在韩国境内Potentilla fragarioides var.sprengeliana的遗传多样 …

根据２２个等位酶位点遗传变异,探讨了韩国境内委陵菜（Ｐｏｔｅｎｔｉｌｌａ ｆｒａｇａｒｉｏｉｄｅｓ Ｌ．ｖａｒ．ｓｐｒｅｎｇｅｌｉａｎａ）的遗传多样性和种群结构。酶位点的多态位点百分比为５９．１％。种和种群水平上的遗传多样性比较高,分别为Ｈｅｓ＝０．２１０,Ｈｅｐ＝０．１９９;而种群的分化水平则相对较低（ＧＳＴ＝０．０７４）。１９个种群中随机交配的偏差为ＦＩＳ＝０．３３１。每代迁移数的间接估计     

不同采样策略对细距堇菜遗传多样性估算的影响

采用水平淀粉凝胶电泳技术对分布于北京金山、檀枯寺、香山樱桃沟的细距堇菜（Ｖｉｏｌａ ｔｅｎｕｉｃｏｒｎｉｓ Ｗ．Ｂｅｃｋ．）的遗传变异和群体分化进行了初步研究。对８个酶系统１１个等位酶位点的检测表明,该种在上述地区的遗传变异水平明显高于多年生草本的平均值,多成位点百分率Ｐ＝７２．７％,等位基因平均数Ａ＝２．４,平均期望杂合度Ｈｅ＝０．２４３;群体间的遗传分化略小于多年生草本的平均值,杂和性基因多样     

根茎禾草沙鞭的等位酶变异及克隆多样性

沙鞭（Ｐｓａｍｍｏｃｈｌｏａｖｉｌｏｓａ（Ｔｒｉｎ．）Ｂｏｒ）是禾本科的一种沙生旱生植物,靠根茎进行无性生殖。采用１０种酶系统共１５个基因位点对中国科学院植物研究所内蒙古伊克昭盟鄂尔多斯沙地草地生态研究站的４个天然居群进行了遗传结构和克隆多样性分析。结果表明,和同类植物相比,沙鞭的遗传变异水平和克隆多样性均较低。沙鞭４个居群的遗传组成明显不同。石龙庙流动沙丘和石灰庙固定沙丘的基株数目多,遗传变异水平较高,而石龙庙固定沙丘和石灰庙半流动沙丘的基株数目少,只有１株或２株,且多样性水平极低。环境差异在沙鞭的等位酶变异上未得到反映。和其它克隆植物相似,沙鞭的大部分变异存在于居群间（ＧＳＴ＝６２．１６％）,居群内变异所占比例较少。沙鞭９１．６７％的基因型属地方型,无广布基因型。     

燕麦草（Arrhenatherum elatius）多倍体复合体的等位酶多样性研究

对欧洲及地中海地区燕麦草复合体２７个居群的等位酸电泳调查表明,燕麦草复合体维持比较高的等位酶多样性（Ｈｅ＝０．４４７,Ａ＝３．２９）,亚种间遗传分化较小（Ｇ（ＳＴ）＝０．０５３）;在四个亚种内,也维持着比较高的多样性（Ｈｅ：０．３２５—０．５３３）,各亚种内的基因多样度主要存在于居群之内,居群间分化较小．四倍体的基因多样性高于二倍体的．燕麦草复合体内居群间基因流较高,表明燕麦草繁育方式主要为风媒远交．对Ｎｅｉ氏标准遗传距离的ＵＰＧＭＡ聚类结果表明,四倍体是从二倍体有鳞茎的ｓｓＰ．ｂａｅｔｉｃｕｍ中产生的．     

燕麦草多倍体复合体的等位酶多样性研究

对欧洲及地中海地区燕麦草复合体２７个居群的等位酶电泳调查表明,燕麦草复合体维持比较高的等位酶多样性（Ｈｅ＝０．４４７,Ａ＝３．２９）,亚种间遗传分化较小（ＧＳＴ＝０．０５３）;在四个亚种内,也维持着比较高的多样性（Ｈｅ：０．３２５－０．５３３）,各亚种内的基因多样度主要存在于居群之内,居群间分化较小。四倍体的基因多样性高于二倍体的。燕麦草复合体内居群间基因流较高,表明燕麦草繁育方式主要为风媒远交。     

四川省凉山彝族自治州南部三县苦荞麦栽培居群的遗传多样性研究

采用等位酶电泳 技术测定了四川省凉山彝族自治州南部金阳、雷波和米易３县的苦荞麦「Ｆａｇｏｐｙｒｕｍ ｔａｔａｒｉｃｕｍ（Ｌ．）Ｇａｅｒｔｎ．」８个栽培居群的遗传多样性和分化,结合农业生物学性状进行了分析。苦荞麦居群的遗传多样性水平较高,每个位点的等位基因平均数为１．８,多态位点比率为４６．６％,平均实际杂合度和预期杂合度分别为０．１８７和０．２１８,ＦＳＴ值为０．２２,居群间存在较明显的遗传分化,     

苍术（Atractybeslancea（Thunb．）DC．）种内遗传多样性分析

分析了苍术（Ａｔｒａｃｔｙｌｏｄｅｓｌａｎｄｅａ（Ｔｈｕｎｂ．）ＤＣ．）５种等位酶（ＭＤＨ,ＧＤＨ,ＰＰＯ,ＳＯＤ,ＰＥＲ）１２个位点上２５个等位基因的分化特征。结果表明：群体内多态位点比例平均为０．６１,每个位点的平均杂合率为０．２６,每个位点发现的平均等位基因数为１．７８。苍术种内基因多样性的８６％产生在群体内,群体间分化的明显效果为１４％。所有配对组合,群体间的平均遗传距离是０．１１,遗传同一性是０．９０。说明苍术种内变异很大。同时探讨茅苍术的分类位置,认为茅苍术不是苍术和白术的杂交种。     

天然红松林等位酶研究

利用红松种子的单倍体胚乳,采用水平切片淀粉凝胶电泳技术,对采自三个地区的天然红松林的材料进行了１０种酶系统的等位酶实验,共获得了１８个等位基因位点,对这１８个位点等位基因的统计分析表明：红松种群的多态位点百分数为Ｐ＝７７．７８％,等位基因平均数为Ａ＝２．０,预期杂合度为Ｈｅ＝０．１６４８。红松种群间遗传分化程度在松属于较低水平。在红松１８个等位基因位点的变异中,绝大部分变异９４．２％来自种群内部,     

湖北海棠的等位酶变异和遗传多样性研究

采用超薄平板微型聚丙烯酰胺等电聚焦电泳方法对湖北海棠（Malus hupehensis)的9个野生居群和2个人工栽培居群的等位酶变异和遗传多样性进行了初步研究。通过对12个酶系统29个酶位点的检测,结果表明湖北海棠有25个酶位点的等位基因频率分布差异,,有10个居群发现稀有等位基因,并有11个（37．9％）重复位点;湖北海棠的遗传多样性水平很高,等位基因平均数A＝2．127,多态位点百分率P＝74．927,平均预期杂合度He=0.376;居群间的基因分化系数GST＝0．224。与其他苹果属植物相比,湖北海棠具有中等丰富的遗传变异水平。居群间的基因流仅为Nm=0.866,表明遗传漂变是影响居群遗传变异和遗传结构的一个重要因素。     

版纳青海居群的遗传多样性和群体分化

我国龙脑香料特有种版纳青海（Vatica guangxiensis）仅局限分布于滇南（勐腊）和植西南（那坡）,本文应用“水平切片淀粉凝胶电泳等位酶分析”方法,对其进行了遗传多样性和群体分化的研究。对14个酶系统23个等位酶点的研究表明,其居群变异水平很低,多态位点比率P为13．0％－21．7％,等位基因平均数A为1．1－1．2,平均期望杂合度0．056－0．130,平均观察杂合度H为0．055－0．130。F统计分析表明版纳青梅具有较高水平的群体分化,基因分化系数高达CST＝0．265。这与其居群内存在一定程度的近交,以及种子的重力散布有关;另外,也可能是在其进化过程中,由于居群的缩小而发生了遗传漂变。此外,本研究也从等位酶水平为广西青梅（V．guangxiensis)和版纳青梅（V．sishuangbannaensis）的合并作一佐证。     

Multiclonal tussocks in the grass Achnatherum splendens (Trinius) Nevskia (Poaceae)

Clonal plant species often form genetically diverse populations, even when sexual reproduction in a population is rarely observed. Here we test whether the spatially discrete clusters of plants (tussocks of graminoids) formed within populations of some clonal species can likewise be multiclonal. We sampled leaves of ramets (shoots) within 20 tussocks of the grass Achnatherum splendens in the Otindag Sandland in Inner Mongolia, China, and genotyped the ramets using standard molecular protocols. The 20 tussocks were allocated to three classes: (i) small, circular, (ii) large, circular and (iii) large, irregular. Most tussocks (80%) were multiclonal and some contained at least eight different clones. Irregularly shaped tussocks contained twice as many clones as circular tussocks; neither size nor cover within a tussock affected number of clones per tussock, and the smaller clones in a tussock showed no tendency to occur on the edge or near the center of a tussock. These patterns seem more consistent with formation of multiclonal tussocks by coalescence than by colonization. Therefore, individual tussocks, especially large, irregular ones, cannot a priori be treated as genetic individuals without assessing their genetic information in, e.g., population demography, genetics and evolution studies.     

论克隆植物的遗传多样性

概述了克隆植物的类型与特点 ,对克隆植物的遗传多样性及其遗传结构的一些特点进行了综述 ,并讨论了克隆植物遗传变异的来源。总体而言 ,克隆植物拥有比早期推测大得多的遗传变异 ,虽然克隆种与其近缘有性繁殖种相比 ,遗传多样性较低 ,但广泛的遗传单态性却很罕见。克隆植物种群的遗传结构有所改变 ,广布基因型很少 ,大多数基因型仅分布于某一种群之内 ,种群间基因型多态性存在广泛的变异。不同克隆植物之间遗传多样性相差很大 ,遗传结构也有巨大差异。说明除生殖模式外 ,其他的一些因素 ,如地理分布范围、生境特点 ,散布方式和种群历史等都对克隆植物遗传多样性有重要影响。     

竹叶眼子菜居群遗传多样性和克隆结构

采用ISSR技术对长江中游南岸豹澥湖和大冶湖不同生境中的竹叶眼子菜(Potamogeton malaianus)居群的遗传多样性及克隆结构进行了研究.结果表明,在两居群的106株个体中,利用6条ISSR引物共得到40条符合3/N标准并无连锁不平衡的清晰位点,竹叶眼子菜具有较高的遗传多样性,其多态位点百分率为75.0％,Shannon多样性指数为0.3736, 两居群的遗传分化很小.竹叶眼子菜的克隆多样性很高(D=0.9917),两居群间的克隆分化很大,不具有共有的基因型.竹叶眼子菜的基株分布为游击型构型,位于湖心的大冶居群克隆距离(3.0～31.5 m)明显地大于湖岸豹澥居群(2.4～6.7 m).     

羊草种群克隆多样性的初步研究

 采用水平淀粉凝胶电泳技术检测了松嫩草原上两种叶色类型(灰绿型和黄绿型)羊草(Leymus chinensis)种群的克隆多样性。羊草种群中克隆多样性较高,Simpson指数平均为0.983,97.7% 的基因型为局部分布;在克隆特性上,灰绿型和黄绿型羊草也明显不同,黄绿型种群的克隆多样性低于灰绿型。由基株数据计算的种群遗传多样性与由分株计算的结果一致,进一步确认了黄绿型和灰绿型羊草间存在着明显的遗传分化。种群中不时有实生苗补充及环境异质性引起的分化选择作用可能是维持种群内基因型多样性的重要因素。     

Allozyme Variance and Clonal Diversity in the Rhizomatous Grass Psammochloa villosa(Gramineae)

Psammochloa villosa (Trin.) Bor (Gramineae) is a rhizomatous grass with characteristic sand fixation. Ten enzymes encoded with 15 allozymic loci were used to examine the genetic structures of four natural populations in Inner Mongolia from different habitats. Electrophoretie data indicated that P. viUosa had lower genetic variation (He = 0.104) and lower clonal diversity (D = 0.764) than other similar plants. Genetic compositions of the 4 populations were different. In Shilongmiao mobile dune and Shihuimiao fixed dune there were more genotypes and higher levels of variation than in Shilongndao fixed dune and Shihuimiao semi-mobile dune. Just hke other clonal plants, most genetic variation of P. villosa resided among populations ( Gst = 62,16% ). Most genotypes were local, and there were no spread genotypes. Factors contributed to the genetic structure are herein discussed.     

Feed-backs between genetic structure and perturbation-driven decline in seagrass (<Emphasis Type="Italic">Posidonia oceanica</Emphasis>) meadows

We explored the relationships between perturbation-driven population decline and genetic/genotypic structure in the clonal seagrass Posidonia oceanica, subject to intensive meadow regression around four Mediterranean fish-farms, using seven specific microsatellites. Two meadows were randomly sampled (40 shoots) within 1,600 m² at each site: the “impacted” station, 5–200 m from fish cages, and the “control” station, around 1,000 m downstream further away (considered a proxy of the pre-impact genetic structure at the site). Clonal richness (R), Simpson genotypic diversity (D*) and clonal sub-range (CR) were highly variable among sites. Nevertheless, the maximum distance at which clonal dispersal was detected, indicated by CR, was higher at impacted stations than at the respective control station (paired t-test: P < 0.05, N = 4). The mean number of alleles (Â) and the presence of rare alleles ( _r) decreased at impacted stations (paired t-test: P < 0.05, and P < 0.02, respectively, N = 4). At a given perturbation level (quantified by the organic and nutrient loads), shoot mortality at the impacted stations significantly decreased with CR at control stations (R ² = 0.86, P < 0.05). Seagrass mortality also increased with  (R ² = 0.81, P < 0.10), R (R ² = 0.96, P < 0.05) and D* (R ² = 0.99, P < 0.01) at the control stations, probably because of the negative correlation between those parameters and CR. Therefore, the effects of clonal size structure on meadow resistance could play an important role on meadow survival. Large genotypes of P. oceanica meadows thus seem to resist better to fish farm-derived impacts than little ones. Clonal integration, foraging advantage or other size-related fitness traits could account for this effect.     

Genetic diversity of yacon (Smallanthus sonchifolius (Poepp. & Endl.) H. Robinson) and its wild relatives as revealed by ISSR markers

Set of 29 accessions of Smallanthus sonchifolius, an important tuber crop from South America, and its three wild relatives were analysed using the Inter Simple Sequence Repeats (ISSR) markers. Seven primers out of 30 primers screened gave clear and reproducible spectra. The range of amplified bands was from 2500 bp to 300 bp. These seven primers generated in total 77 bands, from which 75 (97.4%) were polymorphic. Nei's genetic distances between samples varied from 0.01 to 0.24. The Shannon's index (I) was estimated as 0.0392. The UPGMA dendrogram created using the Neighbour joining method and based on the Dice's dissimilarity coefficient separated clearly the wild accessions from all S. sonchifolius samples, which remained close to each other, confirming the clonal origin and thus a very low genetic variability within the genus.     

GENOTYPIC VARIATION AND CLONAL STRUCTURE IN CORAL POPULATIONS WITH DIFFERENT DISTURBANCE HISTORIES

Genotypic diversity in six populations of the endemic Hawaiian reef coral, Porites compressa, was directly related to habitat-disturbance history. The highest diversity (lowest amount of clonal proliferation) was found in populations that had been intensely or recently disturbed. In these populations, space was not limited and mean colony size was small (< 500 cm²), suggesting early stages of recolonization. In an undisturbed, protected habitat, lower genotypic diversity was a result of a significant degree of clonal replication of established genotypes. Unoccupied substratum was rare in this habitat, and average colony size was large (> 2500 cm²). Populations in intermediately disturbed habitats showed intermediate levels of diversity and clonal structure as a result of the combined contributions of sexual and asexual reproduction. Individual clones were distributed over small areas (< 4 m²) or distances (< 1 m) in young populations, and more broadly (> 256 m²) and over longer distances (> 90 m) in the older, undisturbed population. Interpretations of life-history parameters and estimates of total genetic variability in species that have the potential to reproduce asexually are dependent upon an assessment of the overall clonal structure of populations. The power of genotypic assays to reliably detect clonal versus unique colonies, as well as the spatial scales over which clonal populations are sampled, are critical to such assessments.     

Isolation and characterization of 11 microsatellite loci from Carex macrocephala (Cyperaceae)

Carex macrocephala (Cyperaceae) is a species of great conservation concern along the northwest coast of North America. Using a biotinylated-streptavidin bead protocol, we successfully isolated and characterized 11 microsatellite loci from a C. macrocephala genomic library. Although these loci are polymorphic, the scored populations exhibit a significant deficiency in heterozygosity. Carex macrocephala is a self-pollinating rhizomatously spreading sedge, consequently this may contribute to the observed patterns.