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1.
生态群落中不同物种间发生多样化的相互作用, 形成了复杂的种间互作网络。复杂生态网络的结构如何影响群落的生态系统功能及稳定性是群落生态学的核心问题之一。种间互作直接影响到物质和能量在生态系统不同组分之间的流动和循环以及群落构建过程, 使得网络结构与生态系统功能和群落稳定性密切相关。在群落及生态系统水平上开展种间互作网络研究将为群落的构建机制、生物多样性维持、生态系统稳定性、物种协同进化和性状分化等领域提供新的视野。当前生物多样性及生态系统功能受到全球变化的极大影响, 研究种间互作网络的拓扑结构、构建机制、稳定性和生态功能也可为生物多样性的保护和管理提供依据。该文从网络结构、构建机制、网络结构和稳定性关系、种间互作对生态系统功能的影响等4个方面综述当前种间网络研究进展, 并提出在今后的研究中利用机器学习和多层网络等来探究环境变化对种间互作网络结构和功能的影响, 并实现理论和实证研究的有效整合。 相似文献
2.
- The dispersal of organisms in fragmented habitats connects spatially separated local populations at the regional, metapopulation scale, with potential consequences for spatial population dynamics and persistence. As any dispersing organism is engaged in trophic interactions as well, dispersal also connects local food webs at the regional scale, and differential dispersal among taxa of different trophic levels has the potential to strongly influence spatial food‐web dynamics.
- We used a combination of field surveys and experiments to test the significance of passive dispersal via overflowing water for population and food‐web dynamics in a system of freshwater rock pools on Appledore Island, Maine, U.S.A. The rock pools contain a three‐trophic‐level food chain consisting of phytoplankton (primarily chlorophyte algae), grazer zooplankton (two species of Cladocera) and a predatory insect (Trichocorixa), all of which are passively dispersed between rock pools when the pools overflow during rain events.
- During the summers of 2010 and 2011, rain events were observed (on average) every two and a half days. Three‐quarters of rain events generated overflows, and observed overflow rates varied over four orders of magnitude (0.5–474 mL s?1). A Monte Carlo simulation showed that, on average, a pool is expected to overflow 5.6 times during a summer.
- Despite all three taxa dispersing in overflows, and dispersing more at higher flow rates, a mesocosm experiment showed that dispersal rates decreased significantly with increasing trophic level, such that Trichocorixa dispersed less than cladocerans, which dispersed less than phytoplankton. Results from a follow‐up experiment suggest that this decrease in dispersal is primarily due to organisms at higher trophic levels being more able to avoid currents, rather than an ability to swim more strongly against currents.
- Finally, we conducted a field experiment to determine the influence of overflows on population and food‐web dynamics in situ. Populations in pools that were part of experimental overflows were significantly more variable than nearby populations that were not in the overflow, and taxa at all three trophic levels were influenced similarly by the overflows.
- This study demonstrates that passive dispersal of aquatic organisms among habitat patches is likely to occur at different rates for different taxa, which may have strong effects on spatial food‐web dynamics.
3.
Motivated by the results of recent laboratory experiments, as well as many earlier field observations, that evolutionary changes
can take place in ecosystems over relatively short ecological time scales, several ‘unified’ mathematical models of evolutionary
ecology have been developed over the last few years with the aim of describing the statistical properties of data related
to the evolution of ecosystems. Moreover, because of the availability of sufficiently fast computers, it has become possible
to carry out detailed computer simulations of these models. For the sake of completeness and to put these recent developments
in perspective, we begin with a brief summary of some older models of ecological phenomena and evolutionary processes. However,
the main aim of this article is to review critically these ‘unified’ models, particularly those published in the physics literature,
in simple language that makes the new theories accessible to a wider audience 相似文献
4.
Food webs have markedly non‐random network structure. Ecologists maintain that this non‐random structure is key for stability, since large random ecological networks would invariably be unstable and thus should not be observed empirically. Here we show that a simple yet overlooked feature of natural food webs, the correlation between the effects of consumers on resources and those of resources on consumers, substantially accounts for their stability. Remarkably, random food webs built by preserving just the distribution and correlation of interaction strengths have stability properties similar to those of the corresponding empirical systems. Surprisingly, we find that the effect of topological network structure on stability, which has been the focus of countless studies, is small compared to that of correlation. Hence, any study of the effects of network structure on stability must first take into account the distribution and correlation of interaction strengths. 相似文献
5.
Population dynamics theory forms the quantitative core from which most ecologists have developed their intuition about how species interactions, heterogeneity, and biodiversity play out in time. Throughout its development, theoretical population biology has built on variants of the Lotka–Volterra equations and in nearly all cases has taken a single‐currency approach to understanding population change, abstracting populations as aggregations of individuals or biomass. In this review, we explore how depicting organisms as built of more than one thing (for example, C and an important nutrient, such as P) in stoichiometrically explicit models results in qualitatively different predictions about the resulting dynamics. Fundamentally, stoichiometric models incorporate both food quantity and food quality effects in a single framework, allow key feedbacks such as consumer‐driven nutrient recycling to occur, and generally appear to stabilize predator–prey systems while simultaneously producing rich dynamics with alternative domains of attraction and occasionally counterintuitive outcomes, such as coexistence of more than one predator species on a single‐prey item and decreased herbivore performance in response to increased light intensity experienced by the autotrophs. In addition to the theoretical background, we also review recent laboratory and field studies considering stoichiometric effects on autotroph–herbivore systems, emphasizing algae–Daphnia interactions. These studies support the predictions of stoichiometric theory, providing empirical evidence for alternative stable states under stoichiometric constraints, for negative effects of solar radiation on herbivores via stoichiometric food quality, and for diversity‐enhancing effects of poor food quality. Stoichiometric theory has strong potential for both quantitative and qualitative improvements in the predictive power of population ecology, a major priority in light of the multivariate anthropogenic and natural perturbations experienced by populations. However, full development and testing of stoichiometric population dynamics theory will require greater intellectual tolerance and exchange between researchers working in ecosystem and population ecology. 相似文献
6.
To assess the effects of fluctuating prey availability on predator population dynamics and grazing impact on phytoplankton, we measured growth and grazing rates of three heterotrophic dinoflagellate species—Oxyrrhis marina, Gyrodinium dominans and Gyrodinium spirale—before and after depriving them of phytoplankton prey. All three dinoflagellate species survived long periods (> 10 d) without algal prey, coincident with decreases in predator abundance and cell size. After 1–3 wks, starvation led to a 17–57% decrease in predator cell volume and some cells became deformed and transparent. When re‐exposed to phytoplankton prey, heterotrophs ingested prey within minutes and increased cell volumes by 4–17%. At an equivalent prey concentration, continuously fed predators had ~2‐fold higher specific growth rates (0.18 to 0.55 d?1) than after starvation (?0.16 to 0.25 d?1). Maximum specific predator growth rates would be achievable only after a time lag of at least 3 d. A delay in predator growth poststarvation delays predator‐induced phytoplankton mortality when prey re‐emerges at the onset of a bloom event or in patchy prey distributions. These altered predator‐prey population dynamics have implications for the formation of phytoplankton blooms, trophic transfer rates, and potential export of carbon. 相似文献
7.
Lothar D. J. Kuijper Matty P. Berg Elly Morriën Bob W. Kooi Herman A. Verhoef 《Global Change Biology》2005,11(2):249-265
Global change may affect the structure and functioning of decomposer food webs through qualitative changes in freshly fallen litter. We analyzed the predicted effects of a changing environment on a dynamic model of a donor‐controlled natural decomposer ecosystem near Wekerom, the Netherlands. This system consists of fungi, bacteria, fungivores, bacterivores and omnivores feeding on microbiota and litter as well. The model concentrates on carbon and nitrogen flows through the trophic niches that define this decomposer system, and is designed to predict litter masses and abundances of soil biota. For modeling purposes, the quality of freshly fallen leaf litter is defined in terms of nitrogenous and non‐nitrogenous components, of which refractory and labile forms are present. The environmental impacts of elevated CO2, enhanced UV‐B and eutrophication, each with their own influence on leaf litter quality, are studied. The model predicts steady‐state dynamics exclusively, for all three scenarios. Environmental changes impact most demonstratively on the highest trophic niches, and affect microbiotic abundances and litter decomposition rates to a lesser extent. We conclude that the absence of trophic cascade effects may be attributed to weak trophic links, and that non‐equilibrium dynamics occurring in the system are generally because of encounter rates based on fractional substrate densities in the litter. We set out a number of experimentally testable hypotheses that may improve understanding of ecosystem dynamics. 相似文献
8.
Matthew J. Smith Elizabeth Sander György Barabás Stefano Allesina 《Ecology letters》2015,18(6):593-595
Neutel & Thorne (Ecology Letters, 17:651–661, June 2014) provide an approximation for the leading eigenvalue of a food web community matrix involving coefficients of its characteristic polynomial. Though valuably incorporating three‐way species interactions, two critical problems emerge when one considers the dimensions of the system, calling the approach's accuracy and precision into question. 相似文献
9.
Scavenging plays a vital role in maintaining ecosystem health and contributing to ecological functions; however, research in this sub‐discipline of ecology is underutilized in developing and implementing wildlife conservation and management strategies. We provide an examination of the literature and recommend priorities for research where improved understanding of scavenging dynamics can facilitate the development and refinement of applied wildlife conservation and management strategies. Due to the application of scavenging research broadly within ecology, scavenging studies should be implemented for informing management decisions. In particular, a more direct link should be established between scavenging dynamics and applied management programs related to informing pharmaceutical delivery and population control through bait uptake for scavenging species, prevention of unintentional poisoning of nontarget scavenging species, the epidemiological role that scavenging species play in disease dynamics, estimating wildlife mortalities, nutrient transfer facilitated by scavenging activity, and conservation of imperiled facultative scavenging species. This commentary is intended to provide information on the paucity of data in scavenging research and present recommendations for further studies that can inform decisions in wildlife conservation and management. Additionally, we provide a framework for decision‐making when determining how to apply scavenging ecology research for management practices and policies. Due to the implications that scavenging species have on ecosystem health, and their overall global decline as a result of anthropic activities, it is imperative to advance studies in the field of scavenging ecology that can inform applied conservation and management programs. 相似文献
10.
The Standing Committee on Ecotoxicology of the Health Council of the Netherlands (see note at the end of this article) has reported on the potential and limitations associated with the use of food web models in ecotoxicological risk assessment. This paper closely follows the executive summary of that report. The current appoach in ecotoxicological risk assessment is based on single species toxicity tests. It is felt that the food web approach, which takes feeding relationships between species in ecosystems into account, provides an opportunity to address effects of toxic substances on the ecosystem level. It is considered to be particularly useful in site-specific risk assessment concerning specific (types of) ecosystems. However, supplementary research must be carried out before food web models can be used in ecotoxicological risk assessment. 相似文献
11.
Martina Kadin Morten Frederiksen Susa Niiranen Sarah J. Converse 《Ecology and evolution》2019,9(15):8587-8600
Alternatives in ecosystem‐based management often differ with respect to trade‐offs between ecosystem values. Ecosystem or food‐web models and demographic models are typically employed to evaluate alternatives, but the approaches are rarely integrated to uncover conflicts between values. We applied multistate models to a capture–recapture dataset on common guillemots Uria aalge breeding in the Baltic Sea to identify factors influencing survival. The estimated relationships were employed together with Ecopath‐with‐Ecosim food‐web model simulations to project guillemot survival under six future scenarios incorporating climate change. The scenarios were based on management alternatives for eutrophication and cod fisheries, issues considered top priority for regional management, but without known direct effects on the guillemot population. Our demographic models identified prey quantity (abundance and biomass of sprat Sprattus sprattus) as the main factor influencing guillemot survival. Most scenarios resulted in projections of increased survival, in the near (2016–2040) and distant (2060–2085) future. However, in the scenario of reduced nutrient input and precautionary cod fishing, guillemot survival was projected to be lower in both future periods due to lower sprat stocks. Matrix population models suggested a substantial decline of the guillemot population in the near future, 24% per 10 years, and a smaller reduction, 1.1% per 10 years, in the distant future. To date, many stakeholders and Baltic Sea governments have supported reduced nutrient input and precautionary cod fishing and implementation is underway. Negative effects on nonfocal species have previously not been uncovered, but our results show that the scenario is likely to negatively impact the guillemot population. Linking model results allowed identifying trade‐offs associated with management alternatives. This information is critical to thorough evaluation by decision‐makers, but not easily obtained by food‐web models or demographic models in isolation. Appropriate datasets are often available, making it feasible to apply a linked approach for better‐informed decisions in ecosystem‐based management. 相似文献
12.
13.
Michael Doebeli 《Evolution; international journal of organic evolution》1996,50(2):532-546
This study examines the dynamics of a competition and a host-parasite model in which the interactions are determined by quantitative characters. Both models are extensions of one-dimensional difference equations that can exhibit complicated dynamics. Compared to these basic models, the phenotypic variability given by the quantitative characters reduces the size of the density fluctuations in asexual populations. With sexual reproduction, which is described by modeling the genetics of the quantitative character explicitly with many haploid loci that determine the character additively, this reduction in fitness variance is magnified. Moreover, quantitative genetics can induce simple dynamics. For example, the sexual population can have a two-cycle when the asexual system is chaotic. This paper discusses the consequences for the evolution of sex. The higher mean growth rate implied by the lower fitness variance in sexual populations is an advantage that can overcome a twofold intrinsic growth rate of asexuals. The advantage is bigger when the asexual population contains only a subset of the phenotypes present in the sexual population, which conforms with the tangled bank theory for the evolution of sex and shows that tangled bank effects also occur in host-parasite systems. The results suggest that explicitly describing the genetics of a quantitative character leads to more flexible models than the usual assumption of normal character distributions, and therefore to a better understanding of the character's impact on population dynamics. 相似文献
14.
试论土壤线虫多样性在生态系统中的作用 总被引：17，自引：0，他引：17
土壤线虫的物种多样性和功能群丰富, 不同功能群的土壤线虫取食习惯也不一样, 而土壤线虫取食习惯的多样性以及它们自身的一些属性决定了它们在土壤中与其他生物之间关系的复杂性。土壤中不同生物之间的相互作用决定了土壤食物网的复杂性, 进而影响着土壤生态系统功能。然而, 有关土壤线虫的多样性与土壤生态系统功能之间的关系的研究还很不足。要全面了解土壤线虫在生态系统中的作用, 研究工作必须: (1) 结合室内模拟和野外控制实验; (2) 结合物种多样性调查和不同功能群的功能分析。 相似文献
15.
Energetic and dynamic constraints have been proposed as rival factors in determining food-web structure. Food-web length might be controlled either by the amount of energy entering the web (energetic constraints) or by time span between consecutive disturbances relative to time needed to build up a population (dynamic constraints). Dynamic constraints are identified with processes functioning at a regional scale such as climate, lithology and hydrogeology. Energetic constraints are related with processes operating both at a regional and a local scale. We studied the contribution of energetic constraints to food-web organization in two temporary saline lakes with similar dynamic constraints. Lakes were sampled fortnightly during two hydroperiods (1994/1995 and 1995/1996). Differences in energetic constraints between lakes result in divergent assemblages of primary producers. Consumer assemblages in both lakes, however, are similar in species composition although differ in total biomass and species abundances. Food-webs are short with a high proportion of omnivores. To simulate an increase in the energy input entering to these systems, an addition of nutrients (to a final concentration of 100 gl–1 P-PO43-) was done in mesocosms placed within the lakes in order to obtain an increase in the phytoplankton biomass. No significant response to nutrient enrichment was found in food-web structure (composition, density or biomass). 相似文献
16.
A model is proposed for the dynamics of a forest insect population with account of food consumption and the response of plants to damage. Equations are derived relating the propagation coefficient, female mass, pest conversion efficacy, and plant reaction. Outbreak scenarios are analyzed as dependent on steady-state female weight. The results are compared with the data of observations in nature. 相似文献
17.
基于稳定同位素的湿地食物源判定和食物网构建研究进展 总被引：1，自引：0，他引：1
湿地生物营养动力学是湿地生态系统结构和功能评价研究的基础.碳、氮稳定同位素作为识别营养关系的方法,已在湿地生态系统食物来源、组成和食物链传递研究中得到广泛运用.本文系统综述了稳定同位素食物贡献度计算模型和营养级确定的基本方法和理论;讨论了动物营养分馏值和基线的选择依据;概括了湿地生态系统典型食物源及其稳定同位素变化特征;总结了草食、杂食和肉食等不同营养级动物的食物来源.指出了稳定同位素在湿地食物源溯源和食物网研究中的不足;基于国内外研究现状和发展趋势及需求,展望了未来同位素技术在湿地食物网生态学研究中的运用前景和研究重点,提出需要加强稳定同位素营养分馏和基线的影响因素、样品处理和保存方式研究以及胃含物、分子标记物和多元素同位素结合分析. 相似文献
18.
1. Allometric theory makes specific predictions about how density, and consequently biomass, scale with organism size within trophic levels, across trophic levels and across food webs. 2. Diversity-yield relationships suggest that more diverse food webs can sometimes support more biomass through mechanisms involving niche complementarity or selection effects that are sometimes attributed to organism size. 3. We combine the above two approaches and show that, generally, density and biomass scale with organism size within and between trophic levels as predicted by allometric theory. Further, food webs converged in total biomass despite persistent differences in the composition and size of the organisms among food webs; species richness explained deviations from the constant yield of biomass expected from size-abundance relationships. 4. Our results suggest that organism size plays only a transient role in controlling community biomass because population increases or decreases lead to rapid convergence in biomass. Species richness affects community biomass independently by effectively increasing the mass of organisms that can be supported in a given productivity regime. 相似文献
19.
The North Sea, one of the most productive of the earth's seas and oceans, is also surrounded by some of earth's most densely
populated and heavily industrialized regions. A growing number of signals are being received which indicate that this valuable
ecosystem is increasingly under stress. This has generated a corresponding increase in concern over the steps to be taken
to protect the North Sea. While there are divergent views on what constitutes an ‘ideal’ North Sea, there is a general recognition
that any decisions that are made should be based on a good understanding of this ecosystem. The intention of this paper is
to give an overview of what is presently known, and to identify areas where more studies are needed. A brief summary of the
hydrography and the biota of the North Sea is given. Biotic and abiotic structure justify partitioning the North Sea into
three ecologically different regions: southern, central, and northern. For the most part, neither the top predators,e.g. marine birds and mammals, nor the macroalgae and sea grasses are included in this overview. 相似文献
20.
C.‐N. Tsai W.‐C. Chiang C.‐L. Sun K.‐T. Shao S.‐Y. Chen S.‐Z. Yeh 《Journal of fish biology》2014,84(2):354-371
To examine trophic dynamics over different size classes, an isotopic study of sailfish Istiophorus platypterus life‐history stages was carried out. Samples were collected from eastern Taiwan and the South China Sea during April 2009 and February 2012. A total of 263 samples (111–245 cm, lower jaw fork length, LLJFL) were examined for changes in trophic structure in relation to LLJFL by using stable isotope analysis of carbon (δ13C) and nitrogen (δ15N). The δ15N values for I. platypterus ranged from 7·51 to 14·19‰ (mean ± s.d . = 12·06 ± 1·16‰) and the δ13C values ranged from ?22·04 to ?15·48‰ (mean ± s.d . = ?17·62 ± 1·10‰). The δ15N values were positively dependent on LLJFL (r2 = 0·377), whereas δ13C were negatively dependent on LLJFL (r2 = 0·063). There were significantly different seasonal changes in nitrogen and carbon isotopic concentration, but no significant differences in concentrations between eastern Taiwan and the South China Sea were reported. The trophic level (TL) of each LLJFL class was correlated, starting from 2·84 TL for size class I (LLJFL < 140 cm) and reaching 5·03 TL for size class VI (LLJFL > 221 cm). The mean ± s.d . TL was 4·43 ± 0·19 for all samples. The results reveal that I. platypterus occupies a wide range of trophic levels and different size classes occupy different trophic positions in the pelagic ecosystem. 相似文献