金门岛北部海域浮游植物的季节变动及与环境的关联

采用2013—2014年四季度月在金门岛北部海域获取的浮游植物及环境因子监测数据, 分析该区浮游植物的群落结构和季节变化及其与温度、盐度、悬浮物、营养盐、叶绿素等的关系, 初步探讨涉海工程建设对浮游植物群落的潜在影响。结果显示, 鉴定出的浮游植物隶属3门43属82种(不含未定种), 群落构成以硅藻为主, 其次是甲藻, 蓝藻仅1种。物种组成的季节差异较大, 3月物种贫乏, 1月次之, 7月和11月最丰富。四季丰度平均为47.09×103 cells/L, 1月丰度最高, 7月次之, 11月最低, 3月高于11月少许。四季优势种均为硅藻, 13个优势种分别为柔弱几内亚藻(Guinardia delicatula)、短角弯角藻(Ecampia zoodicaus)、骨条藻(Skeletonema spp.)、具槽帕拉藻(Paralia sulcata)、微小海链藻(Thalassiosira exigua)、标志星杆藻(Asterionella notula)、旋链角毛藻(Chaetoceros curvisetus)、新月菱形藻(Nitzchia closterium)、派格棍形藻(Bacillaria paxillifera)、异常角毛藻(Chaetoceros abmormis)、小细柱藻(Leptocylindrus minutum)、宽角曲舟藻(Pleurosigma angulatum)和美丽曲舟藻(Pleurosigma formosum)。不同季节优势种有一定程度交错, 仅在单季占优的有6种, 有2/3在3个以上季节出现, 具槽帕拉藻、骨条藻为四季优势种。浮游植物物种多样性和均匀度总体较好, 群落结构稳定。与毗邻海区相比, 本区物种丰富度偏低, 丰度高于毗邻海区, 种类组成相似, 优势种却有较大差别。Pearson相关分析表明, 溶解无机氮及活性磷酸盐仅在1月与丰度存在极显著的正相关, 是促使丰度为四季最高的原因。涉海工程施工产生的悬浮物和冲击波是影响浮游植物群落的主要因素, 大量海洋工程建设案例表明, 施工期造成的浮游植物丰度下降趋势和优势种更替混乱在工程结束后能得以恢复。     

IRBAS: An online database to collate,analyze, and synthesize data on the biodiversity and ecology of intermittent rivers worldwide

Key questions dominating contemporary ecological research and management concern interactions between biodiversity, ecosystem processes, and ecosystem services provision in the face of global change. This is particularly salient for freshwater biodiversity and in the context of river drying and flow‐regime change. Rivers that stop flowing and dry, herein intermittent rivers, are globally prevalent and dynamic ecosystems on which the body of research is expanding rapidly, consistent with the era of big data. However, the data encapsulated by this work remain largely fragmented, limiting our ability to answer the key questions beyond a case‐by‐case basis. To this end, the Intermittent River Biodiversity Analysis and Synthesis (IRBAS; http://irbas.cesab.org ) project has collated, analyzed, and synthesized data from across the world on the biodiversity and environmental characteristics of intermittent rivers. The IRBAS database integrates and provides free access to these data, contributing to the growing, and global, knowledge base on these ubiquitous and important river systems, for both theoretical and applied advancement. The IRBAS database currently houses over 2000 data samples collected from six countries across three continents, primarily describing aquatic invertebrate taxa inhabiting intermittent rivers during flowing hydrological phases. As such, there is room to expand the biogeographic and taxonomic coverage, for example, through addition of data collected during nonflowing and dry hydrological phases. We encourage contributions and provide guidance on how to contribute and access data. Ultimately, the IRBAS database serves as a portal, storage, standardization, and discovery tool, enabling collation, synthesis, and analysis of data to elucidate patterns in river biodiversity and guide management. Contribution creates high visibility for datasets, facilitating collaboration. The IRBAS database will grow in content as the study of intermittent rivers continues and data retrieval will allow for networking, meta‐analyses, and testing of generalizations across multiple systems, regions, and taxa.     

Herbivore regulation of plant abundance in aquatic ecosystems

Herbivory is a fundamental process that controls primary producer abundance and regulates energy and nutrient flows to higher trophic levels. Despite the recent proliferation of small‐scale studies on herbivore effects on aquatic plants, there remains limited understanding of the factors that control consumer regulation of vascular plants in aquatic ecosystems. Our current knowledge of the regulation of primary producers has hindered efforts to understand the structure and functioning of aquatic ecosystems, and to manage such ecosystems effectively. We conducted a global meta‐analysis of the outcomes of plant–herbivore interactions using a data set comprised of 326 values from 163 studies, in order to test two mechanistic hypotheses: first, that greater negative changes in plant abundance would be associated with higher herbivore biomass densities; second, that the magnitude of changes in plant abundance would vary with herbivore taxonomic identity. We found evidence that plant abundance declined with increased herbivore density, with plants eliminated at high densities. Significant between‐taxa differences in impact were detected, with insects associated with smaller reductions in plant abundance than all other taxa. Similarly, birds caused smaller reductions in plant abundance than echinoderms, fish, or molluscs. Furthermore, larger reductions in plant abundance were detected for fish relative to crustaceans. We found a positive relationship between herbivore species richness and change in plant abundance, with the strongest reductions in plant abundance reported for low herbivore species richness, suggesting that greater herbivore diversity may protect against large reductions in plant abundance. Finally, we found that herbivore–plant nativeness was a key factor affecting the magnitude of herbivore impacts on plant abundance across a wide range of species assemblages. Assemblages comprised of invasive herbivores and native plant assemblages were associated with greater reductions in plant abundance compared with invasive herbivores and invasive plants, native herbivores and invasive plants, native herbivores and mixed‐nativeness plants, and native herbivores and native plants. By contrast, assemblages comprised of native herbivores and invasive plants were associated with lower reductions in plant abundance compared with both mixed‐nativeness herbivores and native plants, and native herbivores and native plants. However, the effects of herbivore–plant nativeness on changes in plant abundance were reduced at high herbivore densities. Our mean reductions in aquatic plant abundance are greater than those reported in the literature for terrestrial plants, but lower than aquatic algae. Our findings highlight the need for a substantial shift in how biologists incorporate plant–herbivore interactions into theories of aquatic ecosystem structure and functioning. Currently, the failure to incorporate top‐down effects continues to hinder our capacity to understand and manage the ecological dynamics of habitats that contain aquatic plants.     

艾比湖区域景观格局空间特征与地表水质的关联分析

为进一步明确区域土地利用/覆被—景观格局对河流水质影响的空间尺度。选择新疆艾比湖区域为研究对象,以25个水质采样点为中心,建立5种尺度的河流缓冲区并提取不同尺度下的土地利用/覆被-景观格局数据。首先,通过主成分分析获得水环境的主要水质变量。其次,利用冗余分析(RDA)方法探讨研究区不同宽度缓冲区土地利用/覆被—景观格局对河流水质的影响,获得水质管理的有效缓冲区。最后,引入突变点分析方法进一步寻找导致水质变量沿景观梯度突变的特定位置。结果表明:(1)土地利用/覆被—景观格局在不同宽度缓冲区内对河流水质的影响不同。4 km缓冲区土地利用/覆被—景观格局对区域水质有较强的分异解释能力,因此4 km缓冲区的景观格局合理配置对河流水质管理尤为重要。(2)通过偏RDA分析发现4 km缓冲区中,影响区域水质的主要环境变量为景观水平斑块密度、类型水平耕地斑块密度和森林聚集度。(3)在偏RDA分析的基础上,对4 km缓冲区内的景观指数进行突变点分析研究,发现区域景观水平斑块密度为90—105 m/hm~2,类型水平耕地的斑块密度ED值在90—110 m/hm~2、林草地的AI值在70%—90%,是艾比湖区域水质保护的最佳突变值,该值为艾比湖区域水质保护的阈值。本研究从多个角度对新疆艾比区域的土地利用/覆被—景观格局对区域水质的影响进行定量分析,揭示该地区景观生态变化的规律,为区域景观格局优化和土地合理规划提供理论依据,并对改善"丝绸之路经济带"生态环境、实现资源可持续利用具有重要的现实意义和理论价值。     

一种基于E-index方法区分复杂性状的分析工具

目前,生物遗传学领域在区分复杂性状的研究上正面临着巨大挑战,许多方法都被用来应对这项挑战,其中分子标记法,QTL作图法和序列分析法等就是用来区分控制复杂性状基因的主要应对策略。测定生物复杂性状对于研究生物多样性具有重要意义,也是进一步研究基因控制性状作用机理的重要途径,但是,现有的方法并不成熟也不完善,因此给有效区分复杂性状带来了一定难度。近年来,由于生长曲线能够有效地描述复杂性状,基于生长曲线来区分复杂性状的方法是目前常用的方式,Functional Mapping(FM)就是其中具有代表性的一种方法。在过去的十年间,FM方法是复杂性状区分效果最好的,但不能有效处理非单调类型的生长曲线。Earliness index(E-index)方法的问世,解决了非单调类型的曲线不能有效识别的难题,它能够将任意生物类型的复杂性状发展过程描述为生长曲线并加以区分。基于E-index方法的原理,开发了一套Eindex Application(EIA)分析工具,该工具中集成了E-index方法,利用生物数据可视化技术动态绘制生长曲线,包含数据获取、数据处理和结果输出等功能,为遗传工作者的研究提供了良好平台。仿真实验的结果证明了EIA分析工具具有高效、实时和准确的性能,是区分复杂性状的有力工具。     

The recent colonization of south Brazil by the Azores chromis Chromis limbata

The damselfish Chromis limbata is native to the Macaronesian Archipelagos (Azores, Madeira and Canaries) and the western coast of Africa between Senegal and Angola. During the austral summers of 2008 and 2009 the species was recorded for the first time in the south‐western Atlantic Ocean around Campeche and Xavier Islands, in Florianópolis, Santa Catarina State, Brazil. Here, the progression of C. limbata in southern Brazilian waters is described using visual counts and genetic surveys and changes in the density of the native congener Chromis multilineata were also investigated. Underwater visual censuses of both Chromis species were carried out from 2009 to 2014. Chromis limbata tissue samples were collected and the mtDNA control region was sequenced and compared with mtDNA haplotypes from the natural range to confirm species identity, compare genetic diversity and to infer connectivity between newly established Brazilian populations. The Brazilian population of C. limbata increased significantly over the past 5 years and the effect on C. multilineata is still an open question, longer time‐series data will be necessary to clarify possible interactions. The molecular analyses confirmed species identity, revealed strong haplotype connectivity among Brazilian study sites and showed a low genetic diversity in Brazil when compared with the native populations, suggesting few individuals started the invasion. Four hypotheses could explain this colonizing event: C. limbata was released by aquarium fish keepers; larvae or juveniles were transported via ship ballast water; the species has rafted alongside oil rigs; they crossed the Atlantic Ocean through normal larval dispersal or naturally rafting alongside drifting objects. The rafting hypotheses are favoured, but all four possibilities are plausible and could have happened in combination.     

Polymorphism in the neotropical termite Serritermes serrifer

Serritermitidae (Isoptera) is a small and little known Neotropical termite family which includes only two genera: Glossotermes and Serritermes. Despite the lack of detailed studies, it has been assumed that these termites have a true worker caste. A recent study revealed that Glossotermes has a linear development pathway and lacks true workers. Here, we present a study of the polymorphism of Serritermes serrifer Hagen & Bates, a species endemic to the Cerrado ecoregion of central Brazil which lives as an inquiline inside nests of Cornitermes spp. A morphometric analysis was performed based on measurements taken of 11 body parts of 544 specimens of immatures, worker‐like individuals, soldiers, and alates. Sex of specimens was determined by dissection and examination of the seventh sternite. A principal component analysis (PCA) was used to evaluate morphological changes during development. Contrary with previous information from the literature and similar to Glossotermes, Serritermes shows a linear development pathway with two larval instars, two sizes of pseudergates, and a single nymphal morph. Pseudergates apparently undergo stationary molts. Sex ratio among pseudergates is male‐biased, but not as strongly as in Glossotermes. Typical colonies have a single physogastric primary queen and a single primary king. Ergatoid reproductives are relatively rare and some female ergatoids may become strongly physogastric. Nymphoid reproductives were not found. All soldiers are male and bear well‐developed testes.     

Dual Role of Prostaglandins (PGE2) in Regulation of Channel Density and Open Probability of Epithelial Na+ Channels in Frog Skin (R. pipiens)

Prostaglandins are important in signaling pathways involved in modulating the rates of Na⁺ transport in a diverse group of tissues possessing apical membrane epithelial channels. PGE₂ is known to cause either stimulation, inhibition or transient stimulatory changes of Na⁺ transport. We have continued our studies of frog skins that are known to respond to forskolin and PGE₂ with large steady-state increases of transport and have used noninvasive methods of blocker-induced noise analysis of Na⁺ channels to determine their channel densities (N _T ) and open probabilities (P _o ). In the absence of exogenous hormones, baseline rates of Na⁺ transport are especially high in scraped skins (R. pipiens pipiens) studied in the fall of the year. Na⁺ transport was inhibited by indomethacin and by removal of the unstirred layers of the corium (isolated epithelia) alone suggesting that PGE₂ is responsible for the sustained and elevated rates of transport in scraped skins. Changes of transport caused by indomethacin, forskolin or PGE₂ were unquestionably mediated by considerably larger changes of N _T than compensatory changes of P _o . Since cAMP caused no change of P _o in tissues pretreated with indomethacin, PGE₂ appears in this tissue to serve a dual role, increasing the steady state N _T by way of cAMP and decreasing P _o by unknown mechanisms. Despite appreciable PGE₂-related decreases of P _o , the net stimulation of transport occurs by a considerably greater cAMP-mediated increase of N _T . Received: 28 February 1996/Revised: 22 August 1996     

半夏种内居群形态变异的模糊聚类分析

在同一栽培条件下,对主要引自长江中下游地区的１５个半夏〔Ｐｉｎｅｌｉａｔｅｒｎａｔａ（Ｔｈｕｎｂ．）Ｂｒｅｉｔ．〕居群的１６个主要形态性状进行模糊聚类分析,在置信水平λ＝０．６７６４时,将１５个居群划分成４个类型：（１）双珠芽类型：主要形态特征为叶柄上均具双珠芽,但叶型和块茎形状变异较小;（２）普通类型：主要形态特征为叶柄上均只着生单珠芽,但叶型和块茎形状变异较大;（３）长茎类型：主要形态特征为叶柄上具单珠芽,但着生位置较低,块茎呈矩圆形;（４）复合类型：主要形态特征为叶柄上具单珠芽,但居群内常有双珠芽个体出现。     

The effect of electrical gradients on current fluctuations and impedance recorded fromNecturus gallbladder

Summary Transepithelial current fluctuations were recorded inNecturus gallbladder, clamped at negative as well as positive potentials up to 64 mV. With NaCl-Ringer's (+10mm TAP) on both sides a mucosa-negative potential enhanced the relaxation noise component, present at zero potential, and produced peaking in the power spectrum at potentials above –36mV. Concomitantly at these potentials an inductive as well as a capacitive low-frequency feature appeared in the impedance locus. Clamping at positive potentials of 18 mV suppressed the relaxation noise component. At potentials above 51mV the spectral values increased predominantly at low frequencies. In this case the power spectrum showed only a 1/f noise component. The experiments confirm the previous finding that a K⁺ efflux through fluctuating apical K⁺ channels exists under normal conditions. With serosal KCl-Ringer's the initial Lorentzian component was enhanced at negative but suppressed at positive potentials. The increase at negative potentials was less pronounced than in experiments with NaCl-Ringer's on both sides, indicating saturation of the fluctuating K⁺ current component. With mucosal KCl-Ringer's a negative potential depressed the initial relaxation noise component, whereas it was enhanced at +18 mV clamp potential. In the latter case an additional Lorentzian component became apparent at higher frequencies. At potentials of 36 mV and above the low-frequency Lorentzian disappeared whereas the corner frequency of the high-frequency component increased. The latter experiments demonstrate that the relaxation noise component inNecturus gallbladder consists of two superimposed Lorentzians. As the relaxation times of these two components behave differently under an electrical field, there may exist two different types of K⁺ channels. It is demonstrated that peaking in the plateau of power spectra can be explained by frequency-dependent attenuation effects, caused by a polarization impedance.