scholarly journals Dominance structure of assemblages is regulated over a period of rapid environmental change

2018 ◽  
Vol 14 (6) ◽  
pp. 20180187 ◽  
Author(s):  
Faith A. M. Jones ◽  
Anne E. Magurran
Keyword(s):  
Dominant Species ◽  
Meta Analysis ◽  
Environmental Drivers ◽  
Systematic Change ◽  
Ecosystem Responses ◽  
Multiple Components ◽  
Dominance Structure ◽  
Biodiversity Change ◽  
Permutation Models ◽  
Assemblage Size

Ecological assemblages are inherently uneven, with numerically dominant species contributing disproportionately to ecosystem services. Marked biodiversity change due to growing pressures on the world's ecosystems is now well documented. However, the hypothesis that dominant species are becoming relatively more abundant has not been tested. We examined the prediction that the dominance structure of contemporary communities is shifting, using a meta-analysis of 110 assemblage timeseries. Changes in relative and absolute dominance were evaluated with mixed and cyclic-shift permutation models. Our analysis uncovered no evidence of a systematic change in either form of dominance, but established that relative dominance is preserved even when assemblage size (total N ) changes. This suggests that dominance structure is regulated alongside richness and assemblage size, and highlights the importance of investigating multiple components of assemblage diversity when evaluating ecosystem responses to environmental drivers.

scholarly journals Systematic review and meta-analysis of 50 years of coral disease research visualized through the scope of network theory

2018 ◽  
Author(s):  
Luis M. Montilla ◽  
Alfredo Ascanio ◽  
Alejandra Verde ◽  
Aldo Croquer
Keyword(s):  
Research Effort ◽  
Coral Disease ◽  
Meta Analysis ◽  
Limited Range ◽  
Environmental Drivers ◽  
Network Nodes ◽  
Host Genus ◽  
Disease Research ◽  
Multiple Processes ◽  
Black Band

AbstractCoral disease research encompasses five decades of undeniable progress. Since the first descriptions of anomalous signs, we have come to understand multiple processes and environmental drivers that interact with coral pathologies. To gain a better insight into the knowledge we already have, we explored how key topics in coral disease research have been related to each other using network analysis. We reviewed 719 papers and conference proceedings published from 1965 to 2017. From each study, four elements determined our network nodes: 1) studied disease(s); 2) host genus; 3) marine ecoregion(s) associated with the study site; and 4) research objectives. Basic properties of this network confirmed that there is a set of specific topics comprising the majority of research. The top five diseases, genera, and ecoregions studied accounted for over 48% of the research effort in all cases. The community structure analysis identified 15 clusters of topics with different degrees of overlap among them. These clusters represent the typical sets of elements that appear together for a given study. Our results show that while some coral diseases have been studied considering multiple aspects, the overall trend is for most diseases to be understood under a limited range of approaches, e.g. bacterial assemblages have been considerably studied in Yellow and Black band diseases while immune response has been better examined for the aspergillosis-Gorgonia system. Thus, our challenge in the near future is to identify and resolve potential gaps in order to achieve a more comprehensive progress on coral disease research.

scholarly journals Comprehensive insights into arsenic- and iron-redox genes, their taxonomy and associated environmental drivers deciphered by a meta-analysis

2021 ◽  
Vol 146 ◽  
pp. 106234
Author(s):  
Maria Luíza S. Suhadolnik ◽  
Patrícia S. Costa ◽  
Giovanni M. Castro ◽  
Francisco P. Lobo ◽  
Andréa M.A. Nascimento
Keyword(s):  
Meta Analysis ◽  
Environmental Drivers ◽  
Iron Redox

When Does Partitioned Pricing Lead to More Favorable Consumer Preferences?: Meta-Analytic Evidence

2018 ◽  
Vol 55 (5) ◽  
pp. 686-703 ◽  
Author(s):  
Ajay T. Abraham ◽  
Rebecca W. Hamilton
Keyword(s):  
Consumer Preferences ◽  
Meta Analysis ◽  
Product Category ◽  
Partitioned Pricing ◽  
Multiple Components ◽  
Pricing Research ◽  
High Benefit ◽  
Price Presentation ◽  
The Impact ◽  
Total Price

Evidence of the impact of partitioned pricing is contradictory. Research indicates that partitioning a price into multiple components can result in more favorable preferences, due to a lower recalled price, or less favorable preferences, due to unfavorable surcharge evaluations. To explain these divergent effects, the authors examine the role of price presentation moderators, which reflect how managers convey prices to consumers (e.g., Is the total price present or absent?), magnitude moderators, which reflect the actual prices charged (e.g., What is the surcharge magnitude?), and contextual moderators, which reflect nonprice transaction characteristics (e.g., Is the product category hedonic or utilitarian?). A meta-analysis of 17 years of partitioned pricing research examining 149 observations in 27 papers (N = 12,878) suggests that consumers respond more favorably to partitioned pricing than to all-inclusive pricing when the total price is absent, as the price level increases, when the surcharges are typical for the product category, when the surcharges are perceived as offering high benefit, and when the product category is utilitarian.

scholarly journals Dynamics of Cyanobacteria and Related Environmental Drivers in Freshwater Bodies Affected by Mitten Crab Culturing: A Study of Lake Guchenghu, China

Water ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2468
Author(s):  
Hongmin Li ◽  
Huihui Chen ◽  
Xiaohong Gu ◽  
Zhigang Mao ◽  
Qingfei Zeng ◽  
...  
Keyword(s):  
Environmental Variables ◽  
Phytoplankton Biomass ◽  
Dominant Species ◽  
N:P Ratio ◽  
Water Bodies ◽  
Environmental Drivers ◽  
Mitten Crab ◽  
Total Phytoplankton ◽  
Freshwater Bodies ◽  
Harmful Species

Mitten crab aquaculture is prevalent in China, however, knowledge about the threat of cyanobacteria in mitten crab aquaculture-impacted water bodies is limited. Here, seasonal variations of cyanobacteria and their relationships with environmental factors were investigated for Lake Guchenghu area. Results suggested the changes of cyanobacteria community in crab ponds distinguished from the adjacent lake. In the lake, cyanobacterial biomass (3.86 mg/L, 34.6% of the total phytoplankton) was the highest in autumn with the dominance of Oscillatoria, Aphanocapsa and Pesudanabaena. By contrast, in crab ponds, cyanobacteria (46.80 mg/L, 97.2% of the total phytoplankton biomass) were the most abundant in summer when Pesudanabaena and Raphidiopsis were the dominant species. Of particular note was that obviously higher abundance of filamentous and potentially harmful species (e.g., Raphidiopsis raciborskii and Dolichospermum circinale) were observed in ponds compared to the lake. Specifically, water depth (WD), permanganate index (CODMn), total phosphorus (TP), N:P ratio, and NO 2 −-N were the key environmental variables affected cyanobacteria composition. For crab ponds, N:P ratio, water temperature (WT) and TP were the potential environmental drivers of cyanobacteria development. This study highlighted the fact that mitten crab culture had non-negligible influences on the cyanobacteria community and additional attention should be paid to the cyanobacteria dynamics in mitten crab culture-impacted water bodies, especially for those potentially harmful species.

scholarly journals Comment on “Mycorrhizal association as a primary control of the CO2 fertilization effect”

Science ◽  
2017 ◽  
Vol 355 (6323) ◽  
pp. 358.2-358 ◽  
Author(s):  
R. J. Norby ◽  
M. G. De Kauwe ◽  
A. P. Walker ◽  
C. Werner ◽  
S. Zaehle ◽  
...  
Keyword(s):  
Nitrogen Availability ◽  
Meta Analysis ◽  
Terrestrial Ecosystem ◽  
Mycorrhizal Symbiosis ◽  
Primary Control ◽  
Soil Nitrogen Availability ◽  
Ecosystem Responses ◽  
Mycorrhizal Association ◽  
Fertilization Effect ◽  
Enrichment Experiments

Terrer et al. (Reports, 1 July 2016, p. 72) used meta-analysis of carbon dioxide (CO2) enrichment experiments as evidence of an interaction between mycorrhizal symbiosis and soil nitrogen availability. We challenge their database and biomass as the response metric and, hence, their recommendation that incorporation of mycorrhizae in models will improve predictions of terrestrial ecosystem responses to increasing atmospheric CO2.

scholarly journals Meta-analysis of high-latitude nitrogen-addition and warming studies imply ecological mechanisms overlooked by land models

2014 ◽  
Vol 11 (8) ◽  
pp. 12375-12414 ◽  
Author(s):  
N. J Bouskill ◽  
W. J Riley ◽  
J. Tang
Keyword(s):  
High Latitude ◽  
Field Experiments ◽  
Meta Analysis ◽  
Nitrogen Addition ◽  
Nutrient Competition ◽  
Ecosystem Responses ◽  
Nitrogen Concentrations ◽  
Ecological Mechanisms ◽  
Underlying Mechanisms ◽  
Meta Analyses

Abstract. Accurate representation of ecosystem processes in land models is crucial for reducing predictive uncertainty in energy and greenhouse gas feedbacks with the atmosphere. Here we describe an observational and modeling meta-analysis approach to benchmark land models, and apply the method to the land model CLM4.5 with two versions of belowground biogeochemistry. We focused our analysis on the above and belowground high-latitude ecosystem responses to warming and nitrogen addition, and identified mechanisms absent, or poorly parameterized in CLM4.5. While the two model versions predicted similar trajectories for soil carbon stocks following both types of perturbation, other variables (e.g., belowground respiration) differed from the observations in both magnitude and direction, indicating the underlying mechanisms are inadequate for representing high-latitude ecosystems. The observational synthesis attribute these differences to missing representations of microbial dynamics, characterization of above and belowground functional processes, and nutrient competition. We use the observational meta-analyses to discuss potential approaches to improving the current models (e.g., the inclusion of dynamic vegetation or different microbial functional guilds), however, we also raise a cautionary note on the selection of data sets and experiments to be included in a meta-analysis. For example, the concentrations of nitrogen applied in the synthesized field experiments (average =72 kg ha−1 yr−1) are many times higher than projected soil nitrogen concentrations (from nitrogen deposition and release during mineralization), which preclude a rigorous evaluation of the model responses to nitrogen perturbation. Overall, we demonstrate here that elucidating ecological mechanisms via meta-analysis can identify deficiencies in both ecosystem models and empirical experiments.

scholarly journals Biodiversity mediates the effects of stressors but not nutrients on litter decomposition

2020 ◽  
Author(s):  
Léa Beaumelle ◽  
Frederik De Laender ◽  
Nico Eisenhauer
Keyword(s):  
Environmental Change ◽  
Litter Decomposition ◽  
Ecosystem Functioning ◽  
Structural Equation ◽  
Environmental Changes ◽  
Meta Analysis ◽  
Biodiversity Loss ◽  
Nutrient Inputs ◽  
Biodiversity Change ◽  
Biodiversity Changes

AbstractUnderstanding the consequences of ongoing biodiversity changes for ecosystems is a pressing challenge. Controlled biodiversity-ecosystem function experiments with random biodiversity loss scenarios have demonstrated that more diverse communities usually provide higher levels of ecosystem functioning. However, it is not clear if these results predict the ecosystem consequences of environmental changes that cause non-random alterations in biodiversity and community composition. We synthesized 69 independent studies reporting 660 observations of the impacts of two pervasive drivers of global change (chemical stressors and nutrient enrichment) on animal and microbial decomposer diversity and litter decomposition. Using meta-analysis and structural equation modelling, we show that declines in decomposer diversity and abundance explain reduced litter decomposition in response to stressors but not to nutrients. While chemical stressors generally reduced biodiversity and ecosystem functioning, detrimental effects of nutrients occurred only at high levels of nutrient inputs. Thus, more intense environmental change does not always result in stronger responses, illustrating the complexity of ecosystem consequences of biodiversity change. Overall, these findings provide strong empirical evidence for significant real-world biodiversity-ecosystem functioning relationships when human activities decrease biodiversity. This highlights that the consequences of biodiversity change for ecosystems are nontrivial and depend on the kind of environmental change.

scholarly journals Effectiveness and Social Validity of FBAs for Youth At-Risk or With High Incidence Disabilities: A Meta-Analysis

2019 ◽  
Vol 9 (1) ◽  
pp. 41
Author(s):  
John W. Maag
Keyword(s):  
Functional Analysis ◽  
Visual Analysis ◽  
Meta Analysis ◽  
Challenging Behaviors ◽  
Social Validity ◽  
Effect Sizes ◽  
Systematic Change ◽  
Improvement Rate ◽  
High Incidence ◽  
High Incidence Disabilities

This meta-analysis examined the effectiveness and social validity of 44 functional behavioral assessment (FBA) studies using single case research designs (SCRDs) conducted with youth displaying challenging behaviors or had high incidence disabilities. Three effect sizes were calculated: standard mean difference (SMD), Tau-U, and improvement rate difference (IRD). Fisher’s conservative dual criterion (CDC), which is a statistical aid to visual analysis, was also applied. Social validity was assessed by using indicators described by Kazdin (2010). Effect sizes were in ranges indicating moderate to large effects. Approximately 71% of AB contrasts reflected CDC systematic change. However, only 44% of studies assessed social validity. There were no significant differences in effectiveness of interventions whether or not a functional analysis was conducted nor whether the controlling function was escape or attention. Results are discussed in terms of FBA implementation issues related to social validity and the necessity for conducting a functional analysis for these youth.

scholarly journals Observations of deep-sea fishes and mobile scavengers from the abyssal DISCOL experimental mining area

2019 ◽  
Vol 16 (16) ◽  
pp. 3133-3146 ◽  
Author(s):  
Jeffrey C. Drazen ◽  
Astrid B. Leitner ◽  
Sage Morningstar ◽  
Yann Marcon ◽  
Jens Greinert ◽  
...  
Keyword(s):  
Deep Sea ◽  
Fish Community ◽  
Population Level ◽  
Mining Area ◽  
Hermit Crabs ◽  
Fish Density ◽  
Environmental Drivers ◽  
Large Contribution ◽  
Ecosystem Responses ◽  
Polymetallic Nodule

Abstract. Industrial interest in deep-sea mineral extraction began decades ago, and today it is at an all-time high, accelerated by global demand for metals. Several seafloor ecosystem disturbance experiments began in the 1970s, including the Disturbance and Recolonization experiment (DISCOL) conducted in the Peru Basin in 1989. A large seafloor disturbance was created by repeatedly ploughing the seafloor over an area of ∼10.8 km2. Though a number of studies in abyssal mining regions have evaluated megafaunal biodiversity and ecosystem responses, few have included quantitative and detailed data on fishes or scavengers despite their ecological importance as top predators. We used towed camera transects (1989–1996, 2015) and baited camera data (1989–1992) to evaluate the fish community at the DISCOL site. The abyssal fish community included 16 taxa and was dominated by Ipnops meadi. Fish density was lower in ploughed habitat at 6 months and 3 years following disturbance but thereafter increased over time. Twenty-six years after disturbance there were no differences in overall total fish densities between reference and experimental areas, but the dominant fish, I. meadi, still exhibited much lower densities in ploughed habitat, likely avoiding these areas and suggesting that the fish community remains affected after decades. At the scale of industrial mining, these results could translate to population-level effects. The scavenging community was dominated by eelpouts (Pachycara spp.), hermit crabs (Probeebei mirabilis) and shrimp. The large contribution of hermit crabs appears to be unique amongst abyssal scavenger studies worldwide. The abyssal fish community at DISCOL was similar to that in the more northerly Clarion–Clipperton Zone (CCZ), though some species have only been observed at DISCOL thus far. Also, further species-level identifications are required to refine this assessment. Additional studies across the polymetallic nodule provinces of the Pacific are required to further evaluate the environmental drivers of fish density, diversity and species biogeographies. This information will be important for the development of appropriate management plans aimed at minimizing human impact from deep-sea mining.

scholarly journals A meta-analysis on environmental drivers of marine phytoplankton C : N : P

2020 ◽  
Vol 17 (11) ◽  
pp. 2939-2954 ◽  
Author(s):  
Tatsuro Tanioka ◽  
Katsumi Matsumoto
Keyword(s):  
Inorganic Nitrogen ◽  
Meta Analysis ◽  
Expression Patterns ◽  
Critical Role ◽  
Inorganic Phosphorus ◽  
Marine Phytoplankton ◽  
Environmental Drivers ◽  
Carbon Export ◽  
Elemental Stoichiometry ◽  
Eukaryotic Phytoplankton

Abstract. The elemental stoichiometry of marine phytoplankton plays a critical role in global biogeochemical cycles through its impact on nutrient cycling, secondary production, and carbon export. Although extensive laboratory experiments have been carried out over the years to assess the influence of different environmental drivers on the elemental composition of phytoplankton, a comprehensive quantitative assessment of the processes is still lacking. Here, we synthesized the responses of P:C and N:C ratios of marine phytoplankton to five major drivers (inorganic phosphorus, inorganic nitrogen, inorganic iron, irradiance, and temperature) by a meta-analysis of experimental data across 366 experiments from 104 journal articles. Our results show that the response of these ratios to changes in macronutrients is consistent across all the studies, where the increase in nutrient availability is positively related to changes in P:C and N:C ratios. We found that eukaryotic phytoplankton are more sensitive to the changes in macronutrients compared to prokaryotes, possibly due to their larger cell size and their abilities to regulate their gene expression patterns quickly. The effect of irradiance was significant and constant across all studies, where an increase in irradiance decreased both P:C and N:C. The P:C ratio decreased significantly with warming, but the response to temperature changes was mixed depending on the culture growth mode and the growth phase at the time of harvest. Along with other oceanographic conditions of the subtropical gyres (e.g., low macronutrient availability), the elevated temperature may explain why P:C is consistently low in subtropical oceans. Iron addition did not systematically change either P:C or N:C. Overall, our findings highlight the high stoichiometric plasticity of eukaryotes and the importance of macronutrients in determining P:C and N:C ratios, which both provide us insights on how to understand and model plankton diversity and productivity.

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