并基角毛藻是硅藻门角毛藻属的典型种类, 以“相邻角毛基部并行融合”作为标志性特征, 但该特征是否稳定, 及如何赋予其分类学价值？尚存较多争议.研究以符合现存并基角毛藻分类标准的藻株作为目标藻株,采用毛细管显微操作技术从我国沿海代表水域分离藻株, 建立了目标藻株的单克隆培养株系, 利用光学显微镜、扫描电镜和透射电镜分别对其形态学特征进行观察, 同时还扩增了核糖体大亚基编码基因的D1-D3区序列, 并构建系统进化树.综合分析形态学特征和分子系统学数据, 初步得到以下结论： （1）具有相同遗传特征的并基角毛藻株系在“相邻角毛基部并行融合”特征上具有不稳定性, 即“相邻角毛基部并行融合”不能作为并基角毛藻种类的标志性特征; （2）并基角毛藻和洛氏角毛藻作为相似种类, 均显示出较高的物种多样性, 高于目前的认知, 预示着或许存在隐形种或拟隐形种; （3）推测并基角毛藻单胞变型只是并基角毛藻原种的-个生活史阶段, 是并基角毛藻的同种异名, 不宜继续保留其独立的分类学地位.

并基角毛藻是硅藻门角毛藻属的典型种类, 以“相邻角毛基部并行融合”作为标志性特征, 但该特征是否稳定, 及如何赋予其分类学价值？尚存较多争议.研究以符合现存并基角毛藻分类标准的藻株作为目标藻株,采用毛细管显微操作技术从我国沿海代表水域分离藻株, 建立了目标藻株的单克隆培养株系, 利用光学显微镜、扫描电镜和透射电镜分别对其形态学特征进行观察, 同时还扩增了核糖体大亚基编码基因的D1-D3区序列, 并构建系统进化树.综合分析形态学特征和分子系统学数据, 初步得到以下结论： （1）具有相同遗传特征的并基角毛藻株系在“相邻角毛基部并行融合”特征上具有不稳定性, 即“相邻角毛基部并行融合”不能作为并基角毛藻种类的标志性特征; （2）并基角毛藻和洛氏角毛藻作为相似种类, 均显示出较高的物种多样性, 高于目前的认知, 预示着或许存在隐形种或拟隐形种; （3）推测并基角毛藻单胞变型只是并基角毛藻原种的-个生活史阶段, 是并基角毛藻的同种异名, 不宜继续保留其独立的分类学地位.

正 从1949年以来,在我国渤海、黄海及东海各渔场调查所得的浮游生物标本看来,角毛硅藻属在种类及个体的数目上在这些海区都占有极重要的位置。它们在海水中的分布及季节变异情况都和海况及渔况有一定的关联。但直至目前,我国渔场的角毛硅藻只在种类方面有一点零星记载,还没曾有过比较详细的研究。因此著者愿把在烟、威鲐鱼渔场及共附近海区,自1953至1955年三年间渔场定站调查和一年多的逐月采集所得的角毛硅藻属材料,在分类及生态两方面的研究结果先发表出来。就正于和这方面有关系的科学工作者。

正 从1949年以来,在我国渤海、黄海及东海各渔场调查所得的浮游生物标本看来,角毛硅藻属在种类及个体的数目上在这些海区都占有极重要的位置。它们在海水中的分布及季节变异情况都和海况及渔况有一定的关联。但直至目前,我国渔场的角毛硅藻只在种类方面有一点零星记载,还没曾有过比较详细的研究。因此著者愿把在烟、威鲐鱼渔场及共附近海区,自1953至1955年三年间渔场定站调查和一年多的逐月采集所得的角毛硅藻属材料,在分类及生态两方面的研究结果先发表出来。就正于和这方面有关系的科学工作者。

正 早在19世纪末叶浮游生物学者们即已注意到在外洋水中和近岸水中浮游生物组成的不同。H(?)ckel(1890)将繁生在外海和近岸水中的浮游生物区分为外洋种(Oceanic species)和近岸种(Neritic species)两大类。接着Sch(?)tt(1893)、Cleve(1896,1897a,1897b,1900)、Aurivillius(1898)和Gran(1902)诸学者更进一步地试用浮游生物来鉴别水团。近

正 早在19世纪末叶浮游生物学者们即已注意到在外洋水中和近岸水中浮游生物组成的不同。H(?)ckel(1890)将繁生在外海和近岸水中的浮游生物区分为外洋种(Oceanic species)和近岸种(Neritic species)两大类。接着Sch(?)tt(1893)、Cleve(1896,1897a,1897b,1900)、Aurivillius(1898)和Gran(1902)诸学者更进一步地试用浮游生物来鉴别水团。近

正 海洋生物区系是各海区的地理环境、水文状况和这些环境条件的历史发展情况对生物自然分布综合影响的反映。为探讨海洋生物自然分布的演变过程及规律,近年来海洋生物区系的研究日益受到重视。角毛藻属包括从寒带到热带的各种生态性质的种类,在太平洋西部浅海区本属的出现种数居浮游硅藻之冠,也是黄海浮游硅藻区系组成的最重要成分。角毛藻属在海洋上层水中营浮游生活,生命周期很短,其分布可随水文条件的变化而迅速改观。因此,研究角毛藻属区系时,除考虑种类和地理分布外,还要结合其生态反映一并分析。而这样综合性的报告至今还很少见。本文旨在从此三方面,对黄海角毛藻属区系的性质及与邻近区系间的亲疏关系进行初步探讨。

正 海洋生物区系是各海区的地理环境、水文状况和这些环境条件的历史发展情况对生物自然分布综合影响的反映。为探讨海洋生物自然分布的演变过程及规律,近年来海洋生物区系的研究日益受到重视。角毛藻属包括从寒带到热带的各种生态性质的种类,在太平洋西部浅海区本属的出现种数居浮游硅藻之冠,也是黄海浮游硅藻区系组成的最重要成分。角毛藻属在海洋上层水中营浮游生活,生命周期很短,其分布可随水文条件的变化而迅速改观。因此,研究角毛藻属区系时,除考虑种类和地理分布外,还要结合其生态反映一并分析。而这样综合性的报告至今还很少见。本文旨在从此三方面,对黄海角毛藻属区系的性质及与邻近区系间的亲疏关系进行初步探讨。

Recent controversies testify that the tax shield valuation remains a hot topic in the financial literature. Basically, two methods have been proposed to incorporate the tax benefit of debt in the present value computation: The adjusted present value (APV), and the classical weighted average cost of capital (WACC). This note clarifies the relationship between these two apparently different approaches by offering a general formula for the WACC. This formula encompasses earlier results obtained by Modigliani and Miller (1963) and Harris and Pringle (1985).

The genus Chaetoceros , one of the most important genera of diatoms in the marine plankton, has been investigated from 20 stations in Danish waters during the period 19910900091995. Thirty-five taxa were identified, 18 of which were brought into culture for further morphological studies. Three taxa are reported for the first time from Danish coastal waters and one new species is proposed, C. impressus. Chaetoceros affinis var. circinalis is raised to species level. Material referred to previously as Chaetoceros sp. B. by Sundstr0109m is considered to represent C. pseudobrevis . Twelve taxa found previously in the area by other authors are also described, resulting in a total of 47 descriptions. An artificial key is provided for identifications of all species presently recorded in inner Danish coastal waters.

The diatom Chaetoceros cf. lorenzianus was found for the first time in the southern Baltic Sea: in November 2003 in the Gulf of Gdańsk and in October 2005 in the Lithuanian coastal waters. The nearest known location of the species is in the Kattegat and the Belt Sea area, approximately 50002km to the west and the discontinuity implies a non-indigenous distribution of this species. Since its appearance in the Polish and Lithuanian waters, C. cf. lorenzianus has been documented each year from September until November–December, usually reaching a maximum abundance between the end of September and the beginning of November. The highest abundance observed was 1.202×0210602cells02l611, corresponding to a biomass of 3.302×0210302μg02l611, which accounted for more than 70% of the diatom biomass and caused C. cf. lorenzianus to dominate the diatom community. In October of 2006, 2008 and September 2009–2011, large abundances of the characteristic resting spores of typical C. lorenzianus were observed. However, many of the cells possessed features of both C. lorenzianus and Chaetoceros decipiens, suggesting that the population may be an intermediate form. This study is important as C. cf. lorenzianus is new to the southern and south-eastern Baltic Proper and has become an important member of the autumn phytoplankton community.

在整合两岸学者有关台湾海峡的浮游植物物种多样性研究的基础上,作者提出了一份台湾海峡小型浮游植物物种名录,共包含620种,并按照其生态类群和赤潮种类进行了区分。同时以1984年5月至1985年2月在福建海岸带和台湾海峡共86个观测站四个季度月浮游植物的344份调查资料为基础,来阐明物种分布的基本格局和丰度变化的时空趋势。结果表明:此次调查所鉴定的299种浮游植物中硅藻门为199种,其丰度占浮游植物丰度的99.25%,对本海区浮游植物的分布起支配作用。浮游植物的种类数和丰度年高峰均在夏季。就平面分布而言,海峡区的种类数多于近岸区,与海水的温度和盐度成正相关关系;而近岸区的丰度高于海峡区,Shannon-Wiener指数和均匀度则是海峡区高于近岸区。

在整合两岸学者有关台湾海峡的浮游植物物种多样性研究的基础上,作者提出了一份台湾海峡小型浮游植物物种名录,共包含620种,并按照其生态类群和赤潮种类进行了区分。同时以1984年5月至1985年2月在福建海岸带和台湾海峡共86个观测站四个季度月浮游植物的344份调查资料为基础,来阐明物种分布的基本格局和丰度变化的时空趋势。结果表明:此次调查所鉴定的299种浮游植物中硅藻门为199种,其丰度占浮游植物丰度的99.25%,对本海区浮游植物的分布起支配作用。浮游植物的种类数和丰度年高峰均在夏季。就平面分布而言,海峡区的种类数多于近岸区,与海水的温度和盐度成正相关关系;而近岸区的丰度高于海峡区,Shannon-Wiener指数和均匀度则是海峡区高于近岸区。

In order to elucidate the phylogeny and evolutionary history of the Bacillariaceae we conducted a phylogenetic analysis of 42 species (sequences were determined from more than two strains of many of the Pseudo-nitzschia species) based on the first 872 base pairs of nuclear-encoded large subunit (LSU) rDNA, which include some of the most variable domains. Four araphid genera were used as the outgroup in maximum likelihood, parsimony and distance analyses. The phylogenetic inferences revealed the Bacillariaceae as monophyletic (bootstrap support 90%). A clade comprising Pseudo-nitzschia, Fragilariopsis and Nitzschia americana (clade A) was supported by high bootstrap values ( 94%) and agreed with the morphological features revealed by electron microscopy. Data for 29 taxa indicate a subdivision of clade A, one clade comprising Pseudo-nitzschia species, a second clade consisting of Pseudo-nitzschia species and Nitzschia americana, and a third clade comprising Fragilariopsis species. Pseudo-nitzschia as presently defined is paraphyletic and emendation of the genus is probably needed. The analyses suggested that Nitzschia is not monophyletic, as expected from the great morphological diversity within the genus. A cluster characterized by possession of detailed ornamentation on the frustule is indicated. Eighteen taxa (16 within the Bacillariaceae) were tested for production of domoic acid, a neurotoxic amino acid. Only P. australis, P. multiseries and P. seriata produced domoic acid, and these clustered together in all analyses. Since Nitzschia navis-varingica also produces domoic acid, but is distantly related to the cluster comprising the Pseudo-nitzschia domoic acid producers, it is most parsimonious to suggest that the ability of species in the Bacillariaceae to produce domoic acid has evolved at least twice.

Understanding the evolutionary history of living organisms is a central problem in biology. Until recently the ability to infer evolutionary relationships was limited by the amount of DNA sequence data available, but new DNA sequencing technologies have largely removed this limitation. As a result, DNA sequence data are readily available or obtainable for a wide spectrum of organisms, thus creating an unprecedented opportunity to explore evolutionary relationships broadly and deeply across the Tree of Life. Unfortunately, the algorithms used to infer evolutionary relationships are NP-hard, so the dramatic increase in available DNA sequence data has created a commensurate increase in the need for access to powerful computational resources. Local laptop or desktop machines are no longer viable for analysis of the larger data sets available today, and progress in the field relies upon access to large, scalable high-performance computing resources. This paper describes development of the CIPRES Science Gateway, a web portal designed to provide researchers with transparent access to the fastest available community codes for inference of phylogenetic relationships, and implementation of these codes on scalable computational resources. Meeting the needs of the community has included developing infrastructure to provide access, working with the community to improve existing community codes, developing infrastructure to insure the portal is scalable to the entire systematics community, and adopting strategies that make the project sustainable by the community. The CIPRES Science Gateway has allowed more than 1800 unique users to run jobs that required 2.5 million Service Units since its release in December 2009. (A Service Unit is a CPU-hour at unit priority).

Abstract Since its introduction in 2001, MrBayes has grown in popularity as a software package for Bayesian phylogenetic inference using Markov chain Monte Carlo (MCMC) methods. With this note, we announce the release of version 3.2, a major upgrade to the latest official release presented in 2003. The new version provides convergence diagnostics and allows multiple analyses to be run in parallel with convergence progress monitored on the fly. The introduction of new proposals and automatic optimization of tuning parameters has improved convergence for many problems. The new version also sports significantly faster likelihood calculations through streaming single-instruction-multiple-data extensions (SSE) and support of the BEAGLE library, allowing likelihood calculations to be delegated to graphics processing units (GPUs) on compatible hardware. Speedup factors range from around 2 with SSE code to more than 50 with BEAGLE for codon problems. Checkpointing across all models allows long runs to be completed even when an analysis is prematurely terminated. New models include relaxed clocks, dating, model averaging across time-reversible substitution models, and support for hard, negative, and partial (backbone) tree constraints. Inference of species trees from gene trees is supported by full incorporation of the Bayesian estimation of species trees (BEST) algorithms. Marginal model likelihoods for Bayes factor tests can be estimated accurately across the entire model space using the stepping stone method. The new version provides more output options than previously, including samples of ancestral states, site rates, site d(N)/d(S) rations, branch rates, and node dates. A wide range of statistics on tree parameters can also be output for visualization in FigTree and compatible software.

2014年8月20日—9月6日对南海北部(18°~22°N,114°~116°E)的11个站位进行了浮游植物群落结构的调查,其中2个站位为时间连续站。共鉴定出浮游植物4门68属229种(包括变种、变型及未定种),其中硅藻门43属147种,甲藻门20属75种。浮游植物平均细胞丰度为16.318×103 cells/L,硅藻的平均细胞丰度为14.653×103 cells/L,占总丰度的89.80%,硅藻的分布决定了浮游植物的分布。近岸冲淡水含有丰富的营养盐,因此近岸海域的细胞丰度高于大洋海域,垂直分布表现出先增加后降低的趋势。本次调查的优势种为铁氏束毛藻(Trichodesmium thiebautii)、中肋骨条藻(Skeletonema costatum)、拟脆杆藻(Fragilariopsis sp.)、短孢角毛藻(Chaetoceros brevis)、菱形海线藻(Thalassionema nitzschioides)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)、尖刺伪菱形藻(Pseudo-nitzschia pungens)、扁面角毛藻(Chaetoceros compressus)、洛氏角毛藻(Chaetoceros lorenzianus)以及海洋角毛藻(Chaetoceros pelagicus),各优势种的分布趋势相似,呈现出近岸高于外海的趋势。Shannon-Weiner多样性指数与Pielou均匀度指数的平均值分别为2.37和0.56。浮游植物昼夜垂直变化明显。典范对应分析结果显示浮游植物空间分布主要受总氮盐、硅酸盐、微型浮游动物与盐度的影响。根据细胞丰度进行的站位的聚类分析显示浮游植物群落明显可划分为近岸群聚与大洋群聚。

2014年8月20日—9月6日对南海北部(18°~22°N,114°~116°E)的11个站位进行了浮游植物群落结构的调查,其中2个站位为时间连续站。共鉴定出浮游植物4门68属229种(包括变种、变型及未定种),其中硅藻门43属147种,甲藻门20属75种。浮游植物平均细胞丰度为16.318×103 cells/L,硅藻的平均细胞丰度为14.653×103 cells/L,占总丰度的89.80%,硅藻的分布决定了浮游植物的分布。近岸冲淡水含有丰富的营养盐,因此近岸海域的细胞丰度高于大洋海域,垂直分布表现出先增加后降低的趋势。本次调查的优势种为铁氏束毛藻(Trichodesmium thiebautii)、中肋骨条藻(Skeletonema costatum)、拟脆杆藻(Fragilariopsis sp.)、短孢角毛藻(Chaetoceros brevis)、菱形海线藻(Thalassionema nitzschioides)、柔弱伪菱形藻(Pseudo-nitzschia delicatissima)、尖刺伪菱形藻(Pseudo-nitzschia pungens)、扁面角毛藻(Chaetoceros compressus)、洛氏角毛藻(Chaetoceros lorenzianus)以及海洋角毛藻(Chaetoceros pelagicus),各优势种的分布趋势相似,呈现出近岸高于外海的趋势。Shannon-Weiner多样性指数与Pielou均匀度指数的平均值分别为2.37和0.56。浮游植物昼夜垂直变化明显。典范对应分析结果显示浮游植物空间分布主要受总氮盐、硅酸盐、微型浮游动物与盐度的影响。根据细胞丰度进行的站位的聚类分析显示浮游植物群落明显可划分为近岸群聚与大洋群聚。

为了澄清洛氏角毛藻复合群的物种多样性,并明确洛氏角毛藻和并基角毛藻的种间界限,文章以广东沿海为例,建立了洛氏角毛藻复合群的22个单克隆培养株系,利用光学显微镜和电子显微镜技术,开展了基于生活史的连续形态学观察;结合基于核糖体大亚基编码基因D1-D3区序列的分子系统学分析。结果表明：文章支持近年研究的观点,认为＂角毛基部并行融合＂不是稳定特征,不宜继续作为并基角毛藻的标志特征;发现洛氏角毛藻形态相似藻株聚类在2个分支上,确认了洛氏角毛藻确实存在隐藏的物种多样性。其中一类与目前认知的洛氏角毛藻最为接近,而另一类在角毛孔纹、休眠孢子上存在明显区别。经过对洛氏角毛藻历史文献的对比研究,发现洛氏角毛藻的物种界定存在混乱和模糊的情况,如休眠孢子形态,及其初生壳面是否具有二叉状分布结构等,均存在相互矛盾或不一致的历史报道。

为了澄清洛氏角毛藻复合群的物种多样性,并明确洛氏角毛藻和并基角毛藻的种间界限,文章以广东沿海为例,建立了洛氏角毛藻复合群的22个单克隆培养株系,利用光学显微镜和电子显微镜技术,开展了基于生活史的连续形态学观察;结合基于核糖体大亚基编码基因D1-D3区序列的分子系统学分析。结果表明：文章支持近年研究的观点,认为＂角毛基部并行融合＂不是稳定特征,不宜继续作为并基角毛藻的标志特征;发现洛氏角毛藻形态相似藻株聚类在2个分支上,确认了洛氏角毛藻确实存在隐藏的物种多样性。其中一类与目前认知的洛氏角毛藻最为接近,而另一类在角毛孔纹、休眠孢子上存在明显区别。经过对洛氏角毛藻历史文献的对比研究,发现洛氏角毛藻的物种界定存在混乱和模糊的情况,如休眠孢子形态,及其初生壳面是否具有二叉状分布结构等,均存在相互矛盾或不一致的历史报道。