生物间非传递性竞争研究进展

生物间的竞争关系是决定群落中物种共存和生物多样性的关键因素。传统研究主要关注物种两两之间的竞争作用, 而对多物种相互竞争形成的网络研究相对较少。近年来, 类似于“石头-剪刀-布”游戏的非传递性竞争被认为是一种重要的物种共存和生物多样性的维持机制, 越来越受到生态学家们的关注。本文首先回顾了非传递性竞争定义的发展过程, 并介绍了非传递环的不同结构。其次介绍了基于竞争结局矩阵以及入侵增长率的非传递性竞争度量指标, 并对比不同指标的特点与适用情形。随后通过多个研究实例介绍了非传递性竞争在自然群落中的普遍性, 并指明物种之间的权衡是非传递性竞争产生的生物学机制。最后介绍了非传递性竞争对生物多样性与生态系统功能的影响。非传递性竞争本质上是物种两两之间相互作用的组合, 是只包含单一作用类型的特殊网络结构。因此, 非传递性竞争如何影响生物多样性-生态系统功能关系和群落稳定性, 如何受到环境与高阶相互作用的影响, 以及如何将竞争网络拓展到包含不同相互作用类型的生态网络, 将是未来非传递性竞争研究的重要方向。对非传递性竞争的研究有助于整合生物间的各种相互作用, 构建更加现实合理的生态网络, 并加深对物种共存和生物多样性维持机制的认识, 进而有助于指导生物多样性的保护和恢复工作。     

大气CO2浓度和气温升高对麦田节肢动物群落的影响

为了预测气候变化对麦田节肢动物群落多样性的影响, 本研究在麦田开放环境中设置4种处理, 分别是高温(高于当时气温2℃和当前CO₂浓度)、高CO₂浓度(500 μL/L和当时气温)、高温+高CO₂浓度和对照(当前CO₂浓度和气温)等, 采用定期随机抽样方法调查节肢动物群落的多样性, 用经典的多样性指数对整体节肢动物群落以及不同食性节肢动物群落多样性进行分析。共采到节肢动物3纲10目42科52种。仅“高温”和“高温+高CO₂”处理显著增大节肢动物群落的均匀度, 其余处理均无显著影响。“高温+高CO₂”处理的影响随小麦生长发育期不同而略有差异, 在苗期可增大Shannon-Wiener多样性指数, 而在后期使该指数减小; “高温+高CO₂”与“高温”处理的群落多样性较为相似。对不同食性节肢动物群落的分析表明, 与对照相比, 植食性昆虫群落在“高CO₂”下丰富度显著增大; 寄生性昆虫群落的多度在“高温”下显著增大; 腐食性等节肢动物群落的多度在“高CO₂+高温”和“高温”处理下有所增大、均匀度在“高温”下略降低, 但均未达统计上的显著水平; 捕食性节肢动物群落不受影响。本研究说明, CO₂浓度和气温升高不同程度地影响麦田节肢动物群落的物种多样性, 两类因素同时升高与各自单独升高的影响不完全一致。     

中国草原/荒漠植物多样性监测网 模式植物群落监测方案

“模式群落”是指能够反映某种植被分类单元基本特征, 并可作为准确描述该植被类型“标准”的典型植物群落。中国生物多样性监测网络——草原/荒漠植物多样性监测网旨在统一监测方法和技术规范的基础上, 在草原/荒漠植被主要群系分布的典型地段建立模式植物群落监测固定样方, 定期复查, 长期监测草原和荒漠的植物多样性变化。文章强调了典型植物群落监测是生物多样性监测的重要组成部分, 阐述了模式群落的概念, 介绍了草原/荒漠植物多样性监测网的总体思路和布局, 以及主要监测内容、方法、指标和预期产出。     

本科遗传学教学中的遗传漂变概念探讨

遗传漂变是遗传学教学的难点之一,因其涉及随机性和概率,特别容易引起误解。定义中的“抽样误差”常被误解为遗传漂变是由于“抽样”这一研究方法干扰才导致基因频率的随机变化。本文首先对国内外《遗传学》教材中的遗传漂变定义进行了分析比较,发现“抽样误差”的定义为各教材普遍采用,但只有少数教材对“抽样误差”概念进行了正确的解释,多数未作进一步的说明。文章介绍了遗传漂变的研究历史,亦即Wright、 Fisher和Kimura等学者对遗传漂变研究的贡献。进而,特别介绍了近年来国外关于本科生遗传漂变教学的两篇代表性教学研究论文,指出本科生在学习过程中容易出现错误理解是难以避免的现象,对此也提供了初步的解决办法。作者最后结合自己的教学实践,提出本科生教学中遗传漂变仍然采用含有“抽样误差”概念的定义,只是需要对“抽样误差”做进一步的解释,指出“抽样误差”是等位基因世代传递过程中存在的、配子间的随机结合,“相当于”对整个参与交配的配子库中的配子进行的一次“随机抽样”,而与一般遗传学研究中的人为抽样行为无关。本文旨在为本科遗传学教学中关于遗传源变概念的讲解提供借鉴和参考。     

中国与“一带一路”参与国家抗击新冠肺炎疫情的国际科技合作现状与展望

2019年底暴发并席卷全球的新型冠状病毒肺炎疫情已经成为需要世界各国共同努力克服的全球重大卫生安全挑战。当前,中国已基本控制国内新冠肺炎疫情,并在疫情相关科学研究及公共卫生产品研发方面取得重大进展,同时加强了与“一带一路”参与国家开展国际科技合作。对中国与“一带一路”参与国家抗击新冠肺炎疫情的基础研究合作、国际科技合作项目等方面进行梳理,可以看到:中国与“一带一路”参与国家形成了领域交叉、节点多样的复杂合作网络,并主要与东南亚、中东欧和西亚各国合作密切;中国与“一带一路”参与国家的科研机构已在防控、流行病学和治疗等领域展开了大量实质研究,合作关系更偏向援助型合作。未来应加强与“一带一路”参与国家的生物技术产业合作与技术转移,发挥“一带一路”区域支点国家的示范效应等方面构建与“一带一路”参与国家更丰富、紧密、务实的科技合作关系。     

植物群落稀有种维持机制与土壤反馈的研究进展

自Janzen-Connell (J-C)假说提出后半个世纪以来, 生态学家在热带及亚热带森林对该假说开展的大量实证研究表明, 由专性天敌导致的J-C效应所引起的负密度制约是维持森林多样性和决定群落组成的重要驱动力, 该假说成功地解释了热带及亚热带森林的丰富多样性。土壤病原真菌所引起的植物-土壤负反馈是J-C效应最主要的表现形式。然而, 对于植物-土壤负反馈是否能够维持森林群落中的大量稀有种仍然存在许多争议。基于当代物种共存理论的“稀有种优势”假说认为, 只有在满足“可入侵准则” (即物种在稀有时具有种群增加的趋势)的前提下, 稀有种才能在群落中与其他物种长期共存。然而, 当前基于土壤反馈的实验结果与该理论预测相悖, 因此在稀有种的维持机制方面仍存在较大的分歧。本文通过介绍植物-土壤反馈理论, 整合了可能对稀有种维持有较大影响的因素, 包括共生菌根真菌、土壤养分以及植物细根性状等在影响土壤负反馈方面的相关研究, 并对这些因素如何影响群落中物种多度和稀有种在群落中的维持进行了探讨。最后, 我们也从其他角度探讨了一些对稀有种维持的研究。我们认为在未来对稀有种的研究中, 探讨使其长期存续的“优势”和制约其种群扩大的“限制”同等重要, 将当代物种共存理论与新技术、新方法相结合对于探究稀有种的维持机制具有重要的意义, 可为稀有种保护提供理论依据。     

金融稳定性与生态稳定性

亚洲金融危机以后,世界各国评估和诊断金融体系稳健程度的实务性研究取得了很大进展,但金融稳定性问题的理论研究仍相对滞后.本文讨论了用生态稳定性思想方法研究金融稳定性问题.文章先比较了金融稳定性的概念和生态学中有关稳定性的概念的异同,把生态稳定性概念移植、引申到金融系统中,建立了金融群落数学模型,给出了金融群落金融稳定的定义,论证了金融种群确定模型和随机模型的稳定性,介绍了金融群落随机模型的稳定性,最后分析了金融群落等级结构的稳定性.     

刺槐木质部栓塞脆弱性检测的方法比较

在全球变暖的背景下, 植物木质部栓塞脆弱性是林木死亡率升高的重要生理学因素。然而不同方法在长导管树种上建立的栓塞脆弱性曲线存在较大差异。该研究以长导管树种刺槐(Robinia pseudoacacia)为研究对象, 利用自然干燥法、Cochard Cavitron离心机法以及Sperry离心机法建立了栓塞脆弱性曲线, 旨在探讨不同检测方法的合理性。在Sperry离心法中, 使用了两种规格的转子, 从而对“开口导管假象”学说进行了检验。研究结果表明: 自然干燥法建立的栓塞脆弱性曲线为“s”形, 而Cochard Cavitron离心机法和Sperry离心机法建立的栓塞脆弱性曲线为“r”形; 自然干燥法与离心机法建立的曲线存在显著性差异, 且两种离心机法建立的曲线也具有显著性差异。尽管刺槐枝条的导管长度分布表明14.4 cm长的刺槐枝条具有更高比例的开放导管, 但用Sperry离心机法在27.4 cm和14.4 cm长茎段上建立的栓塞脆弱性曲线相似, 表明Sperry离心机法检测刺槐脆弱性曲线时未产生“开口导管假象”, 具有更为可靠的检测结果。     

基于土壤食物网的生态系统复杂性-稳定性关系研究进展

复杂性-稳定性关系是生态学核心问题之一。作为模式食物网,土壤食物网在探索生态系统复杂性-稳定性关系中起了极大的作用。总结了以Moore、de Ruiter、Neutel等为代表的理论生态学家以土壤食物网为工具研究生态系统复杂性-稳定性关系的方法、结论及不足之处,并展望了未来的发展方向。Moore、de Ruiter、Neutel等将土壤食物网功能群生物量数据、土壤食物网Lotka-Volterra模型和面向过程模型三者结合起来,描述相互作用强度大小格局、分室、能流组织形式等复杂性特征;将土壤食物网Lotka-Volterra模型与群落矩阵结合起来分析局域稳定性,进而探讨生态系统复杂性-稳定性关系的一般规律。在此基础上,Moore、de Ruiter、Neutel等证明了与随机食物网相比,真实食物网的相互作用强度格局、分室等复杂性特征提高了生态系统稳定性,生产力与稳定性共同决定了食物链的长度,并指出建立在平衡态基础上的静态土壤食物网模型在探索生态系统复杂性-稳定性关系方面具有较大的不足,动态土壤食物网是未来以土壤食物网为工具研究生态系统复杂性-稳定性关系的发展方向。     

Comparison of methods for detecting vulnerability of xylem embolism in Robinia pseudoacacia

在全球变暖的背景下, 植物木质部栓塞脆弱性是林木死亡率升高的重要生理学因素。然而不同方法在长导管树种上建立的栓塞脆弱性曲线存在较大差异。该研究以长导管树种刺槐(Robinia pseudoacacia)为研究对象, 利用自然干燥法、Cochard Cavitron离心机法以及Sperry离心机法建立了栓塞脆弱性曲线, 旨在探讨不同检测方法的合理性。在Sperry离心法中, 使用了两种规格的转子, 从而对“开口导管假象”学说进行了检验。研究结果表明: 自然干燥法建立的栓塞脆弱性曲线为“s”形, 而Cochard Cavitron离心机法和Sperry离心机法建立的栓塞脆弱性曲线为“r”形; 自然干燥法与离心机法建立的曲线存在显著性差异, 且两种离心机法建立的曲线也具有显著性差异。尽管刺槐枝条的导管长度分布表明14.4 cm长的刺槐枝条具有更高比例的开放导管, 但用Sperry离心机法在27.4 cm和14.4 cm长茎段上建立的栓塞脆弱性曲线相似, 表明Sperry离心机法检测刺槐脆弱性曲线时未产生“开口导管假象”, 具有更为可靠的检测结果。     

Positive complexity-stability relations in food web models without foraging adaptation

May's [1972. Will a large complex system be stable? Nature 238, 413-414] local stability analysis of random food web models showed that increasing network complexity leads to decreasing stability, a result that is contradictory to earlier empirical findings. Since this seminal work, research of complexity-stability relations became one of the most challenging issues in theoretical ecology. We investigate conditions for positive complexity-stability relations in the niche, cascade, nested hierarchy, and random models by evaluating the network robustness, i.e., the fraction of surviving species after population dynamics. We find that positive relations between robustness and complexity can be obtained when resources are large, Holling II functional response is used and interaction strengths are weighted with the number of prey species, in order to take foraging efforts into account. In order to obtain these results, no foraging dynamics needs to be included. However, the niche model does not show positive complexity-stability relations under these conditions. By comparing to empirical food web data, we show that the niche model has unrealistic distributions of predator numbers. When this distribution is randomized, positive complexity-stability relations can be found also in the niche model.     

What is the role of predation on stability of natural communities? A theoretical investigation.

A basic question in ecology concerns the role of species interaction on dynamics of natural communities. In this framework, ecologists have considered predation, competition, mutualism, the three most important interactions, highlighting their specific effects on distribution and abundance of species, providing knowledge about phenomena like coexistence and extinction. This paper seeks to identify the effects of predation on stability of natural communities by mathematical models. Simple multispecies community models, organized in trophic levels, are analyzed by means of a qualitative technique, loop analysis, combined with a computer calculation procedure. Results do not support the hypothesis of predation as a stabilizing factor. Rather, the outcomes of the analysis suggest that predation may or may not stabilize a community. This depends on the predator's behaviour and on the network of the community.     

Complexity does not affect stability in feasible model communities

The complexity-stability relation is a central issue in ecology. In this paper, we show how the sampling method most often used to parameterize an ecological community, can affect the conclusions about whether or not complexity promotes stability and we suggest a sampling algorithm that overcomes the problem. We also illustrate the importance of treating feasibility separately from stability when constructing model communities. Using model Lotka-Volterra competition communities we found that probability of feasibility decreases with increasing interaction strength and number of species in the community. However, for feasible systems we found that local stability probability and resilience do not significantly differ between communities with few or many species, in contrast with earlier studies that, did not account for feasibility and concluded that species-poor communities had higher probability of being locally stable than species-rich communities.     

Predicting rates of interspecific interaction from phylogenetic trees

Integrating phylogenetic information can potentially improve our ability to explain species' traits, patterns of community assembly, the network structure of communities, and ecosystem function. In this study, we use mathematical models to explore the ecological and evolutionary factors that modulate the explanatory power of phylogenetic information for communities of species that interact within a single trophic level. We find that phylogenetic relationships among species can influence trait evolution and rates of interaction among species, but only under particular models of species interaction. For example, when interactions within communities are mediated by a mechanism of phenotype matching, phylogenetic trees make specific predictions about trait evolution and rates of interaction. In contrast, if interactions within a community depend on a mechanism of phenotype differences, phylogenetic information has little, if any, predictive power for trait evolution and interaction rate. Together, these results make clear and testable predictions for when and how evolutionary history is expected to influence contemporary rates of species interaction.     

Network structure, predator–prey modules, and stability in large food webs

Large, complex networks of ecological interactions with random structure tend invariably to instability. This mathematical relationship between complexity and local stability ignited a debate that has populated ecological literature for more than three decades. Here we show that, when species interact as predators and prey, systems as complex as the ones observed in nature can still be stable. Moreover, stability is highly robust to perturbations of interaction strength, and is largely a property of structure driven by predator–prey loops with the stability of these small modules cascading into that of the whole network. These results apply to empirical food webs and models that mimic the structure of natural systems as well. These findings are also robust to the inclusion of other types of ecological links, such as mutualism and interference competition, as long as consumer–resource interactions predominate. These considerations underscore the influence of food web structure on ecological dynamics and challenge the current view of interaction strength and long cycles as main drivers of stability in natural communities. Electronic Supplementary Material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Anti-predator defence and the complexity-stability relationship of food webs

The mechanism for maintaining complex food webs has been a central issue in ecology because theory often predicts that complexity (higher the species richness, more the interactions) destabilizes food webs. Although it has been proposed that prey anti-predator defence may affect the stability of prey-predator dynamics, such studies assumed a limited and relatively simpler variation in the food-web structure. Here, using mathematical models, I report that food-web flexibility arising from prey anti-predator defence enhances community-level stability (community persistence and robustness) in more complex systems and even changes the complexity-stability relationship. The model analysis shows that adaptive predator-specific defence enhances community-level stability under a wide range of food-web complexity levels and topologies, while generalized defence does not. Furthermore, while increasing food-web complexity has minor or negative effects on community-level stability in the absence of defence adaptation, or in the presence of generalized defence, in the presence of predator-specific defence, the connectance-stability relationship may become unimodal. Increasing species richness, in contrast, always lowers community-level stability. The emergence of a positive connectance-stability relationship however necessitates food-web compartmentalization, high defence efficiency and low defence cost, suggesting that it only occurs under a restricted condition.     

Community stability,complexity and species life history strategies

The essence of the contradiction between traditional ecological complexity-stability hypothesis and recent theoretical results is clarified. The distinction between resilience and resistance is stressed. The possibilities of field verification of May's model are discussed. No satisfactory method for estimation of connectance and mean interaction strength in plant communities has been found. Relation between these parameters and stability in real communities remains an open question. The relation between connectance and stability (resilience) in purely competitive model communities is more complicated than May's rule predicts. The certain value of connectance having been achieved, stability increases with increasing connectance. We assessed the positive relation between species diversity and resistance, and negative relation between species diversity and resilience in plant communities during old-field succession in xeric habitat. But there is no causal relationship between species diversity and both kinds of stability. Resistance and resilience of the plant communities studied were determined primarily by life history strategies of constituent species. The results are interpreted in terms of Grimes' life history strategies and imply the validity of Gleasonian, population-centered explanation of community phenomena.The nomenclature of plants follows F. Ehrendorfer, 1973, Liste der Gefässpflanzen Mitteleuropas, 2. Aufl. G. Fischer, Stuttgart.Acknowledgements. We thank Pavel Kindlmann for helpful discussion. We are also grateful to reviewers for suggesting ways to improve this paper.