Integrating environmental and spatial processes in ecological community dynamics

2005 ◽  
Vol 8 (11) ◽  
pp. 1175-1182 ◽  
Author(s):  
Karl Cottenie
Keyword(s):  
Community Dynamics ◽  
Ecological Community ◽  
Spatial Processes

scholarly journals Directionality and community-level selection

2018 ◽  
Author(s):  
Guy Bunin
Keyword(s):  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Spatial Dimension ◽  
Complex Interaction ◽  
Community Level ◽  
Interaction Networks ◽  
Ecological Community ◽  
Middle Ground ◽  
Stable States ◽  
Composition Changes

Many ecological community dynamics display some degree of directionality, known as succession patterns. But complex interaction networks frequently tend to non-directional dynamics such as chaos, unless additional structures or mechanisms impose some form of, often fragile or shot-lived, directionality. We exhibit here a novel property of emergent long-lasting directionality in competitive communities, which relies on very minimal assumptions. We model communities where each species has a few strong competitive interactions, and many weak ones. We find that, at high enough diversity, the dynamics become directional, meaning that the community state can be characterized by a function that increases in time, which we call "maturity". In the presence of noise, the community composition changes toward increasingly stable and productive states. This scenario occupies a middle ground between deterministic succession and purely random species associations: there are many overlapping stable states, with stochastic transitions, that are nevertheless biased in a particular direction. When a spatial dimension is added in the form of a meta-community, higher-maturity community states are able to expand in space, replacing others by (exact or approximate) copies of themselves. This leads to community-level selection, with the same maturity function acting as fitness. Classic concepts from evolutionary dynamics provide a powerful analogy to understand this strictly ecological, community-level phenomenon of emergent directionality.

scholarly journals Ecological community dynamics: 20 years of moth sampling reveals the importance of generalists for community stability

2020 ◽  
Vol 49 ◽  
pp. 34-44
Author(s):  
Mathew Seymour ◽  
Nigel Brown ◽  
Gary R. Carvalho ◽  
Courtney Wood ◽  
Sarah Goertz ◽  
...  
Keyword(s):  
Community Dynamics ◽  
Ecological Community ◽  
Community Stability

scholarly journals Environmental filtering and spatial processes equally contributed to macroinvertebrate metacommunity dynamics in the highly urbanized river networks in Shenzhen, South China

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Zhenyuan Liu ◽  
Tingting Zhou ◽  
Yongde Cui ◽  
Zhengfei Li ◽  
Weimin Wang ◽  
...  
Keyword(s):  
South China ◽  
Community Dynamics ◽  
Environmental Filtering ◽  
Ecological Factors ◽  
Urban River ◽  
River Networks ◽  
Ecological Communities ◽  
Spatial Processes ◽  
Metacommunity Ecology ◽  
Dry Seasons

Abstract Background Disentangling the relative roles of environmental filtering and spatial processes in structuring ecological communities is a central topic in metacommunity ecology. Metacommunity ecology in the temperate river ecosystems has been well developed, while less attention has been paid to subtropical urban river networks. Here, we examined the ecological factors and seasonal difference in structuring macroinvertebrates metacommunity assembly in the subtropical urban river networks in Shenzhen, South China. Results Our results revealed that there was no significant distinction of macroinvertebrate community composition among seasons, with only the relative abundance of Mollusca and Odonata significantly differed in both wet and dry seasons. One possible explanation was that most macroinvertebrates are generally pollution-tolerant taxa characterized with nonseasonal life cycle. In addition, distance-based redundancy analysis and variation partitioning approach revealed that metacommunity was determined equally by the environmental and dispersal-related factors. Further, our results showed that, although a slight temporal variation of relative contribution, the identity and explanation power of ecological factors were different among seasons. Specifically, stronger environmental filtering structuring community dynamics was observed in the dry than wet seasons, which might be owing to higher environmental heterogeneity under a low water-flow condition. Moreover, we detected that the influence of spatial processes was stronger in the wet than dry seasons, indicating an obvious dispersal processes due to high connectivity among sites. Conclusion Overall, our results revealed that environmental and spatial factors equally explained variations of macroinvertebrate metacommunity, implying the necessity of considering dispersal-related processes structuring ecological communities in river bioassessment programs. Moreover, degraded habitat conditions and water quality were the predominant factors that affected macroinvertebrate communities, indicating the significance and feasibility of improving local abiotic conditions to sustain local biodiversity. Further, our findings revealed the importance of seasonal dynamics of these urban river networks in structuring macroinvertebrate metacommunity. Thereby, our study improves the understanding of ecological processes governing macroinvertebrate metacommunity and underlines the idea that community ecology studies should go beyond the single snapshot survey in river networks.

scholarly journals The key to complexity in interacting systems with multiple strains

2020 ◽  
Author(s):  
Erida Gjini ◽  
Sten Madec
Keyword(s):  
Community Dynamics ◽  
Multiple Scales ◽  
Environmental Gradients ◽  
Stress Gradient ◽  
Mean Field ◽  
Interaction Coefficient ◽  
Host Population ◽  
Ecological Community ◽  
And Migration ◽  
Multiple Strains

AbstractEcological community structure, persistence and stability are shaped by multiple forces, acting on multiple scales. These include patterns of resource use and limitation, spatial heterogeneities, drift and migration. Pathogen strains co-circulating in a host population are a special type of an ecological community. They compete for colonization of susceptible hosts, and sometimes interact via altered susceptibilities to co-colonization. Diversity in such pairwise interaction traits enables the multiple strains to create dynamically their niches for growth and persistence, and ‘engineer’ their common environment. How such a network of interactions with others mediates collective coexistence remains puzzling analytically and computationally difficult to simulate. Furthermore, the gradients modulating stability-complexity regimes in such multi-player systems remain poorly understood. In a recent study, we presented an analytic framework for N-type coexistence in an SIS epidemiological system with co-colonization interactions. The multi-strain complexity was reduced from O(N2) dimensions of population structure to only N equations for strain frequency evolution on a long timescale. Here, we examine the key drivers of coexistence regimes in such a system. We find the ratio of single to co-colonization μ critically determines the type of equilibrium for multi-strain dynamics. This key quantity in the model encodes a trade-off between overall transmission intensity R0 and mean interaction coefficient in strain space k. Preserving a given coexistence regime, under fixed trait variation, can only be achieved from a balance between higher competition in favourable environments, and higher cooperation in harsher environments, consistent with the stress gradient hypothesis in ecology. Multi-strain coexistence regimes are more stable when μ is small, whereas as μ increases, dynamics tends to increase in complexity. There is an intermediate ratio that maximizes the existence and stability of a unique coexistence equilibrium between strains. This framework provides a foundation for linking invariant principles in collective coexistence across biological systems, and for understanding critical shifts in community dynamics, driven by simple and random pairwise interactions but potentiated by mean-field and environmental gradients.

Toward a general theory of metacommunity ecology

2020 ◽  
pp. 195-220
Author(s):  
Dominique Gravel ◽  
François Massol
Keyword(s):  
Food Webs ◽  
Spatial Ecology ◽  
Community Dynamics ◽  
Local Community ◽  
Large Body ◽  
Spatial Dynamics ◽  
Volterra Equations ◽  
Ecological Interactions ◽  
Spatial Processes ◽  
Coexistence Mechanisms

Investigation of how spatial processes affect the maintenance of biodiversity and its geographic distribution has led to landmark contributions in community ecology. Theory has followed a logical complexification of the objects of study, with specific models at each step, from populations connected by dispersal to ecosystems connected by flows of energy and material. This large body of theory is not only diverse in the questions it addresses, and the scales and organization levels it encompasses, but also in the types of models used to represent spatial dynamics. Unfortunately, this makes it hard to establish clear, standard, quantitative predictions stemming from a coherent mathematical formalism. Here our objectives are : i) to propose a general metacommunity model that allows the investigation of spatial ecology from populations to entire food webs ; ii) use the model to review a set of principles driving coexistence in all types of metacommunities; iii) reveal how these principles constrain the spatial distribution of diversity, with a particular emphasis on species co-distribution. The model is based on the well-established representation of spatial dynamics through colonization and extinction processes. We generalize Levins’ metapopulation model to all types of ecological interactions, using a formalism akin to Lotka–Volterra equations for local community dynamics. Doing so, we revisit coexistence mechanisms proposed for competitive metacommunities, along with the assembly dynamics for spatial food webs and mutualistic interactions.

scholarly journals Assessing the efficacy of eDNA metabarcoding for measuring microbial biodiversity within forest ecosystems

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Zachary S. Ladin ◽  
Barbra Ferrell ◽  
Jacob T. Dums ◽  
Ryan M. Moore ◽  
Delphis F. Levia ◽  
...  
Keyword(s):  
Forest Canopy ◽  
Forest Ecosystems ◽  
Community Dynamics ◽  
Environmental Dna ◽  
Ecological Community ◽  
Microbial Biodiversity ◽  
Functional Roles ◽  
Extant Species ◽  
Terrestrial Environments ◽  
Novel Method

AbstractWe investigated the nascent application and efficacy of sampling and sequencing environmental DNA (eDNA) in terrestrial environments using rainwater that filters through the forest canopy and understory vegetation (i.e., throughfall). We demonstrate the utility and potential of this method for measuring microbial communities and forest biodiversity. We collected pure rainwater (open sky) and throughfall, successfully extracted DNA, and generated over 5000 unique amplicon sequence variants. We found that several taxa including Mycoplasma sp., Spirosoma sp., Roseomonas sp., and Lactococcus sp. were present only in throughfall samples. Spiroplasma sp., Methylobacterium sp., Massilia sp., Pantoea sp., and Sphingomonas sp. were found in both types of samples, but more abundantly in throughfall than in rainwater. Throughfall samples contained Gammaproteobacteria that have been previously found to be plant-associated, and may contribute to important functional roles. We illustrate how this novel method can be used for measuring microbial biodiversity in forest ecosystems, foreshadowing the utility for quantifying both prokaryotic and eukaryotic lifeforms. Leveraging these methods will enhance our ability to detect extant species, describe new species, and improve our overall understanding of ecological community dynamics in forest ecosystems.

Testing ecological release as a compensating mechanism for mass mortality in a keystone predator

2020 ◽  
Vol 637 ◽  
pp. 59-69 ◽  
Author(s):  
J Sullivan-Stack ◽  
BA Menge
Keyword(s):  
Community Dynamics ◽  
Limiting Factor ◽  
Sea Star ◽  
Top Predator ◽  
Oregon Coast ◽  
Ecological Release ◽  
Keystone Predator ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome

Top predator decline has been ubiquitous across systems over the past decades and centuries, and predicting changes in resultant community dynamics is a major challenge for ecologists and managers. Ecological release predicts that loss of a limiting factor, such as a dominant competitor or predator, can release a species from control, thus allowing increases in its size, density, and/or distribution. The 2014 sea star wasting syndrome (SSWS) outbreak decimated populations of the keystone predator Pisaster ochraceus along the Oregon coast, USA. This event provided an opportunity to test the predictions of ecological release across a broad spatial scale and determine the role of competitive dynamics in top predator recovery. We hypothesized that after P. ochraceus loss, populations of the subordinate sea star Leptasterias sp. would grow larger, more abundant, and move downshore. We based these predictions on prior research in Washington State showing that Leptasterias sp. competed with P. ochraceus for food. Further, we predicted that ecological release of Leptasterias sp. could provide a bottleneck to P. ochraceus recovery. Using field surveys, we found no clear change in density or distribution in Leptasterias sp. populations post-SSWS, and decreases in body size. In a field experiment, we found no evidence of competition between similar-sized Leptasterias sp. and P. ochraceus. Thus, the mechanisms underlying our predictions were not in effect along the Oregon coast, which we attribute to differences in habitat overlap and food availability between the 2 regions. Our results suggest that response to the loss of a dominant competitor can be unpredictable even when based in theory and previous research.

The Township, the Pregnant Girl and the Church: Community Dynamics, Gender and Social Control in Early Nineteenth-century Scotland

2019 ◽  
Vol 10 (1) ◽  
pp. 41-67
Author(s):  
Elizabeth Ritchie
Keyword(s):  
Nineteenth Century ◽  
Rural Communities ◽  
Social Control ◽  
Community Dynamics ◽  
Church Discipline ◽  
Sexual Offences ◽  
Early Nineteenth Century ◽  
Female Community ◽  
The Church ◽  
Unmarried Girl

In 1814 in a small Highland township an unmarried girl, ostracised by her neighbours, gave birth. The baby died. The legal precognition permits a forensic, gendered examination of the internal dynamics of rural communities and how they responded to threats to social cohesion. In the Scottish ‘parish state’ disciplining sexual offences was a matter for church discipline. This case is situated in the early nineteenth-century Gàidhealtachd where and when church institutions were less powerful than in the post-Reformation Lowlands, the focus of most previous research. The article shows that the formal social control of kirk discipline was only part of a complex of behavioural controls, most of which were deployed within and by communities. Indeed, Scottish communities and churches were deeply entwined in terms of personnel; shared sexual prohibitions; and in the use of shaming as a primary method of social control. While there was something of a ‘female community’, this was not unconditionally supportive of all women nor was it ranged against men or patriarchal structures.

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