scholarly journals The effect of periodic disturbances and carrying capacity on the significance of selection and drift in complex bacterial communities

2021 ◽  
Author(s):  
Madeleine Stenshorne Gundersen ◽  
Ian Morelan ◽  
Tom Andersen ◽  
Ingrid Bakke ◽  
Olav Vadstein
Keyword(s):  
Community Assembly ◽  
Carrying Capacity ◽  
Community Dynamics ◽  
Temporal Dynamics ◽  
Rate Of Change ◽  
Stochastic Effects ◽  
Periodic Disturbances ◽  
Period 2 ◽  
Biomass Loss ◽  
Ecological Drift

Understanding how periodical disturbances affect the community assembly processes is vital for predicting temporal dynamics in microbial communities. The effect of dilutions as disturbances are poorly understood. We used a marine bacterial community to investigate the effect of disturbance (+/-) and carrying capacity (high/low) over 50 days in a dispersal-limited 2x2 factorial crossover study in triplicates. The community's disturbance regime was crossed halfway. We modelled the rate of change in community composition between replicates and used this rate to quantify selection and ecological drift. The disturbed communities increased in Bray-Curtis similarity with 0.011+/-0.0045 (Period 1) and 0.0092+/-0.0080 day-1 (Period 2), indicating that selection dominated community assembly. The undisturbed communities decreased in similarity at a rate of -0.015+/-0.0038 day-1 in Period 1 and were stable in Period 2 at 0.00050+/-0.0040 day-1, suggesting drift structured community assembly. Interestingly, carrying capacity had minor effects on community dynamics. This study is the first to show that stochastic effects are suppressed by periodical disturbances resulting in exponential growth periods due to density-independent biomass loss and resource input. The increased contribution of selection as a response to disturbances implies that ecosystem prediction is achievable.

scholarly journals The effect of periodic disturbances and carrying capacity on the significance of selection and drift in complex bacterial communities

2021 ◽  
Vol 1 (1) ◽  
Author(s):  
Madeleine S. Gundersen ◽  
Ian Arthur Morelan ◽  
Tom Andersen ◽  
Ingrid Bakke ◽  
Olav Vadstein
Keyword(s):  
Carrying Capacity ◽  
Bacterial Communities ◽  
Periodic Disturbances

scholarly journals Lake sedimentary DNA to reveal long-term changes in aquatic biodiversity and ecosystem functioning

2021 ◽  
Vol 4 ◽  
Author(s):  
Isabelle Domaizon
Keyword(s):  
Community Dynamics ◽  
Temporal Dynamics ◽  
Critical Research ◽  
Aquatic Biodiversity ◽  
Biological Variables ◽  
Long Term Changes ◽  
Research Questions ◽  
Population And Community Dynamics ◽  
Emerging Topics

The emergence of molecular analyses based on the sequencing of sedimentary DNA has opened up many new areas of inquiry in paleolimnology. DNA preserved in sediments (SedDNA) offers the possibility to consider taxa that were traditionally not accessible because they do not leave distinct morphological fossils. Recent applications that considered a diversity of biological groups (including bacteria, protists, zooplankton, fish) illustrate how efficiently SedDNA-based methods complement both classical paleolimnology proxies and limnological data. The knowledge gained from this approach is very diverse in scope, ranging from quantifying natural variability in population and community dynamics to understanding how these biological variables respond to anthropogenic disturbances and climatic change. The use of lake sedimentary DNA to track long-term changes in aquatic biota is a rapidly advancing field of research. Based on recent applications, this presentation illustrates (i) the potential and challenges associated with the study of SedDNA to address critical research questions in lacustrine ecology (ii) the main methodological precautions to be taken into account for implementing these types of DNA analyses (i.e. best practices) and (iii) the emerging topics that could be addressed using sedimentary DNA, in particular to reconstruct the temporal dynamics of lacustrine biodiversity.

When can we distinguish between neutral and non-neutral processes in community dynamics under ecological drift?

2009 ◽  
Vol 12 (9) ◽  
pp. 909-919 ◽  
Author(s):  
Lasse Ruokolainen ◽  
Esa Ranta ◽  
Veijo Kaitala ◽  
Mike S. Fowler
Keyword(s):  
Community Dynamics ◽  
Neutral Processes ◽  
Ecological Drift

scholarly journals Comparative phylogeography of oceanic archipelagos: Hotspots for inferences of evolutionary process

2016 ◽  
Vol 113 (29) ◽  
pp. 7986-7993 ◽  
Author(s):  
Kerry L. Shaw ◽  
Rosemary G. Gillespie
Keyword(s):  
Community Structure ◽  
Community Assembly ◽  
Community Dynamics ◽  
Evolutionary Process ◽  
Comparative Phylogeography ◽  
Origin And Evolution ◽  
Species Radiation ◽  
Remote Island ◽  
Oceanic Archipelagos ◽  
Shed Light

Remote island archipelagos offer superb opportunities to study the evolution of community assembly because of their relatively young and simple communities where speciation contributes to the origin and evolution of community structure. There is great potential for common phylogeographic patterns among remote archipelagos that originate through hotspot volcanism, particularly when the islands formed are spatially isolated and linearly arranged. The progression rule is characterized by a phylogeographic concordance between island age and lineage age in a species radiation. Progression is most likely to arise when a species radiation begins on an older island before the emergence of younger islands of a hotspot archipelago. In the simplest form of progression, colonization of younger islands as they emerge and offer appropriate habitat, is coincident with cladogenesis. In this paper, we review recent discoveries of the progression rule on seven hotspot archipelagos. We then discuss advantages that progression offers to the study of community assembly, and insights that community dynamics may offer toward understanding the evolution of progression. We describe results from two compelling cases of progression where the mosaic genome may offer insights into contrasting demographic histories that shed light on mechanisms of speciation and progression on remote archipelagos.

scholarly journals Temporal Dynamics of South End Tidal Creek (Sapelo Island, Georgia) Bacterial Communities

2008 ◽  
Vol 75 (4) ◽  
pp. 1058-1064 ◽  
Author(s):  
Emily Kara ◽  
Ashley Shade
Keyword(s):  
Bacterial Community ◽  
Community Composition ◽  
Community Dynamics ◽  
Tidal Creek ◽  
Temporal Dynamics ◽  
Bacterial Community Composition ◽  
High Tide ◽  
Cycle Period ◽  
Sapelo Island ◽  
End Tidal

ABSTRACT Bacterial community dynamics in South End tidal creek, Sapelo Island, GA, were studied over a 74-h, five-tidal-cycle period. Observations were made hourly for the first consecutive 24 hours, every 3 hours on the second day, and every 6 hours on the third day. Tide most strongly influenced bacterial community composition (high-tide versus low-tide community analysis of similarities, R = 0.41, P < 0.03). Dissolved oxygen concentration and conductivity were important proximate drivers. However, after accounting for tide and environmental variables colinear with tide, cumulative time became more important in describing community variation. In-stream physical processes, including particulate suspension and sedimentation, may explain tide-associated trends in the bacterial community composition observed.

scholarly journals Quantifying Community Dynamics of Nitrifiers in Functionally Stable Reactors

2007 ◽  
Vol 74 (1) ◽  
pp. 286-293 ◽  
Author(s):  
Lieven Wittebolle ◽  
Han Vervaeren ◽  
Willy Verstraete ◽  
Nico Boon
Keyword(s):  
Dominant Species ◽  
Municipal Wastewater ◽  
Community Dynamics ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Batch Reactor ◽  
Dominant Role ◽  
Treatment Plant ◽  
Sampling Period ◽  
Rate Of Change ◽  
Municipal Wastewater Treatment

ABSTRACT A sequential batch reactor (SBR) and a membrane bioreactor (MBR) were inoculated with the same sludge from a municipal wastewater treatment plant, supplemented with ammonium, and operated in parallel for 84 days. It was investigated whether the functional stability of the nitrification process corresponded with a static ammonia-oxidizing bacterial (AOB) community. The SBR provided complete nitrification during nearly the whole experimental run, whereas the MBR showed a buildup of 0 to 2 mg nitrite-N liter−1 from day 45 until day 84. Based on the denaturing gradient gel electrophoresis profiles, two novel approaches were introduced to characterize and quantify the community dynamics and interspecies abundance ratios: (i) the rate of change [Δ t (week)] parameter and (ii) the Pareto-Lorenz curve distribution pattern. During the whole sampling period, it was observed that neither of the reactor types maintained a static microbial community and that the SBR evolved more gradually than the MBR, particularly with respect to AOB (i.e., average weekly community changes of 12.6% ± 5.2% for the SBR and 24.6% ± 14.3% for the MBR). Based on the Pareto-Lorenz curves, it was observed that only a small group of AOB species played a numerically dominant role in the nitritation of both reactors, and this was true especially for the MBR. The remaining less dominant species were speculated to constitute a reserve of AOB which can proliferate to replace the dominant species. The value of these parameters in terms of tools to assist the operation of activated-sludge systems is discussed.

scholarly journals Seasonal temporal dynamics of marine protists communities in tidally mixed coastal waters

2021 ◽  
Author(s):  
Mariarita Caracciolo ◽  
Fabienne Rigaut-Jalabert ◽  
Sarah Romac ◽  
Frédéric Mahé ◽  
Samuel Forsans ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Temporal Dynamics ◽  
Seasonal Pattern ◽  
Temporal Structure ◽  
Species Abundance ◽  
Temporal Correlation ◽  
Tidal Mixing ◽  
Taxonomic Resolution ◽  
English Channel ◽  
Turnover Rates

AbstractMajor seasonal community reorganizations and associated biomass variations are landmarks of plankton ecology. However, the processes determining marine species and community turnover rates have not been fully elucidated so far. Here, we analyse patterns of planktonic protist community succession in temperate latitudes, based on quantitative taxonomic data from both microscopy counts and ribosomal DNA metabarcoding from plankton samples collected biweekly over 8 years (2009-2016) at the SOMLIT-Astan station (Roscoff, Western English Channel). Considering the temporal structure of community dynamics (creating temporal correlation), we elucidated the recurrent seasonal pattern of the dominant species and OTUs (rDNA-derived taxa) that drive annual plankton successions. The use of morphological and molecular analyses in combination allowed us to assess absolute species abundance while improving taxonomic resolution, and revealed a greater diversity. Overall, our results underpinned a protist community characterised by a seasonal structure, which is supported by the dominant OTUs. We detected that some were partly benthic as a result of the intense tidal mixing typical of the French coasts in the English Channel. While the occurrence of these microorganisms is driven by the physical and biogeochemical conditions of the environment, internal community processes, such as the complex network of biotic interactions, also play a key role in shaping protist communities.

scholarly journals Multiple ecological processes jointly drive the soil microbial community assembly in subalpine coniferous forests

2018 ◽  
Author(s):  
Pengyu Zhao ◽  
Jiabing Bao ◽  
Xue Wang ◽  
Yi Liu ◽  
Cui Li ◽  
...  
Keyword(s):  
Microbial Community ◽  
Stochastic Processes ◽  
Community Assembly ◽  
Soil Microbial Community ◽  
Analytical Methods ◽  
Community Dynamics ◽  
Coniferous Forests ◽  
Ecological Processes ◽  
Soil Microbial ◽  
Microbial Community Assembly

The mechanisms underlying community dynamics, which govern the complicated biogeographical patterns of microbes, have long been a research hotspot in community ecology. However, the mixing of multiple ecological processes and the one-sidedness of analytical methods make it difficult to draw inferences about the community assembly mechanisms. In this study, we investigated the driving forces of the soil microbial community in subalpine coniferous forests of the Loess Plateau in Shanxi, China, by integrating multiple analytical methods. The results of the null model demonstrated that deterministic processes (especially interspecific relationships) were the main driving force of the soil microbial community assembly in this study area, relative to stochastic processes. Based on the results of the net relatedness index (NRI) and nearest taxon index (NTI), we inferred that historical and evolutionary factors, such as climate change and local diversification, may have similar effects on microbial community structure based on the climatic niche conservatism. Based on the results of a functional traits analysis, we found that the effects of ongoing ecological processes on the microbial community assembly varied among sites. Therefore, the functional structures seemed to be more related to ongoing ecological processes, whereas the phylogenetic structures seemed to be more related to historical and evolutionary factors, as well as the tradeoff between deterministic and stochastic processes. The functional and phylogenetic structures were mainly shaped by different ecological processes. By integrating multiple ecological processes, our results provide more details of the mechanisms driving the community assembly

scholarly journals Ecosystem size-induced environmental fluctuations affect the temporal dynamics of community assembly mechanisms

2022 ◽  
Author(s):  
Raven L Bier ◽  
Máté Vass ◽  
Anna J Székely ◽  
Silke Langenheder
Keyword(s):  
Community Assembly ◽  
Temporal Dynamics ◽  
Bacterial Community Composition ◽  
Dispersal Limitation ◽  
Priority Effects ◽  
Environmental Fluctuation ◽  
Species Sorting ◽  
Ecosystem Size ◽  
Environmental Fluctuations ◽  
Over Time

Understanding processes that determine community membership and abundance is important for many fields from theoretical community ecology to conservation. However, spatial community studies are often conducted only at a single timepoint despite the known influence of temporal variability on community assembly processes. Here we used a spatiotemporal study to determine how environmental fluctuation differences induced by mesocosm volumes (larger volumes were more stable) influence assembly processes of aquatic bacterial metacommunities along a press disturbance gradient. By combining path analysis and network approaches, we found mesocosm size categories had distinct relative influences of assembly process and environmental factors that determined spatiotemporal bacterial community composition, including dispersal and species sorting by conductivity. These processes depended on, but were not affected proportionately by, mesocosm size. Low fluctuation, large mesocosms primarily developed through the interplay of species sorting that became more important over time and transient priority effects as evidenced by more time-delayed associations. High fluctuation, small mesocosms had regular disruptions to species sorting and greater importance of ecological drift and dispersal limitation indicated by lower richness and higher taxa replacement. Together, these results emphasize that environmental fluctuations influence ecosystems over time and its impacts are modified by biotic properties intrinsic to ecosystem size.

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