scholarly journals Environmental fluctuations restrict eco-evolutionary dynamics in predator–prey system

2015 ◽  
Vol 282 (1808) ◽  
pp. 20150013 ◽  
Author(s):  
Teppo Hiltunen ◽  
Gökçe B. Ayan ◽  
Lutz Becks
Keyword(s):  
Species Interactions ◽  
Community Dynamics ◽  
Evolutionary Dynamics ◽  
Temporal Dynamics ◽  
Rapid Evolution ◽  
Interactive Effects ◽  
Top Down ◽  
Bottom Up ◽  
Evolutionary Response ◽  
Environmental Fluctuations

Environmental fluctuations, species interactions and rapid evolution are all predicted to affect community structure and their temporal dynamics. Although the effects of the abiotic environment and prey evolution on ecological community dynamics have been studied separately, these factors can also have interactive effects. Here we used bacteria–ciliate microcosm experiments to test for eco-evolutionary dynamics in fluctuating environments. Specifically, we followed population dynamics and a prey defence trait over time when populations were exposed to regular changes of bottom-up or top-down stressors, or combinations of these. We found that the rate of evolution of a defence trait was significantly lower in fluctuating compared with stable environments, and that the defence trait evolved to lower levels when two environmental stressors changed recurrently. The latter suggests that top-down and bottom-up changes can have additive effects constraining evolutionary response within populations. The differences in evolutionary trajectories are explained by fluctuations in population sizes of the prey and the predator, which continuously alter the supply of mutations in the prey and strength of selection through predation. Thus, it may be necessary to adopt an eco-evolutionary perspective on studies concerning the evolution of traits mediating species interactions.

scholarly journals Warming decreases host survival with multiple parasitoids, but parasitoid performance also decreases

2021 ◽  
Author(s):  
Mélanie Thierry ◽  
Nicholas A. Pardikes ◽  
Benjamin Rosenbaum ◽  
Miguel G. Ximénez-Embún ◽  
Jan Hrček
Keyword(s):  
Ecosystem Functioning ◽  
Species Interactions ◽  
Community Dynamics ◽  
Abiotic Factors ◽  
Interactive Effects ◽  
Global Changes ◽  
Ecological Communities ◽  
Top Down ◽  
Multiple Predators ◽  
Abiotic And Biotic Factors

AbstractCurrent global changes are reshaping ecological communities and modifying environmental conditions. We need to recognize the combined impact of these biotic and abiotic factors on species interactions, community dynamics and ecosystem functioning. Specifically, the strength of predator-prey interactions often depends on the presence of other natural enemies: it weakens with competition and interference, or strengthens with facilitation. Such effects of multiple predators on prey are likely to be affected by changes in the abiotic environment, altering top-down control, a key structuring force in both natural and agricultural ecosystems. Here, we investigated how warming alters the effects of multiple predators on prey suppression using a dynamic model coupled with empirical laboratory experiments with Drosophila-parasitoid communities. While the effects of multiple parasitoids on host suppression were the average of the effects of individual parasitoid at ambient temperature, host suppression with multiple parasitoids was higher than expected under warming. Multiple parasitoid species had equivalent effect to multiple individuals of a same species. While multiple parasitoids enhanced top-down control under warming, parasitoid performance generally declined when another parasitoid was present due to competitive interactions, which could reduce top-down control in the long-term. Our study highlights the importance of accounting for interactive effects between abiotic and biotic factors to better predict community dynamics in a rapidly changing world, and better preserve ecosystem functioning and services such as biological control.

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.

scholarly journals Spared bottom-up but impaired top-down interactive effects during naturalistic language processing in schizophrenia: evidence from the visual-world paradigm

2018 ◽  
Vol 49 (08) ◽  
pp. 1335-1345 ◽  
Author(s):  
Hugh Rabagliati ◽  
Nathaniel Delaney-Busch ◽  
Jesse Snedeker ◽  
Gina Kuperberg
Keyword(s):  
Eye Tracking ◽  
Real Time ◽  
Language Processing ◽  
Interactive Effects ◽  
Top Down ◽  
Visual World ◽  
Bottom Up ◽  
Lexical Representations ◽  
Spoken Language Processing ◽  
Level Information

AbstractBackgroundPeople with schizophrenia process language in unusual ways, but the causes of these abnormalities are unclear. In particular, it has proven difficult to empirically disentangle explanations based on impairments in the top-down processing of higher level information from those based on the bottom-up processing of lower level information.MethodsTo distinguish these accounts, we used visual-world eye tracking, a paradigm that measures spoken language processing during real-world interactions. Participants listened to and then acted out syntactically ambiguous spoken instructions (e.g. ‘tickle the frog with the feather’, which could either specify how to tickle a frog, or which frog to tickle). We contrasted how 24 people with schizophrenia and 24 demographically matched controls used two types of lower level information (prosody and lexical representations) and two types of higher level information (pragmatic and discourse-level representations) to resolve the ambiguous meanings of these instructions. Eye tracking allowed us to assess how participants arrived at their interpretation in real time, while recordings of participants’ actions measured how they ultimately interpreted the instructions.ResultsWe found a striking dissociation in participants’ eye movements: the two groups were similarly adept at using lower level information to immediately constrain their interpretations of the instructions, but only controls showed evidence of fast top-down use of higher level information. People with schizophrenia, nonetheless, did eventually reach the same interpretations as controls.ConclusionsThese data suggest that language abnormalities in schizophrenia partially result from a failure to use higher level information in a top-down fashion, to constrain the interpretation of language as it unfolds in real time.

scholarly journals Adaptive genetic variation mediates bottom-up and top-down control in an aquatic ecosystem

2015 ◽  
Vol 282 (1812) ◽  
pp. 20151234 ◽  
Author(s):  
Seth M. Rudman ◽  
Mariano A. Rodriguez-Cabal ◽  
Adrian Stier ◽  
Takuya Sato ◽  
Julian Heavyside ◽  
...  
Keyword(s):  
Genetic Variation ◽  
Intraspecific Variation ◽  
Phenotypic Variation ◽  
Evolutionary Dynamics ◽  
Trophic Levels ◽  
Community Genetics ◽  
Top Down ◽  
Black Cottonwood ◽  
Bottom Up

Research in eco-evolutionary dynamics and community genetics has demonstrated that variation within a species can have strong impacts on associated communities and ecosystem processes. Yet, these studies have centred around individual focal species and at single trophic levels, ignoring the role of phenotypic variation in multiple taxa within an ecosystem. Given the ubiquitous nature of local adaptation, and thus intraspecific variation, we sought to understand how combinations of intraspecific variation in multiple species within an ecosystem impacts its ecology. Using two species that co-occur and demonstrate adaptation to their natal environments, black cottonwood ( Populus trichocarpa ) and three-spined stickleback ( Gasterosteus aculeatus ), we investigated the effects of intraspecific phenotypic variation on both top-down and bottom-up forces using a large-scale aquatic mesocosm experiment. Black cottonwood genotypes exhibit genetic variation in their productivity and consequently their leaf litter subsidies to the aquatic system, which mediates the strength of top-down effects from stickleback on prey abundances. Abundances of four common invertebrate prey species and available phosphorous, the most critically limiting nutrient in freshwater systems, are dictated by the interaction between genetic variation in cottonwood productivity and stickleback morphology. These interactive effects fit with ecological theory on the relationship between productivity and top-down control and are comparable in strength to the effects of predator addition. Our results illustrate that intraspecific variation, which can evolve rapidly, is an under-appreciated driver of community structure and ecosystem function, demonstrating that a multi-trophic perspective is essential to understanding the role of evolution in structuring ecological patterns.

scholarly journals Bottom-Up versus Top-Down Control of Hypo- and Epilimnion Free-Living Bacterial Community Structures in Two Neighboring Freshwater Lakes

2011 ◽  
Vol 77 (11) ◽  
pp. 3591-3599 ◽  
Author(s):  
Lyria Berdjeb ◽  
Jean-François Ghiglione ◽  
Stéphan Jacquet
Keyword(s):  
Bacterial Community ◽  
Temporal Dynamics ◽  
Large Set ◽  
Community Structures ◽  
Top Down ◽  
Free Living ◽  
Bottom Up ◽  
Perialpine Lakes ◽  
Oligotrophic Ecosystem ◽  
Lake Bourget

ABSTRACTBacterioplankton plays a central role in the microbial functioning of lacustrine ecosystems; however, factors that constrain its structural variation are still poorly understood. Here we evaluated the driving forces exerted by a large set of environmental and biological parameters on the temporal and spatial dynamics of free-living bacterial community structures (BCS) in two neighboring perialpine lakes, Lake Bourget and Lake Annecy, which differ in trophic status. We analyzed monthly data from a 1-year sampling period at two depths situated in the epi- and hypolimnia for each lake. Overall, denaturing gradient gel electrophoresis (DGGE) revealed significant differences in the BCS in the two lakes, characterized by a higher number of bands in the oligotrophic ecosystem (i.e., Lake Annecy). The temporal dynamics of BCS differed greatly between depths and lakes, with temporal scale patterns being much longer in the mesotrophic Lake Bourget. Direct-gradient multivariate ordination analyses showed that a complex array of biogeochemical parameters was the driving force behind BCS shifts in both lakes. Our results indicated that 60 to 80% of the variance was explained only by the bottom-up factors in both lakes, indicating the importance of nutrients and organic matter from autotrophic origin in controlling the BCS. Top-down regulation by flagellates together with ciliates or viruses was found only in the hypolimnion and not in the epilimnion for both lakes and explained less than 18% of the bacterial community changes during the year. Our study suggests that the temporal dynamics of the free-living bacterial community structure in deep perialpine lakes are dependent mainly on bottom-up factors and to a lesser extent on top-down factors, whatever the specific environmental conditions of these lakes.

scholarly journals Bottom-up and top-down control of dispersal across major organismal groups: a coordinated distributed experiment

2017 ◽  
Author(s):  
Emanuel A. Fronhofer ◽  
Delphine Legrand ◽  
Florian Altermatt ◽  
Armelle Ansart ◽  
Simon Blanchet ◽  
...  
Keyword(s):  
Evolutionary Dynamics ◽  
Local Population ◽  
Space Use ◽  
Life History Trait ◽  
Population Fluctuations ◽  
Top Down ◽  
Bottom Up ◽  
Ecological Forecasting ◽  
Cascading Effects ◽  
Wide Range

AbstractOrganisms rarely experience a homogeneous environment. Rather, ecological and evolutionary dynamics unfold in spatially structured and fragmented landscapes, with dispersal as the central process linking these dynamics across spatial scales. Because dispersal is a multi-causal and highly plastic life-history trait, finding general drivers that are of importance across species is challenging but highly relevant for ecological forecasting.We here tested whether two fundamental ecological forces and main determinants of local population dynamics, top-down and bottom-up control, generally explain dispersal in spatially structured communities. In a coordinated distributed experiment spanning a wide range of actively dispersing organisms, from protozoa to vertebrates, we show that bottom-up control, that is resource limitation, consistently increased dispersal. While top-down control, that is predation risk, was an equally important dispersal driver as bottom-up control, its effect depended on prey and predator space use and whether dispersal occurred on land, in water or in the air: species that routinely use more space than their predators showed increased dispersal in response to predation, specifically in aquatic environments. After establishing these general causes of dispersal, we used a metacommunity model to show that bottom-up and top-down control of dispersal has important consequences for local population fluctuations as well as cascading effects on regional metacommunity dynamics. Context-dependent dispersal reduced local population fluctuations and desynchronized dynamics between communities, two effects that increase population and community stability.Our study provides unprecedented insights into the generality of the positive resource dependency of dispersal as well as a robust experimental test of current theory predicting that predator-induced dispersal is modulated by prey and predator space use. Our experimental and theoretical work highlights the critical importance of the multi-causal nature of dispersal as well as its cascading effects on regional community dynamics, which are specifically relevant to ecological forecasting.

scholarly journals Positive species interactions strengthen in a high-CO 2 ocean

2021 ◽  
Vol 288 (1954) ◽  
pp. 20210475
Author(s):  
Camilo M. Ferreira ◽  
Sean D. Connell ◽  
Silvan U. Goldenberg ◽  
Ivan Nagelkerken
Keyword(s):  
Ocean Acidification ◽  
Primary Productivity ◽  
Species Interactions ◽  
Keystone Species ◽  
Predatory Fish ◽  
Positive Interactions ◽  
Rocky Reef ◽  
Top Down ◽  
Bottom Up ◽  
Food Web Interactions

Negative interactions among species are a major force shaping natural communities and are predicted to strengthen as climate change intensifies. Similarly, positive interactions are anticipated to intensify and could buffer the consequences of climate-driven disturbances. We used in situ experiments at volcanic CO 2 vents within a temperate rocky reef to show that ocean acidification can drive community reorganization through indirect and direct positive pathways. A keystone species, the algal-farming damselfish Parma alboscapularis, enhanced primary productivity through its weeding of algae whose productivity was also boosted by elevated CO 2 . The accelerated primary productivity was associated with increased densities of primary consumers (herbivorous invertebrates), which indirectly supported increased secondary consumers densities (predatory fish) (i.e. strengthening of bottom-up fuelling). However, this keystone species also reduced predatory fish densities through behavioural interference, releasing invertebrate prey from predation pressure and enabling a further boost in prey densities (i.e. weakening of top-down control). We uncover a novel mechanism where a keystone herbivore mediates bottom-up and top-down processes simultaneously to boost populations of a coexisting herbivore, resulting in altered food web interactions and predator populations under future ocean acidification.

Short Note: Paradigms need hypothesis testing: no evidence for top-down forcing on Adélie and emperor penguin populations

2008 ◽  
Vol 20 (4) ◽  
pp. 391-392 ◽  
Author(s):  
Christophe Barbraud ◽  
Cedric Cotte
Keyword(s):  
Southern Ocean ◽  
Species Interactions ◽  
Research Effort ◽  
Marine Ecosystem ◽  
Short Note ◽  
Emperor Penguin ◽  
Ecological Research ◽  
Top Down ◽  
Bottom Up ◽  
Ecosystem Interactions

In their recent review article “Paradigm lost, or is top-down forcing no longer significant in the Antarctic marine ecosystem?” Ainley et al. (2007) questioned why Southern Ocean marine ecologists apparently have shifted to a central paradigm where bottom-up forcing by physics and climate change has become the single most important driver of food web dynamics in the Southern Ocean. Ainley et al. (2007) suggest that top-down forcing (forcing by biotic processes) is no longer considered in the interpretation of ecological research results aimed at understanding ecosystem processes of the Southern Ocean. Based on two examples from the literature they suggest that population trends could better be explained by including species interactions in the modelling rather than by changes in climate related physical processes alone. Nicol et al. (2007) questioned the paradigm shift proposed by Ainley et al. (2007) and made a broad review of the ecological research conducted in the Southern Ocean ecosystems. They concluded that there has been considerable research effort into ecosystem interactions over the last 25 years in the Southern Ocean, and that there seems little evidence that there has been an almost complete shift in paradigms; rather both bottom-up and top-down processes are recognized to govern ecosystems functioning.

scholarly journals Onset, intensification, and decline of phytoplankton blooms in the Southern Ocean

2015 ◽  
Vol 72 (6) ◽  
pp. 1971-1984 ◽  
Author(s):  
Joan Llort ◽  
Marina Lévy ◽  
Jean-Baptiste Sallée ◽  
Alessandro Tagliabue
Keyword(s):  
Southern Ocean ◽  
Temporal Dynamics ◽  
Accumulation Rate ◽  
Vertical Mixing ◽  
Biomass Accumulation ◽  
Detection Methods ◽  
Biogeochemical Model ◽  
Iron Availability ◽  
Top Down ◽  
Bottom Up

Abstract The seasonal cycle of phytoplankton biomass in the Southern Ocean (SO) is characterized by a period of rapid accumulation, known as bloom, that is typical of high-latitude regions. Recent studies have illustrated how spatial and temporal dynamics of blooms in the SO are more complex than in other oceans. This complexity is likely related to differences in vertical mixing and the iron availability. In this work, we examine the sensitivity of bloom dynamics to changes in vertical mixing and iron availability using a biogeochemical model. Under idealized physical forcing, we produce seasonal cycles of phytoplankton for an ensemble of SO scenarios and we describe the bloom dynamics in terms of the net biomass accumulation rate. Based on this metric, we define three crucial bloom phases: the onset, the climax, and the apex. For the ensemble of modelled blooms, onsets always occur in winter and can be either bottom-up (increase in productivity) or top-down (decrease in grazing) controlled. Climaxes are mostly found in spring and their magnitudes are bottom-up controlled. Apexes are always found in late spring and strongly top-down controlled. Our results show that while a “strict” onset definition is consistent with a winter onset, the surface spring bloom is associated with the climax of the integrated bloom. Furthermore, we demonstrate that onset phase can be distinguished from climax phase using appropriate bloom detection methods based on surface satellite-based products. The ensemble of these results suggests that Sverdrup's blooming conditions are not indicative of the bloom onset but of the climax. We conclude that the recent bloom onset debate may partly be due to a confusion between what is defined here as the bloom onset and the climax, and that the SO observed complexity is due to the factors that control the climax.

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