自然条件下风箱果的克隆构型

在自然条件下,风箱果(Physocarpus amurensis)主要靠克隆繁殖维持种群。植物克隆构型的可塑性变化对于其适应环境异质性具有重要意义。为探求风箱果的克隆构型及根茎生长动态,研究了其地下根茎的构筑型、形态特征、根茎的直径随长度变化的规律和地下根茎间的夹角。结果表明:风箱果的地下根茎的构筑型基本上属于游击型;风箱果无性系平均含有(6±2)个分株和(9.33±3.48)个根茎;根茎的直径随长度变化的曲线为抛物线型;分枝夹角较为稳定,多为30°和70°。风箱果生产大量的根茎系统,每一个克隆片段能够占据一定的空间,以保证自身生存和维持种群繁衍。     

匍匐茎草本绢毛匍匐委陵菜对局部遮荫的克隆可塑性

采自林窗和林内生境的绢毛匍匐委陵菜 (PotentillareptansL .var.sericophyllaFranch)“分株对”(即由一匍匐茎节间相连着的两个分株 ,其一为“目标分株” ,另一为“相连分株”)在一户外实验中经历了全不遮荫、全部遮荫和局部遮荫处理。该植物的基株生物量、匍匐茎总长度、分株数、匍匐茎比节间重、叶柄长、比叶柄重在遮荫条件下较小。匍匐茎节间长度没有对遮荫处理发生反应。在局部遮荫处理 ,遮荫斑块的分株的叶柄长度由于连着未遮荫斑块中分株而变得更长。这种克隆整合对克隆形态可塑性的修饰作用只在林窗生境来源的实验植物中观察到。其他克隆生长和克隆形态特征的可塑性在不同生境来源的实验植物间没有差异。     

艾纳香野生种群克隆多样性及克隆结构研究

艾纳香是具有克隆生长习性的多年生宿根性草本植物,其广布于中国南部,为了更有效地保护和合理利用艾纳香资源,本文利用RAPD分子标记技术,对4个野生艾纳香种群进行了克隆结构和克隆多样性(单克隆种群或多克隆种群)进行了初步研究。结果表明:(1)10对10bp随机引物共检测到70条谱带,其中多态带为60条,占85.71%,检测到64个基因型,且全部为局限基因型;(2)与Ellstrand Roose(1987)总结的克隆多样性平均值(PD=0.17,D=0.62)相比艾纳香的种群克隆多样性水平稍高,Simpson指数平均为0.973,基因型比率PD平均为0.800;(3)遗传一致度和遗传距离分析表明,4个艾纳香野生种群被分成两组,一组是海南的所有种群,另外一组是云南类群。     

Clonal Plasticity in Response to Partial Neutral Shading in the Stoloniferous Herb Potentilla reptans var. sericophylla

Ramet-pairs of Potentilla reptans L. var.sericophylla Franch from forest gap and forest understory were subjected to unshading, shading and partial shading treatments in a pot experiment. The genet biomass, total length of stolons, number of ramets, specific stolon weight, petiole length and specific petiole weight of the plant species under the shaded condition were smaller than those under the unshaded condition. The stolon internode length did not respond to the various treatments. In the plants from the forest gap, the petiloes of ramet grown in the shaded patch were longer as connected to plant part in the unshaded patch than as connected to plant part under the same shaded condition. Such modification of local response of ramet petiole to shading due to physiological integration was not observed in the plants from the understory. There was no effect of connection to ramets in shaded patches on the local response of the rest ramet characters to the partial unshading.     

Thoughts on clonal integration: Facing the evolutionary context

Summary In this essay, I have pointed out that the appropriate evolutionary context for plant clonality dictates a focus on the impact of the derived trait of potential independence of subunits on the evolutionarily primitive trait of obligate interdependence of plant subunits, i.e. the advantages of independence. This fact prescribes a major shift in approach from previous lines of investigation which have assumed that clonal plants should fall apart and sought to determine the advantages of interdependence. The delineated reorientation calls for a significant change in the investigation of the ecology of clonality in higher plants, emphasizing factors that select for physical and physiological disintegration of the genet and de-emphasizing the need to derive ecological explanations for properties a plant will possess entirely by reason of its phylogenetic and developmental heritage. I suggest that (1) patterns of ramet independence may result from selective pressures on the cost of interconnections (2) programmed ramet independendence may be a response to the selective pressure of a high possibility of traumatic breakage and (3) programmed ramet independence may allow escape of the genet from mortality due to pathogen infestation.     

克隆植物对异质生境的适应对策研究进展

生境异质性是自然生态系统的基本特征,植物生长的必需资源和环境胁迫因子均存在着复杂的时间和空间异质性。克隆植物是指在自然条件下具有克隆特性的植物,即可通过与母株相连的芽、根茎、分蘖或枝条等繁殖体产生无性繁殖的植物,这些繁殖体一旦定居便可成为潜在的独立个体。克隆植物具有独特的生境适应策略(如形态可塑性、克隆整合、克隆分工、觅食行为、风险分摊等),面对异质性的生境条件,它可以通过调整自身的生理和形态结构来适应异质生境。目前,对于克隆植物在异质生境适应行为的研究已有很多报道,然而系统性的归纳和总结尚有欠缺。综述了克隆植物在不同资源异质生境(光照、养分、水分)和不同胁迫生境(盐碱胁迫、风沙胁迫、重金属胁迫)下独特的适应对策。最后,针对克隆植物对异质生境的适应对策,进行了总结并对未来的重点研究方向提出建议：(1)时间异质性尺度上的考量;(2)异质性生境中生物因子的调控作用;(3)克隆植物入侵机制;(4)克隆植物在生态修复中的应用潜力。     

匍匐茎草本蛇莓克隆构型对土壤水分的可塑性反应

克隆植物构型的可塑性有可能促进它对斑块性分布土壤水分资源的利用,因而可能具有生态学意义.在田间实验中,匍匐茎草本蛇莓(Duchesnea indica Focke)经历了不同土壤水分水平(土壤最大含水量的40%、60%、80%、100%等)处理,以研究土壤水分对蛇莓克隆构型的影响.结果表明:间隔子长度、分株密度、分枝角度和分枝强度呈二次曲线变化,土壤含水为最大含水量的80%的生境为最适.在不同土壤水分水平生境中,蛇莓克隆构型相关特征的可塑性变化可用动态Logistic模型进行模拟和预测,拟合效果较好.结合植物对环境异质性的利用对策,对所揭示的蛇莓克隆构型可塑性进行了讨论.     

林缘和荒草坡不同草本层盖度小生境中积雪草的等级可塑性

为研究克隆植物在不同生境中对小生境的利用能力和对不同尺度异质性生境的等级可塑性及其格局差异,比较了林缘和荒草坡不同草本层盖度小生境中积雪草(Centella asiatica)分株种群、克隆片段和叶水平的形态和生理特征。在分株种群水平,林缘和荒草坡积雪草被测的分株种群特征差异均不显著,不同草本层盖度小生境间积雪草根冠比差异显著,即在盖度小的小生境中其根冠比显著大于盖度大的小生境。在克隆片段水平,林缘和荒草坡生境显著影响积雪草的根干重、花果干重、一级匍匐茎节间长和总匍匐茎节间长,而不同草本层盖度小生境则显著影响花果干重、根冠比、一级匍匐茎数、二级匍匐茎节间长和总匍匐茎节间长。荒草坡积雪草拥有更大的根干重和花果干重,但一级匍匐茎节间长和总匍匐茎节间长较短。草本层盖度小的小生境中积雪草的根冠比和一级匍匐茎数显著高于盖度大的小生境,而花果干重、二级匍匐茎节间长和总匍匐茎节间长则相反。在叶水平,荒草坡和草本层盖度大的小生境中,积雪草的叶片长、叶片宽和叶面积都较大,而草本层盖度大的小生境中积雪草叶柄长和比叶柄长都显著大于盖度小的小生境;林缘和荒草坡生境与不同草本层盖度小生境对4个叶绿素指标影响均不显著,林缘和荒草坡生境与不同草本层盖度小生境的交互作用对所有测量特征均无显著影响。上述结果表明,积雪草对不同生境和有草本层盖度差异的小生境的反应存在等级可塑性,但是二者的等级差异格局不同;等级反应格局的差异反映出积雪草对不同生境条件有不同的生态适应对策,且对生境小尺度异质性的可塑性强于对大尺度异质性的可塑性。     

东北样带上的克隆植物及其重要性与环境的关系

1997年野外调查资料,对中国东北样带克隆植物沿样带的分布,克隆植物在群落中的重要性以及其与环境因子之间的关系进行了研究,结果表明;克隆植物相对种数（C/Pt)和克隆植物相对重要值（IV）随样带上环境梯度变化呈增加的趋势,群落中克隆植物相对种数与土壤全氮含量负相关,与海拔高度正相关,与年平均温度和年降水相关不显著;克隆植物相对重要值与土壤全氮含量负相关,与海拔高度正相关,与年平均温度和年降水相关不显著,研究还发现,群落中克隆植物种数与非克隆植物种数随样带上海拔高度、年平均温度、年降水梯度变化相关性较差,而克隆植物种数与土壤全氮含量负相关不显著,非克隆植物物种数与土壤全氮含量正相关不显著,根茎型、分蘖型及鳞茎球茎型克隆植物在土壤湿度较差的生境中出现频率较高,而匍匐茎型、根茎鳞茎及根茎球茎型克隆植物在土壤湿度较好的生境中出现频率较高。     

匍匐茎草本植物蛇莓小尺度克隆结构

采用ISSR分子标记技术比较分析了3个斑块匍匐茎草本植物蛇莓的遗传多样性、克隆多样性和克隆结构,探讨蛇莓克隆结构的形成机制及与环境的相关性.结果表明蛇莓的遗传多样性较低,多态位点百分率P为37.93%, Shannon信息指数I为0.2402, Nei指数h为0.1677;蛇莓的克隆多样性与其它克隆植物较为接近,基因型比率G/N=0.2013,Simpson多样性指数D为0.6396,基因型分布的均匀度E为0.5862;蛇莓的遗传变异大部分存在于斑块间,基因流较小,仅为0.1019.3个斑块蛇莓的遗传多样性以临海斑块(LH)最高(P=10.34%, I =0.0513, h =0.0344),安吉斑块(AJ)次之(P=10.34%, I =0.0443, h =0.027),而天台斑块(TT)最低(P=5.17%, I =0.0325, h =0.0227).基株数目、基因型比率、Simpson多样性指数和基因型分布的均匀度均表明克隆多样性以LH斑块最大(G=12, G/N=0.3077, D=0.8677, E=0.8380),AJ斑块次之(G=9, G/N=0.1800, D=0.5870, E=0.4753),TT斑块最低(G=5, G/N=0.1163, D=0.4642, E=0.4453).3个斑块中均存在优势克隆,但优势克隆的大小在3个斑块中均不相同,以LH斑块最小,AJ斑块次之,TT斑块最大.空间自相关分析显示LH斑块在20 cm和40 cm时存在显著性正相关,其X轴截矩为49.959;AJ斑块仅在20 cm时存在显著性正相关,其X轴截矩为63.333;TT斑块在20 cm、30 cm、40 cm和70 cm时均存在显著性正相关,其X-轴截矩高达90.512.这表明3个不同斑块内蛇莓基因型的空间分布距离不同,TT斑块最大,AJ斑块最小;克隆所能到达的距离也不同,TT斑块最大,LH斑块最小.3个不同斑块蛇莓的遗传多样性、克隆多样性与克隆结构具有明显的差异.蛇莓的遗传多样性与克隆多样性与蛇莓较强的克隆繁殖能力和较低的种子萌发率有关.蛇莓的遗传结构、克隆结构及克隆的空间分布格局与不同斑块所处生境的生态因子及其它因素(如干扰、演替和突变)有关.     

莲草直胸跳甲取食对空心莲子草和莲子草克隆整合的影响

很多外来入侵植物都具有克隆生长习性,探究克隆整合特性与外来克隆植物入侵性间的关系对阐明其生态适应性及入侵机制具有重要的意义。本研究以入侵植物空心莲子草及其本地同属种莲子草为研究对象,比较在生防昆虫莲草直胸跳甲的取食下,克隆整合对两种植物先端分株、基端分株及整个克隆片段生长和生物量分配的影响。结果表明: 在莲草直胸跳甲取食下,有克隆整合的空心莲子草先端分株的叶片数、茎长、分株数及整个克隆片段的地径均显著高于无克隆整合植株,其基端分株及整个克隆片段的地下生物量和总生物量相较于无克隆整合植株分别降低了78.2%、60.9%和48.7%、37.2%;有克隆整合的莲子草先端分株的地径及整个克隆片段的叶片数与无克隆整合植株相比显著增加,其基端分株数显著降低了21.7%,而其先端分株、基端分株及整个克隆片段的生物量均无显著差异。耗益分析表明,在莲草直胸跳甲取食下,空心莲子草先端分株的分株数与生物量及莲子草先端分株的分株数均能通过克隆整合显著受益,而两种植物基端的分株数、生物量的耗益则不受克隆整合处理的影响。这些结果表明,克隆整合虽能在一定程度缓解莲草直胸跳甲对于两种植物先端分株的取食压力,且空心莲子草的克隆整合作用要强于莲子草,但在整个克隆片段水平上,两种植物并不能通过克隆整合显著获益。     

匍匐茎草本蛇莓克隆构型对土壤养分的可塑性反应

克隆植物构型的可塑性可使它在养分斑块性分布的环境中,相应地调整对土壤养分的获取对策,因而可能具有重要的生态学意义。在一项田间实验中,匍匐茎草本蛇莓(Duchesnea indica Focke）经历了不同土壤养分水平（高、中、低和对照）处理,以研究土壤养分对蛇莓克隆构型的影响。结果表明：随着土壤养分水平的增加,间隔子的长度和分枝角度均逐渐降低,而分枝强度和分株密度增加。在不同养分水平生镜中,蛇莓克隆构型相关特征的可塑性变化可用动态Logistic模型进行模拟和预测,拟合效果较好。结合植物对环境异质性的利用对策,对所揭示的蛇莓克隆构型可塑性进行了讨论。     

匍匐茎草本蛇莓克隆构型对土壤水分的可塑性反应

克隆植物构型的可塑性有可能促进它对斑块性分布土壤水分资源的利用,因而可能具有生态学意义。在田间实验中,匍匐茎草本蛇莓（Duchesnea indica Focke)经历了不同土壤水分水平（土壤最大含水量的40%,60%,80%,100%等）处理,以研究土壤水分对蛇莓克隆构型的影响,结果表明：间隔子长度,分株密度,分枝角度和分枝强度呈二次曲线变化,土壤含水为最大含水量的80%的生境为最适,在不同土壤水分水平生境中,蛇莓克隆构型相关特征的可塑性变化可用动态Logistic模型进行模拟和预测,拟事效果较好,结合植物对环境异质性的利用对策,对所揭示的蛇莓克隆构型可塑性进行了讨论。     

不同年龄巴山木竹种群克隆结构

很多竹类植物是典型的克隆植物,也是大熊猫的食物。研究典型竹子种群克隆结构的形成和发展对竹林的生产和抚育具有理论和实践意义,可为预测该竹林群落的演替趋势和大熊猫保护提供科学依据。利用SSR标记研究不同年龄A(7龄)、B(30龄)和C(60龄)巴山木竹种群的克隆结构和多样性,探讨小尺度范围内不同年龄巴山木竹种群的克隆结构及斑块的建立和发展。8对SSR引物共扩增出了118个位点,3个种群样地的256个样本共检测到了49个克隆(基因型),A、B和C种群分别检测出31、10个和8个克隆。随着种群年龄的增长,巴山木竹克隆面积增加,克隆数量减少;A和B样地各克隆分布格局为团块状,而C样地克隆既有团块状又有离散状。这一结果显示出在幼苗定居的初期,基株可能以短距离的克隆延伸为主从而呈现出团块状;而随着年龄的增长,克隆面积不断扩大,当复轴混生型的巴山木竹克隆受到强大的压迫时,基株可能会进行较多的单轴和长距离克隆延伸,呈现出离散状。Mantel检测和空间自相关分析都支持3个样地在小尺度范围内存在明显的克隆空间遗传结构。3个样地在10 m等级下显著的正相关空间遗传结构距离为3.1、28、48 m,X-轴截距为9.051、30.698和50.536,空间自相关系数的范围分别为0.1—0.167、0.008—0.703和0.006—0.735。由此可推断,随着年龄的增长,巴山木竹克隆斑块的规模在不断地扩大,同一克隆的分株数量增加,在均匀取样情况下,正相关空间遗传结构距离范围内取到具有相同基因型的可能性越大。A、B和C 3样地的基因型比率(G/N)为1、0.14和0.055,Simpson多样性指数(D)分别为1、0.876和0.744。这说明巴山木竹幼苗期基因型比例远远高于成年的竹林,随着年龄的增长巴山木竹克隆多样性虽有所降低,但由于有性繁殖的作用仍然保持了较高的多样性。聚类和主坐标分析均表明总体上各样地的克隆被聚为一类,但不同样地少数克隆的基因型有重叠和聚集,可推断出不同巴山木竹种群之间可能存在着基因流动和近似的克隆起源。     

Within-population spatial genetic structure, neighbourhood size and clonal subrange in the seagrass Cymodocea nodosa

Abstract The extent of clonality within populations strongly influences their spatial genetic structure (SGS), yet this is hardly ever thoroughly analysed. We employed spatial autocorrelation analysis to study effects of sexual and clonal reproduction on dispersal of the dioecious seagrass Cymodocea nodosa. Analyses were performed both at genet level (i.e. excluding clonal repeats) and at ramet level. Clonal structure was characterized by the clonal subrange, a spatial measure of the linear limits where clonality still affects SGS. We show that the clonal subrange is equivalent to the distance where the probability of clonal identity approaches zero. This combined approach was applied to two meadows with different levels of disturbance, Cadiz (stable) and Alfacs (disturbed). Genotypic richness, the proportion of the sample representing distinct genotypes, was moderate (0.38 Cadiz, 0.46 Alfacs) mostly due to dominance of a few clones. Expected heterozygosities were comparable to those found in other clonal plants. SGS analyses at the genet level revealed extremely restricted gene dispersal in Cadiz (Sp = 0.052, a statistic reflecting the decrease of pairwise kinship with distance), the strongest SGS found for seagrass species, comparable only to values for selfing herbaceous land plants. At Cadiz the clonal subrange extended across shorter distances (20-25 m) than in Alfacs (30-35 m). Comparisons of sexual and vegetative components of gene dispersal suggest that, as a dispersal vector within meadows, clonal spread is at least as important as sexual reproduction. The restricted dispersal and SGS pattern in both meadows indicates that the species follows a repeated seedling recruitment strategy.     

克隆植物对种间竞争的适应策略

克隆植物种群因其寿命的持久性、空间上的可移动性和繁殖方式的多样化等特征与非克隆植物有很大区别, 在自然生态系统中占有重要地位, 甚至成为优势种或者建群种。该文通过归纳有关克隆植物的种间竞争适应策略研究案例, 阐述了克隆植物的竞争能力差异和影响竞争力的因素; 论述了克隆植物在构件形态、克隆构型、繁殖对策等方面对种间竞争的响应, 以及生理整合作用与种间竞争的关系; 分析了导致某些同类研究的结论不一致的原因, 认为实验对象差异、实验设计、生境条件与克隆植物形态及生理上的时空动态变化等都可能影响实验结果; 提出了全球变化背景下的克隆植物种间竞争及其分子生态学机制等可能是今后需要重点关注的问题。     

Timing and intensity of herbivory: Its influence on the performance of clonal woodland herbs

Herbaceous woodland species account for a significant amount of the biodiversity of temperate deciduous forests. A wide diversity of life-history strategies is known for woodland herbs, and several systems have been used to categorize the range of life-history characteristics. Clonal growth, one common feature of many woodland herbaceous species, provides several benefits including the ability to respond to disturbances by sharing resources among ramets. There is evidence that resource sharing is common among ramets of some species of woodland herbs but not others. Herbivory is a common form of disturbance among woodland herbs, but little is known about effects of the timing and intensity of herbivory. In this paper, we use an existing system of classification of life-history traits of clonal species to make predictions about how woodland herbs would respond to the timing and intensity of defoliation. Examples from a preliminary study in Maryland, USA, are used to demonstrate that the timing and intensity of herbivory can play an important role in determining patterns of future growth and resource allocation.     

Asexual and sexual reproductive strategies in clonal plants

Most plants can reproduce both sexually and asexually (or vegetatively),and the balance between the two reproductive modes may vary widely between and within species.Extensive clonal growth may affect the evolution of life history traits in many ways.First,in some clonal species,sexual reproduction and sex ratio vary largely among populations.Variation in sexual reproduction may strongly affect plant's adaptation to local environments and the evolution of the geographic range.Second,clonal growth can increase floral display,and thus pollinator attraction,while it may impose serious constraints and evolutionary challenges on plants through geitonogamy that may strongly influence pollen dispersal.Geitonogamous pollination can bring a cost to plant fitness through both female and male functions.Some co-evolutionary interactions,therefore,may exist between the spatial structure and the mating behavior of clonal plants.Finally,a trade-off may exist between sexual reproduction and clonal growth.Resource allocation to the two reproductive modes may depend on environmental conditions,competitive dominance,life span,and genetic factors.If different reproductive modes represent adaptive strategies for plants in different environments,we expect that most of the resources should be allocated to sexual reproduction in habitats with fluctuating environmental conditions and strong competition,while clonal growth should be dominant in stable habitats.Yet we know little about the consequence of natural selection on the two reproductive modes and factors which control the balance of the two reproductive modes.Future studies should investigate the reproductive strategies of clonal plants simultaneously from both sexual and asexual perspectives.     

Asexual and sexual reproductive strategies in clonal plants

Most plants can reproduce both sexually and asexually (or vegetatively), and the balance between the two reproductive modes may vary widely between and within species. Extensive clonal growth may affect the evolution of life history traits in many ways. First, in some clonal species, sexual reproduction and sex ratio vary largely among populations. Variation in sexual reproduction may strongly affect plant’s adaptation to local environments and the evolution of the geographic range. Second, clonal growth can increase floral display, and thus pollinator attraction, while it may impose serious constraints and evolutionary challenges on plants through geitonogamy that may strongly influence pollen dispersal. Geitonogamous pollination can bring a cost to plant fitness through both female and male functions. Some co-evolutionary interactions, therefore, may exist between the spatial structure and the mating behavior of clonal plants. Finally, a trade-off may exist between sexual reproduction and clonal growth. Resource allocation to the two reproductive modes may depend on environmental conditions, competitive dominance, life span, and genetic factors. If different reproductive modes represent adaptive strategies for plants in different environments, we expect that most of the resources should be allocated to sexual reproduction in habitats with fluctuating environmental conditions and strong competition, while clonal growth should be dominant in stable habitats. Yet we know little about the consequence of natural selection on the two reproductive modes and factors which control the balance of the two reproductive modes. Future studies should investigate the reproductive strategies of clonal plants simultaneously from both sexual and asexual perspectives. Translated from Acta Phytoecologica Sinica, 2006, 20(1): 174–183 [译自: 植物生态学报]     

Effects of salinity and clonal integration on the amphibiousplant Paspalum paspaloides: growth,photosynthesis and tissue ion regulation

Aims Clonal integration can increase performance of clonal plants suffering from environmental stress, and clonal plants in many wetlands commonly face stress of flooding accompanied by salinity. However, few studies have tested roles of clonal integration in amphibious plants expanding from terrestrial to aquatic saline habitats.