中国部分地区种子植物区系亲缘关系的研究

以植物属分布区类型的百分比为指标,分别采用系统聚类分析的最短距离法、最长距离法、中间距离法、重心法、离差平方和法、类平均法和可变法等7种方法,对中国46个地区的植物区系进行了分析研究,给出了其种子植物属的分布区类型的树状聚类图,求得各地区植物区系之间的亲缘关系。结果表明：在一定的经度范围内(中国东半部地区),两个地区植物区系之间的亲缘关系与其所处的纬度相关,即纬度相近其亲缘关系也相近,反之即疏远。运用系统聚类分析方法所得到的中国46个地区植物区系之间亲缘关系的结果与经典的理论基本吻合。     

宁波北仑山区植被的数量分类

本文运用组平均法、主成份分折法和主坐标分析法对宁波北仑山区28个样地进行了分类,三种分类结果得到较好的统一,初步划分出7个群系与10个群丛,建立了该地区森林植被的分类系统。     

宁波北仓山区植被的数量分类

本文运用组平均法，主成份分析法和主坐标分析法对宁波北仓山区２８个样地进行了分类；三种分类结果得到较好的统一，初步划分出７个群系与１０个群丛，建立了该地区森林植被的分类系统。     

海南岛热带草地的数量分类和排序研究

本文用一些数量分类和排序的方法对海南岛鹦歌岭热带草地进行了分类和排序。所用的方法包括两种多元等级聚合分类--最近邻体法(NN)和最远邻体法(FN),极点排序(PO)和主分量分析(PCA)排序。结果表明：把19个样地分为三大类型、9个群落,其分布格局与坡度、放牧强度和土壤肥力密切相关。所用的四种方法在热带草地的研究中均有一定的适用性。     

系统聚类分析在细菌全细胞脂肪酸模式识别中的应用

用欧氏距离系数和指数相关系数,结合8种常用的系统聚类算法,对用毛细管柱气相色谱祛绘制的34株莫拉氏菌(Moraxella)及其类属菌和13株嗜肺军团杆菌(Legionella pneumo-phila)的全细胞脂肪酸气相色谱图,进行了聚类分析。比较了欧氏距离系数的8种系统聚类算法所得的聚类树状谱。结果表明,奠拉氏菌与嗜肺军团杆菌可以明确区分。在奠拉氏菌中,我国分离的两个新种与目前该属的主要标准株也能明确区分。两种相似系数中,欧氏距离系数的聚类结果较好;8种系统聚类算法中,最长距离法和类平均法的聚类结果较好。     

武陵山东部蚤类区系及不同样地群落物种多样性比较

于2000～2004年对武陵山东部7个不同样地、3个不同海拔梯度和6个不同生境类型的蚤类,进行了5年调查与研究.结果:1)在获得的7科17属30种4 320只蚤类中,有4种为古北界种类,占13.33%,22种为东洋界种类,占73.34%,4种为广布种,占13.33%;该结果与云南无量山及临沧地区的蚤类有着相同或相似的区系渊源,而与一江之隔的大巴山东部地区区系则明显不同,该地区以古北界成分为优势;2)武陵山东部地区蚤类的垂直分布规律主要表现在,1 100 m以下主要为东洋界成分,1 200 m以上有少量古北界种类分布,并随海拔升高,古北界成分略有增加;3)在7个不同样地中,物种丰富度和个体数量随海拔升高而增加,在优势种上,多数样地以偏远古蚤为优势,但在优势数量上缺乏明显规律性,并不是随海拔升高而增加;4)在6个不同生境类型中,优势种与优势数量都具明显的规律性,其中以偏远古蚤为主分为两组,山脊侧缘林、小溪山边林和坡地林为一组,人工林和农田山侧灌木林为另一组,前者平均优势数量达80.03%,后者优势数量在31.56%～48.92%之间;5)相似性系数(q值):在整个山体多数样地中,由北向南相似性系数(q值)随海拔降低和空间距离增大而逐渐降低,仅绿丛坡与牛庄、绿丛坡与独岭有例外,表明整个山体植被的片断化、或斑块化,一方面加剧或减低了样地与样地之间蚤类群落的相似程度,另一方面还要受海拔及空间距离的双重影响与制约,即海拔高度和空间距离愈大,蚤类群落的相似性及多样性越低,山体的片断、斑块或破碎化就越明显,这显然与人为过多或过频干扰有关.     

西双版纳片断季节性雨林蚂蚁物种多样性研究

以西双版纳勐仑自然保护区为对照,采用陷井诱捕法和亲方调查法比较研究了３个不同面积、不同环境状况和片断季节性雨林蚂蚁的群落组成及物种多样性变化。结果表明：所获蚂蚁隶属４亚科２４属５０种,以城子龙山物种数量多。各样地优势种均不相同。４类样地间的共有物种较少,只有４种;相似性较低,相似性系 ０．１６２２～０．３５４８。聚类结果显示,植物园保护区与城子龙山最先聚为一类,然后与自然保护区聚为一类,最后才与曼     

POD同工酶在酸枣、枣分类中的应用

运用聚丙烯酰胺凝胶电泳（ＰＡＧＥ）技术,对来自不同产地的８３个酸枣类型（品种）,及３６个枣品种的叶片过氧化物酶（ＰＯＤ）同工酶扫描数据,进行了主因子分析和聚类分析研究。结果表明,运用距离系统的类平均法（ＵＰＧＭＡ）可将全部试材划分为六大类群和３个特殊型,且聚类结果与地理位置直接相关。此外,依同工酶带的有无,可将全部供试枣品种叶片ＰＯＤ同工酶合并为５种谱型,全部酸枣类型（品种）合并为２２种谱型。大马     

长白山劲松林场植物群落的分类和排序

将长白山白河林业局劲松林场的５４块样地用聚类分析法划分成６个植被类群,再用ＰＣ－ＶＴＡＢ程序中经过改进的Ｂｒａｕｎ－Ｂｌａｎｑｕｅｔ学派的植被排表分析法进行综合,产生了鉴别概要表,为各个等级的植被类群筛选出诊断种。此外,还用鉴别种地样地记录进行主成分分析,以验证诊断种的有效性,结果表明,ＰＣ－ＶＴＡＢ中的植被排表分析法是筛选鉴别种的有效方法,而鉴别种以显著地提高植被分析和排序的质量。     

大源溪流域马尾松林群落类型划分及物种多样性

采用可变聚合法、除趋势对应分析(DCA)及典范对应分析(CCA)对楠溪江上游大源溪流域马尾松林群落类型进行划分,并探讨马尾松林群落的物种多样性。结果表明:(1)通过可变聚合法数量分类,将27个含有马尾松的样地划分为8种群落类型,8种群落类型在DCA排序图上具有明确边界,乔木层优势种是理想的森林群落数量分类依据;(2)由于研究区内森林资源受人为经营干扰严重,蒙特卡罗置换检验表明,CCA排序结果无法接受自然环境因子对物种样方的分布解释,不过结合排序轴特征值可以推测土壤有效氮含量与物种分布具有较强的相关性;(3)马尾松重要值与海拔、有效氮及有效磷均呈边缘显著性相关,与乔木层和草本层多样性呈显著负相关;(4)方差分析表明,与针阔混交林和常绿阔叶林相比,马尾松林的乔木层物种多样性明显较低,其灌木层和草本层多样性虽然较低,但与其他群落类型相比均未表现出显著性差异。     

广西常绿阔叶林的极点排序

极点排序法的最大特点是人为地选择座标轴。根据我们对四种不同选轴方法的对比,发现在排序结果上没有大的区别。这表明在选择端点样地时,只要剔除那些最无关的极端样地后,根据植被变异度来确定端点还是可行的。无论用哪一种选轴方法,为了避免端点样地与其它样地过于无关,凡是与其它样地相异性系数出现100者均不能选为端点样地。四种选轴方法的排序结果与聚类分析结果基本是相一致的,这说明极点排序法仍可作为研究样地相互关系以及与环境关系的一种辅助方法,对群落分类研究是有帮助的。     

Assessing the genetic diversity of tobacco germplasm using intersimple sequence repeat and inter-retrotransposon amplification polymorphism markers

The genetic diversity of 118 tobacco accessions, including flue‐cured tobacco, sun‐/air‐cured tobacco, burley tobacco, oriental tobacco and wild tobacco, was characterised using intersimple sequence repeat (ISSR) and inter‐retrotransposon amplification polymorphism (IRAP) markers. ISSR and IRAP banding patterns and genetic distance (GD) values showed the low level of genetic diversity within and among cultivated tobacco types. There was higher GD and average heterozygosity among wild tobacco types than those among cultivated tobacco. Genetic diversity of tobacco germplasm was low, with a high level of genetic identity (>0.77) between the different types. However, neighbour‐joining cluster analysis of marker‐based GDs showed that the accessions from the same tobacco type, as classified by manufacturing quality traits, were nearly clustered into the same group. These results will help in the formulation of appropriate strategies for variety improvement in tobacco, and ISSR and IRAP markers of the genetic diversity will contribute to further study and improvement of tobacco.     

Mitochondrial DNA sequences of six sturgeon species and phylogenetic relationships within Acipenseridae

Studies on mitochondrial DNA variability amongst six sturgeon species reared in Italian aquaculture plants are reported. Restriction analysis by Rsal of mitochondrial cytochrome b and D-loop fragments amplified by PCR permitted identification of interspecific variations that would be suitable as markers for species diagnosis. Data obtained by partial sequencing of the cytochrome b gene, analyzed through maximum parsimony, neighbour joining, and UPGMA distance methods, revealed species clusters that support previous morpho-meristic and geographical data for sturgeon classification into sub-genera. According to our cluster analysis, the genera Acipenser and Huso are monophyletic. Moreover, these and previous cytogenetic data suggest that three 120-chromosome species (H. huso, H. dauricus and A. ruthenus) are at the base of sturgeon differentiation, which occurred through two different events of polyploidization.     

Coastal sand dune vegetation of Tabasco and Campeche,Mexico

Abstract. Sand dune vegetation along the coast of the Mexican states of Tabasco and Campeche was sampled by means of 1501 releves and the data were analyzed with classification and ordination programs. 36 community types were distinguished, which were grouped into 10 higher-order groups. The communities are described in a sequence reflecting the main vegetation zonation. Beach, embryo dune and foredune community groups include 12 community types, the sheltered zone includes 16 types and the fixed dunes 8 types. The ordination results reveal one main vegetation gradient corresponding to the increase in mean distance from the shoreline and elevation, and being covariant with species richness, mean vegetation cover and mean vegetation height. Additional differences are related to the geographical transition between the Gulf and Caribbean coastal vegetation and environmental conditions, mainly type of sand, occurring in the study area. Siliceous sand and a Gulf climate are characteristic for most of Tabasco, and calcareous sand and a Caribbean-type climate are characteristic for Campeche. Disturbance caused by coconut plantations, cattle grazing and tourism favours the invasion of ruderal species from waste places behind the dunes, which attain local dominance in the dunes described here. Consequently some separate community types had to be distinguished. The distribution of community types is analyzed in the context of the transitions between calcareous and siliceous substrates in the study area.     

An ecological analysis of kwongan vegetation south of Eneabba,Western Australia

A survey of 20 km² of species-rich kwongan (sclerophyllous shrubland or sandplain vegetation) is reported, A total of 429 vascular plant species were found, of which 338 were recorded at the eighty-seven systematically located 0.1 ha releves, Five vegetation units were defined following analysis of the site floristics data. Small but distinctive suites of species (totalling 26% of recorded species) characterized a gradient in soils from the sands and gravels of the lateritic uplands, through the deep sands of the dune sequence, to the clays of the winter-wet depressions. However the soils-related axis in the ordinations accounted for only ca. 6% of the variability in the data, indicating the complexity of the vegetation environment interactions. Species richness was greatest in a zone of apparent overlap between the lateritic group of species and those of the deep sand areas. The winter-wet areas were poorest in species. The distributions of the floristically defined vegetation units did not closely parallel those of physiognomic units defined by interpretation of air photos. Structural dominance was negligible in all but the winter-wet areas and the few dominants appeared poorly correlated with other species and with the physical environment. Comparisons are made with areas of similar vegetation elsewhere in Australia and in South Africa.     

On the determination of optimal levels in phytosociological classification

A method is introduced to compare results of a clustering technique at different levels of abstraction, or of different clustering techniques. The method emphasizes within cluster homogeneity as well as discontinuities between clusters. It has been derived from Hogeweg's method with some important changes. First each cluster is handled separately to determine the ratio between homogeneity and similarity to the nearest neighbour cluster. For a given clustering a weighted average value is computed over all clusters. This average value is standardized using an expected average value for a cluster configuration with the same number of clusters having the same sizes. A low level of the ratio between expected and observed values is supposed to indicate an optimal clustering. A derivation of the criterion is given and results from three sets of data with different properties are evaluated.     

Correspondence Analysis of species by environmental variable matrices

Abstract. Correspondence Analysis of species by environmental variables matrices is a relatively simple method for handling matrices which include many species and variables. If columns represent species and rows represent the states in which the environmental variables have been divided, each element of the matrix shows the number of releves in which the simultaneous occurrence of that species and that environmental variable state have been recorded. In this paper the use of the method for presence-absence data is considered. The method is appropriate for studies whose main purpose is to look for broad correlations between groups of environmental variables and groups of species. It is particularly useful for handling heterogeneous data sets including rare species and species-poor releves, a situation in which Correspondence Analysis and Canonical Correspondence Analysis are frequently complicated by the production of axes explaining the relationship between rare species and species-poor releves. Examples are presented with artificial data as well as with real data collected in the Mexican portion of the Chihuahuan Desert (Bolsón de Mapimi). It is shown for the Mapimi data that the method is robust to the partition of variables into different numbers of states.     

A comparison of some classification methods used to determine benthic macro-invertebrate species associations in river survey work based on data obtained from the River Ely, South Wales

SUMMARY. The results of a survey of the macro-invertebrates of the polluted River Ely, South Wales, are used as a basis for comparing several classification methods which have been used previously in river survey work to determine species groupings. The methods compared are product-moment correlation (clustered by the nearest neighbour technique), Kendall's tau coefficient (clustered by the nearest neighbour and average linkage techniques), and Squared Euclidean-Distance coefficient (clustered by nearest neighbour and Ward's techniques). The species groupings determined by these methods were influenced both by the association coefficient and the technique used to cluster it. Some species were grouped together by all or most of the methods. The ecological validity of these robust groups is examined. A clear recommendation regarding the most appropriate method is frustrated by incomplete knowledge of the ecological requirements of most of the aquatic macro-invertebrates used in the data-set. However, Kendall's tau coefficient clustered by the average linkage technique appeared to produce ecologically meaningful species groups. Product-moment correlation was also reasonably successful and since it is based on absolute abundance data whereas Kendall's tau coefficient is based on relative abundance data, the use of the two together is recommended for determining robust groups.