scholarly journals Higher-order effects, continuous species interactions, and trait evolution shape microbial spatial dynamics

2021 ◽  
Vol 119 (1) ◽  
pp. e2020956119
Author(s):  
Anshuman Swain ◽  
Levi Fussell ◽  
William F. Fagan
Keyword(s):  
Microbial Diversity ◽  
Species Interactions ◽  
Community Dynamics ◽  
Spatial Dynamics ◽  
Higher Order ◽  
Formation Time ◽  
Community Formation ◽  
Order Effects ◽  
Disturbance Regimes ◽  
Antagonistic Interactions

The assembly and maintenance of microbial diversity in natural communities, despite the abundance of toxin-based antagonistic interactions, presents major challenges for biological understanding. A common framework for investigating such antagonistic interactions involves cyclic dominance games with pairwise interactions. The incorporation of higher-order interactions in such models permits increased levels of microbial diversity, especially in communities in which antibiotic-producing, sensitive, and resistant strains coexist. However, most such models involve a small number of discrete species, assume a notion of pure cyclic dominance, and focus on low mutation rate regimes, none of which well represent the highly interlinked, quickly evolving, and continuous nature of microbial phenotypic space. Here, we present an alternative vision of spatial dynamics for microbial communities based on antagonistic interactions—one in which a large number of species interact in continuous phenotypic space, are capable of rapid mutation, and engage in both direct and higher-order interactions mediated by production of and resistance to antibiotics. Focusing on toxin production, vulnerability, and inhibition among species, we observe highly divergent patterns of diversity and spatial community dynamics. We find that species interaction constraints (rather than mobility) best predict spatiotemporal disturbance regimes, whereas community formation time, mobility, and mutation size best explain patterns of diversity. We also report an intriguing relationship among community formation time, spatial disturbance regimes, and diversity dynamics. This relationship, which suggests that both higher-order interactions and rapid evolution are critical for the origin and maintenance of microbial diversity, has broad-ranging links to the maintenance of diversity in other systems.

scholarly journals Bridging parametric and nonparametric measures of species interactions unveils new insights of non-equilibrium dynamics

2020 ◽  
Author(s):  
Chuliang Song ◽  
Serguei Saavedra
Keyword(s):  
Species Interactions ◽  
Community Dynamics ◽  
Self Regulation ◽  
Empirical Work ◽  
Higher Order ◽  
Order Effects ◽  
Regulation Mechanism ◽  
Model Driven ◽  
Model Free ◽  
Non Equilibrium

AbstractA central theme in ecological research is to understand how species interactions contribute to community dynamics. Species interactions are the basis of parametric (model-driven) and nonpara-metric (model-free) approaches in theoretical and empirical work. However, despite their different interpretations across these approaches, these measures have occasionally been used interchangeably, limiting our opportunity to use their differences to gain new insights about ecological systems. Here, we revisit two of the most used measures across these approaches: species interactions measured as constant direct effects (typically used in parametric approaches) and local aggregated effects (typically used in nonparametric approaches). We show two fundamental properties of species interactions that cannot be revealed without bridging these definitions. First, we show that the local aggregated intraspecific effect summarizes all potential pathways through which one species impacts itself, which are likely to be negative even without any constant direct self-regulation mechanism. This property has implications for the long-held debate on how communities can be stabilized when little evidence of self-regulation has been found among higher-trophic species. Second, we show that a local aggregated interspecific effect between two species is correlated with the constant direct interspecific effect if and only if the population dynamics do not have any higher-order direct effects. This other property provides a rigorous methodology to detect direct higher-order effects in the field and experimental data. Overall, our findings illustrate a practical route to gain further insights about non-equilibrium ecological dynamics and species interactions.

Effect of propagule source on competitive ability of pasture grasses: spatial dynamics of six grasses in simulated swards

1994 ◽  
Vol 72 (1) ◽  
pp. 111-121 ◽  
Author(s):  
Roy Turkington
Keyword(s):  
Species Interactions ◽  
Competitive Ability ◽  
Community Dynamics ◽  
Spatial Dynamics ◽  
Phleum Pratense ◽  
The Other ◽  
Individual Species ◽  
Bare Ground ◽  
Lateral Expansion ◽  
Pasture Grasses

Simulated swards were constructed to investigate the potential effect of propagule source on competitive ability of pasture grasses, to monitor the spatial dynamics of pasture communities, and to assess the importance of species interactions and disturbances in community structure. The design used six species of grasses, Agrostis alba, Dactylis glomerata, Holcus lanatus, Lolium perenne, Phleum pratense, and Poa compressa, arranged in a mosaic of hexagonal patches with each hexagon being sown with one species of grass or left as bare ground and being surrounded by each of the other species. Three swards were constructed, one using plant material collected from an 11-year-old pasture, one with material from an adjacent 49-year-old pasture, and the third from material grown from seed. After 20 months of interaction across the interfaces between the patches, the swards were destructively harvested above ground and the contents of each hexagon separated into species. Grasses from four different-aged origins, including the three above, were also grown in plots without any neighbours for 16 months. Each species had its own individual behavior: Agrostis and Phleum from the older pastures were the better invaders, Holcus and Poa were the poorest, and Phleum from the oldest community was the most resistant to lateral expansion of the other species. In a number of cases the grasses from the older pastures, but never from the seeded bed, invaded other patches of grass as readily as they expanded into bare ground. The total aboveground community biomass showed a nonsignificant decline with age, and the community as a whole became more open to lateral expansion by individual species. No results were obtained to support the cyclic regeneration hypothesis of Watt; the functional equivalence arguments of Aarssen may be more appropriate in this fine-grained pasture environment. Key words: community dynamics, invasion, pasture, competitive effect and response, disturbance, patches.

scholarly journals Spatial microbial community dynamics using a continuous species interaction model

2021 ◽  
Author(s):  
Anshuman Swain ◽  
Levi Fussell ◽  
William F Fagan
Keyword(s):  
Microbial Community ◽  
Microbial Communities ◽  
Mutation Rate ◽  
Community Dynamics ◽  
Evolutionary Game ◽  
Species Interaction ◽  
Higher Order ◽  
Community Formation ◽  
Continuous Space ◽  
Wide Range

AbstractComprehending the assembly and maintenance of microbial diversity in natural communities, despite the abundance of antagonistic interactions, is a major problem of interest in biology. A common framework to study the problem is through cyclic dominance games over pairwise interactions. Recent papers incorporating higher-order interactions in these models have successfully explained high diversity of microbes, especially in communities where antibiotic producing, sensitive, and resistant strains co-exist. But most of these models are based on a small number of discrete species, assume a notion of pure cyclic dominance, and focus on low mutation rate regimes, none of which best represents the highly interlinked, quickly evolving and continuous nature of microbial phenotypic space. Here, we present a model of species in a continuous space, with mutual higher order interactions, to examine the assembly and stability of microbial communities. Specifically, we focus on toxin production, vulnerability, and inhibition among the simulated species. We observe intricate interaction between certain parameters that generates highly divergent patterns of diversity and spatial community dynamics. We find that spatial properties are better predicted by species interaction constraints rather than mobility, and that community formation time, mobility, and mutation rate best explain the patterns of diversity.Significance StatementUnderstanding the assembly and maintenance of diverse microbial communities in nature is a question of great interest to theoretical biologists. Previous works, utilizing evolutionary game theory and other techniques, have explained the role of higher order interactions for the coexistence of diverse microbes in different kinds of environments. But these models are usually based on a small number of discrete species and low//no mutation rate, which is not how many natural microbial communities function. In this work, we explore a new framework which incorporates a continuous species model along with a wide range of mutation rates to comprehend the process of microbial community formation.

scholarly journals Habitat loss alters effects of intransitive higher-order competition on biodiversity: a new metapopulation framework

2020 ◽  
Vol 287 (1940) ◽  
pp. 20201571
Author(s):  
Yinglin Li ◽  
Daniel Bearup ◽  
Jinbao Liao
Keyword(s):  
Habitat Loss ◽  
Species Interactions ◽  
Species Coexistence ◽  
Interaction Model ◽  
Higher Order ◽  
Community Diversity ◽  
Rapid Decline ◽  
Order Effects ◽  
Vital Rates ◽  
Model Framework

Recent studies have suggested that intransitive competition, as opposed to hierarchical competition, allows more species to coexist. Furthermore, it is recognized that the prevalent paradigm, which assumes that species interactions are exclusively pairwise, may be insufficient. More importantly, whether and how habitat loss, a key driver of biodiversity loss, can alter these complex competition structures (and therefore species coexistence) remain unclear. We thus present a new, simple yet comprehensive metapopulation framework that can account for any competition pattern and more complex higher-order interactions (HOIs) among species. We find that competitive intransitivity increases community diversity and that HOIs generally enhance this effect. Essentially, intransitivity promotes species richness by preventing the dominance of a few species, unlike the hierarchical competition, while HOIs facilitate species coexistence through stabilizing community fluctuations. However, variation in species’ vital rates and habitat loss can weaken or even reverse such higher-order effects, as their interaction can lead to a more rapid decline in competitive intransitivity under HOIs. Thus, it is essential to correctly identify the most appropriate interaction model for a given system before models are used to inform conservation efforts. Overall, our simple model framework provides a more parsimonious explanation for biodiversity maintenance than the existing theory.

Time after time: support for memory accounts of temporal preparation.

2019 ◽  
Author(s):  
Joe Butler ◽  
Samuel Ngabo ◽  
Marcus Missal
Keyword(s):  
Response Times ◽  
Reaction Times ◽  
Evidence Base ◽  
Higher Order ◽  
Order Effects ◽  
Previous Trial ◽  
Adaptive Responses ◽  
Temporal Preparation ◽  
Subsequent Trial ◽  
Higher Order Effects

Complex biological systems build up temporal expectations to facilitate adaptive responses to environmental events, in order to minimise costs associated with incorrect responses, and maximise the benefits of correct responses. In the lab, this is clearly demonstrated in tasks which show faster response times when the period between warning (S1) and target stimulus (S2) on the previous trial was short and slower when the previous trial foreperiod was long. The mechanisms driving such higher order effects in temporal preparation paradigms are still under debate, with key theories proposing that either i) the foreperiod leads to automatic modulation of the arousal system which influences responses on the subsequent trial, or ii) that exposure to a foreperiod results in the creation of a memory trace which is used to guide responses on the subsequent trial. Here we provide data which extends the evidence base for the memory accounts, by showing that previous foreperiod exposures are cumulative with reaction times shortening after repeated exposures; whilst also demonstrate that the higher order effects associated with a foreperiod remain active for several trials.

scholarly journals Responsible innovation, anticipation and responsiveness: case studies of algorithms in decision support in justice and security, and an exploration of potential, unintended, undesirable, higher-order effects

AI and Ethics ◽  
2021 ◽  
Author(s):  
Marc Steen ◽  
Tjerk Timan ◽  
Ibo van de Poel
Keyword(s):  
Decision Support ◽  
Case Studies ◽  
Personal Data ◽  
Higher Order ◽  
Popular Media ◽  
Responsible Innovation ◽  
Order Effects ◽  
Key Dimensions ◽  
Higher Order Effects

AbstractThe collection and use of personal data on citizens in the design and deployment of algorithms in the domain of justice and security is a sensitive topic. Values like fairness, autonomy, privacy, accuracy, transparency and property are at stake. Negative examples of algorithms that propagate or exacerbate biases, inequalities or injustices have received ample attention, both in academia and in popular media. To supplement this view, we will discuss two positive examples of Responsible Innovation (RI): the design and deployment of algorithms in decision support, with good intentions and careful approaches. We then explore potential, unintended, undesirable, higher-order effects of algorithms—effects that may occur despite good intentions and careful approaches. We do that by engaging with anticipation and responsiveness, two key dimensions of Responsible Innovation. We close the paper with proposing a framework and a series of tentative recommendations to promote anticipation and responsiveness in the design and deployment of algorithms in decision support in the domain of justice and security.

scholarly journals Moving apart together: co-movement of a symbiont community and their ant host, and its importance for community assembly

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
T. Parmentier ◽  
R. Claus ◽  
F. De Laender ◽  
D. Bonte
Keyword(s):  
Community Assembly ◽  
Species Interactions ◽  
Spatial Dynamics ◽  
Joint Movement ◽  
Red Wood Ants ◽  
Ant Nests ◽  
Mobile Species ◽  
Directional Movement ◽  
Wood Ants ◽  
Red Wood Ant

Abstract Background Species interactions may affect spatial dynamics when the movement of one species is determined by the presence of another one. The most direct species-dependence of dispersal is vectored, usually cross-kingdom, movement of immobile parasites, diseases or seeds by mobile animals. Joint movements of species should, however, not be vectored by definition, as even mobile species are predicted to move together when they are tightly connected in symbiont communities. Methods We studied concerted movements in a diverse and heterogeneous community of arthropods (myrmecophiles) associated with red wood ants. We questioned whether joint-movement strategies eventually determine and speed-up community succession. Results We recorded an astonishingly high number of obligate myrmecophiles outside red wood ant nests. They preferentially co-moved with the host ants as the highest densities were found in locations with the highest density of foraging red wood ants, such as along the network of ant trails. These observations suggest that myrmecophiles resort to the host to move away from the nest, and this to a much higher extent than hitherto anticipated. Interestingly, functional groups of symbionts displayed different dispersal kernels, with predatory myrmecophiles moving more frequently and further from the nest than detritivorous myrmecophiles. We discovered that myrmecophile diversity was lower in newly founded nests than in mature red wood ant nests. Most myrmecophiles, however, were able to colonize new nests fast suggesting that the heterogeneity in mobility does not affect community assembly. Conclusions We show that co-movement is not restricted to tight parasitic, or cross-kingdom interactions. Movement in social insect symbiont communities may be heterogeneous and functional group-dependent, but clearly affected by host movement. Ultimately, this co-movement leads to directional movement and allows a fast colonisation of new patches, but not in a predictable way. This study highlights the importance of spatial dynamics of local and regional networks in symbiont metacommunities, of which those of symbionts of social insects are prime examples.

scholarly journals The importance of species interactions in eco-evolutionary community dynamics under climate change

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Anna Åkesson ◽  
Alva Curtsdotter ◽  
Anna Eklöf ◽  
Bo Ebenman ◽  
Jon Norberg ◽  
...  
Keyword(s):  
Climate Change ◽  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Negative Impact ◽  
Trophic Levels ◽  
Temperature Dependent ◽  
Modeling Framework ◽  
Impact Of Climate Change ◽  
The Impact

AbstractEco-evolutionary dynamics are essential in shaping the biological response of communities to ongoing climate change. Here we develop a spatially explicit eco-evolutionary framework which features more detailed species interactions, integrating evolution and dispersal. We include species interactions within and between trophic levels, and additionally, we incorporate the feature that species’ interspecific competition might change due to increasing temperatures and affect the impact of climate change on ecological communities. Our modeling framework captures previously reported ecological responses to climate change, and also reveals two key results. First, interactions between trophic levels as well as temperature-dependent competition within a trophic level mitigate the negative impact of climate change on biodiversity, emphasizing the importance of understanding biotic interactions in shaping climate change impact. Second, our trait-based perspective reveals a strong positive relationship between the within-community variation in preferred temperatures and the capacity to respond to climate change. Temperature-dependent competition consistently results both in higher trait variation and more responsive communities to altered climatic conditions. Our study demonstrates the importance of species interactions in an eco-evolutionary setting, further expanding our knowledge of the interplay between ecological and evolutionary processes.

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