季风常绿阔叶林不同恢复阶段乔木优势种群生态位和种间联结

生态位和种间联结是群落动态研究的重要内容之一,物种间相互作用影响着群落的恢复和演替。本文在对云南普洱地区不同恢复阶段(恢复15年、恢复30年和原始林群落)季风常绿阔叶林群落的野外调查基础上,采用生态位宽度、生态位重叠、方差比率(VR)和基于2×2联列表的χ2检验、联结系数(AC)等方法,分析了不同恢复阶段各种群的变化趋势。结果表明:3种群落类型中物种的重要值与相对应的生态位宽度之间存在着显著的正相关,恢复15年群落有78.22%的种对之间的生态位重叠值在0.4～0.8,说明其群落优势物种存在较强的资源利用性竞争,而恢复30年和原始林群落结构则具有一定的稳定性,多数生态位宽度较大的物种之间的生态位重叠要大于生态位较小的物种,反映出优势物种具有较强的竞争能力;恢复15年和恢复30年群落物种间总体呈不显著正联结,原始林群落则呈不显著负联结;3种群落231种对中,绝大多数种对联结系数未达显著水平,种对间的独立性相对较强,群落中物种间正负联结对数占总种的比例随恢复进程而出现下降趋势。不同恢复阶段群落中联结系数与生态位重叠值之间存在显著正相关,生态位重叠值越大,其联结系数也越大。     

桂林岩溶石山青冈群落灌木层主要物种生态位与种间联结

基于样方调查,采用生态位测定、方差比率法、χ~2检验、Pearson相关检验和Spearman秩相关检验等方法对桂林岩溶石山青冈群落灌木层主要物种的生态位与种间联结进行研究。结果表明:(1)青冈的生态位宽度最大,占绝对竞争优势;重要值较大(小)的物种,其生态位宽度一般较大(小),但两者顺序并非完全一致。(2)主要物种间的生态位相似性较小,各物种对资源利用的相似程度不高;一般生态位宽度较大的物种,其生态位相似性也越大。(3)生态位宽度较大的物种间产生生态位重叠的概率较大,但生态位重叠程度并不一定大;生态位宽度与生态位重叠有一定的联系,但并不存在绝对的正相关关系;生态位相似性和生态位重叠程度的变化趋势基本吻合。(4)灌木层主要物种的总体联结性表现为显著正联结,表明该群落处于相对稳定的演替阶段。(5)χ~2检验、Pearson相关检验和Spearman秩相关检验结果的显著率均较低,种间联结性不强。(6)物种间的Pearson相关系数、Spearman秩相关系数与相应的生态位相似性和生态位重叠程度之间均呈显著正相关,表现为种间正(负)联结越强,生态位相似性和生态位重叠程度越大(小)。     

赤水桫椤群落乔木层优势物种生态位与种间联结性研究

赤水桫椤国家级自然保护区是以桫椤为保护对象的自然保护区,该研究在对保护区桫椤(Alsophila spinulosa)群落进行野外调查的基础上,采用生态位宽度、生态位重叠和基于2×2联列表的方差比率法(VR)、卡方(χ2)检验、联结系数(AC)等方法,分析了群落物种间的相互关系。结果表明:(1)研究区内毛竹(Phyllostachys heterocycla)的生态位宽度最大,其次是桫椤和毛桐(Mallotus barbatus)。(2)马尾松(Pinus massoniana)与油桐(Vernicia fordii)、杉木(Cunninghamia lanceolata),芭蕉(Musa basjoo)与陀螺果(Melliodendron xylocarpum)的生态位重叠值较大。(3)14个乔木层优势物种间总体关联性呈不显著负相关关系;卡方检验表明桫椤与其他种群之间联结性均不显著,群落中90.10%种对的联结性均未达到显著水平,只有极少数种对存在显著关联;大部分种对的AC、Ochai指数(OI)、Jaccard指数(JI)值都不高,种对间相关性较弱,独立性相对较强,且群落负联结的种对多于正联结,处于动态演替不稳定阶段。(4)物种之间的联结性与相应的生态位重叠结合分析表明,两者呈正相关关系,表现为种间正联结越强,生态位重叠越大,负联结越强,生态位重叠越小。     

小黄花茶群落优势木本植物生态位及种间联结性

赤水桫椤国家级自然保护区是小黄花茶物种原产地,近来研究发现小黄花茶种群具有急速衰退的趋势,其物种濒危机制并不清楚。生态位及种间联结性可反映物种利用资源的能力,研究小黄花茶种群生态位及其与伴生种之间的联结性,对探索小黄花茶群落稳定性具有重要意义。采用典型样地调查法对赤水桫椤国家级自然保护区8个小黄花茶集中分布样地进行群落学调查,选择重要值排序前15个优势木本物种,计算生态位宽度(B_S、B_L)、生态位相似比(C_ik)及重叠值(O_ik)、种间联结系数(AC)以及共同出现百分率(PC)等指标,分析物种生态位与物种联结性之间的关系。结果表明：小黄花茶群落木本物种共63种,小黄花茶重要值(0.21)和生态位宽度值(B_S=2.89,B_L=15.76)均为最大。小黄花茶与其它优势种组成14个种对中C_ik≥0.50的有2对,O_ik≥0.50的有3对,优势种生态位相似性和生态位重叠程度均较低。优势种总体联结性和种间联结性呈不显著负关...     

滇西北云南红豆杉群落物种生态位与种间联结

在对滇西北云南红豆杉(Taxus yunnanensis)群落的野外调查基础上,采用生态位宽度、生态位重叠和基于2× 2联列表的χ²检验、联结系数(AC)的方法,分析了群落种群间的相互关系。结果表明:物种的重要值与相对应的生态位宽度存在着极显著正相关;云南红豆杉、丽江铁杉(Tsuga forrestii)与青荚叶(Helwingia japonica)的生态位宽度大于其它种群;在1225个种对中有48.16%的生态位重叠值为0,同时χ²统计量中有4%为中性联结,说明群落中木本植物种群间资源利用性竞争较强。生态位宽度较大的种群间往往生态位重叠也较大;云南红豆杉与丽江铁杉之间的生态位重叠值要明显高于与其它种群的,Schoener指数为0.875。χ²检验表明云南红豆杉与其它种群之间表现为无联结。联结系数中显著负联结的种对要多于显著正联结,群落物种受到较大的外来干扰。联结系数与生态位重叠值之间存在极显著正相关,并能用Cubic指数建立回归方程模型。     

福建琅岐岛台湾相思群落灌木层主要物种生态位与种间联结

为探究福建琅岐岛台湾相思(Acacia confusa)群落种间关系和群落演替动态,对其灌木层主要物种的生态位和种间联结特征进行了分析。结果表明,重要值和生态位宽度最大的物种为雀梅藤(Sageretia thea),其竞争优势、环境适应能力最强;灌木层主要物种的生态位相似性和生态位重叠较小,表明种间对环境资源的利用和要求存在较大差异,表现为较稳定的种间关系;灌木层主要物种的总体联结性为显著正联结,种对间正负联结比为1.72,检验显著率为7.35%,表明种对间联结程度较弱,独立性相对较强,物种竞争不激烈,群落处于相对后期且稳定的演替阶段;红锥(Castanopsis hystrix)与许多物种间存在垂直方向上对生境要求的互补性,生态位重叠较小,种间呈正联结关系;外来物种马缨丹(Lantanacamara)与福建胡颓子(Elaeagnus oldhamii)存在一定的竞争,与灌木层其他主要植物之间的资源竞争不激烈,其对该群落的影响相对较小。琅岐岛台湾相思群落目前已发展为地带性的顶级群落,物种竞争不激烈,种间关系较稳定;而海岛上恶劣的环境和外来物种的扩散会导致植物生境资源短缺,迫使物种聚集在...     

武陵山大木山自然保护区红豆杉群落优势乔木种群生态位和种间联结

应用Pearson相关系数和Spearman秩相关系数检验。对武陵山大木山自然保护区红豆杉群落内13个优势乔木种群的种间关联（或相关）性进行研究,并对13个优势乔木种群生态位宽度、生态位重叠进行分析。结果表明,红豆杉种群对资源的利用能力较强,生态位宽度值较大：红豆杉与其他物种生态特性差异较大,生态位重叠值较低;群落内各种群间关系的相对独立性较弱,红豆杉种群与其他物种大多呈正相关关系。生态位宽度值大的物种,与其他物种的生态位重叠值一般较大;生态位重叠值较大的物种对,其种间联结一般也较显著。     

天然林和人工林外来入侵和本地植物对比研究: 以弄岗国家级自然保护区为例

外来植物的入侵严重威胁了自然保护区的生物多样性。为探讨自然保护区内天然林和人工林林下外来植物入侵状况及其与本地优势植物的种间关系, 本研究以弄岗国家级自然保护区为研究区域, 结合保护区内4种生境72个样方的野外调查数据, 利用生态位宽度、生态位重叠和种间联结指数比较了不同生境中外来入侵草本植物的多样性和生态位宽度以及外来入侵草本植物与本土优势草本植物的生态位重叠和种间联结。结果表明: 弄岗国家级自然保护区4种生境共记录6种外来入侵草本植物, 隶属于3科6属, 其中菊科物种数量最多。外来入侵植物多样性呈现出秋枫(Bischofia javanica)人工林 > 麻竹(Dendrocalamus latiflorus)次生林 > 人面子(Dracontomelon duperreanum)人工林 > 广西澄广花(Orophea polycarpa)次生林的特征。除广西澄广花次生林生境的外来入侵草本植物丰富度与本土草本植物丰富度呈显著正相关外, 其余生境均无显著的相关关系。三叶鬼针草(Bidens pilosa)的生态位宽度最大, 为4种生境均有分布的外来入侵植物。4种生境的外来入侵植物与本土优势植物生态位重叠和种间联结程度均较低, 种间竞争较弱。本研究明确了弄岗国家级自然保护区天然林和人工林中外来入侵草本植物的分布及其与本土草本植物的种间关系。     

黔中喀斯特次生林主要物种的生态位及种间联结性动态变化

为探讨黔中喀斯特次生林演替规律,基于2013-2019年的定点监测数据,从群落物种组成、生态位宽度、生态位重叠值、种间联结等方面研究了黔中喀斯特次生林生态位和种间联结性的动态变化。结果表明,7年间建群种的重要值占比减小,六月雪(Serissa japonica)、珍珠荚蒾(Viburnum foetidum)等物种优势度显著增加。竹叶椒(Zanthoxylum armatum)、小果蔷薇(Rosacymosa)等占据较宽生态位,云南旌节花(Stachyurus yunnanensis)、六月雪等物种对资源的可利用量增加,使得其生态位变窄。生态位重叠值小于0.2的种对比例减少,种间竞争关系更为复杂。主要物种间的总体联结性由不显著正联结变为显著正联结,多数种对间的正负联结比例上升。黔中喀斯特次生林群落中种间竞争激烈且渐趋稳定,种间联结紧密性增强,在正向演替过程中,伴随着六月雪、珍珠荚蒾等耐阴种和中生性种的优势度和竞争力增大,小冻绿树(Rhamnus rosthornii)和杭子梢(Campylotropis macrocarpa)等先锋种竞争不足而衰退。这为喀斯特地区植被恢复和石漠化治理提供参考。     

贺兰山冲积扇荒漠草地拟步甲生态位及种间关联

【目的】拟步甲对维持荒漠半荒漠生境的生物多样性和生态系统功能具有重要作用。本研究旨在揭示拟步甲物种的生态位及种间关联,为冲积扇荒漠草地生境拟步甲群落构建机制研究奠定基础。【方法】2019年5-10月采用陷阱法调查贺兰山冲积扇荒漠草地划分为100个相同大小正方形单元的200 m×200 m样地的拟步甲昆虫群落组成,运用2×2联列表分析、生态位宽度、生态位重叠、方差比率法、 χ²检验、联结系数(AC)、共同出现百分率(PC)、Ochiai指数、Dice指数和Spearman秩相关系数等方法分析物种间的生态位和种间联结性。【结果】6次调查共捕获拟步甲科成虫7属10种1 086头,其中克小鳖甲Microdera kraatzi kraatzi、弯胫东鳖甲Anatolica pandaroides和平坦东鳖甲Anatolica planata是优势种。平坦东鳖甲空间生态位宽度最大,小圆鳖甲Scytosoma pygmaeum时间生态位宽度最大,克小鳖甲时空生态位宽度最大,类沙土甲Opatrum subaratum时间、空间、时空生态位宽度最小,处于竞争劣势。对拟步甲生态位宽度值聚类表明,克小鳖甲、弯胫东鳖甲、小圆鳖甲和裂缘圆鳖甲S. dissilimarginis是广生态位种。种对的时间生态位重叠比空间生态位重叠更显著。方差比率和W检验表明拟步甲昆虫总体呈显著正关联; χ²检验、联结系数(AC)和Spearman 秩相关系数的结果显示正负关联种对的比率大于1,总体趋于正相关。共同出现百分率(PC)、Ochiai指数和Dice指数表明,优势种克小鳖甲、弯胫东鳖甲和平坦东鳖甲种间呈显著正关联。根据Spearman秩相关系数结果,这10种拟步甲可划分为3个生态种组。【结论】优势种类具有较宽的生态位,物种时间生态位和空间生态位宽度变化不一致,正联结性显著的种对生态位重叠相应也较高。生态种组聚类反映了种对生态适应性的差异。研究结果为研究冲积扇荒漠草地生境小尺度空间拟步甲昆虫群落演替提供了参考依据。     

甘菊ClHSP70与ClHSP90基因的克隆及表达分析

该研究以甘菊(Chrysanthemum lavandulifolium)为实验材料,通过RT-PCR方法从甘菊转录组数据中分离出热激蛋白合成相关基因,命名为ClHSP70和ClHSP90。序列分析表明,ClHSP70基因ORF全长为2 559bp,编码852个氨基酸,蛋白功能区预测表明含有典型的HSP70蛋白NBD和SBD保守结构域;ClHSP90基因ORF全长为2 094bp,编码697个氨基酸,含有HATPase结构域和HSP90保守结构域。生物信息学分析表明,甘菊ClHSP70与大豆(Glycine max)和烟草(Nicotiana tomentosiformis)HSP70蛋白有较高的一致性,ClHSP90基因编码的氨基酸序列与紫茎泽兰(Ageratina adenophora)HSP90高度相似;实时荧光定量表达分析表明,在42℃处理不同时间,甘菊叶片中ClHSP70和ClHSP90基因表达均在0.5h时显著增加,1h达到最大值,2h后缓慢下降;不同组织表达分析表明,甘菊在42℃处理1h后,ClHSP70在成熟叶中的表达量显著高于嫩叶和根等其他组织;ClHSP90在成熟茎中的表达量最高。研究说明,ClHSP70和ClHSP90基因具有热激蛋白特征,参与了甘菊热胁迫应答过程,该研究结果为以后深入研究其基因功能奠定了基础。     

New species of Phaeoramularia, Pseudocercospora and Stenella from Western Ghats of India

Four new species of the hyphomycete genera Phaeoramularia viz. Ph. caesalpinae, Pseudocercospora viz., Ps. tiliacearum, Stenella, viz. S. argyreiae and S. grewiae occurring on Caesalpinia bonducella Fleming (Caesalpiniaceae), Grewia sp. (Tiliaceae), Argyrea sp. Lour (Convolvulaceae) and Grewia sp. L. (Tiliaceae), respectively are described and illustrated here. All these fungi were collected from Western Ghats of India.     

Characterisation of cell wall polysaccharides, arabinogalactans-proteins (AGPs) and phenolics of Cola nitida, Cola acuminata and Garcinia kola seeds

Many Cola plant species are endemic to West and Central Africa. Cola acuminata and Cola nitida are used as masticatory when fresh, while the dried nuts are used for beverages and pharmaceutical purposes in Europe and North America. Garcinia kola seeds, that serve as a substitute for the true kola nuts, are used in African traditional medicine for the treatment of various diseases, including colic, headache and liver cirrhosis. Seeds extracts of G. kola are also known for their anti-inflammatory, antimicrobial and antiviral properties. To gain information on the chemical properties of the kolas, we have isolated and analyzed cell wall polysaccharides, arabinogalactan-proteins and phenolic substances from the seeds of the three kola species. The sugar composition of cell wall material of C. acuminata, C. nitida and G. kola revealed that Gal (up to 30%), Ara, GalA and Glc as the predominant monosaccharides, representing approximately 90% by mol of the total hydrolysable sugar present in this material. In Ammonium oxalate cell wall fraction, GalA was found to be the major sugar present in all kola species. In the alkali-soluble fraction, there were significant differences in the level of Glc and Gal. The level of Glc was high in C. acuminata and C. nitida while the level of Gal and Xyl were high in C. nitida and G. cola. Isolation and quantification of arabinogalactan-proteins demonstrate that G. kola seeds contained four to eight times more of these proteoglycans than the seeds of the other two species. Finally, analysis of soluble phenolic substances shows that caffeine and catechin were largely represented in C. acumina and C. nitida seeds, with caffeine accounting for 50% of all soluble phenolics. These findings indicate that the three Kola seeds are highly enriched in pectins and proteoglycans and that C. acuminata and C. nitida can be used as a possible source of caffeine and catechin.     

Evolutionary relationships among aquatic anamorphs and teleomorphs: Lemonniera, Margaritispora, and Goniopila

The hypothesis that similar conidial morphologies in aquatic hyphomycetes are a result of convergent evolution was tested using molecular sequence data. Cladistic analyses were performed on partial sequences of 28S rDNA of seven species of Lemonniera, one species of Margaritispora and one species of Goniopila. Lemonniera has tetraradiate conidia with long arms, whereas Margaritispora and Goniopila have typically globose (isodiametric) conidia, with short conical protuberances in a stellate or quadrangular arrangement. Lemonniera and Margaritispora have phialidic conidiogenesis and both produce dark, minute sclerotia in culture whereas Goniopila has holoblastic conidiogenesis and does not produce sclerotia in culture. Goniopila produces a microconidial phialidic synanamorph in culture. All three genera have schizolytic conidial secession. Molecular analyses demonstrate that Lemonniera species are placed in two distinct clades: one within Leotiomycetes; the other within Pleosporales, Dothideomycetes. Margaritispora is placed with Lemonniera species within Leotiomycetes. Goniopila and Lemonniera pseudofloscula are placed within Dothideomycetes. No morphological character was entirely congruent with the molecular derived phylogeny. This suggests that for the group of species studied, conidial shape is not a reliable indicator of phylogeny but more likely the result of convergent evolution in response to the aquatic environment.     

Molecular and morphological characterization of Leveillula (Ascomycota: Erysiphales) on monocotyledonous plants

Leveillula on monocotyledonous plants have been recorded as L. taurica by several authors, whereas the fungus on Allium has been described as an independent species, namely L. allii, by some authors. We sequenced ca 600 bp of the rDNA ITS region for two Leveillula specimens from Allium and Polianthes (both from monocotyledons) and compared them with several already published sequences from Leveillula isolates from dicotyledons. Pair-wise percentages of sequence divergences were calculated for all Leveillula isolates. The ITS sequence of the Polianthes isolate was identical to L. taurica on Helianthus and Vicia. The sequence of the Allium isolate was 99.5 % identical to L. taurica on Euphorbia, Haplophylum, Peganum, etc. These results suggest close relationships between monocot and dicot pathogenic Leveillula species. The identity between two monocot isolates was 98.4 %. Phylogenetic analysis revealed that the two monocot isolates do not group into a clade together. This result suggests that Leveillula acquired parasitism to monocots at least twice independently.     

下延叉蕨和芽胞叉蕨配子体发育的研究

利用光学显微镜详细观察了叉蕨属(Tectaria)下延叉蕨(Tectaria decurrens)和芽胞叉蕨(T.fauriei)的配子体发育过程,记录了配子体各发育阶段的特征。结果表明:(1)下延叉蕨和芽胞叉蕨的孢子均为单裂缝,具周壁,由周壁形成纹饰,孢子极面观椭圆形,赤道面观豆形或肾形。(2)孢子萌发方式为向心型。(3)原叶体发育方式为三叉蕨型。(4)成熟原叶体心脏形,两翼向斜上方扩展。(5)均具单细胞和多细胞毛状体,在丝状体或片状体阶段出现。研究认为,从配子体发育角度看,叉蕨属是较进化的陆生真蕨类;毛状体的类型、位置和出现时间等特征在叉蕨属种间存在差异,可作为该属种间分类的特征。     

The phylogenetic placement of Ostropales within Lecanoromycetes (Ascomycota) revisited

Results of molecular studies regarding the phylogenetic placement of the order Ostropales and related taxa within Lecanoromycetes were thus far inconclusive. Some analyses placed the order as sister to the rest of Lecanoromycetes, while others inferred a position nested within Lecanoromycetes. We assembled a data set of 101 species including sequences from nuLSU rDNA, mtSSU rDNA, and the nuclear protein-coding RPB1 for each species to examine the cause of incongruencies in previously published phylogenies. MP, minimum evolution, and Bayesian analyses were performed using the combined three-region data set and the single-gene data sets. The position of Ostropales nested in Lecanoromycetes is confirmed in all single-gene and concatenated analyses, and a placement as sister to the rest of Lecanoromycetes is significantly rejected using two independent methods of alternative topology testing. Acarosporales and related taxa (Acarosporaceae group) are basal in Lecanoromycetes. However, if the these basal taxa are excluded from the analyses, Ostropales appear to be sister to the rest of Lecanoromycetes, suggesting different ingroup rooting as the cause for deviating topologies in previously published phylogenies.     

A polysaccharide from Lichina pygmaea and L. confinis supports the recognition of Lichinomycetes

The lichen-forming order Lichinales, generally characterized by prototunicate asci and the development of thalli with cyanobacteria, has recently been recognized as a separate class of ascomycetes, Lichinomycetes, as a result of molecular phylogenetic studies. As alkali and water-soluble (F1SS) polysaccharides reflect phylogeny in other ascomycetes, a polysaccharide from Lichina pygmaea and L. confinis was purified and characterized to investigate whether these F1SS compounds in the Lichinomycetes were distinctive. Nuclear magnetic resonance (NMR) spectroscopy and chemical analyses revealed this as a galactomannan comprising a repeating unit consisting of an α-(1→6)-mannan backbone, mainly substituted by single α-galactofuranose residues at the O-2- or the O-2,4- positions linked to a small mannan core. With the exception of the trisubstituted mannopyranose residues previously described in polysaccharides from other lichens belonging to orders now placed in Lecanoromycetes, the structure of this galactomannan most closely resembles those found in several members of the Onygenales in Eurotiomycetes. Our polysaccharide data support molecular studies showing that Lichina species are remote from Lecanoromycetes as the galactofuranose residues are in the α-configuration. That the Lichinomycetes were part of an ancestral lichenized group can not be established from the present data because the extracted polysaccharide does not have the galactofuranose residue in the β configuration; however, the data does suggest that an ancestor of the Lichinomycetes contained a mannan and was part of an early radiation in the ascomycetes.