially arise in recently fragmented populations. Brown trout is a polytypic species exhibiting substantial genetic differentiation, which may evolve in few generations. Movement (semi‐)barriers in rivers may cause fragmentation, isolation and genetic differentiation in fish. In the Måna River (28 km) flowing from the alpine Lake Møsvatn to the boreal Lake Tinnsjø, construction of four hydropower dams during the period 1906–1957 have fragmented the previously (since last Ice Age) continuous wild resident brown trout population. Samples from the two lakes (N = 40) and six sites in the river (N = 30) isolated at different times were analysed at nine microsatellite loci. All populations showed substantial genetic variation (mean number of alleles per locus 5.3–8.9, observed heterozygosity 0.57–0.65 per population, overall Fst = 0.032). Pairwise multilocus Fst estimates indicated no significant differentiation between populations in the two lakes, and no or little differentiation in the lower river (Fst = 0.0035–0.0091). The microgeographic differentiation among wild resident trout at these sites was less than expected based on similar previous studies. However, results from the upper river, in particular the site immediately below the Lake Møsvatn outlet and dam, indicated isolation (Fst > 0.035). Calculation of genetic distances and assignment tests corroborated these results, as did a significant correlation between years of isolation (since dam construction) and Fst. The population structuring is most likely a result of fragmentation by dams, which has increased overall genetic diversity. This increased local differentiation may be caused by natural selection, but more likely by genetic drift in small, recently fragmented populations. Increased local genetic diversity by genetic drift does not justify conservation measures aiming at preserving genetic diversity.  相似文献   

13.
This study was based on genotyping eight microsatellite loci of 463 brown trout, Salmo trutta L., sampled in nine differently sized tributaries in three areas on the eastern shore of Lake Mjøsa, south‐eastern Norway. The populations were genetically structured, and Mantel's test showed that genetic distance correlated positively with geographical distance. Temporal differentiation FST over a 2‐year period was estimated in five streams and was non‐significant after Bonferroni correction. Effective population size Ne was positively correlated with the habitat length available from the lake (0.3–22 km) and negatively with the number of full sib pairs in the sample. There was no correlation between Ne and genetic diversity, and private alleles were recorded in three medium‐sized streams, but not in the largest two. The importance of small spawning and nursery streams for the maintenance of genetic diversity of brown trout was demonstrated.  相似文献   

14.
邢德  李琪  张景晓 《水产学报》2017,41(12):1838-1846
为了探讨壳白长牡蛎人工选育对群体遗传变异的影响,实验利用4个多重PCR组合共10个微卫星标记分析了连续3代壳白长牡蛎人工选育群体和野生群体及基础群体的遗传多样性。结果发现,6个群体的平均等位基因数量为7.2~12.6,等位基因丰度为6.8~11.0,期望和观测杂合度分别为0.672~0.769和0.486~0.542;与野生群体相比,3代选育群体的平均等位基因数显著降低,但平均期望杂合度并无显著差异。哈迪—温伯格平衡检验结果显示,在60个群体—位点组合中有39个群体—位点组合显著偏离哈迪—温伯格平衡,近交系数F_(is)范围为0.215~0.342。群体间遗传分化指数F_(st)范围为0.005~0.076,处于中—低等的遗传分化水平。研究表明,虽然连续选育对群体的遗传多样性和遗传分化造成了一定程度的影响,但人工选育群体依然表现为较高的遗传多样性,仍可以一定的选择压力对选育群体进行人工选育。  相似文献   

15.
Macrobrachium rosenbergii, known as the giant freshwater prawn or Malaysian prawn, is the sixth largest aquaculture species in Asia. Knowledge of genetic diversity of M. rosenbergii is important to support management and conservation programmes, which will subsequently help in sustainable production of this economically important species. This study aimed to analyse the genetic diversity and population structure of five M. rosenbergii populations using 11 microsatellite loci. In analysing 240 samples, the number of alleles, observed heterozygosity (HO) and expected heterozygosity (HE) ranged from 3 to 20, from 0.250 to 0.978 and from 0.556 to 0.944 respectively. The five stocks of M. rosenbergii displayed high level of genetic diversity. Both the FST and amova analyses showed that there was significant genetic differentiation among all populations. The UPGMA dendrogram based on Nei's genetic distance matrix revealed that the Narmada and Mahi populations were in one cluster and Mahanadi and Subarnarekha populations in another single major branch, whereas the Kerala population clearly showed a separate cluster. This information on genetic variation will be useful for genetic improvement and conservation of Indian populations of giant freshwater prawn M. rosenbergii.  相似文献   

16.
In this study, multiplex PCR panels were developed to amplify 20 microsatellite markers for red sea bream, Pagrus major, with the aim of reducing labor and material costs associated with genetic analysis of this species. The usefulness of these panels was validated in 200 fish collected at five sampling locations. The occurrence of null alleles was suggested at five markers, which were dropped from further analysis. The remaining 15 microsatellite loci showed high levels of heterozygosity (H E range 0.34–0.97, H O range 0.32–1) and a wide range in the number of alleles per locus (A; range 5–46). Increasing the number of microsatellite loci from three to ten and 15 improved the performance of the panels for population differentiation (F ST) and estimation of Nei’s (D S) genetic distance. The results of this study confirm the usefulness of genotyping a large number of microsatellite DNA markers to expand our knowledge of red sea bream population genetics.  相似文献   

17.
Sea trout, Salmo trutta L., populations in the Slupia River basin have been affected by mass stocking with smolts and fry. This work is focused on a small‐scale differentiation in sea trout populations from one basin with a strong emphasis on the relationship between wild and hatchery origin fish. A total of 216 sea trout were genotyped at 10 microsatellite loci. Global FST obtained by amova was low at 0.0165. Pairwise FST were significant for all tests except wild and stocked adults. The highest pairwise difference was found between the hatchery sample and Kwacza (FST = 0.038). Analysis of the genetic structure revealed micro‐geographical differentiation with four subpopulations. The quality of the artificial spawning was found not to be adequate with a high risk of adverse effects to the whole population. All future stocking actions in the basin should consider the existing population structures.  相似文献   

18.
This study describes the genetic structure of five naturalized populations of brown trout in southern Chile using allozyme and microsatellite markers to establish levels of intra‐ and interpopulation genetic variability and divergence. Fourteen enzymatic systems were used comprising 20 loci and three microsatellite loci specific to brown trout. The genetic variability values (allozymes, P=20–35%, average=27%, HO=0.118–0.160, average=0.141; microsatellites, P=33.3–100%, average=66.66%, HO=0.202–0.274, average=0.229) are similar to values described in other naturalized populations of brown trout present in Chile, but higher than those observed in European populations of this species. Values of total genetic diversity (HT) (allozymes=0.1216 and microsatellites=0.3504) and relative genetic divergence (GST) (allozymes=9.5% and microsatellites=15%) were also similar to the results obtained in previous studies of Chilean populations of brown trout. These values, when compared with those obtained in Europe, proved to be similar for HT but lower for GST. The low interpopulational genetic differentiation was in accordance with the small genetic distance observed between the populations analysed (D Nei=0.004–0.025). On the other hand, the high frequency of one of the two alternative alleles of the phylogeographic marker locus LDH‐5* in the populations analysed (LDH‐5*90>0.84) would indicate a European origin, in particular Atlantic as opposed to Mediterranean, for the brown trout introduced into Chile. The high levels of genetic variability suggest a mixed origin for the naturalized brown trout in Chile, which could have originated either before or during the introduction process. Nevertheless, the low level of genetic differentiation between populations could reflect the short lapse of time in evolutionary terms, during which populations introduced into Chile have been exposed to different evolutionary forces, and which has not been sufficiently long to produce greater genetic differentiation between populations.  相似文献   

19.
Pacific cod (Gadus macrocephalus) is a commercially important species in Korea. However, overfishing in the 1990s caused a strong decline in catch, and in response, artificially cultured juveniles have been released annually to enhance the stocks. Cod fishing has recently increased in Korea, and the variation within the cod population necessitates the study of their genetic characteristics. In this study, we utilized two newly developed and eight previously reported microsatellite markers to examine the genetic characteristics of Pacific cod populations. We compared the genetic diversity and genetic structure of three cod populations from the Korean coasts with three populations from the North Pacific Ocean. Genetic differences were identified in the eastern sea cod population from Korea. These genetic differences included a large number of alleles per locus, a large number of unique alleles, higher frequencies of the most common alleles, and lower gene diversity compared to the other Korean populations. Additionally, the eastern sea cod population was genetically significantly differentiated from the southern and western sea populations in Korea, in which no significant genetic differentiation was detected (F ST = 0.033 and 0.031, respectively, P < 0.005).  相似文献   

20.
棘头梅童鱼七个野生群体遗传多样性的微卫星分析   总被引：5，自引：1，他引：4  
为研究中国沿海地区棘头梅童鱼群体的遗传多样性,利用微卫星标记技术,采用9对微卫星引物对中国连云港(LYG)、大丰(DF)、崇明(CM)、舟山(ZS)、温州(WZ)、宁德(ND)、厦门(XM)棘头梅童鱼7个野生群体的遗传多样性和遗传结构进行了分析。结果显示,实验检测到63个等位基因,各位点等位基因数为3~13个,有效等位基因数为1.7510~8.0317;各位点的观测杂合度(Ho)为0.3596~0.7854,期望杂合度(He)为0.4300~0.8780;多态信息含量(PIC)为0.3604~0.8631,其中有2个位点表现为中度多态(0.25PIC0.5),7个位点表现为高度多态(PIC0.5),具有较丰富的遗传多样性水平。Hardy-Weinber平衡分析显示,7个群体的大部分位点未偏离平衡。基于群体间Nei氏标准遗传距离构建的7个野生群体UPGMA系统进化树结果显示,ND和WZ群体遗传关系最近,ZS和WZ群体遗传关系最远,WZ和ND聚为一支,但总体上没有显著的遗传分化。  相似文献   

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