山西桑干河流域湿地植被物种多样性研究

以109个样方调查数据为基础,采用丰富度指数、物种多样性指数和均匀度指数对山西桑干河流域湿地植物群落的物种多样性进行了研究,并用方差分析和多重比较的方法研究了各群落之间多样性指数的差异程度。研究结果表明：各植被类型的物种多样性指数大小排列依次为：柽柳—委陵菜群落＞柽柳+沙棘—鹅观草群落＞柽柳—鹅绒委陵菜群落＞柽柳—芦苇群落＞芦苇+水蓼+莎草群落＞芦苇+苔草群落＞百里香+铁杆蒿群落＞香蒲+水蓼群落＞水葱+轮藻+眼子菜群落＞藨草+莎草+泽泻群落＞水葱+藨草+芦苇群落＞狐尾藻+香蒲群落＞慈姑+芦苇群落＞水蓼+慈姑群落＞水莎草+水稗群落。对12种多样性指数进行比较后发现,R₀、H′和E₄优于其他指数。     

Spatial distribution and diversity of chironomid assemblages in a small hilly stream (Diptera: Chironomidae)

In 2006–2007, spatial variations of chironomid assemblages of a small chalky watercourse were investigated in the hilly region of Balaton Upland, Hungary. Samplings were carried out every three weeks at seven characteristically different sites along the whole length of the watercourse. Altogether 2966 specimens were collected and identified. The chironomid fauna of the stream was relatively rich with 40 taxa belonging to four subfamilies (eight Tanypodinae, one Prodiamesinae, 17 Orthocladiinae, 14 Chironominae). The lowest number of species and number of individuals was found at the spring, and the highest at the middle reach. Based on multivariate analysis the different sections of the creek were characterised by distinctive chironomid communities. Although longitudinal changes in the chironomid community of the Örvényesi creek were detectable due to changes in natural environmental factors, land-use changes also significantly influenced the chironomid community composition and diversity. The natural and anthropogenic effects were hardly distinguishable. Furthermore, we found that the response of different diversity indices to environmental variability was different. This draws attention to the difficulties in evaluating the relationships between stream communities and environmental variables using different diversity indices. The taxonomic diversity, which incorporates the taxonomical relationships between the specimens, proved to be one of the most useful diversity indices to characterise the stream chironomid assemblages.     

Testing the intermediate disturbance hypothesis: when will there be two peaks of diversity?

Succession after disturbances generates a mosaic of patches in different successional stages. The intermediate disturbance hypothesis predicts that intermediate disturbances lead to the highest diversity of these stages on a regional scale resulting in a hump‐shaped diversity–disturbance curve. We tested this prediction using field data of forest succession and hypothetical succession scenarios in combination with analytical and simulation models. According to our study the main factors shaping the diversity–disturbance curve and the position of the diversity maximum were the transition times between the successional stages, the transition type, neighbourhood effects and the choice of diversity measure. Although many scenarios confirmed the intermediate disturbance hypothesis we found that deviations in the form of two diversity maximums were possible. Such bimodal diversity–disturbance curves occurred when early and late successional stages were separated by one or more long‐lived (compared to the early stages) intermediate successional stages. Although the field data which met these conditions among all those tested were rare (one of six), the consequences of detecting two peaks are fundamental. The impact of disturbances on biodiversity can be complex and deviate from a hump‐shaped curve.     

Species-rich Nardus stricta grasslands host a higher vascular plant diversity on calcareous than on siliceous bedrock

Background: Species-rich Nardus stricta grasslands are a priority habitat for conservation in Europe. They typically occur on siliceous substrates and less frequently are found on calcareous bedrock.

Aims: The present paper aimed to identify the environmental factors (i.e. bedrock type, topographic, and climatic factors) that are related with community diversity and to assess if differences in plant diversity between N. stricta communities on calcareous and siliceous bedrock occur. We hypothesised that Nardus grasslands on calcareous bedrock hosted a higher vascular plant diversity than those on siliceous bedrock.

Methods: Based on 579 vegetation surveys carried out in the south-western Alps, we assessed vascular plant diversity (species richness, Shannon diversity, and Pielou’s equitability index) of species-rich Nardus grasslands and compared it between N. stricta communities on calcareous and siliceous bedrock.

Results: Elevation was identified as the main factor related to species composition, while species diversity was mostly related to mean annual precipitation and bedrock type. Species richness, Shannon diversity, and Pielou’s equitability index were higher within the communities on calcareous rather than on siliceous bedrock and a total of 89 and 34 indicator species were detected, respectively.

Conclusions: Based on our results, we suggest to protect primarily, as a habitat of priority interest, N. stricta grasslands on calcareous substrates for the higher vascular plant diversity hosted.     

Disturbance–diversity models: what do they really predict and how are they tested?

The intermediate disturbance hypothesis (IDH) and the dynamic equilibrium model (DEM) are influential theories in ecology. The IDH predicts large species numbers at intermediate levels of disturbance and the DEM predicts that the effect of disturbance depends on the level of productivity. However, various indices of diversity are considered more commonly than the predicted number of species in tests of the hypotheses. This issue reaches beyond the scientific community as the predictions of the IDH and the DEM are used in the management of national parks and reserves. In order to compare responses with disturbance among measures of biodiversity, we used two different approaches of mathematical modelling and conducted an extensive meta-analysis. Two-thirds of the surveyed studies present different results for different diversity measures. Accordingly, the meta-analysis showed a narrow range of negative quadratic regression components for richness, but not evenness. Also, the two models support the IDH and the DEM, respectively, when biodiversity is measured as species richness, but predict evenness to increase with increasing disturbance, for all levels of productivity. Consequently, studies that use compound indices of diversity should present logical arguments, a priori, to why a specific index of diversity should peak in response to disturbance.     

中国不同地理区域鸟兽物种丰富度的相关性

生物类群之间物种丰富度的相关性研究是当前物种多样性研究中的热点问题之一,目前,中国尚无相关的研究报道。我们收集了中国三种区域类型：动物地理亚区、行政区和保护区的鸟兽名录,分析了行政区与保护区、动物地理区和经纬度带中鸟兽物种数比值及其相关性。 结果表明：不同区域、动物地理区和经纬度带中鸟兽物种数都显著相关。保护区尺度鸟兽物种 数的相关系数为0.818和动物地理区中的华北区为0.768,其他所有区域和地理区域的鸟兽物 种数的相关系数都高于0.850。因此,鸟兽物种数的相关关系在一定程度上具有预测价值。我们发现不同区域鸟兽物种数比值无显著性差异;但是,不同区域间鸟兽物种数 比值差异显著。该比值在中国呈中间低四周高的分布趋势,其中东北地区最高。我们还利用历史累积调查数据与非历史累积调查数据进行了鸟兽物种数比值及其相关性分析,发现利用累积数据计算的相关性低于非累积数据计算的相关性,但利用累积数据计算的鸟兽物 种数比值高于非累积数据计算的比值。最后,探讨了为什么鸟类与兽类的物种数目会相关。我们根据物种－面积公式,S=CA^Z,导出了两个生物类群物种丰富度的相关关 系式。利用全国不同区域数据拟合,得到Z₁/Z₂＝0.913,Z₁/Z₂接近于1。于是 ,C₁/C2可视为近似等于R_am。本研究可推广到其他不同生物类群物种。物种数量的相关关系为快速评估区域的物种多样性提供了一条途径。     

Counting Alleles with Rarefaction: Private Alleles and Hierarchical Sampling Designs

The number of alleles (allelic richness) in a population is a fundamental measure of genetic variation, and a useful statistic for identifying populations for conservation. Estimating allelic richness is complicated by the effects of sample size: large samples are expected to have more alleles. Rarefaction solves this problem. This communication extends the rarefaction procedure to count private alleles and to accommodate hierarchical sampling designs.     

外来种入侵与物种多样性

在入侵生态学研究方面 ,物种多样性与生物入侵之间的关系已成为当前研究和争论的焦点。自Elton的经典假说提出以来 ,物种丰富度高的群落比物种贫乏的群落更能抵抗外来种入侵的观点得到广泛接受。一些理论模型和多样性处理实验支持了该假说。但现在越来越多的野外观测和实验研究开始对这一经典假说提出异议 ,甚至反对。同时 ,在入侵生态学广泛受到关注的今天 ,大量的实验研究也提出了一些新的观点。本文对Elton经典假说提出以来全球有关物种多样性与生物入侵关系的主要研究及其观点进行了评述 ,以期为我国有关研究工作的开展提供参考。     

Maintaining heritable variation via sex-limited temporally fluctuating selection: a phenotypic model accommodating non-Mendelian epigenetic effects

Using a phenotypic model, we show that significant heritable variation can be maintained in a population subjected to temporally fluctuating selection if only one sex is subject to selection. In fact, more variation is maintained with sex-limited selection at a given selection intensity than if both sexes are subject to half that selection intensity. This result is commensurate with existing population genetic models. However, genetic models may be inappropriate for sexually selected traits because many of them may be of non-genetic origin, such as maternal effects or – more likely –epigenetic effects. Phenotypic models obviate this problem by accommodating both genetic and epigenetic effects, as well as maternaleffects. Our phenotypic model of sex-limited temporally fluctuating selection shows that substantial heritable variation can be maintained and therebyprovides impetus to develop population epigenetic models.     

丛枝菌根真菌物种多样性研究进展

丛枝菌根(arbuscular mycorrhiza, AM)真菌是生态系统中生物多样性的重要组分之一,具有十分丰富的物种多样性、遗传多样性和功能多样性.该真菌分类地位不断提高已上升至门,下设1个纲、4个目、13个科,19个属,现已报道214种.丛枝菌根对保持生态平衡、稳定和提高生态系统可持续生产力具有重要作用.本文分析了世界范围内丛枝菌根真菌物种多样性研究现状、不同生态系统中影响丛枝菌根真菌物种多样性的关键因子及其调控途径;认为分子生物学技术是今后丛枝菌根真菌物种多样性研究的主要方法.