不同种群海南粗榧(Cephalotaxus mannii)遗传多样性研究

采用垂直板型凝胶电泳技术 ,对海南粗榧 5个种群的遗传多样性进行了研究 ,结果表明 :海南粗榧遗传多样性水平低 ,多态位点比率 P=0 .3 3 ,等位基因平均数 A=1 .3 3 ,平均期望杂合度为 He=0 .1 3 5 ,观察杂合度 Ho=0 .1 3 9,黎母山种群所具有的相对丰富的遗传多样性使其成为保护和科研的重点     

珍稀濒危植物海南粗榧种群遗传多样性研究

利用RAPD技术对珍稀濒危植物海南粗榧(Cephalotaxus mannii Hook . f.)遗传多样性水平、分布、濒危原因及物种保护等问题进行了探讨.结果表明:1. 海南粗榧在海南岛的5个取样地点表现出低水平的遗传多样性,对环境变化的适应能力不强; 2. 海南粗榧种群内和种群间的遗传多样性所占比例有很大差异,绝大部分变异分布于种群内(DNA多样性为85.1%);种群间仅有较低程度的分化;3. 人为砍伐、植被破坏、台风、被食及遗传漂变是海南粗榧遗传多样性低水平的主要原因,也是物种濒危的主要原因;4. 对于呈零星分布的濒危植物海南粗榧的研究与保护,应充分考虑个体小环境之间的差异,考察影响小种群的随机因素;5. 应采取有力措施,就地保护现有种群,并寻求适当的方法迅速扩展种群,降低基因丧失率;选择遗传多样性较高且破坏相对较小的黎母岭种群作为保护重点;同时应加强对其他种群的保护与管理;6. 海南粗榧种群内、种群间的遗传多样性在不同引物之间有较大差别;多态性位点百分率则是种群间的变化大于引物间的变化.     

珍稀濒危植物海南粗榧种群遗传多样性研究

利用RAPD技术对珍稀濒危植物海南粗榧（Cephalotaxus manniiHook.f.)遗传多样性水平,分布、濒危原因及物种保护等问题进行了探讨。结果表明：1、海南粗榧在海南岛的5个取样地点表现出低水平的遗传多样性,对环境变化物适应能力不强;2、海南粗榧种群内和种群间的遗传多样性所占比例有很大差异,绝大部分变异分布于种群内（DAN多样性为85.1%);种群间仅有较低程度的分化;3、人为砍伐,植被破坏,台风、被食用遗传漂变是海南粗榧遗传多样性低水平的主要原因,也是物种濒危的主要原因;4、对于呈零星分布的濒危植物海南粗榧的研究与保护,应充分考虑个体小环境之间的差异。考虑影响小种群的随机因素;5、应采取有力措施,就地保护现有种群,并寻求适当的方法迅速扩展种群,降低基因丧失率;选择遗传多样性较高且破坏相对较小的黎母岭种群作为保护重点;同时应加强对其他种群的保护与管理;6、海南粗榧种群内,种群音质遗传多样性在不同引物之间有较大差别。多态性位点百分率则是种群间的变化大于引物间的变化。     

华东地区青冈种群的遗传多样性及遗传分化

采用垂直板型聚丙烯酰胺凝胶电泳测定了华东地区6个青冈(Cyclobalanopsis glauca(Thunb.)Oerst.)种群的遗传多样性和遗传分化程度以及基因流。青冈种和种群水平都维持有较高的遗传多样性,期望杂合度分别为0.2252和0.2126,观察杂合度分别为0.1661和0.1771。种群间的遗传分化程度较低,分化度仅为5.6％,种群间的遗传一致度和遗传距离的均值分别为0.9729和0.0276。种群间的分化时间为1.4～27万年。基因流分别为4.21和20.49。     

斑节对虾两个野生亲虾种群遗传多样性

采用RAPD和mtDNA 16S rRNA基因序列分析方法对海南和马来西亚斑节对虾(Penaeus monodon)种群进行了遗传多样性和遗传分化研究.结果表明:15个RAPD随机引物共检测到82个位点,海南和马来西亚种群的多态位点比例分别为75.90％和76.83％,杂合度分别为0.199和0.218,遗传多样性指数分别为0.276和0.288,种群间的遗传距离为0.015;16S rRNA基因检测的种内遗传变异较低,马来西亚和海南种群的核苷酸多样性分别为0.011和0,种群之间的遗传距离为0.008;马来西亚种群比海南种群的遗传变异水平要高得多,且海南种群可能起源于马来西亚种群;进行遗传选育时可考虑引进马来西亚亲虾作为奠基群体.     

基于微卫星标记的中国东北地区灰飞虱遗传变异及种群遗传结构分析

【目的】本研究旨在明确我国东北地区灰飞虱Laodelphax striatellus种群遗传变异及种群遗传结构,阐明种群间遗传分化与基因流。【方法】利用9对微卫星引物对采自我国东北地区15个地理种群的375头灰飞虱样品进行测序与分析;利用GeneAlex6.51,GENEPOP4.0.9和STRUCTURE 2.3.4等软件分析灰飞虱地理种群间的遗传多样性、遗传分化、基因流及种群遗传结构。【结果】在所分析的375头灰飞虱个体中,各位点平均有效等位基因数Na=6.898;总体上,灰飞虱不同地理种群遗传多样性较高(平均观测杂合度Ho=0.548;平均期望杂合度He=0.582),各种群间基因流较低(Nm=0.660)。UPGMA聚类树、PCoA及STRCTURE分析结果表明,东北地区灰飞虱种群分为两分支:吉林(JL)和沈阳(SY2012,SY2013和SY2014)种群聚为一支;其余种群聚为一支。AMOVA分析结果表明,灰飞虱遗传变异主要来自种群内(87%),种群间变异水平较低(13%)。【结论】中国东北地区灰飞虱遗传多样性较高,不同地理种群存在一定程度的遗传分化,且基因交流较低,存在一定的种群遗传结构。     

中国4种蝗虫不同种群的遗传分化

采用水平淀粉凝胶电泳技术,应用等位酶分析方法对采自我国山西、江苏、河北等地不同蝗区优势蝗虫种类3科4种8个种群的12种酶18个酶位点进行了检测,比较了4种蝗虫种群水平的等位基因频率变化和它们之间的遗传距离。等位基因频率分析表明：中华稻蝗和笨蝗各位点等位基因丰富,而长翅素木蝗和短额负蝗各位点等位基因较少。在所研究的4种蝗虫8个种群中,多态位点百分率普遍较高(P＝53．3％—100．0％),由于杂合子数目较少而使每个位点的平均杂合度观察值偏低(H。＝0．034—0．139)。受迁飞能力、繁殖方式和活动范围的限制,4种蝗虫的平均杂合度观察值表现出一定的差异：笨蝗较高(H。＝0．089—0．139),其次是中华稻蝗(H。＝0．073—0．090),而长翅素木蝗(H。＝0．0488—0．068)和短额负蝗(H。＝0．034—0．050)相对较低。除Adk-1、Ao-1、Idh-1、Ldh-1、Ldh-2和Me-1在部分蝗虫种群符合Hardy-Weinberg平衡外,其余绝大多数位点的基因型频率显著偏离H—W平衡,但短额负蝗的多个位点符合或接近H—W平衡,表明该种蝗虫在自然种群结构方面明显有别于其他种类。从4种蝗虫的F—统计量(Fst)看,笨蝗种群间基因分化程度最高(Fst＝0．32),其次是短额负蝗(Fst＝0．31),而中华稻蝗相对较低(Fsl＝0．20),长翅素木蝗种群间基因分化程度最低(Fsl＝0．18),利用非加权算术平均法(UPGMA)对I值和D值进行聚类,所得聚类树也证实了这种遗传分化差异,上述结果反映了迁飞能力、适应性和环境因子对不同蝗虫遗传分化的影响。Nei的遗传距离(D)和遗传一致度(I)进行的聚类分析基本符合传统形态学、细胞学等研究结果：即同属于斑腿蝗科的中华稻蝗和长翅素木蝗遗传距离最小(D＝0．559),遗传一致度最高(I＝0．576)。在3个科中,癞蝗科和锥头蝗科之间呈现较小的遗传距离(D＝0．776)和较高的遗传一致度(I＝0．776),而这两科与斑腿蝗科之间的遗传距离相对较大(D＝0．908),遗传一致度相对较低(I＝0．406)。等位酶分析能较好地反映蝗虫不同物种的亲缘关系和种内不同种群之间的遗传分化程度。     

西鄂尔多斯特有种四合木种群遗传多样性及遗传分化研究

利用垂直板聚丙烯酰胺凝胶电泳技术,对西鄂尔多斯高原特有种四合木（Tetraena mogolica）4个种群遗传多样性和遗传分化进行了初步研究。电泳结果表明,四合木在种和种群水平维持较高的遗传多样性,1多态位点百分率P＝60％,等位基因平均数A＝1.6,平均期望杂合度He=0.245。4个种群之间遗传分化很小,基因分化系数GST只有0.052,明不同于其它濒危物种。四合木种较高的遗传多样性和极低的种群间分化,说明不同的种群可能有共同的起源,随机遗传漂变和近交衰退不是影响遗传多样性的主要过程。     

濒危植物长叶榧群体遗传多样性的RAPD分析

借助随机扩增多态DNA方法,分析了中国特有的濒危植物长叶榧的遗传多样性和遗传分化．结果表明：12个随机引物在9个长叶榧自然群体180个样品中可检测到180个可重复位点,其中多态位点119个．长叶榧物种水平的遗传多样性较高,多态位点百分率（P）为66．11％,Shannon信息指数（,）为0．3087,Nei指数（h）为0．2015;而群体水平的遗传多样性较低,P、I和h分别平均为23．76％、0．1221和0．0813．AMOVA分子变异显示,42．57％变异来源于群体内,57．43％变异来源于群体间,群体间的遗传分化系数（Gst）为0．5965,群体间的遗传分化程度高．长叶榧群体间的基因流很低,为0．3382．瓶颈效应、群体隔离和群体间基因流低等因素都加剧了长叶榧群体间的遗传分化．9个长叶榧群体间的平均遗传距离为0．1630．通过UPGMA进行聚类,可将9个长叶榧群体分为浙江和福建两大类群．建议在迁地保护时应尽量避免在群体之间实施种质迁移．     

高原鼠兔四个地理种群的遗传多样性与遗传分化

采用7个多态微卫星DNA标记分析了4个高原鼠兔地理种群（海晏种群、西大滩东种群、西大滩西种群和昆仑山种群）的遗传多样性和遗传分化.采用多态信息含量（PIC）、期望杂合度（He）、观测杂合度（Ho）、基因流（Nm）和基因分化系数（Fst）对种群及物种的遗传多样性水平进行分析;计算各种群间的遗传距离（GD）、遗传相似度（GI）以及遗传距离与地理距离的相关系数,并进行UPGMA聚类分析.研究结果显示,高原鼠兔的遗传多样性在小哺乳动物中处于较高水平,其He和Ho的平均值分别为0.5332和0.6003,其Fst为0.0975,即有9.75%的变异存在于种群之间,即变异主要存在于种群内部.4个种群间的杂合度与多态信息含量均无显著差异,说明它们的遗传多样性水平基本相当.海晏种群与其余3个种群的遗传分化均达到了中度分化水平（Fst= 0.1043）,而另3个种群间几乎没有分化（Fst=0.0253）.Mantel test结果表明地理距离与遗传距离间没有显著的相关性.     

人工与自然恢复条件下地被层优势种大羽藓的遗传多样性比较

基于随机扩增多态性DNA(RAPD)方法比较了川西米亚罗地区3个人工云杉林样地和3个天然次生林样地大羽藓(Thuidium cym bifolium)种群的遗传多样性及分化程度。人工林种群的平均多态位点百分比(PPL)为12.7%,Ne i’s基因多样性(HE)为0.042,Shannon’s信息指数(S)为0.064,种群内遗传一致度(I)为0.952;天然次生林种群则依次为10.0%、0.027、0.043和0.960。人工林种群和天然次生林种群Gst分别为0.592和0.702,Fst分别为0.639和0.695;结合UPGMA聚类和PCA分析,发现种群间的基因交流极少。单因素方差分析显示,人工林下大羽藓种群的遗传多样性水平显著高于天然次生林下种群(p<0.05),表明在皆伐迹地上通过人工造林能有效地促进林下物种遗传多样性的恢复。     

Genetic diversity in Hemileia vastatrix based on RAPD markers

Random amplified polymorphic DNA (RAPD) was used to assess the genetic structure of Hemileia vastatrix populations. Forty-five rust isolates with different virulence spectra and from different hosts and geographical regions were analyzed. Out of 45 bands, generated with three RAPD primers, 35 (78%) were polymorphic and scored as molecular markers. Cluster analysis exhibits unstructured variability of this pathogen with regard to physiological race, geographical origin or host. The genotypic diversity (H') inferred from Shannon's index was higher than gene diversity (Ht), suggesting that diversity is distributed among clonal lineages. Estimates of gene diversity in Africa and Asia populations were higher in total (Ht) as compared to within population diversity (Hs). Genetic differentiation was considerable among coffee rust isolates from Africa (Gst = 0.865) and Asia (Gst = 0.768) but not among isolates from South America (Gst = 0.266). We concluded that genetic diversity in H. vastatrix was moderately low and that the genetic differentiation among populations shows that asexual reproduction is likely to play an important role in the population biology of this fungus. This should be taken into account for the development of breeding programs.     

High genetic diversity vs. low genetic differentiation in Nouelia insignis (Asteraceae), a narrowly distributed and endemic species in China, revealed by ISSR fingerprinting

BACKGROUND AND AIMS: Nouelia insignis Franch., a monotypic genus of the Asteraceae, is an endangered species endemic in Yunnan and Sichuan Provinces of China. Most of the populations are seriously threatened. Some of them are even at the brink of extinction. In this study, the genetic diversity and differentiation between populations of this species were examined in two drainage areas. METHODS: DNA fingerprinting based on inter-simple sequence repeat polymorphisms was employed to detect the genetic variation and population structure in the species. KEY RESULTS: Genetic diversity at species level was high with P=65.05% (percentage of polymorphic loci) and Ht=0.2248 (total genetic diversity). The coefficient of genetic differentiation among populations, Gst, which was estimated by partitioning the total gene diversity, was 0.2529; whereas, the genetic differentiation between populations in the Jinsha and Nanpan drainage areas was unexpectedly low (Gst=0.0702). CONCLUSIONS: Based on the genetic analyses of the DNA fingerprinting, recent habitat fragmentation may not have led to genetic differentiation or the loss of genetic diversity in the rare species. Spatial apportionment of fingerprinting polymorphisms provides a footprint of historical migration across geographical barriers. The high diversity detected in this study holds promise for conservation and restoration efforts to save the endangered species from extinction.     

Genetic structure of continental and island populations of the Mediterranean endemic Cyclamen balearicum (Primulaceae)

Cyclamen balearicum is a self-compatible perennial herb endemic to the western Mediterranean Basin. This species occurs in five geographically isolated terrestrial islands in southern France and on four Balearic islands. In this study, we compare genetic variability and differentiation within and among 11 terrestrial island populations and 17 true island populations. Of nine readable enzyme loci, five were polymorphic in both terrestrial and true islands. F statistics showed a significant heterozygote deficiency in all populations, probably due to high levels of autonomous selfing, restricted gene flow, and subsequent genetic drift. Genetic diversity was higher in terrestrial islands than on the Balearic islands, suggesting that the Balearic islands were colonized when they were in contact with the continent. Population differentiation was greater among terrestrial islands (Fst = 0.417 and Gst = 0.344) than among true islands (Fst = 0.112 and Gst = 0.093). Furthermore, differentiation among populations on the Basses Cévennes terrestrial island was greater (Fst = 0.254) than among populations on the true island of Mallorca (Fst = 0.163). The greater genetic differentiation among terrestrial islands could have been caused by genetic bottlenecks associated with changes in climate and human land use that may have reduced population sizes more severely in terrestrial islands in southern France than on the Balearic islands.     

Comparative Study on the Chloroplast RPL32-TRNL Nucleotide Variation within and Genetic Differentiation among Ancient Tea Plantations of Camellia sinensis var.assamica and C.taliensis (Theaceae) from Yunnan,China

In order to assess genetic diversity and population structure, nine Camellia sinensis var.assamica and three C.taliensis populations from Yunnan, China were evaluated. Based on nucleotide variation of 94 cpDNA RPL32-TRNL sequences, a total of seven distinct haplotypes were detected in the studied populations. It was apparent that C.sinensis var.assamica (h=0.728,π =0.00469) possessed higher levels of genetic diversity than C.taliensis (h =0.610, π =0.00225). However, genetic differentiation among populations of C.sinensis varassamica (Gst=0.580, FST=0.612) was lower than that among C.taliensis populations (Gst=0.696, FST=0.773). Our AMOVA analysis further revealed that the majority of variation was partitioned among populations of the two taxa, while C.sinensis var.assamica (6121%) showed lower level of genetic differentiation than C.taliensis (77.34%). In comparisons to C.taliensis, genetic diversity within C.sinensis var.assamica largely varied among populations, ranging from 0 to 0.809 and from 0 to 0.00487 for haplotype and nucleotide diversity, respectively. Conservation strategies were finally discussed and proposed to efficiently protect ancient tea plantations in China.     

云南古茶园栽培大叶茶和大理茶群体的叶绿体RPL32-TRNL核苷酸变异和遗传分化

对云南地区栽培的大叶茶（Camellia sinensis var. assamica）9个居群和大理茶（C.taliensis）3个居群的遗传多样性和居群遗传结构进行了比较研究。通过对94条叶绿体DNA RPL32-TRNL序列的核苷酸序列变异进行分析,共发现了7个单倍型。研究结果表明,大叶茶（h=0.728,π=0.00469）比大理茶（h=0.610,π=0.00225）拥有更为丰富的遗传变异,但其居群遗传分化水平（Gst=0.580,FST=0.612）却低于大理茶（Gst=0.696,FST=0.773）。AMOVA分析进一步证实了它们的遗传变异主要存在于居群间,且大叶茶（61.21%）低于大理茶（77.34%）。相对于大理茶,遗传多样性水平在本研究所取的大叶茶居群间存在着较大的差异,单倍型多态性水平变化范围为0~0.809,核苷酸多态性水平变化范围为0~0.00487。最后,讨论并提出了科学有效地保护我国古茶园茶种资源的建议和对策。     

滇东南硬叶兜兰核心种质区群体遗传结构

本研究选取国内主要种质采集区-滇东南石灰岩地区7个不同干扰居群为研究对象,旨在对其居群内和居群间遗传变异进行比较研究,以期对其保护措施的提出提供理论依据。通过利用SRAP标记对167个体的遗传多样性和遗传结构研究,结果表明：10对SRAP引物共扩增出288个位点,多态位点比率（PPB）达81.25%,香侬指数（I）为0.3709,在种水平上的具有较高遗传多样性;而居群水平上的多态位点比率仅为47.92%, 香侬指数为0.2348, 居群间平均Nei’s遗传距离为0.1268。经分子遗传变异方差分析（AMOVA）表明,有66.27%的遗传变异来源于居群内,居群间变异占总变异33.73%,此结果与遗传分化系数（Gst=0.3568）结果吻合,居群间基因流（Nm）为0.902, 不同地区间硬叶兜兰居群存在较高的遗传分化; 7个居群的UPGMA聚类在遗传相似性系数达0.863,聚为两支;经Mantel检测（r =0.298, P＞0.05）,表明居群间遗传距离与地理距离无显著相关性。居群当前较高的遗传分化与其交配系统有关,其次,外在因素：人为采集、生境破坏和片断化造成居群内遗传多样性的丧失,加剧居群间的遗传分化,再次,遗传漂变也是另一重要影响因素;此外,适应性进化亦可能加剧了居群间的遗传分化,而基因流对遗传分化的影响不大。     

森林生态系中球孢白僵菌遗传多样性的ISSR分析

应用ISSR分子标记对安徽大别山区的球孢白僵菌遗传多样性进行了研究。从33个引物中筛选出12个多态性高、稳定性好的ISSRs用于正式的扩增分析,在2个自然保护区、3个不同季节和3个不同海拔梯度采集的48个菌株中共扩增出84条带,其中73条为多态性条带,多态性为81％,平均每个引物扩增出7条（2～11）。群体的多态位点百分率（PPL）达81％,Nei’s基因多样性（H）为0.3187,Shannon信息指数（I）为 0.4782。居群间的基因分化系数较小（Gst）0.1028。以上结果表明：安徽大别山区球孢白僵菌有较高的遗传多样性, 居群间遗传变异较小,居群内表现出较高水平的遗传分化。     

大别山山核桃天然群体遗传结构的初步分析

利用RAPD分子标记技术检测了大别山山核桃3个天然居群的遗传多样性和遗传结构。20条10 bp随机引物共检测到238个扩增位点,其中多态性位点162个,多态位点百分率(PPB)为68.1%。居群水平Shannon’s多态性信息指数(I)介于0.2651~0.2801之间;居群水平Ne i’s基因多样性指数(H)介于0.1789~0.1890之间。遗传变异计算显示大别山山核桃居群间基因分化系数(Gst)为0.4063,分子方差分析(AMOVA)表明居群间基因分化水平为0.4177,居群间基因流(Nm)为0.7306,说明大别山山核桃大部分变异存在于居群内,居群间基因交流相对较少。这一结果符合大别山山核桃风媒、异交的繁育系统特点,但其居群间基因分化程度明显高于异交植物的平均水平(Gst=0.1930)。地理隔离、居群内近交及居群间基因流受阻可能是形成目前大别山山核桃天然群体遗传结构的主要因素。