scholarly journals Deviations from dynamic equilibrium in ecological communities worldwide

2019 ◽  
Author(s):  
Michael Kalyuzhny ◽  
Curtis H. Flather ◽  
Nadav M. Shnerb ◽  
Ronen Kadmon
Keyword(s):  
Community Dynamics ◽  
Local Community ◽  
Environmental Changes ◽  
Dynamic Equilibrium ◽  
Ecological Niches ◽  
Ecological Communities ◽  
Parsimonious Explanation ◽  
Primary Driver ◽  
Extinction Events

AbstractEcological communities are assembled by colonization and extinction events, that may be regulated by ecological niches1–5. The most parsimonious explanation of local community assembly is the Dynamic Equilibrium (DE) model, which assumes that community dynamics is shaped by random colonization and extinctions events, effectively ignoring the effects of niches1, 6. Despite its empirical success in explaining diversity patterns1, 5, 7, it is unknown to what extent the assembly dynamics of communities around the globe are consistent with this model. Using a newly developed methodology, we show that in 4989 communities from 49 different datasets, representing multiple taxa, biomes and locations, changes in richness and composition are larger than expected by DE. All the fundamental assumptions of DE are violated, but the large changes in species richness and composition primarily stem from the synchrony in the dynamics of different species. These results indicate that temporal changes in communities are predominantly driven by shared responses of co-occurring species to environmental changes, rather than by inter-specific competition. This finding is in sharp contrast to the long-term recognition of competition as a primary driver of species assembly8–12. While ecological niches are often thought to stabilize species diversity and composition4, 13, 14, we found that they promote large changes in ecological communities.

scholarly journals A framework for quantifying deviations from dynamic equilibrium theory

2019 ◽  
Author(s):  
Michael Kalyuzhny ◽  
Curtis H. Flather ◽  
Nadav M. Shnerb ◽  
Ronen Kadmon
Keyword(s):  
Time Series ◽  
Community Assembly ◽  
Community Dynamics ◽  
Dynamic Equilibrium ◽  
Null Model ◽  
Simulated Data ◽  
Florida Keys ◽  
Alternative Methods ◽  
Ecological Communities ◽  
Extinction Events

AbstractCommunity assembly is governed by colonization and extinction processes, and the simplest model describing it is Dynamic Equilibrium (DE) theory, which assumes that communities are shaped solely by stochastic colonization and extinction events. Despite its potential to serve as a null model for community dynamics, there is currently no accepted methodology for measuring deviations from the theory and testing it. Here we propose a novel and easily applicable methodology for quantifying deviations from the predictions and assumptions of DE by comparing observed community time-series to a randomization-based null model. We show that this methodology has good statistical properties on simulated data, and it can detect deviations from both the assumptions and predictions of DE in the classical Florida Keys experiment. We discuss alternative methods and present guidelines for practical use of the methodology, hoping it will enhance the applicability of DE as a reference for studying changes in ecological communities.

scholarly journals DNA from lake sediments reveals the long-term dynamics and diversity of <i>Synechococcus</i> assemblages

2013 ◽  
Vol 10 (6) ◽  
pp. 3817-3838 ◽  
Author(s):  
I. Domaizon ◽  
O. Savichtcheva ◽  
D. Debroas ◽  
F. Arnaud ◽  
C. Villar ◽  
...  
Keyword(s):  
16S Rrna ◽  
Environmental Conditions ◽  
Trophic Status ◽  
Community Dynamics ◽  
Environmental Changes ◽  
Quantitative Polymerase Chain Reaction ◽  
Additive Models ◽  
Phosphorus Concentration ◽  
Rrna Gene

Abstract. While picocyanobacteria (PC) are important actors in carbon and nutrient cycles in aquatic systems, factors controlling their interannual dynamics and diversity are poorly known due to the general lack of long-term monitoring surveys. This study intended to fill this gap by applying a DNA-based paleolimnological approach to sediment records from a deep subalpine lake that has experienced dramatic changes in environmental conditions during the last century (eutrophication, re-oligotrophication and large-scale climate changes). In particular, we investigated the long-term (100 yr) diversity and dynamics of Synechococcus,, PC that have presumably been affected by both the lake trophic status changes and global warming. The lake's morphological and environmental conditions provided the ideal conditions for DNA preservation in the sediment archives. Generalised additive models applied to quantitative PCR (qPCR; quantitative Polymerase Chain Reaction) results highlighted that an increase in summer temperature could have a significant positive impact on the relative abundance of Synechococcus, (fraction of Synechococcus, in total cyanobacteria). The diversity of Synechococcus, in Lake Bourget was studied by phylogenetic analyses of the 16S rRNA gene and the following internally transcribed spacer (ITS). Up to 23 different OTUs (based on 16S rRNA), which fell into various cosmopolitan or endemic clusters, were identified in samples from the past 100 yr. Moreover, the study of ITS revealed a higher diversity within the major 16S rRNA-defined OTUs. Changes in PC diversity were related to the lake's trophic status. Overall, qPCR and sequencing results showed that environmental changes (in temperature and phosphorus concentration) affected Synechococcus, community dynamics and structure, translating into changes in genotype composition. These results also helped to re-evaluate the geographical distribution of some Synechococcus, clusters. Providing such novel insights into the long-term history of an important group of primary producers, this study illustrates the promising approach that consists in coupling molecular tools and paleolimnology to reconstruct a lake's biodiversity history.

scholarly journals Factors influencing Local Community Participation in Wildlife Conservation Projects in Northeast India

2020 ◽  
Author(s):  
Sayan Banerjee ◽  
Ambika Aiyadurai
Keyword(s):  
Community Participation ◽  
Wildlife Conservation ◽  
Information Dissemination ◽  
Community Dynamics ◽  
Local Community ◽  
Northeast India ◽  
Conservation Projects ◽  
Periodic Feedback ◽  
External Actors

Participation by local communities in wildlife conservation projects have long been advocated since it is socially just and is effective to reach conservation and development goals. Socio&ndash;economic variables that drive participation and impact of participation have been studied, but the contextual process that stir up local community participation remains understudied. In this paper, we studied factors facilitating community participation in three wildlife conservation projects in Northeast India. Through ethnographic fieldwork at these sites we identified conservation actors and examined interactions between them.We found common modes of participation at these sites and these were related to gaining material incentives, providing labour, attending consultative workshops. Levels of interaction and coercion were found to be different in three sites. Three critical factors that drive participation were: (1) trigger, (2) negotiation and (3) sustenance. Trigger factors kickstart participation through establishment of a crisis narrative and facilitation by external actors. Negotiation factors emerge from day&ndash;to&ndash;day interaction between local community and external actors and involve effective entry stage activities, income opportunity, mediating voices within the community and intra&ndash;community dynamics. Sustenance factors affect the long term participation by community in the conservation project and involve tangible/intangible results, capability development of locals, funding and availability to critical information. In our paper we argue that investment of time and fund to understand the stakeholders and their concept of participation, periodic feedback sessions, capacity development of locals for self&ndash;mobilization, innovative information dissemination and securing long term funding are necessary for effective local community participation.

scholarly journals ДОЛГОВРЕМЕННАЯ ДИНАМИКА ОСНОВНЫХ КОМПОНЕНТОВ ЭКОСИСТЕМЫ ОЗЕРА КУЭТСЪЯРВИ (СИСТЕМА РЕКИ ПАСВИК, МУРМАНСКАЯ ОБЛАСТЬ)

2020 ◽  
Vol 11 (4) ◽  
pp. 1
Author(s):  
Е.М. Зубова ◽  
Н.А. Кашулин ◽  
В.А. Даувальтер ◽  
Д.Б. Денисов ◽  
С.А. Валькова ◽  
...  
Keyword(s):  
Heavy Metals ◽  
Environmental Changes ◽  
Life Cycles ◽  
Polluted Water ◽  
Ecological Niches ◽  
Murmansk Oblast ◽  
Sympatric Forms ◽  
Abiotic And Biotic Factors ◽  
Taxonomic Groups

The lake Kuotsjarvi (lower course of Pasvik River, Murmansk Oblast) is located in the borderline territory between Russia and Norway. It one of the most polluted water bodies of European Arctic. Because of the the metallurgic plant Pechenganikel located at the coast of the lake is the source, water and bottom sediments of the lake contain extremely high levels of heavy metals. Long-term comprehensive studies of the ecosystem of the lake revealed that the responses of its ecosystem to global and regional environmental and climatic changes include an increasing toxicity and eutrophication of lake water, decreasing number of stenobiont aqueous species and increasing numbers of ubiquistic and invasive species. The present-time communities in the lake developed as results of interactions between long-term changes in abiotic and biotic factors. Pollution with heavy metals, which lasts since 1990-ies, resulted in the development of communities of species that are tolerant to this impact and are able to maintain their abundance. Adaptations of the communities to changes in their environments are manifested as changes in their species compositions, in proportions of different taxonomic groups, and structures of their populations. In particular, whitefish is able to remain the dominant species and sustain its populations due to development of sympatric forms differing in their ecological niches, morphological features, and life cycle strategies, including transition to shorter life cycles. At difference from changes at the levels of organisms, responses of populations and communities to medium-term environmental changes are more inertial and less specific.

Intra-annual fluctuations dominating temporal dynamics of benthic diatom assemblages in a Chinese mountainous river

2020 ◽  
Vol 56 ◽  
pp. 22
Author(s):  
Shuhan Guo ◽  
Fengzhi He ◽  
Tao Tang ◽  
Lu Tan ◽  
Qinghua Cai
Keyword(s):  
Community Dynamics ◽  
Environmental Changes ◽  
Temporal Dynamics ◽  
Multivariate Time Series ◽  
Multiple Scale ◽  
Benthic Diatom ◽  
Diatom Community ◽  
Diatom Communities ◽  
Mountainous River

Understanding temporal dynamics of community may provide insights on biological responses under environmental changes. However, our knowledge on temporal dynamics of river organisms is still limited. In the present study, we employed a multivariate time-series modeling approach with a long-term dataset (i.e. 72 consecutive months) to investigate temporal dynamics of benthic diatom communities in four sites located in a Chinese mountainous river network. We hypothesized that: (1) there are multi-scale temporal dynamics within the diatom community; (2) intra-annual fluctuations dominate the community dynamics; (3) diatom species composing the community respond distinctly to environmental changes. We found that intra-annual fluctuations with periodicities <12 months explained 8.1–16.1% of community variation. In contrast, fluctuations with periodicities of 13–36 months and 37–72 months only accounted for 1.1–5.9% and 2.8–9.7% of variance in diatom community dynamics, respectively. Taxa correlating significantly to each significant RDA axis (namely, RDA taxa group) displayed distinct temporal dynamics. Conductivity, total nitrogen, and pH were important to most RDA taxa groups across the four sites while their effects were group-specific. We concluded that intra-annual dynamics dominated temporal variation in diatom communities due to community responses to local environmental fluctuations. We suggest that long-term monitoring data are valuable for identifying multiple-scale temporal dynamics within biological communities.

scholarly journals Long-Term Environmental Monitoring in an Arctic Lake Polluted by Metals under Climate Change

Environments ◽  
2020 ◽  
Vol 7 (5) ◽  
pp. 34 ◽  
Author(s):  
Elena M. Zubova ◽  
Nikolay A. Kashulin ◽  
Vladimir A. Dauvalter ◽  
Dmitry B. Denisov ◽  
Svetlana A. Valkova ◽  
...  
Keyword(s):  
Environmental Changes ◽  
Biotic Interactions ◽  
Aquatic Organisms ◽  
Polluted Water ◽  
Ecological Niches ◽  
Murmansk Region ◽  
Large Populations ◽  
High Concentrations ◽  
Taxonomic Groups

Lake Kuetsjarvi (in the lower reaches of the Pasvik River, Murmansk Region, Russia) in the border area between Russia and Norway, is one of the most polluted water reservoirs in the European Arctic. The operation of the Pechenganikel Smelter located on its shores has led to the extremely high concentrations of heavy metals observed in the waters and sediments of the lake. Long-term comprehensive studies of the ecosystem of Lake Kuetsjarvi have made it possible to identify the response of its components to the global and regional change in the environment and climate as a whole, resulting in increased water toxicity and eutrophication, reduction in the number of stenobiont species of aquatic organisms against the background of an increase in the number of eurybiontic and invasive species. Modern communities of Lake Kuetsjarvi are the result of a combination of long-term changes in the abiotic environment and biotic interactions. Heavy-metal pollution of Lake Kuetsjarvi, observed since the 1930s, has led to the formation of a community that is resistant to this type of impact and supports large populations of adapted species. Adaptations of communities to the dynamics of the environmental conditions that their members are exposed to include changes in the species composition, quantitative indicators, ratios between individual taxonomic groups, and the population structure. The development of sympatric forms that differ in the ecological niches they occupy, morphology, and life cycle strategies, including the transition to a short-cycle survival strategy, allows whitefish to remain the dominant species and maintain high population numbers. Unlike the organismal level, responses to medium-term environmental changes on the population and community level are less specific and characterized by stronger inertia.

scholarly journals Different temporal trends in vascular plant and bryophytes communities along elevational gradients over four decades of warming

2020 ◽  
Author(s):  
Antoine Becker-Scarpitta ◽  
Diane Auberson-Lavoie ◽  
Mark Vellend
Keyword(s):  
Plant Communities ◽  
Vascular Plants ◽  
Environmental Changes ◽  
Vascular Plant ◽  
Elevation Gradient ◽  
Temporal Trends ◽  
Community Change ◽  
Ecosystem Functions ◽  
Ecological Communities

Abstract1: Despite many studies showing biodiversity responses to warming, the generality of such responses across taxa remains unclear. Very few studies have tested for evidence of bryophyte community responses to warming, despite the fact that bryophytes are major contributors to diversity in many ecosystems, playing a central role in ecosystem functions. Understanding variation among taxa in their responses to warming is crucial for identifying priorities in conservation.2: We report an empirical study comparing long-term change of bryophyte and vascular plant communities in two sites with contrasting long-term warming trends. To assess long-term responses of ecological communities to warming, we used “legacy” botanical records as a baseline for comparison with contemporary resurveys.We hypothesized that ecological changes would be greater in sites with a stronger warming trends, and that vascular plant communities would be more sensitive than bryophyte communities to climate warming. For each taxon in each site, we quantified the magnitude of changes in species’ distributions along the elevation gradient, species richness, and community composition.3: Temporal changes in vascular plant communities were consistent with the warming hypothesis, but this was not the case for bryophytes. We also did not find clear support for the hypothesis that vascular plants would show greater sensitivity than bryophytes to warming, with results depending on the metric of community change. As predicted for sites with a strong warming trend, we found a significant upward shift in the distributions of vascular plants but not bryophytes.Synthesis: Our results are in accordance with recent literature showing that local diversity can remain unchanged despite strong changes in composition. Regardless of whether one taxon is systematically more or less sensitive to environmental change than another, our results suggest that vascular plants cannot be used as a surrogate for bryophytes in terms of predicting the nature and magnitude of responses to warming. In sites that experienced the same environmental changes, we found that communities of bryophytes and vascular plants did not predictably change in the same ways. Thus, to assess overall biodiversity responses to global change, data from different taxonomical groups and community properties need to be synthesized.

scholarly journals The 'long tail' of anthropogenic CO2 decline in the atmosphere and its consequences for post-closure performance assessments for disposal of radioactive wastes

2015 ◽  
Vol 79 (6) ◽  
pp. 1613-1623 ◽  
Author(s):  
N. S. Lord ◽  
A. Ridgwell ◽  
M. C. Thorne ◽  
D. J. Lunt
Keyword(s):  
Response Function ◽  
Environmental Changes ◽  
Radioactive Wastes ◽  
Performance Assessments ◽  
Long Tail ◽  
Geological Disposal ◽  
The Future ◽  
Primary Driver ◽  
Climate Evolution

AbstractThe extended timescales involved in the decay of radioactive wastes to safe levels mean that geological disposal facilities must continue to function effectively long into the future. It is therefore essential to consider long-term climate evolution in post-closure performance assessments in order to evaluate a geological disposal system's response and robustness to a variety of potential environmental changes, driven by both natural and anthropogenic forcings. In this paper, we illustrate the multiple decay components that characterize the primary driver of climate change – atmospheric CO2 – in response to fossil fuel carbon emissions. We perform a multi-exponential analysis on a series of atmospheric CO2 decay curves predicted by an Earth system model and create an empirical response function that encapsulates the long-term (>1 kyr) removal of excess CO2 from the atmosphere. We present this response function as a simple tool for rapidly projecting the future atmospheric CO2 concentration resulting from any plausible cumulative release of CO2. We discuss the implications of the long 'tail' to this atmospheric CO2 decay curve, both in terms of future climate evolution as well as potential impacts on radioactive waste repositories.

scholarly journals DNA from lake sediments reveals the long-term dynamics and diversity of <i>Synechococcus</i> assemblages

2013 ◽  
Vol 10 (2) ◽  
pp. 2515-2564 ◽  
Author(s):  
I. Domaizon ◽  
O. Savichtcheva ◽  
D. Debroas ◽  
F. Arnaud ◽  
C. Villar ◽  
...  
Keyword(s):  
16S Rrna ◽  
Environmental Conditions ◽  
Trophic Status ◽  
Community Dynamics ◽  
Environmental Changes ◽  
Positive Impact ◽  
Additive Models ◽  
Phosphorus Concentration ◽  
Rrna Gene

Abstract. While picocyanobacteria (PC) are important actors in carbon and nutrient cycles in aquatic systems, factors controlling their interannual dynamics and diversity are poorly known due to the general lack of long-term monitoring surveys. This study intended to fill this gap by applying a DNA-based paleolimnological approach to sediment records from a deep subalpine lake that has experienced dramatic changes in environmental conditions during the last century (eutrophication, re-oligotrophication and large-scale climate changes). We particularly investigated the long-term (100 yr) diversity and dynamics of Synechococcus, PC that have presumably been affected by both the lake trophic status changes and global warming. The lake's morphological and environmental conditions provided ideal conditions for DNA preservation in the sediment archives. Generalised additive models applied to quantitative PCR (qPCR) results highlighted that an increase in summer temperature could have a significant positive impact on the relative abundance of Synechococcus (fraction of Synechococcus in total cyanobacteria). The diversity of Synechococcus in Lake Bourget was studied by phylogenetic analyses of the 16S rRNA gene and internal transcribed spacer (ITS). Up to 23 different OTUs (based on 16S rRNA), which fell into various cosmopolitan or endemic clusters, were identified in samples from the past 100 yr. Moreover, study of the ITS revealed a higher diversity within the major 16S rRNA-defined OTUs. Changes in PC diversity were related to the lake's trophic status. Overall, qPCR and sequencing results showed that environmental changes (here, in temperature and phosphorus concentration) affected Synechococcus community dynamics and structure, translating into changes in genotype composition. These results also helped to re-evaluate the geographical distribution of some Synechococcus clusters. Providing such novel insights into the long-term history of an important group of primary producers, this study illustrates the promising approach that consists in coupling molecular tools and paleolimnology to reconstruct a lake's biodiversity history.

scholarly journals Biological complexity behind plankton system functioning: Synthesis and perspectives from a marine Long Term Ecological Research

2017 ◽  
Vol 8 (2) ◽  
Author(s):  
Domenico D'Alelio
Keyword(s):  
Community Dynamics ◽  
Environmental Changes ◽  
Ecological Research ◽  
Gulf Of Naples ◽  
Long Term Ecological Research ◽  
System Functioning ◽  
Species Evolution ◽  
Population And Community Dynamics ◽  
Different Levels

The functioning of natural communities is the cumulative outcome of multifaceted and intersecting ecological and evolutionary processes occurring at species level. Species are not stable entities but evolve in consequence of contingent factors including the relationships they establish with the environment and other co-occurring species. Studying ecosystems with an eco-evo approach, i.e., by explicitly considering species evolution and interactions, is thus an essential step to envisioning their adaptation to environmental changes. Such approach is particularly suitable for studying plankton, a community of both rapidly evolving and strongly interconnected species. In this context, Long Term Ecological Research studies (LTER) represent a promising approach to explore nature at different levels of complexity, from species to ecosystems. Herein, I examine the most recent results coming from the three-decades plankton LTER ‘MareChiara’ (LTER-MC) in the Gulf of Naples (Mediterranean Sea, Italy) and discuss their suitability in deepening knowledge on: i) evolutionary bases to plankton biodiversity (i.e., the founding property of both species and community adaptive potential); ii) ecological and evolutionary determinants of population and community dynamics; and iii) biological mechanisms behind plankton system functioning.

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