Population Waves as a Condition for Increasing Ecological Stability of Organisms in the Process of Vertical Evolution

Ecological stability of an organism, which determines the possibility of its existence under changing environmental conditions, can be estimated as the probability of the participation of each viable offspring in reproduction. In developing species, the periodic rises and falls in the population size (Chetverikov's waves of life) can lead to changes in ecological stability, which is of macroevolutionary importance. Under conditions of isolation such changes generally result in specialization of intraspecific races but they could then lead to an increase in ecological stability of hybrid forms. Ecological stability of prosperous species increases during macroevolution due to combinative recombination between specialized intraspecific races or closely related species.     

Network spandrels reflect ecological assembly

Ecological networks that exhibit stable dynamics should theoretically persist longer than those that fluctuate wildly. Thus, network structures which are over‐represented in natural systems are often hypothesised to be either a cause or consequence of ecological stability. Rarely considered, however, is that these network structures can also be by‐products of the processes that determine how new species attempt to join the community. Using a simulation approach in tandem with key results from random matrix theory, we illustrate how historical assembly mechanisms alter the structure of ecological networks. We demonstrate that different community assembly scenarios can lead to the emergence of structures that are often interpreted as evidence of ‘selection for stability’. However, by controlling for the underlying selection pressures, we show that these assembly artefacts—or spandrels—are completely unrelated to stability or selection, and are instead by‐products of how new species are introduced into the system. We propose that these network‐assembly spandrels are critically overlooked aspects of network theory and stability analysis, and we illustrate how a failure to adequately account for historical assembly can lead to incorrect inference about the causes and consequences of ecological stability.     

A structural equation modeling approach for formalizing and evaluating ecological integrity in terrestrial ecosystems

Ecological integrity is a functional property that integrates habitat functions and species information for maintaining key ecological interactions in predator-prey systems. As a functional property, ecological integrity can be modeled as a latent concept from observable spatial attributes that measure the ecosystem's capacity to provide suitable habitat conditions for apex predators. Ecological integrity is a tri-dimensional concept that stems from “stable”, “concurrent” and “intact” conditions. A theoretical framework and a methodology is presented here for modeling ecological integrity from observable attributes (as GIS layers) to obtain a spatial representation of the integrity condition. From a theoretical framework, the ecological integrity concept is obtained with a structural equation modeling approach, where several other latent variables are obtained for characterizing a hierarchical network of spatial information. Later on, these observable attributes, and several latent modeled variables are translated into sources of geographic information that can be used to monitor changes in the natural remnant areas due to human impacts. When examining the direct, indirect and total effects of habitat loss and fragmentation on ecological integrity, spatial intactness (e.g., the amount of remnant habitat and connectivity) and stability (resistance in the interaction network and mobile links) are the attributes more affected by the pathway effects. The balance of the formative parameters obtained for the model supports the idea that ecosystems that have a high degree of integrity should maintain a high level of stability, self-organization and naturalness. These attributes are achieved when spatial habitat intactness and species interactions are maintained.     

Some rules of soil invertebrate community organization (by the example of Amur Basin mesofauna)

Some rules of organization of soil communities in the zone of mixed, Jeddo spruce, and larch taiga as well as forest-steppe in the Amur Basin have been formulated on the basis of the factual data. Abundant resources in the soil layer proved to decrease the competition in favor of neutralism, which allows sister species to occupy the same ecological niche. The stability of soil conditions allows considerable contraction of the realized niche volume, which increases species richness in soil. The biocenotic significance of soil organisms is determined by their biomass, productivity, and functional interchangeability. Ecological redundancy makes the mesofauna community much more resistant to environmental factors. The interaction type can change with environmental conditions. Competition prevails in soil communities outside their ecological optimum. Under these conditions, the community demonstrates the concentration of domination and decreased species richness due to the disappearance of closely related invertebrate species largely in biologically regressing groups.     

Evolutionary disarmament in interspecific competition.

Competitive asymmetry, which is the advantage of having a larger body or stronger weaponry than a contestant, drives spectacular evolutionary arms races in intraspecific competition. Similar asymmetries are well documented in interspecific competition, yet they seldom lead to exaggerated traits. Here we demonstrate that two species with substantially different size may undergo parallel coevolution towards a smaller size under the same ecological conditions where a single species would exhibit an evolutionary arms race. We show that disarmament occurs for a wide range of parameters in an ecologically explicit model of competition for a single shared resource; disarmament also occurs in a simple Lotka-Volterra competition model. A key property of both models is the interplay between evolutionary dynamics and population density. The mechanism does not rely on very specific features of the model. Thus, evolutionary disarmament may be widespread and may help to explain the lack of interspecific arms races.     

Effects of environmental change on emerging parasitic diseases

Ecological disturbances exert an influence on the emergence and proliferation of malaria and zoonotic parasitic diseases, including, Leishmaniasis, cryptosporidiosis, giardiasis, trypanosomiasis, schistosomiasis, filariasis, onchocerciasis, and loiasis. Each environmental change, whether occurring as a natural phenomenon or through human intervention, changes the ecological balance and context within which disease hosts or vectors and parasites breed, develop, and transmit disease. Each species occupies a particular ecological niche and vector species sub-populations are distinct behaviourally and genetically as they adapt to man-made environments. Most zoonotic parasites display three distinct life cycles: sylvatic, zoonotic, and anthroponotic. In adapting to changed environmental conditions, including reduced non-human population and increased human population, some vectors display conversion from a primarily zoophyllic to primarily anthrophyllic orientation. Deforestation and ensuing changes in landuse, human settlement, commercial development, road construction, water control systems (dams, canals, irrigation systems, reservoirs), and climate, singly, and in combination have been accompanied by global increases in morbidity and mortality from emergent parasitic disease. The replacement of forests with crop farming, ranching, and raising small animals can create supportive habitats for parasites and their host vectors. When the land use of deforested areas changes, the pattern of human settlement is altered and habitat fragmentation may provide opportunities for exchange and transmission of parasites to the heretofore uninfected humans. Construction of water control projects can lead to shifts in such vector populations as snails and mosquitoes and their parasites. Construction of roads in previously inaccessible forested areas can lead to erosion, and stagnant ponds by blocking the flow of streams when the water rises during the rainy season. The combined effects of environmentally detrimental changes in local land use and alterations in global climate disrupt the natural ecosystem and can increase the risk of transmission of parasitic diseases to the human population.     

Importance of genetic recombination for the preservation and progress of species in the course of evolution

The role of genetic recombinations is considered in the context of ecological stability of organisms. The ecological stability is taken as a special notion distinct from fitness in its original sense as the Maltusian parameter according to R. Fisher. The genetic exchange within the species provides the recovery of a species specific level of ecological stability that is lowered in particular individuals as a result of the accumulation of mutations in microevolutionary processes. It is supposed that the accumulation of the mutations that decrease organisms' ecological stability leads to the action of truncated selection. This type of selection explains the advantage of recombination in the model of A.S. Kondrashov (1982). In the evolving species, ecological stability is gradually increasing in the process of evolution as a result of hybridization between the narrow-specialized races. Genetic recombinations provide a constant DNA homogenization within the species and, therefore, the species integrity as an elementary structure responsible for the preservation and rise in the level of ecological stability of organisms in evolving lineages.     

京津冀地区生态用地稳定性格局及其影响因素

探索生态用地稳定性格局对动态背景下区域生态规划与管理具有重要意义。本文基于2000、2010、2020年京津冀地区生态用地数据基础,提取2000—2010和2010—2020年间稳定性生态用地,借鉴并应用生态用地稳定性指数予以衡量区域生态用地的时空稳定效应,并利用ArcGIS平台空间统计工具对生态用地稳定性空间格局进行分析,最后基于地理探测模型对生态用地稳定性的影响机制及其区域差异进行探索。研究结果显示,(1)2000—2010年和2010—2020年,京津冀地区稳定性生态用地有所减少,集中分布在内蒙古草原生态区和燕山-太行山山地林生态区。(2)两时期生态用地稳定性指数分别为90.85%和83.86%,呈现“西北高、东南低”。生态用地稳定性指数等级结构显示前期极低稳定性和极高稳定性面积占绝对主导,后期极低、高和极高稳定性面积共同主导。生态用地稳定性指数空间格局呈现显著冷热点效应,热点区汇集在燕山-太行山山地林生态区和内蒙古草原生态区,冷点区集中在京津唐城市生态区和华北平原生态区。(3)整体研究区高程、坡度、地貌和土壤类型等地理要素解释力较高;平原区内温度因子解释力度最为突出,地理因素和...     

中国湿地生态站现状、发展趋势及空间布局

湿地调查与监测是全面了解和掌握湿地变化,开展湿地保护和修复的前提和基础。湿地生态站是开展湿地长期监测和野外试验的平台,对研究湿地生态系统过程与功能,揭示湿地变化机理具有重要作用。系统梳理了我国现有的湿地生态站,分析了当前湿地生态站建设中面临的问题,指出：与国际主要生态观测网络相比,我国综合性湿地生态站数量较少、比例偏低,导致在湿地生态系统监测和评估上存在较大空缺;现有生态站存在层级结构不合理、监测指标体系不规范等问题,制约了国家尺度湿地生态系统监测评估的需求。研究基于中国湿地生态站的现状,提出综合性湿地生态站布局原则,认为：应反映湿地生态系统类型代表性及湿地的空间分布特征,体现综合站-区域站-卫星站的层级结构特点,服务国家湿地保护和生态修复的战略需求。按照上述布局原则,对今后综合性湿地生态站的空间布局提出建议。同时,对湿地站发展定位、聚焦的前沿科学问题、湿地联网研究及国际合作方面提出了展望。     

结构稳定性: 概念、方法和应用

群落内物种间相互作用的结构是高度组织化的。群落结构对多物种共存的影响机制是群落生态学的核心科学问题之一。目前生态学界在这一问题上存在多种不同的观点。一个可能的原因是, 由于环境因子的复杂性, 大部分研究忽略了环境因子对群落结构和物种共存的重要影响。在这一背景下, 近期发展起来的结构稳定性理论系统地联系了群落结构、环境因子和物种共存, 并在此基础上建立了一个和经验数据紧密结合的理论框架。本文首先简要回顾了当前关于群落结构研究的争鸣, 然后介绍了结构稳定性的理论框架和计算方法, 最后详细介绍了结构稳定性理论在不同生态群落和不同生态学问题中的应用。在全球气候变化的背景下, 结构稳定性理论提供了一种新的视角来理解群落层面的生物多样性维持机制。     

Dark diversity: shedding light on absent species

Ecological theory and nature conservation have traditionally relied solely on observed local diversity. In this review, we recommend including those species that are absent from an ecosystem but which belong to its species pool; that is, all species in the region that can potentially inhabit those particular ecological conditions. We call the set of absent species 'dark diversity'. Relating local and dark diversities enables biodiversity comparisons between regions, ecosystems and taxonomic groups, and the evaluation of the roles of local and regional processes in ecological communities. Dark diversity can also be used to counteract biodiversity loss and to estimate the restoration potential of ecosystems. We illustrate the dark diversity concept by globally mapping plant dark diversity and the local:dark diversity ratio.     

Quantifying the impact of ecological memory on the dynamics of interacting communities

Ecological memory refers to the influence of past events on the response of an ecosystem to exogenous or endogenous changes. Memory has been widely recognized as a key contributor to the dynamics of ecosystems and other complex systems, yet quantitative community models often ignore memory and its implications.Recent modeling studies have shown how interactions between community members can lead to the emergence of resilience and multistability under environmental perturbations. We demonstrate how memory can be introduced in such models using the framework of fractional calculus. We study how the dynamics of a well-characterized interaction model is affected by gradual increases in ecological memory under varying initial conditions, perturbations, and stochasticity.Our results highlight the implications of memory on several key aspects of community dynamics. In general, memory introduces inertia into the dynamics. This favors species coexistence under perturbation, enhances system resistance to state shifts, mitigates hysteresis, and can affect system resilience both ways depending on the time scale considered. Memory also promotes long transient dynamics, such as long-standing oscillations and delayed regime shifts, and contributes to the emergence and persistence of alternative stable states. Our study highlights the fundamental role of memory in communities, and provides quantitative tools to introduce it in ecological models and analyse its impact under varying conditions.     

中国黄耆属植物旱生类群的区系特点和生态地理分布

根据种的现代地理分布、分布区类型、地理宗的替代关系和生态２特点对中国黄耆属植物的旱生类群进行了研究。结果表明,国产该类群植物９３种,可划分为８个分布区类型和１４个亚型。依其生态理分布规律,又可将这些类群划分为４个生态系列或称为生态区,即帕米尔－昆仑－羌唐生态区,天山－阿尔泰生态区、伊犁－塔城谷地生态区和蒙新荒漠东部生态区。分析认为：黄耆属植物旱生类群的区系发生在中亚西部,中国类群的发生具有显著的中     

生态变异在植物分类学和进化中的重要性

生物群体的变异性是有机体所有类群的一个属性。在本世纪的二十年代至四十年代,植物进化研究的一个重要的目的是了解种内和群体内存在的复杂的变异式样。近一、二十年来,进化生物学研究工作的一个重要的方面已转移到生态因素对个体、群体和种在环境和生物两方面的效应以及这些效应在生态学、分类学和进化中实际的含义上来。种内变异的描述和分类已成为当前最有挑战性的问题和最值得探索的领域之一。可塑性和耐受性在有花植物中普遍存在。但对大多数种来说,可塑性是有限的:一个具有较大分布区的种的不同地区的群体往往具有不同的基因型,而这些基因型是遗传和生态两个因素之间长时期复杂的相互作用的产物。种内变异是生态型性质还是梯度变异性质取决于自然界不同气候带或气候条件之间是急剧过渡还是逐渐过渡。但土壤和生物因素有时也参与宗的分化。群体和种内的变异不一定都有外部形态的变化,而是在多数情况下表现为生理和生化的差异。适应于富含铝、铜或锌等重金属盐的土壤的小地理宗是由足够强大的歧化选择而不是由内在的隔离机制来维持。多态现象,即群体内不同遗传变异体的频率变化,可能与自然选择有关。现有的主要种下分类等级——亚种、变种和变型,不仅不能满足描述种内生态多样性和复杂的变异式样的     

Perspectives for ecosystem management based on ecosystem resilience and ecological thresholds against multiple and stochastic disturbances

Ecosystem resilience is the inherent ability to absorb various disturbances and reorganize while undergoing state changes to maintain critical functions. When ecosystem resilience is sufficiently degraded by disturbances, ecosystem is exposed at high risk of shifting from a desirable state to an undesirable state. Ecological thresholds represent the points where even small changes in environmental conditions associated with disturbances lead to switch between ecosystem states. There is a growing body of empirical evidence for such state transitions caused by anthropogenic disturbances in a variety of ecosystems. However, fewer studies addressed the interaction of anthropogenic and natural disturbances that often force an ecosystem to cross a threshold which an anthropogenic disturbance or a natural disturbance alone would not have achieved. This fact highlights how little is known about ecosystem dynamics under uncertainties around multiple and stochastic disturbances. Here, we present two perspectives for providing a predictive scientific basis to the management and conservation of ecosystems against multiple and stochastic disturbances. The first is management of predictable anthropogenic disturbances to maintain a sufficient level of biodiversity for ensuring ecosystem resilience (i.e., resilience-based management). Several biological diversity elements appear to confer ecosystem resilience, such as functional redundancy, response diversity, a dominant species, a foundation species, or a keystone species. The greatest research challenge is to identify key elements of biodiversity conferring ecosystem resilience for each context and to examine how we can manage and conserve them. The second is the identification of ecological thresholds along existing or experimental disturbance gradients. This will facilitate the development of indicators of proximity to thresholds as well as the understanding of threshold mechanisms. The implementation of forewarning indicators will be critical particularly when resilience-based management fails. The ability to detect an ecological threshold along disturbance gradients should therefore be essential to establish a backstop for preventing the threshold from being crossed. These perspectives can take us beyond simply invoking the precautionary principle of conserving biodiversity to a predictive science that informs practical solutions to cope with uncertainties and ecological surprises in a changing world.     

Recent evolution of host-associated divergence in the seabird tick Ixodes uriae

Ecological interactions are an important source of rapid evolutionary change and thus may generate a significant portion of novel biodiversity. Such changes may be particularly prevalent in parasites, where hosts can induce strong selection for adaptation. To understand the relative frequency at which host-associated divergences occur, it is essential to examine the evolutionary history of the divergence process, particularly when it is occurring over large geographical scales where both geographical and host-associated isolation may playa part. In this study, we use population genetics and phylogeography to study the evolutionary history of host-associated divergence in the seabird tick Ixodes uriae (Acari, Ixodidae). We compare results from microsatellite markers that reflect more ecological timescales with a conserved mitochondrial gene (COIII) that reflects more ancient divergence events. Population structure based on microsatellites showed clear evidence of host-associated divergence in all colonies examined. However, isolated populations of the same host type did not always group together in overall analyses and the genetic differentiation among sympatric host races was highly variable. In contrast, little host or geographical structure was found for the mitochondrial gene fragment. These results suggest that host race formation in I. uriae is a recent phenomenon, that it may have occurred several times and that local interactions are at different points in the divergence process. Rapid divergence in I. uriae implies a strong interaction with its local host species, an interaction that will alter the ecological dynamics of the system and modify the epidemiological landscape of circulating micropathogens.     

Reconciling community ecology with evidence of animal culture: Socially-adapted,localized community dynamics?

A growing body of empirical research suggests many animal species are capable of social learning and even have cultural behavioral traditions. Social learning has implications for community ecology; changes in behavior can lead to changes in inter- and intra-specific (between and within species) interactions. The paper explores possible implications of social learning for ecological community dynamics. Four arguments are made: (1) social learning can result in locally-specific ecological relationships; (2) socially-mediated, locally-specific ecological relationships can have localized indirect interspecific population effects; (3) the involvement of multiple co-existing species in socially learned, locally-specific behavior has the potential to create community-wide effects, including varying levels of stability and instability; and (4) social learning can create new intra- and inter-specific selection pressures on local taxa, potentially resulting in rapid evolution. Implications of all four arguments are discussed in relation to community ecology research and modeling.     

The inherent multidimensionality of temporal variability: how common and rare species shape stability patterns

Empirical knowledge of diversity–stability relationships is mostly based on the analysis of temporal variability. Variability, however, often depends on external factors that act as disturbances, which makes comparisons across systems difficult to interpret. Here, we show how variability can reveal inherent stability properties of ecological communities. This requires that we abandon one‐dimensional representations, in which a single variability measurement is taken as a proxy for how stable a system is, and instead consider the whole set of variability values generated by all possible stochastic perturbations. Despite this complexity, in species‐rich systems, a generic pattern emerges from community assembly, relating variability to the abundance of perturbed species. Strikingly, the contrasting contributions of different species abundance classes to variability, driven by different types of perturbations, can lead to opposite diversity–stability patterns. We conclude that a multidimensional perspective on variability helps reveal the dynamical richness of ecological systems and the underlying meaning of their stability patterns.     

Eco-Evolutionary dynamics enable coexistence via neighbor-dependent selection

Recent studies suggest that selection can allow coexistence in situations where ecological dynamics lead to competitive exclusion, provided that there is a trade-off between traits optimal for interacting with conspecifics and traits optimal for interacting with heterospecifics. Despite compelling empirical evidence, there is no general framework for elucidating how and when selection will allow coexistence in natural communities. Here we develop such a framework for a mechanism that we term "neighbor-dependent selection." We show that this mechanism can both augment coexistence when ecological conditions allow for niche partitioning and enable coexistence when ecological conditions lead to competitive exclusion. The novel insight is that when ecological conditions lead to exclusion, neighbor-dependent selection can allow coexistence via cycles driven by an intransitive loop; selection causes one species to be a superior interspecific competitor when it is rare and an inferior interspecific competitor when it is abundant. Our framework predicts the conditions under which selection can enable coexistence, as opposed to merely augmenting it, and elucidates the effects of heritability on the eco-evolutionary feedbacks that drive coexistence. Given increasing evidence that evolution operates on ecological timescales, our approach provides one means for evaluating the role of selection and trait evolution in species coexistence.