Global biodiversity patterns of marine phytoplankton and zooplankton

Although the oceans cover 70% of the Earth's surface, our knowledge of biodiversity patterns in marine phytoplankton and zooplankton is very limited compared to that of the biodiversity of plants and herbivores in the terrestrial world. Here, we present biodiversity data for marine plankton assemblages from different areas of the world ocean. Similar to terrestrial vegetation, marine phytoplankton diversity is a unimodal function of phytoplankton biomass, with maximum diversity at intermediate levels of phytoplankton biomass and minimum diversity during massive blooms. Contrary to expectation, we did not find a relation between phytoplankton diversity and zooplankton diversity. Zooplankton diversity is a unimodal function of zooplankton biomass. Most strikingly, these marine biodiversity patterns show a worldwide consistency, despite obvious differences in environmental conditions of the various oceanographic regions. These findings may serve as a new benchmark in the search for global biodiversity patterns of plants and herbivores.     

Mobility promotes and jeopardizes biodiversity in rock-paper-scissors games

Biodiversity is essential to the viability of ecological systems. Species diversity in ecosystems is promoted by cyclic, non-hierarchical interactions among competing populations. Central features of such non-transitive relations are represented by the 'rock-paper-scissors' game, in which rock crushes scissors, scissors cut paper, and paper wraps rock. In combination with spatial dispersal of static populations, this type of competition results in the stable coexistence of all species and the long-term maintenance of biodiversity. However, population mobility is a central feature of real ecosystems: animals migrate, bacteria run and tumble. Here, we observe a critical influence of mobility on species diversity. When mobility exceeds a certain value, biodiversity is jeopardized and lost. In contrast, below this critical threshold all subpopulations coexist and an entanglement of travelling spiral waves forms in the course of time. We establish that this phenomenon is robust; it does not depend on the details of cyclic competition or spatial environment. These findings have important implications for maintenance and temporal development of ecological systems and are relevant for the formation and propagation of patterns in microbial populations or excitable media.     

围垦对椒江口夏季浮游植物群落结构和多样性的影响

通过对椒江口(28.67°~28.69°N,121.45°~121.62°E)浮游植物进行的3次采样调查(2007年7月、2008年7月和2010年8月),并与历史数据进行比较,共鉴定出浮游植物5门,167种,三个年份分别为101、96和117种;浮游植物细胞丰度分别为20.34×10~3个/L、266.94×10~3个/L和66.94×10~3个/L;Shannon-Wiener指数(H')分别为1.95、0.60和0.40.围垦前和围垦结束后优势种包括硅藻(Bacillariophyta)和甲藻(Pyrrophyta),如琼氏圆筛藻(Coscinodiscusjonesianus)、辐射圆筛藻(Coscinodiscus radiatus)、中肋骨条藻(Skeletonema costatum)和柔弱根管藻(Rhizosolenia delicatula)等;围垦中只有硅藻,如洛氏角毛藻(Chaetoceros lorenzia—nus)和布氏双尾藻(Ditylum brightwellii).围垦促进了浮游植物细胞丰度的大幅度提升,但改变了浮游植物群落结构,降低了其稳定性和均衡性.CCA分析表明,pH、温度、氮/磷/硅营养盐、溶解氧和化学需氧量是影响浮游植物群落结构的水质参数;影响绿藻(Chlorophyta)、硅藻、蓝藻(Cyanophyta)和甲藻的主要水质参数分别为溶解氧、石油、温度和化学需氧量.长时间尺度与短时时间尺度分析得出相似的结论,围垦前后椒江口水质、浮游植物群落结构及生物多样性均发生相应变化.     

Local dispersal promotes biodiversity in a real-life game of rock-paper-scissors

One of the central aims of ecology is to identify mechanisms that maintain biodiversity. Numerous theoretical models have shown that competing species can coexist if ecological processes such as dispersal, movement, and interaction occur over small spatial scales. In particular, this may be the case for non-transitive communities, that is, those without strict competitive hierarchies. The classic non-transitive system involves a community of three competing species satisfying a relationship similar to the children's game rock-paper-scissors, where rock crushes scissors, scissors cuts paper, and paper covers rock. Such relationships have been demonstrated in several natural systems. Some models predict that local interaction and dispersal are sufficient to ensure coexistence of all three species in such a community, whereas diversity is lost when ecological processes occur over larger scales. Here, we test these predictions empirically using a non-transitive model community containing three populations of Escherichia coli. We find that diversity is rapidly lost in our experimental community when dispersal and interaction occur over relatively large spatial scales, whereas all populations coexist when ecological processes are localized.     

滇池浮游植物的生物多样性调查研究

 根据2001年9月至2002年7月6个月滇池浮游植物种类和数量的调查结果,分析了该湖浮游植物的物种组成,通过Shannon指数、Pielou均匀度指数、Berger-Parker指数计算,从不同侧面研究了滇池的生物多样性水平.结果表明:调查期间共鉴定浮游植物106种及变种;浮游植物生物多样性在3月最高,而其他月份差别不明显,平面分布上南部高于北部,东部高于西部.     

宁夏阅海国家湿地公园春季鸟类物种多样性及群落组成

2018年2月24日至5月5日,对宁夏阅海国家湿地公园及周边环境的鸟类种类及数量进行了调查.当地及周边生境主要包括水域、草本沼泽、绿化带、农田4种,在4种生境分别设置样带或样点进行观察.主要观察鸟类的物种和数量,并分别从鸟类的物种组成、居留型、分布型、保护级别、生态型、生境及群落多样性及鸟类动态等角度进行多方面分析.共进行11次调查,记录到鸟类96种,属15目,34科.采用Shannon-wiener指数和Pielou指数来分析当地春季鸟类的物种多样性和均匀性.研究发现宁夏阅海国家湿地公园春季鸟类物种多样性和均匀性较高,但稳定性较差,自然环境因素和人为干扰因素对鸟类栖息影响很大.最后针对鸟类保护提出建议.     

Adaptive evolution drives divergence of a hybrid inviability gene between two species of Drosophila

Speciation--the splitting of one species into two--occurs by the evolution of any of several forms of reproductive isolation between taxa, including the intrinsic sterility and inviability of hybrids. Abundant evidence shows that these hybrid fitness problems are caused by incompatible interactions between loci: new alleles that become established in one species are sometimes functionally incompatible with alleles at interacting loci from another species. However, almost nothing is known about the genes involved in such hybrid incompatibilities or the evolutionary forces that drive their divergence. Here we identify a gene that causes epistatic inviability in hybrids between two fruitfly species, Drosophila melanogaster and D. simulans. Our population genetic analysis reveals that this gene--which encodes a nuclear pore protein--evolved by positive natural selection in both species' lineages. These results show that a lethal hybrid incompatibility has evolved as a by-product of adaptive protein evolution.     

长江口九段沙附近水体浮游植物的种类组成与数量分布

2005年9月对吴淞口至九段沙下沙近海水域的水体进行了浮游植物调查,结果表明,此调查区域共有浮游植物70属135种．其中硅藻种类最多,共42属82种,占总种数的60．8％;绿藻门14属24种;其他藻类14属29种．浮游植物的数量分布表现为：从吴淞口至江亚南沙段较低,九段沙上沙、中沙段显著高于其他采样点,在九段沙下沙近海水域出现了急剧下降的趋势．中肋骨条藻（Skeletonema costatum（Grev．）Cleve）是调查区域的优势种,其数量占浮游植物总数量的平均百分比达到了71．8％．作者还对该区域浮游植物数量分布的影响因素进行了讨论．     

Global patterns in biodiversity

To a first approximation, the distribution of biodiversity across the Earth can be described in terms of a relatively small number of broad-scale spatial patterns. Although these patterns are increasingly well documented, understanding why they exist constitutes one of the most significant intellectual challenges to ecologists and biogeographers. Theory is, however, developing rapidly, improving in its internal consistency, and more readily subjected to empirical challenge.     

生物多样性研究进展

综合了许多研究资料,就生物多样性的内涵及其研究热点进行了综合评述,生物多样性是 所有生物种类、种内遗传变异和它们生存环境的总称,按照空间尺度可分为遗传多样性、物种多样 性、生态系统多样性和景观多样性.并对生物多样性保护作了介绍.     

Climate-driven population divergence in sex-determining systems

Sex determination is a fundamental biological process, yet its mechanisms are remarkably diverse. In vertebrates, sex can be determined by inherited genetic factors or by the temperature experienced during embryonic development. However, the evolutionary causes of this diversity remain unknown. Here we show that live-bearing lizards at different climatic extremes of the species' distribution differ in their sex-determining mechanisms, with temperature-dependent sex determination in lowlands and genotypic sex determination in highlands. A theoretical model parameterized with field data accurately predicts this divergence in sex-determining systems and the consequence thereof for variation in cohort sex ratios among years. Furthermore, we show that divergent natural selection on sex determination across altitudes is caused by climatic effects on lizard life history and variation in the magnitude of between-year temperature fluctuations. Our results establish an adaptive explanation for intra-specific divergence in sex-determining systems driven by phenotypic plasticity and ecological selection, thereby providing a unifying framework for integrating the developmental, ecological and evolutionary basis for variation in vertebrate sex determination.     

Human population in the biodiversity hotspots

Biologists have identified 25 areas, called biodiversity hotspots, that are especially rich in endemic species and particularly threatened by human activities. The human population dynamics of these areas, however, are not well quantified. Here we report estimates of key demographic variables for each hotspot, and for three extensive tropical forest areas that are less immediately threatened. We estimate that in 1995 more than 1.1 billion people, nearly 20% of world population, were living within the hotspots, an area covering about 12% of Earth's terrestrial surface. We estimate that the population growth rate in the hotspots (1995-2000) is 1.8% yr(-1), substantially higher than the population growth rate of the world as a whole (1.3% yr(-1)) and above that of the developing countries (1.6% yr(-1)). These results suggest that substantial human-induced environmental changes are likely to continue in the hotspots and that demographic change remains an important factor in global biodiversity conservation. The results also underline the potential conservation significance of the continuing worldwide declines in human fertility and of policies and programs that influence human migration.     

Estimating divergence times among subfamilies in Nymphalidae

The mitochondrial cytochrome oxidase subunit Ⅰ （COⅠ） gene and the nuclear elongation factor 1α （EF-1α） gene were sequenced from 13 species of Nymphalidae. Phylogenetic trees of Nymphalidae, which is the largest family in butterflies, were constructed based on the sequences determined from 13 species sequenced in our laboratory and an additional 43 species obtained from GenBank using the maximum likelihood （ML） and Bayesian methods. Relative-rate tests between lineages in these phylogenetic trees were performed. On the basis of the results of the relative-rate tests and fossil information of Satyrinae, Nymphalinae and Biblidinae, the average divergence times among the subfamilies are estimated as 44.2-87.1 million years ago （Ma）. These results will be helpful for better understanding of the origin and evolution of this family, as well as the divergence time of butterflies and other complex taxa.     

深度学习中对比散度算法的有偏性分析

为了给对比散度算法的进一步优化提供理论指导,尝试从理论上分析对比散度算法的收敛性。首先从仅含4个结点的玻尔兹曼机入手,利用单纯形表征模型的概率空间,以及流形表征概率空间与模型参数的关系,形象地表示了对比散度算法和极大似然算法的收敛过程,并从理论上推导出对比散度算法的收敛集与极大似然算法的收敛集之差不为空,从而证明了对比散度算法的有偏性。基于该结论,设计了一种先利用对比散度算法进行预训练,再利用极大似然算法调优的训练策略。实验结果表明,在应用该策略获得同等收敛效果的条件下,训练迭代步骤降低了83.3%。     

连环湖卡拉白鱼放养场的浮游生物组成及水质分析

2004年9月、2006年10月和2007年1月分别调查和报道了连环湖（卡拉白鱼放养场）的浮游植物、浮游动物种类和数量以及水质理化特征：透明度为26cm,PH为8．99,含盐量为1．50mg／L,硬度为2．25mmol／L,碱度为11．64mmol／L,COD为19．16mg／L,水体主要离子含量和离子总量均值依照浓度高低排序为HCO;〉Na^＋和K^＋〉SO4^2-〉Cl^-〉Mg^2＋〉Ca^2＋,水型为带,湖泡属于富营养类型（N为0．7mg／L,P为0．33rag／L）．浮游植物5个门21个种属,其中绿藻门9个种属,数量810．25×10^4ind／L,占42．86％;硅藻门6个种属,数量323．58×10^4ind／L,占28．57％;其他藻类为蓝藻门、裸藻门和隐藻门,共有6个种属,数量64．82×10^4ind／L,占28．57％．浮游动物28个种属,其中轮虫14个种属,数量137ind／L,占50％;枝角类8个种属,数量54ind／L,占28．57％;桡足类6个种属,数量95ind／L,占21．43％．此外,对水质理化指标、营养元素和水域饵料生物的特点进行了讨论．     

河南省小康水平实现程度差异研究

河南省是我国的一个农业大省也是我国第一人口大省,河南省小康水平的发展直接影响着我国小康总体水平的发展。20世纪90年代中期以来,河南省小康水平发展取得长足进展,本文采用综合评分和综合指数相结合的方法,评价了河南省各县小康水平,并对比分析了河南省小康水平的县际差异,揭示产生这些差异的原因,最后提出提高河南省县级小康水平的具体策略。     

翠柳湖浮游植物群落多样性分析

通过对湘南学院翠柳湖四个采样点春、夏、秋、冬四季的浮游植物进行调查,研究了浮游植物的种类、群落组成、优势种和生物多样性,对翠柳湖水质的基本营养状况进行评价分析。研究发现该湖浮游植物共计6门51属84种,其中绿藻门最多,为21属31种,占36.9%;蓝藻门16属29种,占34.5%;二者占总的种类数的70%以上。硅藻13种,占15.5%,隐藻门、甲藻门和裸藻门占比最少仅为2.3%。浮游植物种类在全年分布中春、冬两季数量多。各采样点的浮游植物丰富度在季节变化上均成先上升、后下降趋势,均在夏季浮游植物丰富度最高,最高可达6.67×10⁷ cells·L^-1。夏季优势种主要是铜绿微囊藻、伪鱼腥藻和线性菱形藻,而在冬季转变为铜绿微囊藻和梅尼小环藻。全年Shannon-Wiener指数在2.35～3.84之间,Pielou均匀度指数在0.29～0.81之间。翠柳湖浮游植物多样性随季节变化较明显,呈夏季>春季>秋季>冬季的趋势,空间分布上呈现s4>s3>s1>s2的特征。结果表明,翠柳湖浮游植物多样性较好,分布格局存在一...