Within-species trait diversity reorganizes consumer competitive hierarchy and prey community structure in an experimental microbial ecosystem

Phenotypic trait differences between species are expected to play an essential role in community assembly. However, the magnitude of trait variability between individuals of the same species is increasingly recognized to have significant ecological effects, including maintaining species diversity. Here we ask how within-species trait diversity at the consumer trophic level affects consumer competition and prey community dynamics at lower trophic levels in an experimental microbial ecosystem consisting of ciliated protozoa, nematode worms, and bacterial prey. Although the nematode had an inherent competitive advantage and rapidly excluded ciliates with low trait variance, we found that high trait variance in the ciliate inverted the consumer hierarchy, ultimately excluding the nematode. Competition between the high trait variance ciliate and the nematode altered the temporal trajectories of individual prey species in non-additive ways, mediated by prey traits related to growth rate and defense. We performed pairwise co-cultures with each consumer and prey species and found that high trait variance in the ciliate increased the mean prey consumption rate over the low trait variance ciliate, which led to an increase in selective feeding in the presence of all prey species. Overall, our results are consistent with predictions from the coexistence theory framework and are compelling evidence that intraspecific trait diversity in consumer species 1) modulates competitive differences between species at higher trophic levels and 2) generates cascading effects on the community composition at lower trophic levels.

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Diurnal Changes in Hypoxia Shape Predator-Prey Interaction in a Bird-Fish System

Frontiers in Ecology and Evolution ◽

10.3389/fevo.2021.619193 ◽

2021 ◽

Vol 9 ◽

Author(s):

Juliane Lukas ◽

Felix Auer ◽

Tobias Goldhammer ◽

Jens Krause ◽

Pawel Romanczuk ◽

...

Keyword(s):

Prey Species ◽

Abiotic Factors ◽

Bird Species ◽

Behavioral Flexibility ◽

Trophic Levels ◽

Activity Levels ◽

Diurnal Changes ◽

Predator Prey ◽

Cascading Effects ◽

Oxygen Levels

Animals often face changing environments, and behavioral flexibility allows them to rapidly and adaptively respond to abiotic factors that vary more or less regularly. However, abiotic factors that affect prey species do not necessarily affect their predators. Still, the prey’s response might affect the predator indirectly, yet evidence from the wild for such a classical bottom-up effect of abiotic factors shaping several trophic levels remains sparse. In many aquatic environments, daily changes in oxygen concentrations occur frequently. When oxygen levels drop to hypoxic levels, many fishes respond with aquatic surface respiration (ASR), during which they obtain oxygen by skimming the upper, oxygenated surface layer. By increasing time at the surface, fish become more vulnerable to fish-eating birds. We explored these cascading effects in a sulfidic spring system that harbors the endemic sulphur molly (Poecilia sulphuraria) as prey species and several fish-eating bird species. Sulfide-rich springs pose harsh conditions as hydrogen sulfide (H2S) is lethal to most metazoans and reduces dissolved oxygen (DO). Field sampling during three daytimes indicated that water temperatures rose from morning to (after)noon, resulting in the already low DO levels to decrease further, while H2S levels showed no diurnal changes. The drop in DO levels was associated with a decrease in time spent diving in sulphur mollies, which corresponded with an increase in ASR. Interestingly, the laboratory-estimated threshold at which the majority of sulphur mollies initiate ASR (ASR50: <1.7 mg/L DO) was independent of temperature and this value was exceeded daily when hypoxic stress became more severe toward noon. As fish performed ASR, large aggregations built up at the water surface over the course of the day. As a possible consequence of fish spending more time at the surface, we found high activity levels of fish-eating birds at noon and in the afternoon. Our study reveals that daily fluctuations in water’s oxygen levels have the potential to alter predator-prey interactions profoundly and thus highlights the joined actions of abiotic and biotic factors shaping the evolution of a prey species.

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Trophic Cascades in Grasslands

10.1093/oso/9780198744511.003.0005 ◽

2018 ◽

Author(s):

Brian J. Wilsey

Keyword(s):

Indirect Effects ◽

Prey Species ◽

Trophic Levels ◽

Herbaceous Plant ◽

Direct Effects ◽

Temperate Grasslands ◽

Cascading Effect ◽

Top Predators ◽

Invertebrate Predators ◽

Ecology Of Fear

Top predators have effects that can ‘cascade down’ on lower trophic levels. Because of this cascading effect, it matters how many trophic levels are present. Predators are either ‘sit and wait’ or ‘active’. Wolves are top predators in temperate grasslands and can alter species composition of smaller-sized predators, prey, and woody and herbaceous plant species, either through direct effects or indirect effects (‘Ecology of Fear’). In human derived grasslands, invertebrate predators fill a similar ecological role as wolves. Migrating populations of herbivores tend to be more limited by food than non-migratory populations. The phenology and synchrony of births vary among prey species in a way that is consistent with an adaptation to predation. Precocious species have highly synchronous birth dates to satiate predators. Non-precocious species (‘hiders’) have asynchronous births. Results from studies that manipulate both predators and food support the hypothesis that bottom-up and top-down effects interact.

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Functional trait diversity across trophic levels determines herbivore impact on plant community biomass

Ecology Letters ◽

10.1111/ele.12529 ◽

2015 ◽

Vol 18 (12) ◽

pp. 1346-1355 ◽

Cited By ~ 32

Author(s):

Hélène Deraison ◽

Isabelle Badenhausser ◽

Nicolas Loeuille ◽

Christoph Scherber ◽

Nicolas Gross

Keyword(s):

Plant Community ◽

Functional Trait ◽

Trophic Levels ◽

Community Biomass ◽

Trait Diversity ◽

Herbivore Impact ◽

Functional Trait Diversity

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

Nature Communications ◽

10.1038/s41467-021-24977-x ◽

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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Cascading effects of a top predator on intraspecific competition at intermediate and basal trophic levels

Functional Ecology ◽

10.1111/1365-2435.13131 ◽

2018 ◽

Vol 32 (9) ◽

pp. 2241-2252 ◽

Cited By ~ 3

Author(s):

Catherine M. Matassa ◽

Patrick J. Ewanchuk ◽

Geoffrey C. Trussell

Keyword(s):

Intraspecific Competition ◽

Trophic Levels ◽

Top Predator ◽

Cascading Effects

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Large mammals generate both top-down effects and extended trophic cascades on floral-visitor assemblages

Journal of Tropical Ecology ◽

10.1017/s0266467419000142 ◽

2019 ◽

Vol 35 (4) ◽

pp. 185-198 ◽

Cited By ~ 1

Author(s):

Allison Louthan ◽

Emily Valencia ◽

Dino J. Martins ◽

Travis Guy ◽

Jacob Goheen ◽

...

Keyword(s):

Trophic Cascade ◽

Structural Equation ◽

Trophic Cascades ◽

Trophic Levels ◽

Large Mammals ◽

Top Down ◽

Cascading Effects ◽

Floral Visitor ◽

Show Evidence ◽

Floral Visitors

AbstractCascading effects of high trophic levels onto lower trophic levels have been documented in many ecosystems. Some studies also show evidence of extended trophic cascades, in which guilds dependent on lower trophic levels, but uninvolved in the trophic cascade themselves, are affected by the trophic cascade due to their dependence on lower trophic levels. Top-down effects of large mammals on plants could lead to a variety of extended trophic cascades on the many guilds dependent on plants, such as pollinators. In this study, floral-visitor and floral abundances and assemblages were quantified within a series of 1-ha manipulations of large-mammalian herbivore density in an African savanna. Top-down effects of large mammals on the composition of flowers available for floral visitors are first shown, using regressions of herbivore activity on metrics of floral and floral-visitor assemblages. An extended trophic cascade is also shown: the floral assemblage further altered the assemblage of floral visitors, according to a variety of approaches, including a structural equation modelling approach (model with an extended trophic cascade was supported over a model without, AICc weight = 0.984). Our study provides support for extended trophic cascades affecting floral visitors, suggesting that trophic cascades can have impacts throughout entire communities.

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Trait-based predation suitability offers insight into effects of changing prey communities

PeerJ ◽

10.7717/peerj.5899 ◽

2018 ◽

Vol 6 ◽

pp. e5899 ◽

Cited By ~ 3

Author(s):

Benjamin Weigel ◽

Erik Bonsdorff

Keyword(s):

Functional Diversity ◽

Prey Species ◽

Human Impacts ◽

Food Resource ◽

Food Resources ◽

Trophic Levels ◽

Important Species ◽

Coastal System ◽

Predator Diet ◽

Positive Effect

Increasing environmental pressures and human impacts are reshaping community structures and species interactions throughout all trophic levels. The morphological and behavioural characteristics of species communities contain key ecological information on why prey species appear attractive to predators but are rarely applied when exploring predator-prey (PP) relationships. Expanding our knowledge on how changing prey communities can alter the food resource suitability (RS) for predators is vital for understanding PP dynamics in changing ecosystems. Detailed predator diet data are commonly restricted to commercially important species and often not available over long temporal scales. To find out whether structural changes of prey communities impact the food RS for predator communities over space and time, we apply a novel framework to describe and interpret changes in predator diet-suitability based on predation-relevant traits of prey. We use information on described feeding links from the literature to compile the prey spectrum for each predator and subsequently translate the prey-species into a prey-trait spectrum. For each predator, we then calculate a frequency-based prey-trait affinity score and relate it to the available food resource pool, the community weighted means of prey traits, resulting in a prey-suitability measure. We aim to reveal whether a described multi-decadal change in the community structure of zoobenthos had an impact on the food suitability for the benthic-feeding fish in a coastal system of the Baltic Sea. We assess the direction of change in resource quality from the perspective of benthic-feeding fish and describe predator-specific responses to examine which species are likely to profit or be disadvantaged by changes in their prey spectrum. Furthermore, we test the relationship between functional diversity of prey communities and food suitability for predators, and whether predation linkage-structures are affected through prey community-changes. Our results show that changes in zoobenthic communities had a positive effect on the food suitability for most benthic-feeding fish, implying more suitable food resources. Species-specific responses of predators suggest varying plasticity to cope with prey assemblages of different trait compositions. Additionally, the functional diversity of zoobenthos had a positive effect on the food suitability for predator fish. The changing trait compositions of prey influenced the PP linkage-structure, indicating varying specialisation of benthic feeding fish towards available food resources. Our findings suggest that changing morphological characteristics of prey can impact food RS features for its predators. This approach enables long-term evaluation of prey quality characteristics where no detailed diet data is available and allows for cross-system comparison as it is not relying on taxonomic identities per se.

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Giving-up diversity (GUDiv): top-down effects of foraging decisions on local, landscape and regional biodiversity of resources

10.22541/au.161113483.38126576/v1 ◽

2021 ◽

Author(s):

Jana Eccard ◽

Clara Ferreira ◽

Andres Peredo Arce ◽

Melanie Dammhahn

Keyword(s):

Foraging Behaviour ◽

Functional Trait ◽

Spatial Diversity ◽

Trophic Levels ◽

Community Effects ◽

Wild Rodents ◽

Cascading Effects ◽

Predation Effects ◽

Novel Concept ◽

Adaptive Foraging

Foraging by consumers has direct effects on the community of their resource species, and may serve as a biotic filtering mechanism of diversity. Determinants of foraging behaviour may thus have cascading effects on abundance, diversity, and functional trait composition of the resource community. Here we propose giving-up diversity (GUDiv) as a novel concept and simple measure to quantify community effects of foraging at multiple spatial diversity scales. GUDiv provides a framework linking theories of adaptive foraging behaviour with community ecology. In experimental resource landscapes we showcase effects of patch residency of foraging wild rodents on α-GUDiv, ß-GUDiv and γ- GUDiv, and on functional trait composition of resources. Using GUDiv allows for prediction-based investigation of cascading indirect predation effects (ecology of fear) across multiple trophic levels, of feedbacks between functional trait composition of resource and consumer communities, and of effects of inter-individual differences among foragers on the diversity of resource communities.

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Cascading Effects of Moth Outbreaks on Subarctic Soil Food Webs

10.21203/rs.3.rs-228461/v1 ◽

2021 ◽

Author(s):

Irene Calderón-Sanou ◽

Tamara Münkemüller ◽

Lucie Zinger ◽

Heidy Schimann ◽

Nigel Gilles Yoccoz ◽

...

Keyword(s):

Food Webs ◽

Large Scale ◽

Trophic Levels ◽

Trophic Groups ◽

Holistic View ◽

Cascading Effects ◽

Soil Food Webs ◽

Network Analyses ◽

Northern Fennoscandia ◽

Belowground Diversity

Abstract The increasing severity and frequency of natural disturbances requires a better understanding of their effects on all compartments of biodiversity. In Northern Fennoscandia, recent large-scale moth outbreaks have led to an abrupt change in plant communities from birch forests dominated by dwarf shrubs to grass-dominated systems. However, the indirect effects on the belowground compartment remained unclear. Here, we combined eDNA survey of multiple trophic groups with network analyses to demonstrate that moth defoliation has far-reaching consequences on soil food webs. Following this disturbance, diversity and relative abundance of certain trophic groups declined (e.g. ectomycorrhizal fungi) while many others profited (e.g. bacterivores, omnivores) making soil food webs more diverse and structurally different. Overall, the direct and indirect consequences of moth outbreaks increased belowground diversity at different trophic levels. Our results highlight that a holistic view of ecosystems improves our understanding of cascading effects of major disturbances on soil food webs.

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The impacts of new street light technologies: experimentally testing the effects on bats of changing from low-pressure sodium to white metal halide

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2014.0127 ◽

2015 ◽

Vol 370 (1667) ◽

pp. 20140127 ◽

Cited By ~ 33

Author(s):

Emma Louise Stone ◽

Andrew Wakefield ◽

Stephen Harris ◽

Gareth Jones

Keyword(s):

Low Pressure ◽

Global Scale ◽

County Council ◽

Metal Halide ◽

Trophic Levels ◽

Mercury Vapour ◽

Cascading Effects ◽

Significant Difference ◽

Wide Scale ◽

Species Specific

Artificial light at night is a major feature of anthropogenic global change and is increasingly recognized as affecting biodiversity, often negatively. On a global scale, newer technology white lights are replacing orange sodium lights to reduce energy waste. In 2009, Cornwall County Council (UK) commenced replacement of existing low-pressure sodium (LPS) high intensity discharge (HID) street lights with new Phillips CosmoPolis white ceramic metal halide street lights to reduce energy wastage. This changeover provided a unique collaborative opportunity to implement a before-after-control-impact field experiment to investigate the ecological effects of newly installed broad spectrum light technologies. Activity of the bat species Pipistrellus pipistrellus , P. pygmaeus and Nyctalus/Eptesicus spp. was significantly higher at metal halide than LPS lights, as found in other studies of bat activity at old technology (i.e. mercury vapour) white light types. No significant difference was found in feeding attempts per bat pass between light types, though more passes overall were recorded at metal halide lights. Species-specific attraction of bats to the metal halide lights could have cascading effects at lower trophic levels. We highlight the need for further research on possible ecosystem-level effects of light technologies before they are installed on a wide scale.

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