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opencc-zeroMar 2022View details →

Prey and predator density-dependent interactions under different water volumes

Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density-dependences concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounters rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic modelling approach, we quantified multiple predator effects across differences in prey density and water volume. Predators exhibited Type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e. antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator-prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator-predator interference effects.

opencc-zeroApr 2022View details →

Water availability rather than temperature control soil fauna community structure and prey-predator interactions

The ongoing climate change may strongly impact soil biodiversity with cascading effects on the processes they drive. Thus, it is of prime interest to improve our knowledge about responses by soil organisms such as collembolans to expected shifts in environmental conditions by considering communities comprising both detritivores and predators. The aim of the present study was to evaluate how simulated climate change and predation under laboratory conditions alter a collembolan community. To infer the impact of climate change, we applied a decreased level of soil moisture (60% vs. 30% soil water holding capacity) and an increasing air temperature (15 °C vs. 25 °C) to a collembolan community constituted by four species (Folsomia candida, Protaphorura fimata, Proisotoma minuta and Mesaphorura macrochaeta) exhibiting distinct functional traits, e.g. body size and furca presence, in presence or absence of a predatory gamasid Acari (Stratiolaelaps scimitus) during two months in a microcosm experiment. We observed that decreasing soil moisture altered the collembolan community with species-specific responses. Interaction between soil moisture, temperature and predation indicates that low soil moisture reduced total collembolan abundance especially i) by suppressing the positive effect of increasing temperature and ii) by increasing the predatory control on collembolan abundance. These results highlight that soil moisture is the major driver of Collembola community and by consequence, a shift in climatic parameters with the ongoing climate change should strongly modify the Collembola community structure and the predator-prey interaction. Our findings are highly important since a strengthening of predation impact on Collembola prey could have major consequences on the whole soil food web being able to lead to a slowdown of key ecosystem processes they drive (e.g., litter decomposition and nutrient recycling). Finally, our study promotes the need to study more complex systems considering distinct soil-dwelling species, their functional traits and their trophic interactions to better predict the ecosystem responses to the ongoing climate change.

opencc-zeroDec 2018View details →

Comparing two measures of phenological synchrony in a predator–prey interaction: simpler works better

1. Global climate change has sparked a vast research effort into the demographic and evolutionary consequences of mismatches between consumer and resource phenology. Many studies have used the difference in peak dates to quantify phenological synchrony (match in dates, MD), but this approach has been suggested to be inconclusive, since it does not incorporate the temporal overlap between the phenological distributions (match in overlap, MO). 2. We used 24 years of detailed data on the phenology of a predator–prey system, the great tit (Parus major) and the main food for its nestlings, caterpillars, to estimate MD and MO at the population and brood level. We compared the performance of both metrics on two key demographic parameters: offspring recruitment probability and selection on the timing of reproduction. 3. Although MD and MO correlated quadratically as expected, MD was a better predictor for both offspring recruitment and selection on timing than MO. We argue—and verify through simulations—that this is because quantifying MO has to be based on nontrivial, difficult-to-verify assumptions that likely render MO too inaccurate as a proxy for food availability in practice. 4. Our results have important implications for the allocation of research efforts in long-term population studies in highly seasonal environments.

opencc-zeroDec 2016View details →

Data from: Trait-matching and phylogeny as predictors of predator-prey interactions involving ground beetles

With global change modifying species assemblages, our success in predicting ecosystem level consequences of these new communities will depend, in part, on our ability to understand biotic interactions. Current food web theory considers interactions between numerous species simultaneously, but descriptive models are unable to predict interactions between newly co-occurring species. Incorporating proxies such as functional traits and phylogeny into models could help infer predator/ prey interactions. Here we used trait-matching between predator feeding traits and prey vulnerability traits, along with phylogeny (used as a proxy for chemical defence and other traits difficult to document), to infer predatory interactions using ground beetles as model organisms. A feeding experiment was conducted involving 20 ground beetle and 115 prey species to determine which pair of species did or did not interact. Eight predator and four prey functional traits were measured directly on specimens. Then, using a modeling approach based on the matching-centrality formalism, we evaluated 511 predictive ecological models that tested different combinations of all predator and prey functional traits, and phylogenetic information. The most parsimonious model accurately predicted 81 % of the observed realized and unrealized interactions, using phylogenetic information and the trait-matches predator biting force/ prey cuticular toughness and predator/ prey body size ratio. The best trait-based models predicted correctly >80 % which species interact (realized interactions), but predict <58 % of which species did not interact (unrealized interactions). Adding a phylogenetic term representing the evolutionary distance within each trophic level increased the ability to predict which species did not interact to >75 %. The matching of predator biting force and prey cuticular toughness demonstrated a better predictive power than the commonly used predator/ prey body size ratio. Our novel model combining both functional traits and phylogeny extends beyond existing descriptive approaches and could represent a valuable tool to predict consumer/ resource interactions of newly introduced species and to resolve cryptic food webs.

opencc-zeroDec 2014View details →

Data from: Predator-rodent-plant interactions along a coast-inland gradient in Fennoscandian tundra

Spatial variation in the strength of trophic cascades in arctic tundra has been related to flows of subsidies across ecosystem boundaries. Here, we ask whether the input of marine subsidies in tundra systems would cause spatial variation in the strength of rodent-plant interactions between coastal areas, where predators have access to marine-derived resources, and non-subsidized inland areas of northern Fennoscandia. We present a detailed evaluation of predator-rodent-vegetation interactions along a coast-inland gradient, during the 2011 rodent outbreak and the two following decline years, by using direct assessments of rodent impacts and tracing of marine-derived nutrients in the food web. Our results revealed that the main rodent predator during summer, the long-tailed jaeger Stercorarius longicaudus, did not benefit from marine resources while breeding (relative dietary proportion in chicks' diet = 0-3%). Contrary to this pattern, parasitic jaegers S. parasiticus, bred exclusively near the coast and preyed effectively on both marine resources (41% of chicks' diet) and rodents (12%). Mammalian predators also showed a higher activity during winter near the coast. Despite overall higher predator numbers, no evidence was found for lower rodent population growth rates during the three monitoring summers and for weaker rodent grazing impacts in the coastal area. Instead, we documented pronounced damages caused by lemmings and voles on bryophytes and vascular plants, especially dwarf shrubs (e.g., Vaccinum myrtillus) all along the coast-inland gradient. Taken together, our results did not support the hypothesis that marine subsidies would trigger a trophic cascade in coastal tundra areas of northern Fennoscandia during a major rodent outbreak, probably due to a low diversity of marine-subsidized predators in the region. Comparative observational and experimental studies at large spatial scales in various arctic regions are absolutely necessary for a better understanding of factors causing regional variations in the functioning of arctic food webs.

Figure 7 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 7. The numbers of Eulalia viridis recorded from the eastern side of the Mewsbrook Groyne (and the western side in September 2010) on the occasions when they were observed to be moving over the rock surfaces.

Figure 6 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 6. An experimentally derived plot of the relationship between Carcinus maenas carapace widths and the shell lengths of their chosen Mytilus galloprovincialis prey items attacked by marginal chipping. Open circles represent failed attempts; closed circles represent successful attacks.

Figure 8. A in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 8. A diagrammatic outline of the shell of Mytilus galloprovincialis divided into the four quadrants identified by Morton (2010) and showing the positions of the 17 series of chip marks (♦) and 18 drill holes (open circles represent successful attacks; closed circles represent failed attempts) made by experimentally held individuals of Carcinus maenas and Nucella lapillus, respectively.

Figure 5 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 5. Scanning electrom micrographs of the posterior margins of Mytilus galloprovincialis shells that have been accessed by Carcinus maenas in an experimental situation by (A) Chelal insertion and breaking and by (B) mandibular chipping.

Figure 4 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 4. An experimentally derived three-dimensional regression plot of the relationship between Nucella lapillus shell height (y-axis), the shell lengths of their chosen Mytilus galloprovincialis prey (z-axis) and the time spent atop each prey item (x-axis).

Figure 3 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 3. The relationship between the time Nucella lapillus spent atop its Mytilus galloprovincialis prey in laboratory experiments.

Figure 9 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 9. The relationship between the log-transformed numbers of Nucella lapillus recorded from the eastern side of the Mewsbrook Groyne (and the western side in September 2010) and the similarly log-transformed numbers of Eulalia viridis recorded on the occasions when they were observed to be moving over the rock surfaces

Figure 10 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 10. Plots showing, as a proportion of 100%, all the causes of death of individuals of Mytilus galloprovincialis collected from the Mewsbrook Groyne over the course of the 25-month period from September 2006 until September 2008.

Figure 1 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 1. The numbers of Nucella lapillus recorded from the Mewsbrook Groyne over the period from May 2004 to late August 2010. The first and last three open histograms represent counts from both sides of the groyne in May 2004 (25 individuals) and September 2009 (551 individuals), March 2010 (458 individuals) and late August 2010 (1241 individuals), the closed histograms represent numbers from the east side only.

Figure 2 in Predator-prey-scavenging interactions between Nucella lapillus, Carcinus maenas and Eulalia viridis all exploiting Mytilus galloprovincialis on a rocky shore recovering from tributyl-tin (TBT) pollution

Figure 2. The relationship between the shell heights of Nucella lapillus and the shell lengths of its Mytilus galloprovincialis prey on the Mewsbrook Groyne from May 2004 to August 2008.

opencc-zeroSep 2021View details →

The effects of novel leaf litter deposition on competitive, predator–prey and host–parasite interactions of American toad larvae

Wetland plant communities are changing rapidly due to a wide range of human activities. The deposition of leaf litter from novel plant communities can alter both the chemical and physical habitat of aquatic ecosystems. Lesser understood are the ecological consequences of novel leaf litter inputs in aquatic communities. Towards this goal, we used two plant invasion scenarios (comparing native black huckleberry to exotic autumn olive and native swamp loosestrife to exotic purple loosestrife) to simulate a shift in wetland plant communities. In this study, we investigated the effects of novel leaf litter leachates on three aquatic ecological interactions: intraspecific competition, predation, and parasitism. We examined how leaf litter leachates influence the interactions of American toad larvae (Anaxyrus americanus) with their conspecifics, a dragonfly predator (Anax spp.) and a trematode parasite (Echinostomatidae). We found that leaf litter type influenced competitive interactions only for the huckleberry versus autumn olive comparison. We did not detect any effects of leaf litter type on predator-prey interactions. Finally, litter type strongly influenced host-parasite interactions for both leaf litter comparisons, altering host susceptibility, parasite survival and net infection rates. These results highlight the breadth of potential ecological repercussions of shifting wetland plant communities for native ecosystems.

opencc-zeroOct 2023View details →

Habitat traits and predation interact to drive abundance and body size patterns in macroalgae associated fauna

Habitat-forming organisms provide three-dimensional structure that supports abundant and diverse communities. Variation in the morphological traits of habitat-formers will therefore likely influence how they facilitate associated communities, either via food and habitat provisioning, or by altering predator-prey interactions. These mechanisms, however, are typically studied in isolation and thus we know little of how they interact to affect associated communities. In response to this, we used naturally occurring morphological variability in the alga Sargassum vestitum to create habitat units of distinct morphotypes to test whether variation in the morphological traits (frond size and thallus size) of S. vestitum, or the interaction between these traits, affect their value as habitat for associated communities in the presence and absence of predation. We found morphological traits did not interact, instead having independent effects on epifauna that were negligible in the absence of predation. However, when predators were present, habitat units with large fronds were found to host significantly lower epifaunal abundances than other morphotypes, suggesting large frond alga provided low-value refuge from predators. The presence of predators also influenced the size structure of epifaunal communities from habitat units of differing frond size suggesting the refuge value of S. vestitum was also related to epifauna body size. This suggests that habitat-formers may chiefly structure associated communities by mediating size-selective predation, and not through habitat-provisioning. Furthermore, these results also highlight that habitat traits cannot be considered in isolation, for their interaction with biotic processes can have significant implications for associated communities.

publicApr 2020View details →

Data from: Zooming in on mechanistic predator-prey ecology: integrating camera traps with experimental methods to reveal the drivers of ecological interactions

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publicAug 2020View details →

Temperature and predator cues interactively affect ontogenetic metabolic scaling of aquatic amphipods

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