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1.
Repetitive DNA was cloned from HindIII-digested genomic DNA of Larix leptolepis. The repetitive DNA was about 170 bp long, had an AT content of 67%, and was organized tandemly in the genome. Using fluorescence in situ hybridization and subsequent DAPI banding, the repetitive DNA was localized in DAPI bands at the proximal region of one arm of chromosomes in L. leptolepis and Larix chinensis. Southern blot hybridization to genomic DNA of seven species and five varieties probed with cloned repetitive DNA showed that the repetitive DNA family was present in a tandem organization in genomes of all Larix taxa examined. In addition to the 170-bp sequence, a 220-bp sequence belonging to the same DNA family was also present in 10 taxa. The 220-bp repeat unit was a partial duplication of the 170-bp repeat unit. The 220-bp repeat unit was more abundant in L. chinensis and Larix potaninii var. macrocarpa than in other taxa. The repetitive DNA composed 2.0-3.4% of the genome in most taxa and 0.3 and 0.5% of the genome in L. chinensis and L. potaninii var. macrocarpa, respectively. The unique distribution of the 220-bp repeat unit in Larix indicates the close relationship of these two species. In the family Pinaceae, the LPD (Larix proximal DAPI band specific repeat sequence family) family sequence is widely distributed, but their amount is very small except in the genus Larix. The abundant LPD family in Larix will occur after its speciation.  相似文献   

2.
珍稀濒危植物夏蜡梅遗传多样性的ISSR分析   总被引:18,自引:0,他引:18  
利用ISSR分子标记技术,对濒危植物夏蜡梅10个居群的遗传多样性进行了分析.结果表明:夏蜡梅种的遗传多样性较高,多态位点百分率为73.08%,Shannon指数为0.3097,Nei指数为0.1987;而居群水平的遗传多样性较低,多态位点百分率平均为23.65%,Shannon指数平均为0.1251,Nei指数平均为0.0839.AMOVA分子差异分析显示:居群间遗传分化程度高,57.11%的变异存在于居群间,42.89%存在于居群内,基因分化系数(Gst)为0.5779;居群间的基因流为0.3651.生境的片断化使居群间的基因流受阻,可能是导致居群间高遗传分化和居群水平低遗传多样性的主要原因.10个居群间的平均遗传距离为0.1471.利用UPG-MA法对10个居群进行聚类,结果是天台县内的2个居群、临安市内的8个居群各组成一大类群.  相似文献   

3.
Genetic diversity and population genetic structure of natural Oryza rufipogon populations in China were studied based on ten microsatellite loci. For a total of 237 individuals of 12 populations collected from four regions, a moderate to high level of genetic diversity was observed at population levels with the number of alleles per locus ( A) ranging from 2 to 18 (average 10.6), and polymorphic loci ( P) from 40.0% to 100% (average 83.3%). The observed heterozygosity ( H(O)) varied from 0.163 to 0.550 with the mean of 0.332, and the expected heterozygosity ( H(E)) from 0.164 to 0.648 with the mean of 0.413. The level of genetic diversity for Guangxi was the highest. These results are in good agreement with previous allozyme and RAPD studies. However, it was unexpected that high genetic differentiation among populations was found ( R(ST) = 0.5199, theta = 0.491), suggesting that about one-half of the genetic variation existed between the populations. Differentiation (pairwise theta) was positively correlated with geographical distance ( r = 0.464), as expected under the isolation by distance model. The habitat destruction and degradation throughout the geographic range of O. rufipogon may be the main factor attributed to high genetic differentiation among populations of O. rufipogon in China.  相似文献   

4.
BACKGROUND AND AIMS Habitats in mountains are often isolated. Plants growing in these sites face severe dispersal limitations, but also difficulties for recruitment. The focus was laid on the magnitude of genetic differences among populations but also on the size of potentially occurring clones. METHODS: RAPD fingerprints were obtained from 23 populations in southern Mongolia. Sampling covered the entire distribution range of Galitzkya macrocarpa; samples of G. potaninii represented only the Mongolian part of its mainly northern Chinese range. KEY RESULTS: The Mongolian endemic G. macrocarpa showed moderately strong population differentiation (Phi ST = 0.251), and limited evidence for isolation by distance. Local genetic diversity was not positively correlated to habitat size, and not reduced in peripheral populations. Clonal growth is possible, but most plants originate from sexual reproduction. In contrast, populations of G. potaninii were highly differentiated (Phi ST = 0.550); and the most remote outposts had reduced genetic diversity. In these areas, isolation is expected to date back to glacial times. CONCLUSIONS: Effects of natural fragmentation differ among species. Both are rare, but G. macrocarpa appears to be able to maintain genetic diversity over its range. Clonal growth is an option in its mixed reproduction strategy and allows survival under harsh conditions. In contrast, genetic structure in G. potaninii gives reason for concern, and further studies on population dynamics are needed.  相似文献   

5.
Levels of genetic diversity and population genetic structure of the rare, endangered terrestrial orchid Liparis japonica were examined for eight natural populations (n = 185) in Northeast China using six AFLP primer pairs, where this species has experienced severe habitat loss and fragmentation. Based on 406 DNA bands, a high level of genetic diversity was found at the species level with the PPB of 85.47 %, while the genetic diversity at the population level was low (PPB = 47.48 %). A significantly high degree of population differentiation was found with 42.69 % variation existed among populations as measured by AMOVA, indicating potential restricted gene flow. The genetic distances between populations were independent of the corresponding geographic distances, and the genetic relationship of individuals had no significant correlation with their spatial distribution. The restricted gene flow might be impacted by reduced population size, habitat destruction and fragmentation. The results in this study suggested that habitat protection and keeping a stable environment are critical for the conservation of L. japonica species.  相似文献   

6.
Amitostigma hemipilioides is an endangered terrestrial orchid endemic to China. In the Southwestern China, the species is found restricted growing in the karst limestone or rock in the edge of farmland, moist hillsides or river. In the present study, the genetic diversity and differentiation was estimated within and among habitats, populations and groups of this species by ISSR markers. Using 13 polymorphic primers, an intermediate level of genetic diversity was found at the species level and population level with the percentage of polymorphic bands (P) of 64.7 and 50.9 %, Shannon index of diversity (I) of 0.3873 and 0.2949, respectively. The analysis of molecular variance (AMOVA) showed that the high level of population differentiation was presented with 45.63 % relative to the total genetic variation residing among eight populations. It was noteworthy that as much as 69.17 % of the total diversity was most likely attributed to the difference among the populations in fragmentation habitat conditions, while 16.32 % of the total diversity could be attributed to the difference among the populations in stable and favorable habitat conditions. The in situ conservation is a top strategy, thus the mycorrhizal fungi and pollinators are protected by protecting habitat and avoiding fragmentation which is helpful to the cycle of this endangered orchid species and recovery of its wild populations. In addition, to maintaining the germplasm bank of this species, the ex situ conservation by habitat simulation and reintroduction has been considered in the living collection at Kaili University ecological garden and Yuntai Mountain scenic spot using the plants collected in this study.  相似文献   

7.
Environmentally induced phenotypic plasticity is thought to play an important role in the adaption of plant populations to heterogeneous habitat conditions, and yet the importance of epigenetic variation as a mechanism of adaptive plasticity in natural plant populations still merits further research. In this study, we investigated populations of Vitex negundo var. heterophylla (Chinese chastetree) from adjacent habitat types at seven sampling sites. Using several functional traits, we detected a significant differentiation between habitat types. With amplified fragment length polymorphisms (AFLP) and methylation‐sensitive AFLP (MSAP), we found relatively high levels of genetic and epigenetic diversity but very low genetic and epigenetic differences between habitats within sites. Bayesian clustering showed a remarkable habitat‐related differentiation and more genetic loci associated with the habitat type than epigenetic, suggesting that the adaptation to the habitat is genetically based. However, we did not find any significant correlation between genetic or epigenetic variation and habitat using simple and partial Mantel tests. Moreover, we found no correlation between genetic and ecologically relevant phenotypic variation and a significant correlation between epigenetic and phenotypic variation. Although we did not find any direct relationship between epigenetic variation and habitat environment, our findings suggest that epigenetic variation may complement genetic variation as a source of functional phenotypic diversity associated with adaptation to the heterogeneous habitat in natural plant populations.  相似文献   

8.
内蒙古典型草原羊草种群遗传分化的RAPD分析   总被引:15,自引:3,他引:15  
运用 RAPD技术对内蒙古典型草原不同生境 8个羊草种群进行分析。采用 2 4个随机引物 (10 nt)在 8个种群中共检测到2 2 4个扩增片断 ,其中多态性片断 173个 ,总的多态位点百分率达 77.2 % ,特异性片断 2 2个 ,占 9.82 % ,平均每个引物扩增的DNA带数为 9.3 3条。利用 Nei指数和 Shannon指数估算了 8个种群的遗传多样性 ,并计算种群相似系数和遗传距离 ,运用UPGMA法进行聚类分析。结果表明 :羊草大部分的遗传变异存在于种群内 ,只有少部分的遗传变异存在于种群间 ,Nei指数和Shannon指数计算结果分别为 85.4%和 66.8% ;羊草不同种群的遗传多样性存在差异 ;8个羊草种群平均遗传距离为 0 .2 3 16,变异范围为 0 .1587~ 0 .2 70 0 ,说明 8个羊草种群间的遗传变异不大 ,即 :在较小地理范围内羊草的遗传分化程度较小 ;8个种群可聚为 3个类群 ,聚类结果显示生境相似的种群能够聚在一起 ,而地理距离最近的种群不一定归为一类 ,说明小范围内羊草种群间的遗传分化与地理距离不存在相关性 ,而与其生境间的相似度相关。影响遗传相似性的不是单一因子而是各种因子的综合作用 ,较小地理范围内羊草种群间的遗传分化主要是由环境的异质性所引起的  相似文献   

9.
内蒙古中东部不同草原地带羊草种群遗传分化   总被引:10,自引:2,他引:8  
运用 RAPD技术对内蒙古不同草原地带分布的 5个羊草种群 (共 10 0个个体 )的遗传多样性进行分析。 31个随机引物(10 nt)在 5个羊草种群中共检测到 4 96个扩增片断 ,其中多态性片断 4 89个 ,总的多态位点百分率达 98.6 %。利用 Nei指数和Shannon指数估算了 5个种群的遗传多样性 ,并计算种群相似系数和遗传距离运用 UPGMA法进行聚类分析。结果表明 :无论是种群内还是种群间 ,羊草均存在较高的遗传变异 ,大部分的遗传变异存在于种群内 (Nei指数和 Shannon指数估算结果分别为 85 .4 %和 72 .5 % ) ,只有少部分的遗传变异存在于种群间 ;不同种群的遗传多样性存在差异 ,各种群的遗传多样性与其所处的地理位置具有显著的相关性 ;5个种群的平均遗传距离为 0 .5 0 95 ,变异范围为 0 .4 6 84~ 0 .5 4 76 ;聚类分析结果显示地理距离较近的种群遗传距离较小 ,首先聚在一起 ,而地理距离较远的种群遗传距离较大 ,说明羊草种群间的遗传分化与地理距离存在一定相关性 ;但地理距离最近的两个种群并未最先聚集 ,说明羊草种群间的分化还与其生境的异质性有关  相似文献   

10.
The genetic variation and clonal diversity of two divergent types (grey-green and yellow-green) of clonal populations ofLeymus chinensis Tzvel at 14 loci were compared. Total gene diversity (HT) and the coefficient of genetic differentiation (GsT) were all higher for the yellow-green type (HT = 0.270; GsT = 0.186)than for the grey-green type (HT = 0.250; GsT = 0.157) of L. chinensis. Rare alleles usually occurred as heterozygotes rather than homozygotes and significant deviations from Hardy-Weinberg equilibrium were found only at a few loci. This indicated that these two types of populations were mainly out-crossing. Clonal diversity, evenness of clones, and mean clone size were not significantly different between the two types.We found that differences between the clone size and genetic variation of the yellow-green type of popula tions occurred with different climate and habitat population groups. However, for the grey-green type of populations, these genetic variations decreased under conditions of different climate and habitat popula tion groups.  相似文献   

11.
【目的】葱斑潜蝇Liriomyza chinensis是葱蒜类蔬菜上的重要经济害虫,在我国广泛分布。本研究旨在阐析中国葱斑潜蝇的地理种群遗传分化。【方法】以中国8省12个不同地理种群的253头葱斑潜蝇为样本,测定其mtCOI基因序列;依据获得的mtCOI基因序列,利用MEGA7.0, DnaSP 6.1和Arlequin 3.5等软件对葱斑潜蝇地理种群的遗传多样性、基因流水平和遗传变异等进行分析。【结果】在253头个体的759 bp mtCOI基因片段中,获得13个单倍型,各单倍型间K2P遗传距离均小于0.02;其中单倍型Hap1为12个地理种群所共享,总发生频率高达81.82%。总群体单倍型多样性较低(Hd=0.327),核苷酸多样性(Pi)为0.00159,核苷酸平均差异数(K)为1.21011;葱斑潜蝇总群体遗传分化程度中等(FST=0.06971),基因交流较充分(Nm=3.33629)。分子方差分析(AMOVA)结果表明,遗传变异来源为群体内;总群体Tajima’s D检验值为显著负值;Mantel检测结果说明种群间的遗传距离与地理距离没有相关性。【结论】中国葱斑潜蝇地理种群的遗传多样性较低,基因交流较充分,遗传分化程度中等,且地理距离并不影响其遗传分化程度;葱斑潜蝇总群体在较近的历史时期未经历明显的种群扩张和种群增长。  相似文献   

12.
Psammosilene tunicoides W. C. Wu et C.Y. Wu (Caryophyllaceae) is a rare plant endemic to China. We used the direct amplification of length polymorphism (DALP) method to analyse the genetic diversity of 17 natural populations of this species from Yunnan, Sichuan and Guizhou provinces. The percentage of polymorphic bands (PPB) was 99.1% at the species level and 19.9% at the population level. The total genetic diversity (Ht) was 0.2827; the genetic diversity within populations (Hs) was 0.0594 and the coefficient of gene differentiation (Gst) was 0.7899. The results indicated low levels of genetic diversity within populations and extremely high genetic differentiation among populations. This pattern might be caused by genetic drift resulting from intensive harvesting and habitat fragmentation. It might also be a result of local adaptation. We further performed experiments on its breeding system and found a high rate of selfing in P. tunicoides, which may be partially responsible for its population structure.  相似文献   

13.
The genetic variation and clonal diversity of two divergent types (grey-green and yellow-green) of clonal populations of Leymus chinensis Tzvel at 14 loci were compared. Total gene diversity (HT) and the coefficient of genetic differentiation (GST) were all higher for the yellow-green type (HT = 0.270; GST =0.186) than for the grey-green type (HT = 0.250; GST = 0.157) of L. chinensis. Rare alleles usually occurred as heterozygotes rather than homozygotes and significant deviations from Hardy-Weinberg equilibrium were found only at a few loci. This indicated that these two types of populations were mainly out-crossing. Clonal diversity, evenness of clones, and mean clone size were not significantly different between the two types. We found that differences between the clone size and genetic variation of the yellow-green type of populations occurred with different climate and habitat population groups. However, for the grey-green type of populations, these genetic variations decreased under conditions of different climate and habitat population groups.  相似文献   

14.
濒危植物毛柄小勾儿茶片断化居群的遗传多样性   总被引:3,自引:1,他引:3       下载免费PDF全文
采用扩增片段长度多态性(AFLP)标记对我国特有的濒危植物毛柄小勾儿茶(Berchemiella wilsonii var. pubipetiolata)现存于浙江和安徽的4个片断化居群中的89株个体进行了遗传多样性和遗传结构的研究。结果表明,与其它木本濒危植物相比,毛柄小勾儿茶具有与它们相当的遗传多样性,8对选择扩增引物共扩增出122条清晰的条带,居群的平均多态位点百分率为Pp=26.4%,其中马家河居群最高(29.5%)而湍口居群最低(23.8%),居群的平均基因多样度为Hep=0.162 8(0.140 5~0.172 4);而在物种水平上的遗传多样性为Ps=36.9%, Hes=0.202 4。居群间的遗传分化系数FST=0.193 9,表明居群间有显著的遗传分化,进一步利用AMOVA软件对遗传变异进行等级剖分发现:24.88%的遗传变异存在于地理宗间(浙江地理宗和安徽地理宗),14.71%的遗传变异存在于居群间,60.42%存在于居群内。该研究结果表明,由于人为干扰引起的生境片断化和居群减小导致了毛柄小勾儿茶居群的遗传多样性丧失和遗传分化,并对毛柄小勾儿茶的生存造成潜在威胁。该文还就保育策略进行了讨论。  相似文献   

15.
Detection of the genetic effects of recent habitat fragmentation in natural populations can be a difficult task, especially for high gene flow species. Previous analyses of mitochondrial DNA data from across the current range of Speyeria idalia indicated that the species exhibited high levels of gene flow among populations, with the exception of an isolated population in the eastern portion of its range. However, some populations are found on isolated habitat patches, which were recently separated from one another by large expanses of uninhabitable terrain, in the form of row crop agriculture. The goal of this study was to compare levels of genetic differentiation and diversity among populations found in relatively continuous habitat to populations in both recently and historically isolated habitat. Four microsatellite loci were used to genotype over 300 individuals from five populations in continuous habitat, five populations in recently fragmented habitat, and one historically isolated population. Results from the historically isolated population were concordant with previous analyses and suggest significant differentiation. Also, microsatellite data were consistent with the genetic effects of habitat fragmentation for the recently isolated populations, in the form of increased differentiation and decreased genetic diversity when compared to nonfragmented populations. These results suggest that given the appropriate control populations, microsatellite markers can be used to detect the effects of recent habitat fragmentation in natural populations, even at a large geographical scale in high gene flow species.  相似文献   

16.
中华稻蝗不同地理种群遗传多样性的AFLP分析   总被引:2,自引:0,他引:2  
马晋  李涛  龙文敏  安玮玮  郭亚平  马恩波 《遗传》2010,32(2):163-169
为研究中华稻蝗种群遗传多样性和遗传结构, 文章对我国7省市的7个中华稻蝗种群进行AFLP分析。选取7对引物扩增128个个体, 共产生336条带, 多态性条带292条, 占86.90%。结果表明: 中华稻蝗种群具有较高的遗传多样性水平, 其中海南万宁种群的遗传多样性高于其他各种群。Mantel检验(r=0.27, P=0.89)表明中华稻蝗各种群遗传距离与地理距离间没有显著相关性。种群间具有明显的遗传分化现象。UPGMA(Unweighted pair group method average)聚类分析显示, 7个中华稻蝗种群按地理距离分为3支: 北方北京昌平、山西太原和山东济宁为一支; 南方陕西汉中、湖南长沙和广西来宾为一支; 海南万宁单独为一支。上述结果以及PCA(Principal component analysis)分析均表明由于地理隔离中华稻蝗种群显示出明显的南北分化和岛屿大陆种群遗传分化现象。  相似文献   

17.
同域分布的近缘物种常常发生杂交而导致种间基因渐渗, 从而对相关物种的自然居群遗传结构产生重要影响, 近缘种间的杂交渐渗已成为进化生物学和保护生物学关注的热点。本研究采用8对cpSSR引物对我国西部高原台地向中东部丘陵平原过渡地带同域重叠分布的猕猴桃属(Actinidia)7个物种的自然居群遗传多样性、居群遗传结构和同域分布种间遗传分化进行了检测。结果表明: (1)在6个多态性位点检测到18个等位基因形成的42个单倍型, 尽管各单倍型间显示了复杂的网状进化关系, 但还是具有明显的物种特异性; (2)各物种有丰富的cpSSR遗传多样性, 但种间存在较大差异, 绵毛猕猴桃(Actinidia fulvicoma var. lanata)的遗传多样性水平最高(P = 62.50%, hT = 0.173, HT = 0.897), 美味猕猴桃(A. deliciosa)的最低(P = 37.5%, hT = 0.041, HT = 0.516); (3)尽管不同物种的居群分化程度存在较大差异, 但种内居群间存在明显分化(GST为0.319–0.780, FST为0.401–0.695), 居群间的基因流不足(Nm为0.219–0.747<1); 其中以美味猕猴桃的居群遗传分化度最高(GST = 0.780, FST = 0.695); (4)遗传分化系数GST(unordered alleles)与NST(ordered alleles)无显著差异, 揭示本研究的大多数猕猴桃属物种不存在系统地理结构, 与用Mantel检验得出的居群遗传距离和地理距离不存在显著性相关的结果一致; (5)除了中华/美味猕猴桃复合体(A. chinensis / A. deliciosa complex)的湖北五峰(HW)和广西资源(GZ)两个同域复合居群外, 同域分布的物种间遗传分化强烈(FST为0.476–0.990), 与UPGMA聚类时多数居群按各自物种聚类的结果一致。进一步分析表明, 中华/美味猕猴桃复合体近缘种间存在明显的共祖多态性和杂交渐渗现象, 近缘种植株分布的交错程度以及是否存在亚居群结构对杂交渐渗存在着重要影响。亲缘关系较远的物种间杂交渐渗事件稀少, 但存在个别同塑事件。本研究结果有助于进一步了解猕猴桃属植物自然居群cpDNA的遗传特性和渐渗杂交进化模式, 为我国猕猴桃野生种质资源保育及可持续开发利用提供基础数据和科学依据。  相似文献   

18.
多叶重楼遗传多样性的ISSR分析   总被引:1,自引:0,他引:1  
采用ISSR分子标记对多叶重楼种下3个变种的8个居群共208份样品的遗传多样性进行了分析。l4条引物共检测到251个清晰的扩增位点,其中多态位点235个。在物种水平上,多态位点百分率(PPB)达93.63%,Nei′s基因多样性指数(HE)为0.2204、Shannon′s信息指数(HO)为0.3532。在居群水平上,多态位点百分率(PPB)为50.45%,Nei′s基因多样性指数(HE)为0.1405,Shannon′s信息指数(HO)为0.2194,这些均表明多叶重楼的遗传多样性水平较高。此外,还用NTSYS软件对样品进行了UPGMA聚类分析,结果显示滇重楼的6个居群聚为一支,滇重楼与狭叶重楼有较近的亲缘关系,而与长药隔重楼之间的遗传分化较大。本研究提出了合理保护重楼植物资源的若干措施,为进一步开展滇重楼优质种质引种驯化,实现种质资源多样性的合理保护和可持续利用提供参考。  相似文献   

19.
濒危物种裂叶沙参及其近缘广布种泡沙参的遗传多样性研究   总被引:33,自引:2,他引:33  
葛颂  洪德元 《遗传学报》1999,26(4):410-417
根据对12个形态性状的统计分析和10个基因位点的等位酶检测,探讨了濒危植物裂叶沙参及其近缘广布种泡沙参的遗传多样性水平,对3个裂叶沙参和6个泡沙参天然群体的遗传分析表明,两种沙参属植物均具有很高的遗传变异水平,这种变异性既体现在形态学水平上,也体现在酶位点水平上,在2个茎叶形状以及10个花果和种子形状上,濒危种裂叶沙参的变异性均与广布种相当,同样,根据7个酶系统10个等位酶位点的度量,裂叶沙参群体  相似文献   

20.
基于树轮年代学方法,利用玉龙雪山、哈巴雪山和普达措国家公园海拔上限大果红杉树轮宽度资料,分别建立3个样点大果红杉的差值年表(RES),研究其径向生长对气候响应的异同,探讨影响滇西北大果红杉生长的关键气候因子.结果表明: 生长季初期(5月和6月)温度是影响滇西北大果红杉生长的主要因子,与3个样点的径向生长表现出显著正相关关系,同时普达措国家公园大果红杉还受生长季以前温度的影响,分别与上年7月和11月温度呈显著负相关和显著正相关;3个样点大果红杉生长对降水的响应存在差异,随着纬度升高主要由负相关转为正相关,大果红杉径向生长与降水的关系在玉龙雪山(纬度梯度最南)主要表现为与生长季初期降水量呈显著负相关,在哈巴雪山(纬度梯度中部)表现为与9月降水量呈显著负相关,在普达措国家公园(纬度梯度最北)表现为与3月降水量呈显著正相关.另外,7月降水的增多有利于玉龙雪山大果红杉的生长.基于气候模型预测,综合大果红杉对温度和降水响应模式与响应程度分析,未来气候变化有利于滇西北高原大果红杉的径向生长.  相似文献   

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