Stability of ecosystems enhanced by species-interaction constraints

Significant reductions in the water volume of shallow lakes impose a restriction on species segregation promoting more interactions in the trophic relationships. The diets of three closely related zooplanktivorous silversides belonging to the Atherinopsidae species flock of lake Chapala , Mexico, were analyzed at two sites (Chirostoma jordani, C. labarcae, and C. consocium). Diets were described in critical shallow (August 2000) and volume recovery conditions (August 2005). Diets included mainly cladocerans (Bosmina, Ceriodaphnia, and Daphnia) and copepods (Cyclops). A significant difference in diets was detected when comparing years (MRPP analysis, A = 0.22, p < 0.0001) and sites at different years (MRPP analysis, A = 0.17, p = 0.004). According to niche breadth mean values, species were classified as specialized and intermediate feeders. In shallow conditions, the small range of niche breadth (1.72 to 3.64) and high diet overlap values (D = 0.64, L = 8.62) indicated a high potential for interspecific exploitative interaction. When the lake volume recovered, an increase in the niche breadth range (1.04 to 4.96) and low niche overlap values (D = 0.53, L = 2.32) indicated a reduction of the species interaction. The Mann-Whitney U-test supported this pattern by showing a significant difference between years for niche overlap (p = 0.006). The increased interaction during the low volume suggests alternative segregation in life-history variations and other niche dimensions such as spatial or temporal distribution.

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Assembly processes of gastropod community change with horizontal and vertical zonation in ancient Lake Ohrid: a metacommunity speciation perspective

Biogeosciences ◽

10.5194/bg-13-2901-2016 ◽

2016 ◽

Vol 13 (10) ◽

pp. 2901-2911 ◽

Cited By ~ 9

Author(s):

Torsten Hauffe ◽

Christian Albrecht ◽

Thomas Wilke

Keyword(s):

Community Composition ◽

Community Assembly ◽

Environmental Filtering ◽

Dispersal Limitation ◽

Species Interaction ◽

Relative Importance ◽

Lake Depth ◽

Ancient Lake ◽

Lake Ohrid ◽

Speciation Model

Abstract. The Balkan Lake Ohrid is the oldest and most diverse freshwater lacustrine system in Europe. However, it remains unclear whether species community composition, as well as the diversification of its endemic taxa, is mainly driven by dispersal limitation, environmental filtering, or species interaction. This calls for a holistic perspective involving both evolutionary processes and ecological dynamics, as provided by the unifying framework of the “metacommunity speciation model”.The current study used the species-rich model taxon Gastropoda to assess how extant communities in Lake Ohrid are structured by performing process-based metacommunity analyses. Specifically, the study aimed (1) to identifying the relative importance of the three community assembly processes and (2) to test whether the importance of these individual processes changes gradually with lake depth or discontinuously with eco-zone shifts.Based on automated eco-zone detection and process-specific simulation steps, we demonstrated that dispersal limitation had the strongest influence on gastropod community composition. However, it was not the exclusive assembly process, but acted together with the other two processes – environmental filtering and species interaction. The relative importance of the community assembly processes varied both with lake depth and eco-zones, though the processes were better predicted by the latter.This suggests that environmental characteristics have a pronounced effect on shaping gastropod communities via assembly processes. Moreover, the study corroborated the high importance of dispersal limitation for both maintaining species richness in Lake Ohrid (through its impact on community composition) and generating endemic biodiversity (via its influence on diversification processes). However, according to the metacommunity speciation model, the inferred importance of environmental filtering and biotic interaction also suggests a small but significant influence of ecological speciation. These findings contribute to the main goal of the Scientific Collaboration on Past Speciation Conditions in Lake Ohrid (SCOPSCO) deep drilling initiative – inferring the drivers of biotic evolution – and might provide an integrative perspective on biological and limnological dynamics in ancient Lake Ohrid.

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Facilitation costs and benefits function simultaneously on stress gradients for animals

Proceedings of The Royal Society B Biological Sciences ◽

10.1098/rspb.2018.0983 ◽

2018 ◽

Vol 285 (1885) ◽

pp. 20180983 ◽

Cited By ~ 7

Author(s):

Olivier Dangles ◽

Mario Herrera ◽

Carlos Carpio ◽

Christopher J. Lortie

Keyword(s):

Conceptual Framework ◽

Environmental Conditions ◽

Species Interactions ◽

Stress Gradient ◽

Species Interaction ◽

Positive Interactions ◽

Costs And Benefits ◽

Strong Basis ◽

Stress Gradients ◽

High Resource

Understanding the variation in species interactions along environmental stress gradients is crucial for making robust ecological predictions about community responses to changing environmental conditions. The facilitation–competition framework has provided a strong basis for predictions (e.g. the stress-gradient hypothesis, SGH), yet the mechanisms behind patterns in animal interactions on stress gradients are poorly explored in particular for mobile animals. Here, we proposed a conceptual framework modelling changes in facilitation costs and benefits along stress gradients and experimentally tested this framework by measuring fitness outcomes of benefactor–beneficiary interactions across resource quality levels. Three arthropod consumer models from a broad array of environmental conditions were used including aquatic detritivores, potato moths and rainforest carrion beetles. We detected a shift to more positive interactions at increasing levels of stress thereby supporting the application of the SGH to mobile animals. While most benefactors paid no significant cost of facilitation, an increase in potato moth beneficiary's growth at high resource stress triggered costs for benefactors. This study is the first to experimentally show that both costs and benefits function simultaneously on stress gradients for animals. The proposed conceptual framework could guide future studies examining species interaction outcomes for both animals and plants in an increasingly stressed world.

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Permanence of a general discrete-time two-species-interaction model with nonlinear per-capita growth rates

Discrete & Continuous Dynamical Systems - B ◽

10.3934/dcdsb.2013.18.2123 ◽

2013 ◽

Vol 18 (8) ◽

pp. 2123-2142 ◽

Cited By ~ 2

Author(s):

Yun Kang ◽

Keyword(s):

Discrete Time ◽

Growth Rates ◽

Interaction Model ◽

Species Interaction ◽

Per Capita

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Dynamic population stage structure due to juvenile–adult asymmetry stabilizes complex ecological communities

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2023709118 ◽

2021 ◽

Vol 118 (21) ◽

pp. e2023709118

Author(s):

André M. de Roos

Keyword(s):

Self Regulation ◽

Interaction Network ◽

Population Level ◽

Stage Structure ◽

Current Theory ◽

Species Interaction ◽

Interaction Matrix ◽

Foraging Efficiency ◽

Ecological Communities ◽

The Stability

Natural ecological communities are diverse, complex, and often surprisingly stable, but the mechanisms underlying their stability remain a theoretical enigma. Interactions such as competition and predation presumably structure communities, yet theory predicts that complex communities are stable only when species growth rates are mostly limited by intraspecific self-regulation rather than by interactions with resources, competitors, and predators. Current theory, however, considers only the network topology of population-level interactions between species and ignores within-population differences, such as between juvenile and adult individuals. Here, using model simulations and analysis, I show that including commonly observed differences in vulnerability to predation and foraging efficiency between juvenile and adult individuals results in up to 10 times larger, more complex communities than observed in simulations without population stage structure. These diverse communities are stable or fluctuate with limited amplitude, although in the model only a single basal species is self-regulated, and the population-level interaction network is highly connected. Analysis of the species interaction matrix predicts the simulated communities to be unstable but for the interaction with the population-structure subsystem, which completely cancels out these instabilities through dynamic changes in population stage structure. Common differences between juveniles and adults and fluctuations in their relative abundance may hence have a decisive influence on the stability of complex natural communities and their vulnerability when environmental conditions change. To explain community persistence, it may not be sufficient to consider only the network of interactions between the constituting species.

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In vitrocommunity synergy between bacterial soil isolates can be facilitated by pH stabilisation of the environment

10.1101/347039 ◽

2018 ◽

Author(s):

Jakob Herschend ◽

Klaus Koren ◽

Henriette L. Røder ◽

Asker Brejnrod ◽

Michael Kühl ◽

...

Keyword(s):

Metabolic Activity ◽

Local Environment ◽

Single Species ◽

Species Interaction ◽

Individual Species ◽

Community Members ◽

Community Interactions ◽

Community Growth ◽

Over Time

AbstractComposition and development of naturally occurring microbial communities is defined by a complex interplay between the community and the surrounding environment and by interactions between community members. Intriguingly, these interactions can in some cases cause community synergies where the community is able to outperform it single species constituents. However, the underlying mechanisms driving community interactions are often unknown and difficult to identify due to high community complexity. Here we show how pH stabilisation of the environment through the metabolic activity of specific community members acts as a positive inter-species interaction drivingin vitrocommunity synergy in a model consortium of four co-isolated soil bacteria:Microbacterium oxydans,Xanthomonas retroflexus,Stenotrophomonas rhizophilaandPaenibacillus amylolyticus. Using micro-sensor pH measurements to show how individual species change the local pH micro-environment, and how co-cultivation leads to a stabilised pH regime over time. Specifically,in vitroacid production fromPaenibacillus amylolyticusand alkali production primarily fromXanthomonas retroflexuslead to an overall pH stabilisation of the local environment over time, which in turn resulted in enhanced community growth. This specific type of interspecies interaction was found to be highly dependent on media type and media concentration, however similar pH drift from the individual species could be observed across media variants.ImportanceWe show thatin vitrometabolic activity of individual members of a synthetic, co- isolated model community presenting community synergistic growth arises through the inter-species interaction of pH stabilization of the community micro-environment. The observed inter-species interaction is highly media specific and most pronounced under high nutrient availability. This adds to the growing diversity of identified community interactions leading to enhanced community growth.

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