巨龙竹种下不同变异类型的RAPD分析

巨龙竹 (Dendrocalamussinicus)其种下具有 2个明显不同的变异类型 ,即“通直型”和“歪脚型”。本文利用 2 0个随机引物对 5 6份巨龙竹材料进行RAPD标记。首先用RAPDis tance软件计算各个体间的相似性系数 ,再用NTSYS软件对巨龙竹 5 6个样品以UPGMA方法进行聚类 ,聚类图中有 2个明显的分枝 ,一为“通直型” ,一为“歪脚型” ,结果表明巨龙竹表型的差异与遗传因素密切相关。同时用POPGENE软件和AMOVA软件分析表明 :巨龙竹种下不同变异类型的遗传变异较大 ,具有丰富的遗传多样性 ;歪脚类型的遗传多样性高于通直类型 ;巨龙竹变异类型群体之间及群体之内均出现显著的分化。     

锐药竹种子苗光合生理生态特性分析

为了解引自埃塞俄比亚的锐药竹(Oxytenanthera abyssinica)幼苗的生长情况,对2年生竹株的光合生理生态特性进行了研究。结果表明,锐药竹的Chl a/b接近2.3∶1,Chl b含量偏高,说明具有一定的耐阴性。当光照强度为800~1600μmol m~(-2)s~(-1)时,未出现光抑制现象,表明其对光照具有较强的适应性。锐药竹的表型性状与生理生态性状间存在较好的相关性。根据主成分分析,确认Chl b、ФPSⅡ、Chl a、Fo为其主成分因子,累计方差贡献率达86.89%。根据种质聚类分析,可划分为4个类型。因此,锐药竹实生苗单株在表型、生理生态性状上存在较大差异,具有遗传保育的形态、生理基础。     

沙生植物沙鞭不同居群形态变异研究

以沙鞭(Psammochloa villosa Bor.)20个自然居群为研究对象,对其株高、花序长度、旗叶长度、旗叶宽度和小穗长度等12个表型性状进行形态变异研究。结果显示,12个性状群体间F值为1.832~8.958,达到显著或极显著水平,表明沙鞭不同居群表型性状存在广泛变异,且变异程度各不相同;主成分分析结果显示,前4个主成分代表了沙鞭形态多样性的82.277%,其中旗叶长度、旗叶宽度、颖片长度、小穗长度等是造成不同居群表型性状差异的主要因素;依据欧式距离对参试居群进行的UPGMA聚类分析结果表明,当遗传距离为20.5时,可以将20个沙鞭野生居群划分为两类,且各表型性状并没有依居群地理分布而聚类。     

不同产地栽培薏苡种子性状的变异分析

通过观察和测量中国8省区9产地栽培薏苡种子的各种性状,运用SPSS 11.5软件进行统计分析,探讨了不同产地栽培薏苡种子的变异及原因。结果表明:中国尤其是西南地区的栽培薏苡种子性状差异性显著,除种子长度、种子与颖果重量差之外,薏苡种子的其他形态指标均呈极显著差异(P<0.01);颖果长度与产地的平均气温和年降雨量、颖果长宽比与海拔均呈显著相关;而其它地理、气候等生态因子与种子性状相关不显著;聚类分析显示9个产地的栽培薏苡可聚为5类。综上所述,栽培薏苡的种子性状变异是遗传信息、栽培方法和生态因子等内外部原因共同作用的结果,可能主要是受到基因交流和人工驯化选择的影响。     

秦巴山区野板栗居群遗传多样性AFLP分析

利用荧光AFLP标记技术对来自秦巴山区的野板栗10个居群共262个单株进行遗传多样性研究.10对AFLP引物共扩增出1297条谱带,其中多态性位点数1011个,多态位点百分率为77.95%;Nei's基因多样性指数为0.1439～0.2046,总体为0.2518;Shannon信息指数的变异范围为0.1972～0.2895,总体为0.4089;甘肃地区野板栗居群遗传多样性水平最高,陕西宝鸡居群的遗传多样性水平最低.AMOVA分析表明野板栗居群闻的遗传变异占总变异的17.51%,居群内变异占69.76%.UPGMA聚类可将供试10个居群划分为3类,聚类结果表现出明显的地域性.     

珍稀油料树种琴叶风吹楠果实和种子形态变异

以云南野生琴叶风吹楠(Horsfieldia pandurifolia)为材料,对39株树的果实和种子的形态进行变异分析。结果表明,果实和种子形态指标株间变异大,株内变异小。单株间果实表现出从卵圆形至长椭圆形的变异,果长4~7 cm,先端圆钝至锐尖,基部不同程度偏斜,与文献记录差异较大;单株间种子形态表现出从卵形、长卵形至细长形或近锥形的变异。单株平均种长变幅为25.05~35.66 mm,种宽为13.30~19.62 mm,长宽比为1.47~2.32,单因素方差分析表明此3个性状单株间差异极显著(p<0.01)。灰白色种皮具褐色斑块,种脐和胚位于种子基部,种子先端突尖或具短喙是稳定的性状,有重要的分类学价值。     

茶条槭自然种群种子和果实表型多样性研究

为探析茶条槭(Acer ginnala)种子和果实表型差异程度及变异规律,该研究采用巢式方差分析、主成分分析、聚类分析等方法,对茶条槭主要分布区内7个种群种子和果实的12个表型性状进行比较研究,分析茶条槭种群间和种群内的表型多样性以及与地理生态因子的关系。结果表明:除种子长/宽(SLW)外,其它11个表型性状在茶条槭种群间和种群内均具有显著差异;各性状平均变异系数(CV)为13.90%,变异幅度为8.14%～32.08%;种群间翅果性状的平均变异系数(15.63%)高于种子性状的平均变异系数(8.71%),表明种子性状的稳定性高于果实性状。主成份分析中,果实形态特征对茶条槭种群表型的贡献率大于种子贡献率。种群间表型分化系数为35.47%,说明种群内变异(64.53%)大于种群间变异(35.47%),暗示变异主要来源于种群内变异。茶条槭种子和果实表型性状受地理生态因子影响较小,主要受自身遗传因素的影响。基于种群间欧式距离的聚类分析将茶条槭7个种群分为2大支,没有严格按照地理距离而聚类,表明茶条槭种群表型性状变异的不连续性。茶条槭不同种群种子和果实具有较高的表型多样性,与其分布范围和生物学特性有关。     

太空环境对四季薰衣草的诱变效应(英文)

为了探究太空环境对植物造成的诱变效应,对搭载过"神州八号"飞船的四季薰衣草种子进行种植研究。研究表明,辐照组四季薰衣草的第一代植株在表观性状和基因变异上都与对照组存在很大的差异。首先,辐照组四季薰衣草在花期、花产量、叶形和株高的表观性状上与对照组存在很大的差异。其次,随机扩增多态性DNA标记实验(random amplified polymorphic DNA,RAPD)的结果表明,辐照组植株的DNA与对照组相比具有高变异率和宽变异谱的特点。RAPD聚类图中,具有相似表观性状特征的辐照组植株都能很好地汇聚到一起。综上所述,太空环境对植物能产生显著的诱变效应,植株的变异具有不定向性和多样性。     

大明竹属遗传多样性ISSR分析及DNA指纹图谱研究

利用对竹类有较好多态性的18条引物及已优化的ISSR反应体系和扩增程序,分析大明竹属25种竹的遗传多样性。研究结果：共扩增出重复性好的多态位点高达88.3%,平均每个引物扩增8.61个,DNA分子量在160-3000 bp,此25种竹类的平均遗传距离为0.5006,变异幅度为0.1486-0.7191,说明大明竹属具有高的遗传多样性,种间遗传相对复杂。ISSR结果聚类分析,在遗传距离0.5396处将25种竹划分为3类,与形态分类结果大致一致,说明ISSR技术能精确检测大明竹属部分植物的遗传多样性及亲缘关系,有助于该属的分类。试验用U807、U815、U835、U836、U840、U841、U844 7条引物构建大明竹属25种竹的数字指纹识别码,为大明竹属部分植物的分类及种质鉴定提供参考。     

基于形态及分子标记的濒危植物夏蜡梅自然居群的遗传变异研究

比较了濒危植物夏蜡梅(Sinocalycanthus chinensis)大明山、大雷山、龙须山3个居群的果实与种子的形态变异,采用ISSR分子标记技术分析DNA序列的变异,综合评价夏蜡梅3个居群的遗传变异。结果如下:果实性状中,果柄长、果实长、果实重、每果种子数等指标均以大明山居群最大、大雷山居群次之、龙须山居群最小,它们之间差异显著(P<0.05)。种子重、种子长、种子宽、种子厚等指标均以大雷山居群最大,与大明山居群和龙须山居群差异显著(P<0.05)。基于果实形态特征的表型分化系数(VST)在0.5518—0.9750之间,平均为0.8930,所有果实形态指标的变异大部分存在于居群间。基于种子形态特征的VST在0.1669—0.8678之间,平均为0.6240,除种子长外,其他种子形态指标的变异也大部分存在于居群间。ISSR分析表明,3个居群的多态位点百分率、Shannon信息指数、Nei基因多样性均是大明山居群最高、龙须山居群次之、大雷山居群最低。居群间的遗传分化系数(GST)为0.6050。基于ISSR分子标记数据的聚类结果显示大明山居群先与龙须山居群聚在一起,再与大雷山居群相聚,这与基于种子性状特征的聚类结果相似,而与基于果实性状特征的聚类结果不同。3个居群的种子形态特征变异系数与遗传多样性水平具有显著的正相关,且基于果实形态特征估算的VST要高于GST,而基于种子形态特征估算的VST仅略高于GST,表明夏蜡梅不同居群间的种子形态变异主要由遗传变异所造成的,而环境因子在果实形态变异中起了重要作用。Mantel检验显示3个居群基于分子标记数据的遗传距离矩阵和基于果实及种子形态特征的欧氏距离矩阵之间的相关性不显著,表明果实与种子在居群间出现的表型分化除了受遗传因素影响外,还受到其它环境因子的强烈影响。     

COMPETITION PROLONGS EXPRESSION OF MATERNAL EFFECTS IN SEEDLINGS OF ERIGERON ANNUUS (ASTERACEAE)

The timing of expression of environmental maternal effects on seedling growth was investigated in greenhouse-grown populations of Erigeron annuus (Asteraceae). Maternal differences were generated in genetically identical lines grown under high and low nutrient conditions. There were significant differences among maternal families within genotypes for seed size, cotyledon size, number of leaves, and rosette diameter. When seedlings were grown individually, effects of the maternal fertilizer treatment on leaf number and rosette diameter were present early but could not be detected after eight weeks. When seedlings from HIGH and LOW lines were grown in competition, the maternal effects and the relative size advantage of seedlings from HIGH parents increased throughout the experiment. Most of the variation among nutrient treatments for seedling size characters could be explained by variation in initial seed size. In the competition experiment, the increasing magnitude of maternal environmental differences over time masked genetic variation for seedling characters; without competition, the relative contribution of genetic variation increased through time. Under competitive conditions that generate persistent maternal effects on fitness, maternal environmental effects may retard natural selection.     

风箱果有性繁殖研究

对风箱果（Physocarpus amurensis）适宜的采种时期、不同母树种子的成熟差异和幼苗的生长特征进行了研究。结果表明,风箱果种子的最适采种期在7月末,种子成熟后有休眠特性;方差分析表明,不同植株间种子的发芽率和千粒重都达到极显著水平（p<0.01）,并且发芽率与种子重量呈正相关,其相关程度最佳的为幂函数,确定系数是75.75%（p<0.01）;风箱果幼苗类型为子叶出土型,幼苗生物量对根的投资最大,其次是叶,茎的最少,在这3部分生物量投资中,对根和叶的投资比较稳定（其变异系数分别为6.8%和11.03%）,对茎的生物量投资具有较大的变异（其变异系数为21.81%）。基径是衡量风箱果幼苗空间大小的重要数量指标。风箱果构件生物量（根生物量、茎生物量、叶生物量及总生物量）各组分均随基径的增加,呈线性函数形式增长,这表明随着植株的空间扩展,各构件有着相同的物质生产与积累规律。     

祁连山青海云杉天然群体的种实性状表型多样性

 以系统揭示其表型变异程度和变异规律为目的,对祁连山青海云杉(Picea crassifolia )天然分布区的10个群体的8个种实性状进行了比较分析。采用方差分析、多重比较,相关分析、聚类分析等多种分析方法,对群体间和群体内的表型多样性进行了讨论。方差分析结果表明,各种实性状在群体间都存在极显著差异,除球果干质量和球果长/球果径外,其余性状在群体内都存在着极显著的差异;表型分化系数即群体间变异为27.18%,小于群体内的变异(72.82%);球果长、球果径、球果干质量、球果形状指数、种子长、种子宽、千粒重和种子形状指数的变异系数分别为：10.08%、5.80%、19.29%、9.66%、8.38%、15.34%、6.52%和13.94%;8个种实性状间多数呈极显著或显著的正相关,球果干质量、种子长、千粒重、球果长和球果径为青海云杉易测定和重要的种实性状;种实性状呈现出以经度变异为主的梯度规律性;通过表型性状的聚类分析可以将青海云杉10个群体划分为4类。     

贵州省野生皂荚种实表型性状多样性分析

为深入了解贵州省野生皂荚(Gleditsia sinensis)荚果表型性状的遗传多样性及其变异类型,为皂荚的遗传改良、种质鉴定、亲本选择以及品种培育奠定理论基础。该研究以贵州省7个野生皂荚群体70个个体为研究对象,采用方差分析、主成分分析、相关性分析及多性状综合评价等方法对皂荚群体的10个种实表型性状进行系统分析和综合评价。结果显示：(1)所测皂荚的表型性状差异在群体内均达到极显著水平(P＜0.01);在群体间,除每荚粒数、种子宽、种子长宽积以及种子长宽比之外,其余表型性状的差异均达极显著水平(P＜0.01)。(2)7个居群野生皂荚各性状平均变异系数为21.16%,其中凯里市(P4)居群的变异系数最高(24.44%);居群间荚果的变异(29.22%)高于种子的变异(11.04%),且变异主要来自于群体内。(3)相关分析显示,皂荚种实各性状之间存在不同程度的关联性;主成分分析显示,前4个主成分(皂荚种子大小、单个荚果出籽数量、种子形态指数因子、与荚果长和种子厚相关的因子)的累积贡献率达69.783%,可基本反映皂荚表型性状的大部分信息;以10个种实性状对皂荚野生群体进行综合评价发现,来自于惠水县(P7)群体的皂荚种实性状综合评价最高。研究表明,贵州省野生皂荚在群体间及群体内具有丰富的表型变异,且群体内的变异大于群体间的变异,变异主要来自于群体内。     

Demographic genetics of the American beech (Fagus grandifolia Ehrh.) III. Genetic substructuring of coastal plain population in Maryland

Spatiotemporal genetic substructurings were investigated in the American beech population of the east-central coastal plain in Maryland. All trees including seedlings, various sizes of juveniles, and mature trees within the study site (10 × 100 m) were mapped, diameters measured, and leaves collected for allozyme analyses. Eleven polymorphic loci in eight enzyme systems were examined: 6Pgdh2, 6Pgdh3, Acp2, Adh1, Adh2, Fum, Got1, Got3, Lap, Pgi, and Pgm2. A total of 1945 trees were analyzed and 595 multilocus genotypes were detected. Six size-classes and 10 spatial blocks were discriminated for spatiotemporal analyses. Parameters for genetic variations (heterozygosity, Simpson's index, Shannon-Weaver's index, and inbreeding coefficient) decreased in larger size-classes. These genetic parameters fluctuated in spatial blocks of 10 m intervals, in which certain alleles were characteristic of specific blocks. The spatial autocorrelation by Moran's I and coancestry revealed the ranges of genetic relatedness to be only 20–30 m. Multilocus genotype analyses showed that higher genetic variations occur in larger size-classes and at gap openings where seed shadows for mother trees are overlapped. The relationships among reproductive trees, seedlings and juveniles suggested that the seed dispersal range of the American beech is normally in the range of 30–40 m. The mechanisms of a remarkably high genetic polymorphism maintained in this once artificially disturbed and grazed forest are discussed as related to conservation biology.     

Do seed transfer zones for ecological restoration reflect the spatial genetic variation of the common grassland species Lathyrus pratensis?

A common ecological restoration approach is the reestablishment of vegetation using seed mixtures. To preserve the natural genetic pattern of plant species local seed material should be used. Consequently, seed transfer zones (seed production areas and seed provenance regions) have been delineated for ecological restoration in Germany. Although it is assumed that these transfer zones represent genetic variation, there remains a lack of empirical data. In this study, we analyzed whether seed transfer zones reflect the genetic variation of the common grassland species Lathyrus pratensis. We sampled 706 individuals from 37 populations in Bavaria, Germany and analyzed genetic variation using amplified fragment length polymorphisms. In our study, we observed higher levels of genetic variation and fragment rarity in the southern Bavarian populations compared to northern populations. Our analyses revealed a strong genetic differentiation between southern and northern Bavarian populations delineated along the Danube River. However, seed production areas and seed provenance regions reflected genetic variation of L. pratensis only to a limited degree. Our study illustrates that the level of genetic variation within populations strongly depends on population history. Furthermore, the geomorphological and climatic attributes, which have been used to delineate seed provenance regions, do not reduce gene flow among populations. Seed collections for gene banks and seed production should comprise seeds from populations in southern and northern Bavaria representing the strong genetic variation between both regions, but prioritize southern populations due to higher levels of variation.     

Genetic structure of age classes in Camellia japonica (Theaceae)

Camellia japonica L. (Theaceae), an insect- and bird-pollinated, broad-leaved evergreen tree, is widely distributed in Japan and the southern Korean peninsula. The species has a relatively even age distribution within populations, which may influence the spatial genetic structure of different age classes relative to species with typical L-shaped age distributions. To determine whether the internal spatial genetic structure found in seedlings and young individuals carries over into adults, we used allozyme loci, F-statistics, spatial autocorrelation statistics (Moran's I), and coancestry measures to examine changes in genetic structure among seven age classes in a population (60-m x 100-m area) in southern Korea. In seedlings, weak but significant positive values of Moran's I-statistics and coancestry measures were found for distances less than 14 m, which is consistent with a mechanism of limited seed dispersal combined with overlapping seed shadows. This spatial structure, however, dissipates in older age classes, and in adults genetic variation has an essentially random spatial distribution. Morisita's index of dispersion of individuals in each age class showed that seedlings and juveniles are more highly clustered than are older individuals. These results suggest that self-thinning changes the spatial relationships of individuals, and thus genotypes. A multilocus estimate of FST (0.008) shows a small but statistically significant difference in allele frequencies among age classes. In summary, intrapopulation genetic structure within and among age classes of C. japonica was significant but weak. Despite presumably limited seed dispersal, weak spatial genetic structure in juveniles suggests overlapping seed shadows followed by self-thinning during recruitment. The present study also demonstrates that studies of spatial genetic structure focusing on limited numbers of generations may not be sufficient to reveal the entire picture of genetic structure in populations with overlapping generations.     

Mediation of seed provisioning in the transmission of environmental maternal effects in Maritime pine (Pinus pinaster Aiton)

Although maternal environmental effects are increasingly recognized as an important source of phenotypic variation with relevant impacts in evolutionary processes, their relevance in long-lived plants such as pine trees is largely unknown. Here, we used a powerful sample size and a strong quantitative genetic approach to analyse the sources of variation of early seedling performance and to identify seed mass (SM)-dependent and -independent maternal environmental effects in Maritime pine. We measured SM of 8924 individual seeds collected from 10 genotypes clonally replicated in two environments of contrasting quality (favourable and stressful), and we measured seedling growth rate and biomass allocation to roots and shoots. SM was extremely variable (up to 14-fold) and strongly determined by the maternal environment and the genotype of the mother tree. The favourable maternal environment led to larger cones, larger seeds and reduced SM variability. The maternal environment also determined the offspring phenotype, with seedlings coming from the favourable environment being 35% larger and with greater root/shoot ratio. Transgenerational plasticity appears, thus, to be a relevant source of phenotypic variation in the early performance of this pine species. Seed provisioning explained most of the effect of the maternal environment on seedling total biomass. Environmental maternal effects on seedling biomass allocation were, however, determined through SM-independent mechanisms, suggesting that other epigenetic regulation channels may be involved.     

Restoration of genetic diversity from soil seed banks in a threatened aquatic plant, <Emphasis Type="Italic">Nymphoides peltata</Emphasis>

Populations of a threatened aquatic plant, Nymphoides peltata, have rapidly degenerated under the influence of recent artificial changes in Lake Kasumigaura of Japan. To estimate the potential of soil seed banks for genetic restoration of the species, we used 10 microsatellite markers to analyze the genetic variation in adults and in seedlings that emerged from soil seed banks. About 187 leaf samples from the cultured stocks that were collected in 17 adult subpopulations in 1995 and 2000 and from three subpopulations that were newly discovered in 2002 were analyzed. As a result, only 18 genets could be identified, suggesting that clonal diversity of the adult population had already become extremely low. Genetic tests were performed on 430 seedlings from seed banks at six locations of natural lakeshores and three of the restoration sites that were artificially constructed in an attempt to assign them to the remnant adult population; many of the seedlings showed genetic variation different from the adults. Furthermore, the seedlings preserved seven alleles that had been lost from remnant adults. However, they had lower average numbers of alleles and heterozygosity levels (NA = 1.5–3.1, H _E = 0.146–0.487) than the remnant adults (NA = 3.5, H _E = 0.539) and showed high inbreeding coefficients, suggesting that the seed banks were produced by inbreeding. Thus, although the seed banks had a certain potential to restore genetic diversity, the fitness reduction in seed banks caused by inbreeding could affect the success of restoration based on seed banks.     

CONFLICTING SELECTION FROM AN ANTAGONIST AND A MUTUALIST ENHANCES PHENOTYPIC VARIATION IN A PLANT

The raw material for evolution is variation. Consequently, identifying the factors that generate, maintain, and erode phenotypic and genetic variation in ecologically important traits within and among populations is important. Although persistent directional or stabilizing selection can deplete variation, spatial variation in conflicting directional selection can enhance variation. Here, we present evidence that phenotypic variation in limber pine (Pinus flexilis) cone structure is enhanced by conflicting selection pressures exerted by its mutualistic seed disperser (Clark's nutcracker Nucifraga columbiana) and an antagonistic seed predator (pine squirrel Tamiasciurus spp.). Phenotypic variation in cone structure was bimodal and about two times greater where both agents of selection co‐occurred than where one (the seed predator) was absent. Within the region where both agents of selection co‐occurred, bimodality in cone structure was pronounced where there appears to be a mosaic of habitats with some persistent habitats supporting only the seed disperser. These results indicate that conflicting selection stemming from spatial variation in community diversity can enhance phenotypic variation in ecologically important traits.