780 results on '"functional responses"'
Search Results
2. Impact of Nanomaterial in the Marine Environment: Through Mathematical Modelling by Eco-Path Framework
- Author
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Kalyan Das, M.N. Srinivas, Aktar Saikh, and Md. Haider Ali Biswas
- Subjects
phytoplankton zooplankton ,nanoparticles ,mathematical model ,functional responses ,stability analysis ,bifurcation ,Biology (General) ,QH301-705.5 ,Mathematics ,QA1-939 - Abstract
We propose and analyze a simple modification to the Rosenzweig-MacArthur predator (zooplankton)-prey (phytoplankton) model to account for the interference of the predators with the impacts of nanoparticles. We have taken into account the influence of predators by quantifying the impact of nanoparticles in actual environments. It is shown that the influence of the nanoparticles may reduce the prey's maximum physiological per-capita growth rate. An elementary Lotka-Volterra uptake term is taken into consideration in order to investigate the nanoparticle dynamics or interactions. Most importantly, our research shows that phytoplankton growth suppression caused by nanoparticles can destabilize the system and cause periodic oscillation. Additionally, it was demonstrated that a decrease in the equilibrium densities of both phytoplankton and zooplankton might occur from an increase in the rate of interaction between the nanoparticles and phytoplankton. Additionally, the study shows that the stable coexistence of the system dynamics depends critically on the aquatic system's nanoparticles being depleted. We also looked into the system using different kinds of functional reactions. Compared to other commonly used ecology, The complex relationship that exists between phytoplankton and nanoparticles in the natural environment is better described by the Monod-Haldane functional response.
- Published
- 2024
- Full Text
- View/download PDF
3. Common camas (Camassia quamash) response across an urban–rural gradient in coastal oak meadows in Greater Victoria, Canada.
- Author
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Rolleman, Erin, Lantz, Trevor, Mathews, Darcy, and Shackelford, Nancy
- Subjects
URBAN ecology ,SOIL compaction ,KEYSTONE species ,SOIL depth ,PHOSPHORUS in soils - Abstract
Coastal oak meadows are fragmented across an increasingly urbanized landscape in Greater Victoria with implications for common camas (qʷɫəɫ/KȽO,EL/Camassia quamash) fitness. Common camas, frequently present in coastal oak meadows, is an ecologically important cultural keystone species that forms the foundation of one of the most important Indigenous food systems in the region. Previous research has examined how the pressures associated with urbanization shape plant community composition and structure, but how these pressures influence individual plant fitness remains unclear. To improve our understanding, we assessed environmental conditions and common camas growth and reproductive traits across an urban-rural gradient in Greater Victoria. We found that urbanization on this landscape alters several key environmental variables (namely increased trampling and soil compaction, and decreased soil depth, canopy cover, and soil phosphorus) and that common camas appears to be responding to these altered conditions with a reduction in growth and reproductive trait values. By targeting the identified pressures, management can work towards supporting more successful urban camas populations into the future. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Networking nutrients: How nutrition determines the structure of ecological networks.
- Author
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Cuff, Jordan P., Evans, Darren M., Vaughan, Ian P., Wilder, Shawn M., Tercel, Maximillian P. T. G., and Windsor, Fredric M.
- Subjects
- *
ECOSYSTEMS , *NUTRITION , *FUNCTIONAL foods , *LANDSCAPES , *HYPOTHESIS - Abstract
Nutrients can shape ecological interactions but remain poorly integrated into ecological networks. Concepts such as nutrient‐specific foraging nevertheless have the potential to expose the mechanisms structuring complex ecological systems. Nutrients also present an opportunity to predict dynamic processes, such as interaction rewiring and extinction cascades, and increase the accuracy of network analyses.Here, we propose the concept of nutritional networks. By integrating nutritional data into ecological networks, we envisage significant advances to our understanding of ecological processes from individual to ecosystem scales.We show that networks can be constructed with nutritional data to illuminate how nutrients structure ecological interactions in natural systems through an empirical example. Throughout, we identify fundamental ecological hypotheses that can be explored in a nutritional network context, alongside methods for resolving those networks.Nutrients influence the structure and complexity of ecological networks through mechanistic processes and concepts including nutritional niche differentiation, functional responses, landscape diversity, ecological invasions and ecosystem robustness. Future research on ecological networks should consider nutrients when investigating the drivers of network structure and function. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Editorial: Effects of microplastics on ecosystem functioning of eukaryotic marine microbes.
- Author
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Kumar, Ram, Dhanker, Raunak, Pinê Américo-Pinheiro, Juliana Heloisa, Kumar, Dilip, Jiang-Shiou Hwang, and Murray, Dennis
- Subjects
MICROPLASTICS ,MICROORGANISMS ,MARINE zooplankton ,ECOSYSTEMS ,MARINE biodiversity ,DISSOLVED organic matter - Abstract
Microplastics (MPs) are a growing concern in marine ecosystems, with their presence reported in various aquatic environments. This editorial highlights the need for a better understanding of the ecological consequences of MPs, particularly their effects on eukaryotic microbes (EM). EM play a crucial role in carbon transfer and are affected by MPs through ingestion and interactions with other components of the microbial loop. The articles featured in this research topic explore the effects of MPs on copepod microbiota, the gut microbiome of ventiferous crabs, prey-predator interactions, and the overall functioning of marine ecosystems. These studies emphasize the far-reaching impacts of MPs on energy flow and the need for further research in this area. [Extracted from the article]
- Published
- 2024
- Full Text
- View/download PDF
6. Consistent geographical gradient of water use efficiency evidences local adaptations to drought across the complete latitudinal distribution of Quercus suber
- Author
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Lourdes Morillas, María José Leiva, Jacinto Gandullo, Ignacio M. Pérez-Ramos, Jesús Cambrollé, and Luis Matías
- Subjects
Cork oak ,Drought resistance ,Functional responses ,Physiological traits ,Climate change ,Phenotypic plasticity ,Plant ecology ,QK900-989 - Abstract
Rationale: Increased aridity has led to drought-induced mortality or loss of health for many tree species. Of particular interest is to explore the response of the Mediterranean tree species cork oak (Quercus suber) to this declining phenomenon due to its severity and its large implications for the local economy and the provision of highly relevant ecosystem services. Approach: To assess geographical variations in the response to water stress, we analyzed under controlled conditions the effects of four watering levels and the resistance to a terminal drought on seedlings collected from nine populations covering the complete latitudinal distribution of the species. We explored the response of a number of physiological traits and markers of oxidative stress potentially related with drought-resistance. Findings: We found a highly plastic phenotypic response of most variables to water availability and a large influence of seedlings provenance in the drought-resistance strategies. Although the oxidative stress enzymes ruled out differential water stress throughout the distribution range, we found that seedlings from the southern limit are less vulnerable to drought than other populations. Southern seedlings adapted to xeric conditions displayed a larger sensitivity of stomata to changes in soil humidity and a higher water use efficiency. These physiological local adaptations coupled with larger acorn size in the southern populations, resulted in larger aboveground biomass and higher drought resistance at the southern distribution edge. Conclusions: Our data suggest that this evergreen tree species relies on its physiological plasticity to develop adaptative features that allows it to overcome water shortage and that southern populations hold genetic diversity that could improve the specie´s adaptation in the forecasted drought context with relevant implications for conservation programs.
- Published
- 2024
- Full Text
- View/download PDF
7. Editorial: Effects of microplastics on ecosystem functioning of eukaryotic marine microbes
- Author
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Ram Kumar, Raunak Dhanker, Juliana Heloisa Pinê Américo-Pinheiro, Dilip Kumar, and Jiang-Shiou Hwang
- Subjects
microplastics ,ecosystem functioning ,eukaryotic microbes ,functional responses ,pseudo-satiation ,entanglement ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Published
- 2024
- Full Text
- View/download PDF
8. Predation evaluation of the green lacewing, Chrysopa pallens on the pink tea mite pest, Acaphylla theae (Watt) (Acarina: Eriophyidae)
- Author
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Qian Wang, Meng Zhang, Qiuyu Guo, Chenxin Wu, and Liang Sun
- Subjects
Acaphylla theae ,Chrysopa pallens ,DNA-based gut content analyses ,predator-prey interactions ,functional responses ,Physiology ,QP1-981 - Abstract
A better understanding of predator-prey interactions is crucial for the development of biological control strategies. The green lacewing, Chrysopa pallens, is a well-known generalist predator and reportedly functions as one of the most important biological control agents of insect pests. However, information regarding C. pallens’ predation on tea plant pests, particularly notorious tea mites, remains largely unknown. In this study, we focused on the predator-prey relationship between C. pallens and an important tea mite pest, Acaphylla theae. We designed species-specific primers for the detection of A. theae DNA and established a PCR-based DNA gut content analysis assay. These results demonstrated that the primers were A. theae-specific and suitable for its molecular identification. The laboratory feeding experiment showed that the detectability success (DS50) of A. theae DNA remaining in C. pallens’ guts was 2.9 h. We then performed a molecular detection of field predation, and achieved a 23.53% positive detection rate of A. theae DNA in the guts of field-collected C. pallens. This, for the first time, provides direct evidence that C. pallens can prey on A. theae in tea plantations. Finally, we tested the prey preference and estimated the predation ability of C. pallens on different developmental stages of A. theae. The results revealed that C. pallens had no significant preference for different developmental stages of A. theae. The functional responses of C. pallens’ predation on different densities of A. theae at different developmental stages followed a Type II Holling model. The initial attack rate (a’) ranged from 0.735 to 0.858 and the handling time (Th) was approximately 0.01. This study is the first to demonstrate the trophic interactions between C. pallens and A. theae and provides evidence for the development of biological control strategies against A. theae using C. pallens as a candidate predator.
- Published
- 2023
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9. Incorporating neurological and behavioral mechanisms of sociality into predator-prey models.
- Author
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Lichtenstein, James L. L. and Schmitz, Oswald J.
- Subjects
SOCIAL defeat ,COMPETITION (Biology) ,BEHAVIORAL neuroscience ,BEHAVIORAL research ,FORAGING behavior - Abstract
Consumer-resource population models drive progress in predicting and understanding predation. However, they are often built by averaging the foraging outcomes of individuals to estimate per capita functional responses (functions that describe predation rate). Reliance on per-capita functional responses rests on the assumption that that individuals forage independently without affecting each other. Undermining this assumption, extensive behavioral neuroscience research has made clear that facilitative and antagonistic interactions among conspecifics frequently alter foraging through interference competition and persistent neurophysiological changes. For example, repeated social defeats dysregulates rodent hypothalamic signaling, modulating appetite. In behavioral ecology, similar mechanisms are studied under the concept of dominance hierarchies. Neurological and behavioral changes in response to conspecifics undoubtedly play some sort of role in the foraging of populations, but modern predator-prey theory does not explicitly include them. Here we describe how some modern approaches to population modeling might account for this. Further, we propose that spatial predator-prey models can be modified to describe plastic changes in foraging behavior driven by intraspecific interaction, namely individuals switching between patches or plastic strategies to avoid competition. Extensive neurological and behavioral ecology research suggests that interactions among conspecifics help shape populations’ functional responses. Modeling interdependent functional responses woven together by behavioral and neurological mechanisms may thus be indispensable in predicting the outcome of consumer–resource interactions across systems. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
10. Estimation for the bivariate quantile varying coefficient model with application to diffusion tensor imaging data analysis.
- Author
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Pietrosanu, Matthew, Shu, Haoxu, Jiang, Bei, Kong, Linglong, Heo, Giseon, He, Qianchuan, Gilmore, John, and Zhu, Hongtu
- Subjects
- *
QUANTILE regression , *IMAGE analysis , *DATA analysis , *DIFFUSION tensor imaging , *REGRESSION analysis , *GESTATIONAL age - Abstract
Despite interest in the joint modeling of multiple functional responses such as diffusion properties in neuroimaging, robust statistical methods appropriate for this task are lacking. To address this need, we propose a varying coefficient quantile regression model able to handle bivariate functional responses. Our work supports innovative insights into biomedical data by modeling the joint distribution of functional variables over their domains and across clinical covariates. We propose an estimation procedure based on the alternating direction method of multipliers and propagation separation algorithms to estimate varying coefficients using a B-spline basis and an |$L_2$| smoothness penalty that encourages interpretability. A simulation study and an application to a real-world neurodevelopmental data set demonstrates the performance of our model and the insights provided by modeling functional fractional anisotropy and mean diffusivity jointly and their association with gestational age and sex. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
11. Incorporating neurological and behavioral mechanisms of sociality into predator-prey models
- Author
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James L. L. Lichtenstein and Oswald J. Schmitz
- Subjects
functional responses ,trait plasticity ,social behavior ,social dominance ,intraspecific competition ,mechanistic predation models ,Neurosciences. Biological psychiatry. Neuropsychiatry ,RC321-571 - Abstract
Consumer-resource population models drive progress in predicting and understanding predation. However, they are often built by averaging the foraging outcomes of individuals to estimate per capita functional responses (functions that describe predation rate). Reliance on per-capita functional responses rests on the assumption that that individuals forage independently without affecting each other. Undermining this assumption, extensive behavioral neuroscience research has made clear that facilitative and antagonistic interactions among conspecifics frequently alter foraging through interference competition and persistent neurophysiological changes. For example, repeated social defeats dysregulates rodent hypothalamic signaling, modulating appetite. In behavioral ecology, similar mechanisms are studied under the concept of dominance hierarchies. Neurological and behavioral changes in response to conspecifics undoubtedly play some sort of role in the foraging of populations, but modern predator-prey theory does not explicitly include them. Here we describe how some modern approaches to population modeling might account for this. Further, we propose that spatial predator-prey models can be modified to describe plastic changes in foraging behavior driven by intraspecific interaction, namely individuals switching between patches or plastic strategies to avoid competition. Extensive neurological and behavioral ecology research suggests that interactions among conspecifics help shape populations’ functional responses. Modeling interdependent functional responses woven together by behavioral and neurological mechanisms may thus be indispensable in predicting the outcome of consumer–resource interactions across systems.
- Published
- 2023
- Full Text
- View/download PDF
12. Some historical thoughts on the functional responses of predators to prey density
- Author
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Charles J. Krebs
- Subjects
population dynamics ,functional responses ,predator prey interactions ,C.S. Holling ,models in ecology ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Abstract
The introduction of the functional response into population ecology in 1949 by Maurice Solomon was focused on explaining population regulation by density-dependent mortality caused by predators and natural enemies. Like many simple ecological measures originating at the population level, it was soon being used for other purposes at the single species and individual predator level. It is thus necessary when we use this important response function that we have a clear hypothesis in mind that is being tested. Here I provide a capsular summary of the origins of the functional response and suggest five problems with its application in population and community ecology. The functional response has much utility as a critical component of understanding population and community dynamics but must be carefully aimed at specific questions.
- Published
- 2022
- Full Text
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13. Effect of migrations on synchrony in host-parasitoid system.
- Author
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Kushal, Appilineni and Hastings, Alan
- Subjects
- *
PHASE oscillations , *SYNCHRONIC order , *CELLULAR automata , *TREE crops , *PARASITISM , *ECOSYSTEMS , *COMPETITION (Biology) , *DEFOLIATION - Abstract
Insect outbreaks can cause large scale defoliation of forest trees or destruction of crops, leading to ecosystem degradation and economic losses. Some outbreaks occur simultaneously across large geographic scales and some outbreaks occur periodically every few years across space. Parasitoids are a natural enemy of these defoliators and could help mitigate these pest outbreaks. A holistic understanding of the host-parasitoid interactions in a spatial context would thus enhance our ability to understand, predict and prevent these outbreaks. We use a discrete time deterministic model of the host parasitoid system with populations migrating between 2 patches to elucidate features of spatial host outbreaks. We show that whenever populations persist indefinitely, host outbreaks in both patches can occur alternatively (out of phase) at low migration between patches whereas host outbreaks always occur simultaneously (in phase) in both patches at high migration between patches. We show that our results are robust across a large range of parameters across different modelling approaches used typically to model intraspecific competition among hosts and parasitism, in the host-parasitoid literature. We give an analytical expression for the period of oscillations when the migration is low i.e. , when host outbreaks in both patches are out of phase, show it is in agreement with numerical results. We end our paper by showing that we get the same results whether we include the biologically rooted formulations from May et al. (1981) or a general cellular automata model with qualitative rules. • Synchrony is robust to the modelling intraspecific competition and parasitism. • Out of phase solutions are stable at low migration, time period decreases with more. • Higher migration introduces new stable solutions, destabilizing out of phase ones. • Time period for out of phase oscillations is derived which matches the numerics. • Cellular automata model mirrors synchrony seen in biologically detailed spatial host parasitoid model. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
14. Evolution of prudent predation in complex food webs.
- Author
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Gutiérrez Al‐Khudhairy, Orestes U., Rossberg, Axel G., and Jordan, Ferenc
- Subjects
- *
PREDATION , *INTRODUCED species , *MARINE ecology , *COMPETITION (Biology) , *ECOLOGICAL models - Abstract
Prudent predators catch sufficient prey to sustain their populations but not as much as to undermine their populations' survival. The idea that predators evolve to be prudent has been dismissed in the 1970s, but the arguments invoked then are untenable in the light of modern evolution theory. The evolution of prudent predation has repeatedly been demonstrated in two‐species predator–prey metacommunity models. However, the vigorous population fluctuations that these models predict are not widely observed. Here we show that in complex model food webs prudent predation evolves as a result of consumer‐mediated ('apparent') competitive exclusion of resources, which disadvantages aggressive consumers and does not generate such fluctuations. We make testable predictions for empirical signatures of this mechanism and its outcomes. Then we discuss how these predictions are borne out across freshwater, marine and terrestrial ecosystems. Demonstrating explanatory power of evolved prudent predation well beyond the question of predator–prey coexistence, the predicted signatures explain unexpected declines of invasive alien species, the shape of stock–recruitment relations of fish, and the clearance rates of pelagic consumers across the latitudinal gradient and 15 orders of magnitude in body mass. Specific research to further test this theory is proposed. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
15. Consistent geographical gradient of water use efficiency evidences local adaptations to drought across the complete latitudinal distribution of Quercus suber
- Author
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Universidad de Sevilla. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla. RNM-318: Ecología de Sistemas Agrarios, Ganaderos y Forestales., Ministerio de Ciencia, Innovación y Universidades (MICINN). España, Junta de Andalucía, Universidad de Sevilla, Morillas Viñuales, Lourdes, Leiva Morales, María José, Gandullo Tovar, Jacinto Manuel, Pérez Ramos, Ignacio Manuel, Cambrollé Silva, Jesús, Matías Resina, Luis, Universidad de Sevilla. Departamento de Biología Vegetal y Ecología, Universidad de Sevilla. RNM-318: Ecología de Sistemas Agrarios, Ganaderos y Forestales., Ministerio de Ciencia, Innovación y Universidades (MICINN). España, Junta de Andalucía, Universidad de Sevilla, Morillas Viñuales, Lourdes, Leiva Morales, María José, Gandullo Tovar, Jacinto Manuel, Pérez Ramos, Ignacio Manuel, Cambrollé Silva, Jesús, and Matías Resina, Luis
- Abstract
Rationale: Increased aridity has led to drought-induced mortality or loss of health for many tree species. Of particular interest is to explore the response of the Mediterranean tree species cork oak (Quercus suber) to this declining phenomenon due to its severity and its large implications for the local economy and the provision of highly relevant ecosystem services. Approach: To assess geographical variations in the response to water stress, we analyzed under controlled conditions the effects of four watering levels and the resistance to a terminal drought on seedlings collected from nine populations covering the complete latitudinal distribution of the species. We explored the response of a number of physiological traits and markers of oxidative stress potentially related with drought-resistance. Findings: We found a highly plastic phenotypic response of most variables to water availability and a large influence of seedlings provenance in the drought-resistance strategies. Although the oxidative stress enzymes ruled out differential water stress throughout the distribution range, we found that seedlings from the southern limit are less vulnerable to drought than other populations. Southern seedlings adapted to xeric conditions displayed a larger sensitivity of stomata to changes in soil humidity and a higher water use efficiency. These physiological local adaptations coupled with larger acorn size in the southern populations, resulted in larger aboveground biomass and higher drought resistance at the southern distribution edge. Conclusions: Our data suggest that this evergreen tree species relies on its physiological plasticity to develop adaptative features that allows it to overcome water shortage and that southern populations hold genetic diversity that could improve the specie´s adaptation in the forecasted drought context with relevant implications for conservation programs.
- Published
- 2024
16. Nitrogen and phosphorus additions interactively affected composition and carbon budget of soil nematode community in a temperate steppe.
- Author
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Zhang, Zhi-Wei, Li, Qi, Hu, Yan-Yu, Wei, Hai-Wei, Hou, Shuang-Li, Yin, Jiang-Xia, and Lü, Xiao-Tao
- Subjects
- *
CARBON in soils , *GRASSLAND soils , *NUTRIENT cycles , *SOIL nematodes , *STEPPES , *CARBON cycle , *NITROGEN - Abstract
Purpose: Soil nematodes play a fundamental role in regulating ecosystem carbon and nutrient cycling. It is widely recognized that soil nematode community composition is sensitive to nutrient enrichment, but the linkage between community assembly processes and functional changes under nutrient enrichment condition remains poorly understood. Methods: We examined the compositional and functional responses and quantified the role of main community assembly processes (genus losses, genus gains, and context-dependent variations of abundance) in driving the carbon budget of soil nematode communities in response to nitrogen (N) and phosphorus (P) addition in a temperate grassland. Results: Nitrogen and P addition significantly interacted to affect nematodes abundance, biomass, and functional variables of C cycling, in that P addition increased all the variables under ambient N condition but not under N enriched condition. Soil pH, ammonium concentration, and total phosphorus concentration played important roles in driving the variations of nematode C budgets, indicating the minor role of plant community characteristics. The enhancement of all variables following P addition was caused by the increases in the abundance of common genera (e.g. Acrobeles, Scutylenchus, and Tylencholaimus). The variation of genus richness contributed to the P-induced increases of nematode abundance but not to the increases of carbon budgets. Conclusions: Our results uncover the linkages between community assembly processes and the abundance and C cycling function of soil nematode community under nutrient enrichment conditions. The significant interactive effects between N and P addition highlight the complexity in predicting the compositional and functional changes in soil nematode community under a scenario of multiple-nutrient enrichment. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
17. Guiding Students to Understand Functional Responses: Holling's Disc Experiment Revisited.
- Author
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Pulley, Melissa, Rodriguez, Leoncio, Lewis, Matthew, Kohler, Brynja, and Gordillo, Luis
- Subjects
- *
BIOLOGICAL mathematical modeling , *FUNCTIONAL equations , *COMPUTER simulation - Abstract
Inspired by the approach first employed by C.S. Holling in his classic "disc experiment," this article provides a sequence of learning activities that increase students' understanding of the mechanisms behind saturating effects in predator-prey scenarios. The proposed lesson is recommended for inclusion in courses that address mathematical biology or modeling from introductory to advanced levels. The featured activities include a theoretical derivation of Holling's type II functional response model, a hands-on experiment for data gathering, and tools for further exploration through individual-based computer simulations. This multi-faceted approach gives students the opportunity to gather different sets of data in order to meet multiple learning objectives. Classroom trials conducted in Spring 2019 indicate that the proposed instructional resources and activities are effective for improving students' understanding of the mechanisms in Holling's type II functional response equation, and deepen students' appreciation of authentic data-driven mathematical modeling in ecology. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
18. Neoseiulus mites as biological control agents against Megalurothrips usitatus (Thysanoptera: Thripidae) and Frankliniella intonsa (Thysanoptera: Thripidae) on cowpea crop: laboratory to field.
- Author
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Zhang YF, Zang LS, Guo LH, Sukhwinder S, Wu SY, Yang X, and Tang LD
- Subjects
- Animals, Predatory Behavior, Larva growth & development, Larva physiology, Pest Control, Biological, Vigna, Mites physiology, Thysanoptera physiology, Nymph growth & development, Nymph physiology
- Abstract
Megalurothrips usitatus (Bagnall) (Thysanoptera: Thripidae) and Frankliniella intonsa (Trybom) (Thysanoptera: Thripidae) have been detrimental to cowpea production in many countries. Laboratory experiments were conducted to determine the prey stage preference and functional response of 2 predatory mites species, Neoseiulus barkeri (Hughes) (Acari: Phytoseiidae), and Neoseiulus californicus (McGregor) (Acari: Phytoseiidae), towards 2 thrips species (TS), M. usitatus, and F. intonsa, at varying densities and life stages on cowpea. Results shown that Neoseiulus species had a preference for different life stages of prey. Neoseiulus barkeri consumed more M. usitatus nymphs, while N. californicus consumed more F. intonsa (second-instar nymphs). The functional response of the 2 Neoseiulus spp. to nymphs of 2 TS was Type II on cowpea. The higher attack rate coefficient (a') and shorter handling time (Th) values were found on N. barkeri against M. usitatus, and a similar trend was found for those in N. californicus against F. intonsa. Field-caged trials were conducted to evaluate the effectiveness of Neoseiulus spp. in controlling 2 TS. The results have shown that Neoseiulus spp. was effective in controlling the 2 TS, with varying control efficacies at high or low release rates. The study provided valuable information on using Neoseiulus spp. as biological control agents against M. usitatus and F. intonsa in cowpea crops., (© The Author(s) 2024. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For commercial re-use, please contact reprints@oup.com for reprints and translation rights for reprints. All other permissions can be obtained through our RightsLink service via the Permissions link on the article page on our site—for further information please contact journals.permissions@oup.com.)
- Published
- 2024
- Full Text
- View/download PDF
19. Temperature and prey morphology influence attack rate and handling time in a predator–prey interaction.
- Author
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Robertson, Miles L. and Hammill, Edd
- Subjects
- *
PREDATION , *PREDATORY animals , *MORPHOLOGY , *BODY size , *PARAMECIUM , *HIGH temperatures - Abstract
Functional responses describe how the proportion of prey consumed by a predator changes as prey density changes. For predators consuming a single prey species, functional responses are determined by two parameters: attack rate and handling time. These parameters may be influenced by morphological and behavioral differences in prey stemming from interspecific or environmentally-driven processes. Here we investigate how interspecific morphological differences and changes in movement rate impact a predator's functional response. Using a flatworm predator (Stenostomum virginianum) consuming either Paramecium aurelia or P. multimicronucleatum we show that movement rate changes significantly with temperature, leading to changes in attack rate. We also show how body size affects the amount of time predators require to handle prey. We fit a mechanistic functional response model to demonstrate how changes in attack rate and handling time affect overall rates of predation. Our results demonstrate that S. virginianum attack rates are greater for P. aurelia than P. multimicronucleatum. In addition, higher temperature increases S. virginianum attack rates on both species, and reduces the time needed to handle P. aurelia. These differences in predation rate appear related to prey species' traits, and the temperature-mediated changes in these traits, highlighting the complex processes that underpin predator–prey interactions. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
20. Breathing space: deoxygenation of aquatic environments can drive differential ecological impacts across biological invasion stages.
- Author
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Dickey, James W. E., Coughlan, Neil E., Dick, Jaimie T. A., Médoc, Vincent, McCard, Monica, Leavitt, Peter R., Lacroix, Gérard, Fiorini, Sarah, Millot, Alexis, and Cuthbert, Ross N.
- Abstract
The influence of climate change on the ecological impacts of invasive alien species (IAS) remains understudied, with deoxygenation of aquatic environments often-overlooked as a consequence of climate change. Here, we therefore assessed how oxygen saturation affects the ecological impact of a predatory invasive fish, the Ponto-Caspian round goby (Neogobius melanostomus), relative to a co-occurring endangered European native analogue, the bullhead (Cottus gobio) experiencing decline in the presence of the IAS. In individual trials and mesocosms, we assessed the effect of high, medium and low (90%, 60% and 30%) oxygen saturation on: (1) functional responses (FRs) of the IAS and native, i.e. per capita feeding rates; (2) the impact on prey populations exerted; and (3) how combined impacts of both fishes change over invasion stages (Pre-invasion, Arrival, Replacement, Proliferation). Both species showed Type II potentially destabilising FRs, but at low oxygen saturation, the invader had a significantly higher feeding rate than the native. Relative Impact Potential, combining fish per capita effects and population abundances, revealed that low oxygen saturation exacerbates the high relative impact of the invader. The Relative Total Impact Potential (RTIP), modelling both consumer species' impacts on prey populations in a system, was consistently higher at low oxygen saturation and especially high during invader Proliferation. In the mesocosm experiment, low oxygen lowered RTIP where both species were present, but again the IAS retained high relative impact during Replacement and Proliferation stages at low oxygen. We also found evidence of multiple predator effects, principally antagonism. We highlight the threat posed to native communities by IAS alongside climate-related stressors, but note that solutions may be available to remedy hypoxia and potentially mitigate impacts across invasion stages. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
21. Salinity induced alterations in ionic concentration of haemolymph and its effects on histopathology of gills and digestive gland in razor clam (Solen dactylus von Cosel, 1989; Bivalvia, Solenidae).
- Author
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Farzadfar, Fariba, Doustshenas, Babak, Rezaie, Annahita, and Mousavi, Seyed Mohammad
- Abstract
Solen dactylus is one of the most common razor clams in the tidal zone in the western Indian Ocean and Persian Gulf. Habitats of these clams may be subject to salinity fluctuations due to high evaporation and heavy rainfall. To assess their adaptation, in the laboratory clams were placed in 50-litre tanks with 40 cm depth of natural substrate and were kept in salinity of 45 ppt for a week before subsequent experiments. They were then exposed to salinities of 5, 20, 35, 45 and 65 ppt for three weeks. Concentrations of Na+, Cl–, K+, Ca2+, and Mg2+, as well as osmolality in the haemolymph and tank water were measured at 1, 24, 72 h, one week and three weeks after the start of the experiment. Haemolymph Na+ and Cl– values followed the concentrations of the external medium so that they decreased at low salinities and increased at high salinities. The Ca2+, Mg2+ and K+ ions all showed a common pattern, and their trend was independent of the external environment. Histopathological analysis showed severe tissue damage at low salinities with expanded intercellular spaces, an increase of intracytoplasmic vacuoles in the digestive tubules, and necrosis and destruction of lamellae in gill tissues. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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22. Efficient Estimation for Varying-Coefficient Mixed Effects Models with Functional Response Data.
- Author
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Cai, Xiong, Xue, Liugen, Pu, Xiaolong, and Yan, Xingyu
- Subjects
- *
ALZHEIMER'S disease , *WHITE matter (Nerve tissue) - Abstract
In this article, we focus on the estimation of varying-coefficient mixed effects models for longitudinal and sparse functional response data, by using the generalized least squares method coupling a modified local kernel smoothing technique. This approach provides a useful framework that simultaneously takes into account the within-subject covariance and all observation information in the estimation to improve efficiency. We establish both uniform consistency and pointwise asymptotic normality for the proposed estimators of varying-coefficient functions. Numerical studies are carried out to illustrate the finite sample performance of the proposed procedure. An application to the white matter tract dataset obtained from Alzheimer's Disease Neuroimaging Initiative study is also provided. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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23. The impacts of Harmonia axyridis cues on foraging behavior of Aphidius gifuensis to Myzus persicae.
- Author
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Xia, Peng-Liang, Yu, Xing-Lin, Li, Ze-Tao, and Feng, Yi
- Abstract
[Display omitted] • Aphidius gifuensis avoid foraging in patches with Harmonia axyridis cues. • Functional response of A. gifuensis was not significantly affected by H. axyridis cues. • Aphidius gifuensis might exhibit flexible behavioral responses to predator cues. This study investigated the effect of adult associated cues of the multicolored Asian ladybird Harmonia axyridis Pallas (Coleoptera: Coccinellidae) on the foraging behavior of the aphid parasitoid, Aphidius gifuensis Ashmead (Hymenoptera: Aphididae) with three assays: 1) whole aphid leaf-disc with H. axyridis tracks; 2) aphid leaf-disc with only half contaminated with H. axyridis tracks; 3) aphid leaf-discs without H. axyridis tracks. Foraging behavior of A. gifuensis was recorded using the Observer® XT 11 and EthoVsion® XT 12. In addition, functional responses of A. gifuensis in patches with or without H. axyridis cues were also tested. Aphidius gifuensis females preferred oviposition in arenas where no adult tracks of H. axyridis were present. However, no significant difference between functional responses of A. gifuensis foraging in plants with and without H. axyridis cues was detected. Our study suggests that H. axyridis associated cues could influence the foraging behavior and activity of A. gifuensis under laboratory conditions. On the other hand, the foraging efficiency of A. gifuensis was not significantly affected by H. axyridis walking tracks in a single plant system. Aphidius gifuensis might exhibit flexible behavioral responses to predator associated cues. The risk of intraguild interactions and the possibility of mitigating such risks for parasitoids are important components for ultimately determining the compatibility of biological control agents. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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24. A Multi-Trait Comparison of an Urban Plant Species Pool Reveals the Importance of Intraspecific Trait Variation and Its Influence on Distinct Functional Responses to Soil Quality
- Author
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Dorothy Borowy and Christopher M. Swan
- Subjects
eco-evolutionary dynamics ,functional responses ,interspecific variation ,intraspecific variation ,plant functional traits ,urban ecology ,Evolution ,QH359-425 ,Ecology ,QH540-549.5 - Abstract
Mounting evidence indicates that the inclusion of intraspecific trait variability (ITV) can strengthen the signal of trait-environment relationships, as well as provide insights into the eco-evolutionary strategies that allow species to establish and persist in different environments. Such information is particularly valuable in urban systems where unique environmental conditions impose strong filtering effects on resident species and where, despite such pressures, high proportions of non-native species persist. In an effort to elucidate functional trait patterns of an urban species pool, we experimentally assessed the effect of soil on trait patterns of 56 plant species collected as seeds from vacant land in Baltimore City, MD, United States. We assessed the relative importance of explained trait variation at different ecological levels by decomposing the variance of six measured traits into three levels: within-species (ITV), between-species (BTV), and across functional groups (FGTV). We then compared functional responses – classified by differences in mean and variance patterns of trait values – across species, traits, and functional groups. Mean trait values varied in response to species and soil (urban vs. potting soil) for all traits, except root ash-free dry mass (AFDM) for soil. Variance decomposition of the species factor into each level showed that variance patterns for species were trait-specific, however, ITV explained a substantial proportion of the total variance for the majority of study traits. When accounting for mean and variance trait patterns between soil types, we found that species with specialized strategies (i.e., C4 photosynthesis and legumes) exhibited functional responses consistent with preadaptation, as defined by no change in the mean or the variance of trait values between soil types, for all traits. Native species showed higher proportions of trait divergence, as defined by shifts in mean trait values between soil types, but not change in variance, relative to introduced species, which showed higher proportions of preadaptation for all traits except specific leaf area (SLA). Species exhibiting trait constriction, or no shift in the mean but a significant change in the variance between soil types, consistently showed decreased variance in urban soil, which supports the idea that urban soils impose strong filtering effects that constrain species trait values. Overall, our study indicates that accounting for ITV, and how it relates to general functional responses associated with changes in the mean and variance of trait values, can provide a clearer understanding of the eco-evolutionary dynamics of plant species in urban environments.
- Published
- 2020
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25. Functional responses and parasitoid success rate of aphelinid Eretmocerus sp. (Hymenoptera: Aphelinidae) on Bemisia tabaci Genn. (Homoptera: Aleyrodidae)
- Author
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WenJun Zhang
- Subjects
Eretmocerus sp. ,Bemisia tabaci Genn. ,functional responses ,parasitization ,host feeding ,parasitoid success rate ,Zoology ,QL1-991 - Abstract
Poinsettia (Euphorbia pulcherrima Willd Ex Koltz) is an important ornamental and medicinal plant. One of its major insect pests is sweetpotato whitefly, Bemisia tabasi Genn. (Homoptera: Aleyrodidae). Eretmocerus sp. (Hymenoptera: Aphelinidae) is an important natural enemy agent on sweetpotato whitefly, which mainly parasitizes 2nd and 3rd instar nymphs of B. tabaci and often feeds the nymphs. With poinsettia (Euphorbia pulcherrima Willd Ex Koltz) as the host plant, the present study showed that the functional responses for parasitization of E. sp. on 2nd and 3rd instar nymphs of B. tabaci coincided with Holling-III equation. The handling time against the 2nd and 3rd instar nymphs were 76.2 min and 117.2 min respectively. The maximum parasitization against the 2nd and 3rd instar nymphs were 18.9 per day and 12.3 per day respectively. The functional responses for host feeding of E. sp. on 2nd and 3rd instar nymphs of B. tabaci coincided with the Holling-II equation. The handling time against the 2nd and 3rd instar nymphs were 201.7 min and 298.8 min respectively. The maximum host feeding against the 2nd and 3rd instar nymphs was 7.1 per day and 4.8 per day respectively. The parasitoid success rate of E. sp. against B. tabaci reached 86.5%. The result suggested that the host feeding of E. sp. was a significant component in the natural control of B. tabaci.
- Published
- 2018
26. Wolf habitat selection in relation to recreational structures in a national park.
- Author
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Malcolm, Kimberly, Cheveau, Marianne, and St-Laurent, Martin-Hugues
- Subjects
- *
HABITAT selection , *NATIONAL parks & reserves , *BUSINESS parks , *WOLVES , *PARKING facilities , *PUBLIC safety - Abstract
Although most predators usually avoid human activity, some individuals instead will habituate to it. Habituation to human presence and infrastructure by predator species such as wolves may lead to conflicts implicating serious risks for public safety and for the survival of the animals involved. Accordingly, this research project aims to shed light on the relationship between wolves and recreational structures using telemetry data from 10 wolves located in the Parc National du Mont-Tremblant (Québec, Canada) and its surrounding area. Using resource selection functions (RSFs), we observed wolf habitat selection in relation to these structures during three biological periods (denning: May–June; rendezvous: June–October; and nomadic: October–April). Our results revealed that wolves selected proximity to linear structures (roads and trails) during the denning and rendezvous periods, but this selection depended on the density of such structures in the surroundings (i.e. functional response in habitat selection): wolves selected proximity to linear structures when these structures were present at greater densities. Wolves avoided housing structures (campsites, cabins, park facilities), especially when these structures were present at greater densities, suggesting that wolves perceived them as a risk. These results suggest that conflicts between visitors and wolves were unlikely to occur in campgrounds during the time of our study. This could indicate that the management measures implemented by the park following the past episodes of conflict were effective. However, wolves' use of linear structures could lead to increased tolerance to human proximity if left unmanaged. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
27. Geographic variation in responses of kelp forest communities of the California Current to recent climatic changes.
- Author
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Beas‐Luna, Rodrigo, Micheli, Fiorenza, Woodson, C. Brock, Carr, Mark, Malone, Dan, Torre, Jorge, Boch, Charles, Caselle, Jennifer E., Edwards, Matt, Freiwald, Jan, Hamilton, Scott L., Hernandez, Arturo, Konar, Brenda, Kroeker, Kristy J., Lorda, Julio, Montaño‐Moctezuma, Gabriela, and Torres‐Moye, Guillermo
- Subjects
- *
CLIMATE change , *COMMUNITY forests , *HEAT waves (Meteorology) , *SOUTHERN oscillation , *FOREST monitoring , *KELPS , *MARINE biodiversity - Abstract
The changing global climate is having profound effects on coastal marine ecosystems around the world. Structure, functioning, and resilience, however, can vary geographically, depending on species composition, local oceanographic forcing, and other pressures from human activities and use. Understanding ecological responses to environmental change and predicting changes in the structure and functioning of whole ecosystems require large‐scale, long‐term studies, yet most studies trade spatial extent for temporal duration. We address this shortfall by integrating multiple long‐term kelp forest monitoring datasets to evaluate biogeographic patterns and rates of change of key functional groups (FG) along the west coast of North America. Analysis of data from 469 sites spanning Alaska, USA, to Baja California, Mexico, and 373 species (assigned to 18 FG) reveals regional variation in responses to both long‐term (2006–2016) change and a recent marine heatwave (2014–2016) associated with two atmospheric and oceanographic anomalies, the "Blob" and extreme El Niño Southern Oscillation (ENSO). Canopy‐forming kelps appeared most sensitive to warming throughout their range. Other FGs varied in their responses among trophic levels, ecoregions, and in their sensitivity to heatwaves. Changes in community structure were most evident within the southern and northern California ecoregions, while communities in the center of the range were more resilient. We report a poleward shift in abundance of some key FGs. These results reveal major, ongoing region‐wide changes in productive coastal marine ecosystems in response to large‐scale climate variability, and the potential loss of foundation species. In particular, our results suggest that coastal communities that are dependent on kelp forests will be more impacted in the southern portion of the California Current region, highlighting the urgency of implementing adaptive strategies to sustain livelihoods and ensure food security. The results also highlight the value of multiregional integration and coordination of monitoring programs for improving our understanding of marine ecosystems, with the goal of informing policy and resource management in the future. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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28. Neimark–Sacker bifurcation analysis in an intraguild predation model with general functional responses.
- Author
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Blé, Gamaliel, Dela-Rosa, Miguel Angel, and Loreto-Hernández, Iván
- Subjects
- *
DISCRETE systems , *BIFURCATION diagrams , *COEXISTENCE of species , *SYSTEM dynamics , *FOOD chains - Abstract
We analyse the dynamics of a discrete system coming from an intraguild food web model by using the average method. The intraguild predation model is formed by three populations corresponding to prey (P), mesopredator (MP) and superpredator (SP), where these last two populations are specialist. We give sufficient condition to guarantee the existence of a coexistence point at which the intraguild predation discrete model undergoes a Neimark–Sacker bifurcation independently of the functional responses that govern the interactions. We show numerical applications that consist in to assume that P has logistic growth and that the relation of MP–P is through a Holling type II functional response. Besides, we will consider that the interaction of MP–P is such that population MP has defense. The interaction of SP–P will be through a Holling functional response type III or IV. In particular, we give sufficient conditions to guarantee that the three species coexist. The techniques used to obtain the results can be applied to other models with different functional responses. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
29. RapidAIM 2.0: a high-throughput assay to study functional response of human gut microbiome to xenobiotics.
- Author
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Li L, Mayne J, Beltran A, Zhang X, Ning Z, and Figeys D
- Abstract
Aim: Our gut microbiome has its own functionalities which can be modulated by various xenobiotic and biotic components. The development and application of a high-throughput functional screening approach of individual gut microbiomes accelerates drug discovery and our understanding of microbiome-drug interactions. We previously developed the rapid assay of individual microbiome (RapidAIM), which combined an optimized culturing model with metaproteomics to study gut microbiome responses to xenobiotics. In this study, we aim to incorporate automation and multiplexing techniques into RapidAIM to develop a high-throughput protocol. Methods: To develop a 2.0 version of RapidAIM, we automated the protein analysis protocol, and introduced a tandem mass tag (TMT) multiplexing technique. To demonstrate the typical outcome of the protocol, we used RapidAIM 2.0 to evaluate the effect of prebiotic kestose on ex vivo individual human gut microbiomes biobanked with five different workflows. Results: We describe the protocol of RapidAIM 2.0 with extensive details on stool sample collection, biobanking, in vitro culturing and stimulation, sample processing, metaproteomics measurement, and data analysis. The analysis depth of 5,014 ± 142 protein groups per multiplexed sample was achieved. A test on five biobanking methods using RapidAIM 2.0 showed the minimal effect of sample processing on live microbiota functional responses to kestose. Conclusions: Depth and reproducibility of RapidAIM 2.0 are comparable to previous manual label-free metaproteomic analyses. In the meantime, the protocol realizes culturing and sample preparation of 320 samples in six days, opening the door to extensively understanding the effects of xenobiotic and biotic factors on our internal ecology., Competing Interests: Figeys D cofounded MedBiome, a clinical microbiomic company. Zhang X is an Editorial Board member of the journal Microbiome Research Reports. All other authors declared that there are no conflicts of interest., (© The Author(s) 2024.)
- Published
- 2024
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30. Differential consumption of scleractinian and non-scleractinian coral larvae by planktivorous damselfishes.
- Author
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Quimpo, Timothy Joseph R., Cabaitan, Patrick C., and Hoey, Andrew S.
- Subjects
SCLERACTINIA ,LARVAE ,FISH larvae ,CORAL reef fishes ,ACROPORA ,NUTRITIONAL value ,CORALS - Abstract
Planktivorous fishes are known to consume coral larvae due to their high nutritional value that can benefit both the individual and their progeny. However, how the consumption of coral larvae varies among coral and fish taxa, between day and night and with the density of coral larvae is not well understood. Here, we used a series of laboratory feeding assays to determine how the consumption of coral larvae by five planktivorous damselfish species (Abudefduf sexfasciatus, Amblyglyphidodon curacao, Dascyllus trimaculatus, D. reticulatus, and Chromis viridis) differed (1) between larvae of the broadcast-spawning scleractinian coral Acropora tenuis and the brooding non-scleractinian coral Heliopora coerulea when offered at a constant density (100 larvae/50 L), (2) between day and night (A. tenuis only), and (3) among larval densities (A. tenuis: 5–500 larvae/50 L; H. coerulea: 5–250 larvae/50 L). When coral larvae were offered at 100 larvae/50 L, all five fish species examined consumed A. tenuis (78–97 larvae h
−1 ) at a greater rate than H. coerulea (23–57 larvae h−1 ), with these differences likely related to the behavior and/or pigmentation of the larvae. Consumption also varied among the fishes examined, though the differences were small when compared to differences between coral species. Consumption of A. tenuis was twofold higher at day than night likely reflecting the diurnally active feeding behavior of the fishes examined. When the density of coral larvae offered to the fishes was varied, three of five species exhibited a type II functional response (decelerating intake rate) for A. tenuis, while four out of five damselfish species exhibited a type III (sigmoidal intake rate) or type I (linear intake rate) for H. coerulea. This study demonstrates that predation by fishes contributes significantly to coral larvae mortality and that differences in consumption rates among coral species may affect the composition of coral recruits and ultimately coral assemblages. [ABSTRACT FROM AUTHOR]- Published
- 2019
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31. Non-triangular cross-diffusion systems with predator–prey reaction terms.
- Author
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Desvillettes, L. and Soresina, C.
- Abstract
A predator–prey system involving cross-diffusion is obtained at the formal level as a singular limit of a four-species reaction–diffusion system, following the approach proposed in the context of ODEs by Geritz and Gyllenberg (J Theor Biol 314:106–108, 2012). Part of this derivation can be made rigorous. The possibility of appearance of Turing patterns for this cross-diffusion system is studied, and compared to what happens when standard diffusion terms replace the cross-diffusion terms. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
32. Differential effects of climate warming on reproduction and functional responses on insects in the fourth trophic level.
- Author
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Chen, Cong, Gols, Rieta, Biere, Arjen, Harvey, Jeffrey A., and Barribeau, Seth
- Subjects
- *
FOOD chains , *ECOSYSTEM dynamics , *HEAT waves (Meteorology) , *GLOBAL warming , *POPULATION dynamics , *REPRODUCTION - Abstract
Understanding the effects of anthropogenic global warming (AGW) on species interactions is essential for predicting community responses to climate change. However, while effects of AGW on resource–consumer interactions at the first and second trophic level have been well studied, little is known about effects on interactions at higher trophic levels at the terminal end of food chains (e.g. in the third and fourth trophic levels).Here, we examined the effects of temperature variability by simulating heatwaves on functional responses of two species at the fourth trophic level (hyperparasitoids) that parasitize host species at the third trophic level (parasitoid cocoons).We found that host cocoons developed faster under simulated heatwave conditions, decreasing the temporal window of susceptibility of the host cocoons to parasitism by the two hyperparasitoids, and consequently parasitism declined with temperature. However, the effects of a simulated heatwave markedly differed among the two hyperparasitoid species; temperature and host quality had a much stronger effect on early reproduction in the less fecund hyperparasitoid Gelis agilis, than in the more fecund species Acrolyta nens.Our results suggest that exposure to heatwaves, that are expected to increase in frequency, will affect the ability of species at higher trophic levels to exploit transient resources whose suitability is temperature‐dependent. In turn, the observed effects of AGW on the functional responses of the hyperparasitoids may disrupt trophic interactions and have profound impact on population dynamics and ecological processes. A plain language summary is available for this article. Plain Language Summary [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
33. The influence of warming on the biogeographic and phylogenetic dependence of herbivore–plant interactions.
- Author
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Mu, Xidong, Xu, Meng, Ricciardi, Anthony, Dick, Jaimie T. A., Luo, Du, Wei, Hui, Hu, Yinchang, and Wei, Qiwei
- Subjects
- *
BIOGEOGRAPHY , *PHYLOGENY , *HERBIVORES , *PLANT invasions , *POMACEA - Abstract
Evolutionary experience and the phylogenetic relationships of plants have both been proposed to influence herbivore–plant interactions and plant invasion success. However, the direction and magnitude of these effects, and how such patterns are altered with increasing temperature, are rarely studied. Through laboratory functional response experiments, we tested whether the per capita feeding efficiency of an invasive generalist herbivore, the golden apple snail, Pomacea canaliculata, is dependent on the biogeographic origin and phylogenetic relatedness of host plants, and how increasing temperature alters these dependencies. The feeding efficiency of the herbivore was highest on plant species with which it had no shared evolutionary history, that is, novel plants. Further, among evolutionarily familiar plants, snail feeding efficiency was higher on those species more closely related to the novel plants. However, these biogeographic dependencies became less pronounced with increasing temperature, whereas the phylogenetic dependence was unaffected. Collectively, our findings indicate that the susceptibility of plants to this invasive herbivore is mediated by both biogeographic origin and phylogenetic relatedness. We hypothesize that warming erodes the influence of evolutionary exposure, thereby altering herbivore–plant interactions and perhaps the invasion success of plants. This is the first experimental evidence that the susceptibility of plants to invasive herbivores is not only dependent on biogeographic and phylogenetic contexts, but is probably altered by increasing temperature. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
34. All ecological models are wrong, but some are useful.
- Author
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Stouffer, Daniel B. and Gill, Jennifer
- Subjects
- *
ECOLOGICAL models , *POPULATION dynamics , *PREDATION , *FOOD chains , *ALLOMETRY - Abstract
In Focus:Curtsdotter, A., Banks, H. T., Banks, J. E., Jonsson, M., Jonsson, T., Laubmeier, A. N., ... Bommarco, R. (2019). Ecosystem function in predator‐prey food webs—Confronting dynamic models with empirical data. Journal of Animal Ecology, 88, https://doi.org/10.1111/1365-2656.12892 Species' population dynamics are influenced by a variety of abiotic and biotic factors. Curtsdotter et al. (2019) used a food web model to investigate the role of predator–prey interactions in the population dynamics of the bird cherry‐oat aphid Rhopalosiphum padi. Their analysis hinged on linking the observed population dynamics to a mathematical description of the multi‐species system via inverse methods—an approach less utilized in ecology but that allows one to search a wide space of possible parameterizations and identify best‐fit model parameters. By scrutinizing the fit of this model to observed aphid population dynamics in 10 separate barley fields, they identified fields in which predation was the key driving force; in others, they found that accurate predictions depended on the existence of an unpredictable and unidentified extrinsic driver of aphid mortality. By scrutinizing areas where the model gave poor or biologically counterintuitive fits, their study provides a path forward to better link ecological theory to ecosystem function. Species' population dynamics are influenced by a variety of abiotic and biotic factors. Curtsdotter et al. (2019) used a food web model and inverse methods to investigate the role of predator–prey interactions in the population dynamics of the bird cherry‐oat aphid Rhopalosiphum padi. Rather than just focusing on the good, their detailed scrutinizing of areas where the model gave poor or biologically counterintuitive fits provides a compelling path forward to better link ecological theory to ecosystem function. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
35. Effects of land cover changes and hydropower development on fish communities in Amazonian floodplain rivers
- Author
-
Grinstead Hessburg, Samuel Baron
- Subjects
- fish community, functional responses, Amazonian fish, Neotropical fish, fish diversity, hydropower, threshold responses, environmental gradient, forest loss, Biodiversity, Ecology and Evolutionary Biology, Other Ecology and Evolutionary Biology
- Abstract
In Amazonian River systems, diverse fish communities depend on the floodplains for providing feeding opportunities and critical spawning habitat during the seasonal flood pulse, which annually submerges floodplain forests. In the Amazon, large-scale deforestation and hydroelectric dam construction can have profound impacts on entire ecosystems by altering river-floodplain connectivity. This study attempts to improve understanding of Amazonian fish responses to these two stressors. The first chapter aims to understand how deforestation impacts floating meadow fish assemblages. For this study, we surveyed fish in floodplain lakes along the lower Amazon River, recording their abundance in relation to forest cover and local environmental factors. Using Threshold Indicator Taxa Analysis (TITAN2), we found that forest-sensitive species declined sharply below ~40% forest cover, while species tolerant of low forest cover increased notably below ~10%. Small-bodied, sedentary species, and species in the families Cichlidae and Characidae were linked with high forest cover, while large-bodied, migratory species, as well as species of Serrasalmidae were associated with low forest cover. These findings highlight how deforestation affects floating meadow fish communities, indicating specific thresholds of fish occurrence and abundance correlated with forest cover changes, ultimately altering taxonomic and functional community structure. The second chapter analyzes long-term taxonomic and functional impacts of dam construction on fish communities in the Madeira River, the largest tributary to the Amazon River, where two dams were built in 2012. Data on fish assemblages have been collected over 19 total years covering periods before dam construction, short-term post-construction, and long-term post-construction, using gillnet sets upstream, between reservoirs, and downstream of the dams. We modeled responses of the occurrence of fish using Hierarchical Models of Species Communities (HMSC), and found that in sections containing reservoirs, there was a short-term spike in species richness and the occurrence of almost all fishes, particularly in functional groups of fishes with increased feeding opportunities in newly created reservoirs. This was followed by long-term declines in richness and occurrence, which was especially pronounced in groups of fishes that rely on floodplain forest connectivity for feeding and reproductive opportunities. In the free-flowing downstream section, we documented steady long-term declines of most groups of fish, particularly species of Pacu, and other fish that depend on seasonal access to floodplain forest. This study adds to a growing body of literature that dams in the Amazon detrimentally impact most groups of fishes through the disruption of river-floodplain connectivity, and that this impact amplifies across long time scales. Impacts on fish communities identified in this thesis have ecological, cultural, and commercial implications. Monitoring fish community responses to increasing land-cover change is imperative for conservation of ecosystems and livelihoods.
- Published
- 2024
36. Functional responses of recently emerged seedlings of an endemic Mexican oak (Quercus eduardii) under climate change conditions
- Author
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Ernesto I. Badano, Francisco A. Guerra-Coss, Sandra M. Gelviz-Gelvez, Joel Flores, and Pablo Delgado-Sánchez
- Subjects
abandoned fields ,Climate change ,Forest ecosystems ,Functional responses ,Oak seedlings ,Botany ,QK1-989 - Abstract
Background: Climate change will increase temperature and reduce rainfall across temperate forests of Mexico. This can alter tree establishment dynamics within forest and in neighbouring man-made clearings. Hypotheses: Climate change will reduce emergence and survival of tree seedlings, and surviving plants will display functional responses matching with these changes. These effects should be more noticeable in clearings due to the lack of canopy cover. Studied species: Quercus eduardii (Fagaceae, section Lobatae) an oak species endemic to Mexico. Study site and years of study: Tree growing season 2015-2016 (rainy season) in a mature oak forest and a neighbouring clearing in Sierra de Álvarez, state of San Luis Potosí. Methods: In both habitats, we established control plots (under current climatic conditions) and climate change simulation plots (increased temperature and reduced rainfall). At the beginning of the growing season, we sowed acorns of Q. eduardii in these plots and monitored the emergence, survival and growth of seedlings. At the end of the growing season, we assessed functional responses on surviving seedlings. Results: Seedling emergence and survival were lower in climate change plots from both habitats. However, differences in survival between climate treatments were larger within the forest. Seedlings from climate change plots displayed functional responses indicating higher levels of thermal and water stress. Conclusions: This study indicates that climate change will constrain tree recruitment in Mexican oak forests. However, contrary to our expectations, it seems that these effects will be higher within forests than in man-made clearings.
- Published
- 2018
- Full Text
- View/download PDF
37. Coexistence of species in a tritrophic food chain model with Holling functional response type IV.
- Author
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Blé, Gamaliel, Castellanos, Víctor, and Dela‐Rosa, Miguel A.
- Subjects
- *
HOPF bifurcations , *FOOD chains , *COEXISTENCE of species , *LIMIT cycles , *DIFFERENTIAL equations - Abstract
We determine conditions on the parameters of a tritrophic food chain model, implying the coexistence of the species. We consider that both predators corresponding to middle and top trophic levels have Holling functional responses type IV, and the prey at the lower trophic level has either linear or logistic growth rate. We prove that the differential system has an equilibrium point in which it exhibits a supercritical Hopf bifurcation independently of the growth rate of the prey. In the logistic case, we prove the existence of at least three equilibrium points in the positive octant and one of them exhibits a supercritical Hopf bifurcation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
38. About reaction–diffusion systems involving the Holling-type II and the Beddington–DeAngelis functional responses for predator–prey models.
- Author
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Conforto, F., Desvillettes, Laurent, and Soresina, C.
- Published
- 2018
- Full Text
- View/download PDF
39. When the ground cover brings guests: is Anaphothrips obscurus a friend or a foe for the biological control of Tetranychus urticae in clementines?
- Author
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Gómez-Martínez, María Antonia, Jaques, Josep A., Ibáñez-Gual, María Victoria, and Pina, Tatiana
- Subjects
- *
GROUND cover plants , *TWO-spotted spider mite , *CLEMENTINE , *BIOLOGICAL control of agricultural pests , *PHYTOSEIIDAE - Abstract
Biological control of Tetranychus urticae Koch (Acari: Tetranychidae), a key pest of clementines, can be improved in this crop with the establishment of a ground cover of Festuca arundinacea Schreber (Poaceae). This cover houses an abundant and diverse community of predatory Phytoseiidae mites including Euseius stipulatus (Athias-Henriot), Neoseiulus barkeri Hughes, Neoseiulus californicus (McGregor) and Phytoseiulus persimilis Athias-Henriot and a dense population of the grass thrips Anaphothrips obscurus Müller (Thysanoptera: Thripidae) throughout the year. The aim of this study was to determine whether the presence of this thrips species could be related to the improvement in the biological control of T. urticae. Therefore, the capacity of the abovementioned phytoseiids to feed and reproduce on A. obscurus and their feeding preferences when T. urticae and A. obscurus were simultaneously offered, were analyzed. The results show that E. stipulatus, N. barkeri and N. californicus have a type II functional response when offered A. obscurus nymphs, whereas P. persimilis barely feeds on this thrips species. Furthermore, N. barkeri and N. californicus can reproduce feeding only on thrips. Regarding prey preference, the Tetranychus spp.- specialist P. persimilis preferably preyed on T. urticae, the generalists N. barkeri and E. stipulatus preferred A. obscurus, and the selective predator of tetranychid mites N. californicus showed no preference. Therefore, we hypothesize that the enhanced biological control of T. urticae observed could be related to A. obscurus becoming an alternative prey for non-specialist phytoseiids, without altering the control exerted by the T. urticae-specialist P. persimilis and likely reducing intraguild predation. [ABSTRACT FROM AUTHOR]
- Published
- 2018
- Full Text
- View/download PDF
40. Dynamics of a predator-prey system with prey subject to Allee effects and disease
- Author
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Yun Kang, Sourav Kumar Sasmal, Amiya Ranjan Bhowmick, and Joydev Chattopadhyay
- Subjects
eco-epidemiological system. ,bi-stability ,functional responses ,disease/predation-driven extinction ,tri-stability ,allee effect ,Biotechnology ,TP248.13-248.65 ,Mathematics ,QA1-939 - Abstract
In this article, we propose a general predator-prey system where prey is subject to Allee effects and disease with the following unique features: (i) Allee effects built in the reproduction process of prey where infected prey (I-class) has no contribution; (ii) Consuming infected prey would contribute less or negatively to the growth rate of predator (P-class) in comparison to the consumption of susceptible prey (S-class). We provide basic dynamical properties for this general model and perform the detailed analysis on a concrete model (SIP-Allee Model) as well as its corresponding model in the absence of Allee effects (SIP-no-Allee Model); we obtain the complete dynamics of both models: (a) SIP-Allee Model may have only one attractor (extinction of all species), two attractors (bi-stability either induced by small values of reproduction number of both disease and predator or induced by competition exclusion), or three attractors (tri-stability); (b) SIP-no-Allee Model may have either one attractor (only S-class survives or the persistence of S and I-class or the persistence of S and P-class) or two attractors (bi-stability with the persistence of S and I-class or the persistence of S and P-class). One of the most interesting findings is that neither models can support the coexistence of all three S, I, P-class. This is caused by the assumption (ii), whose biological implications are that I and P-class are at exploitative competition for S-class whereas I-class cannot be superior and P-class cannot gain significantly from its consumption of I-class. In addition, the comparison study between the dynamics of SIP-Allee Model and SIP-no-Allee Model lead to the following conclusions: 1) In the presence of Allee effects, species are prone to extinction and initial condition plays an important role on the surviving of prey as well as its corresponding predator; 2) In the presence of Allee effects, disease may be able to save prey from the predation-driven extinction and leads to the coexistence of S and I-class while predator can not save the disease-driven extinction. All these findings may have potential applications in conservation biology.
- Published
- 2014
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41. HDAC inhibition prevents transgene expression downregulation and loss-of-function in T-cell-receptor-transduced T cells
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Jessica Fleser, Bernard A. Fox, Annika Dalheim, David C. Murray, Chris Fountain, Constantine Godellas, Tamson V. Moore, Brendan D. Curti, Joseph I. Clark, Jodi Speiser, Siao Yi Wang, Michael I. Nishimura, Mallory Thomas, Matthew DeJong, Courtney Regan Wagner, Tarsem Moudgil, Gina Scurti, and Kelli A. Hutchens
- Subjects
0301 basic medicine ,Cancer Research ,medicine.medical_treatment ,Transgene ,Biology ,TCR-transduced T cells ,lcsh:RC254-282 ,Cell therapy ,03 medical and health sciences ,chemistry.chemical_compound ,gene silencing ,0302 clinical medicine ,Downregulation and upregulation ,Cancer immunotherapy ,HDAC inhibitors ,medicine ,Gene silencing ,Pharmacology (medical) ,sodium butyrate ,cancer immunotherapy ,T-cell receptor ,Sodium butyrate ,lcsh:Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,030104 developmental biology ,transgene silencing ,Oncology ,chemistry ,vorinostat ,030220 oncology & carcinogenesis ,functional responses ,Cancer research ,Molecular Medicine ,Original Article ,Histone deacetylase ,cell therapy ,gene-modified T cells - Abstract
T cells that are gene-modified with tumor-specific T cell receptors are a promising treatment for metastatic melanoma patients. In a clinical trial, we treated seven metastatic melanoma patients with autologous T cells transduced to express a tyrosinase-reactive T cell receptor (TCR) (TIL 1383I) and a truncated CD34 molecule as a selection marker. We followed transgene expression in the TCR-transduced T cells after infusion and observed that both lentiviral- and retroviral-transduced T cells lost transgene expression over time, so that by 4 weeks post-transfer, few T cells expressed either lentiviral or retroviral transgenes. Transgene expression was reactivated by stimulation with anti-CD3/anti-CD28 beads and cytokines. TCR-transduced T cell lentiviral and retroviral transgene expression was also downregulated in vitro when T cells were cultured without cytokines. Transduced T cells cultured with interleukin (IL)-15 maintained transgene expression. Culturing gene-modified T cells in the presence of histone deacetylase (HDAC) inhibitors maintained transgene expression and functional TCR-transduced T cell responses to tumor. These results implicate epigenetic processes in the loss of transgene expression in lentiviral- and retroviral-transduced T cells., Graphical Abstract, Nishimura and colleagues demonstrate that transgene expression in gene-modified anti-tumor T cells is reversibly downregulated over time in vivo and in vitro. Treatment with IL-15 or with HDAC inhibitors (sodium butyrate or vorinostat) reduced this downregulation and maintained T cell functional responses to tumor cells.
- Published
- 2021
42. Functional responses of cougars (<italic>Puma concolor</italic>) in a multiple prey‐species system.
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SORIA‐DÍAZ, Leroy, FOWLER, Mike S., MONROY‐VILCHIS, Octavio, and ORO, Daniel
- Subjects
- *
PUMAS , *PREDATION , *BIOMASS , *ARMADILLOS , *CARNIVOROUS animals - Abstract
Abstract: The study of predator–prey interactions is commonly analyzed using functional responses to gain an understanding of predation patterns and the impact they have on prey populations. Despite this, little is known about predator–prey systems with multiple prey species in sites near the equator. Here we studied the functional response of cougars (
Puma concolor ) in relation to their main prey, armadillo (Dasypus novemcinctus ), coati (Nasua narica ) and white‐tailed deer (Odocoileus virginianus ). Between 2004 and 2010, cougar scats were collected along 5 transects to estimate the consumption of different prey species. A relative abundance index (RAI ) was calculated for each prey species and cougar using 18 camera traps. We compared Holling type I, II and III functional response models to determine patterns in prey consumption based on the relative abundance and biomass of each prey species consumed. The 3 main prey species comprised 55% (armadillo), 17% (coati) and 8% (white‐tailed deer) of the diet. Type I and II functional responses described consumption of the 2 most common prey species armadillos and coati similarly well, while a type I response best characterized consumption of white‐tailed deer. A negative correlation between the proportions of armadillo versus coati and white‐tailed deer biomass in cougar scats suggests switching to consume alternative prey, confirming high foraging plasticity of this carnivore. This work represents one of the few studies to compare functional responses across multiple prey species, combined with evidence for prey‐switching at low densities of preferred prey. [ABSTRACT FROM AUTHOR]- Published
- 2018
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43. A trophic interaction framework for identifying the invasive capacity of novel organisms.
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Penk, Marcin, Saul, Wolf‐Christian, Dick, Jaimie T.A., Donohue, Ian, Alexander, Mhairi E., Linzmaier, Stefan, Jeschke, Jonathan M., and Kriticos, Darren
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BIOLOGICAL invasions ,INTRODUCED animals ,PREDATION ,FOOD chains ,TRANSGENIC organisms - Abstract
The likelihood and impacts of invasions by novel organisms (e.g. non-native species, genetically modified organisms) on the composition and functioning of receiving biological communities hinges on their capacity to exploit resources and/or avoid predation relative to resident counterparts. While assessment of invasion risk based on the comparison of functional responses (per-capita consumption rate as a function of resource density) of novel species with native analogues has been gaining popularity, it may be undermined if alternative prey and potential predators are not represented realistically., Here, we propose a conceptual framework that enables rigorous identification of trophic traits conducive to invasion success by novel organisms-irrespective of their trophic position-and their likely ecological impacts, given their arrival and establishment. We focus on consumption here, but our framework can also be used for autotrophic energy acquisition, and extended to non-trophic and indirect interactions., The framework enables a structured and prioritized selection of subsets of trophic links for invasion risk assessment. It is based on foraging theory and advances in comparative functional responses in invasion ecology. It can even be used in the absence of a resident comparator organism and when resources or predators are only partly known., Our approach enhances the predictive power of species screening, and thus advances prevention and management of invasions under a common framework for all types of novel organisms. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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44. Responses of Mytilus galloprovincialis hemocytes to environmental strains of Vibrio parahaemolyticus, Vibrio alginolyticus, Vibrio vulnificus.
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Ciacci, C., Manti, A., Canonico, B., Campana, R., Camisassi, G., Baffone, W., and Canesi, L.
- Subjects
- *
MYTILUS galloprovincialis , *VIBRIO parahaemolyticus , *BLOOD cells , *IMMUNE response , *AQUATIC microbiology - Abstract
Marine bivalves are exposed to different types of bacteria in the surrounding waters, in particular of the Vibrio genus. In the hemocytes of the mussel Mytilus spp. immune responses to different vibrios have been largely characterized. However, little information is available on the hemocyte responses to human pathogenic vibrios commonly detected in coastal waters and bivalve tissues that are involved in seafood-borne diseases. In this work, functional parameters of the hemocytes from the Mediterranean mussel M. galloprovincialis were evaluated in response to in vitro challenge with different vibrios isolated from environmental samples of the Adriatic sea (Italy): V. parahaemolyticus Conero, V. alginolyticus 1513 and V. vulnificus 509. V. parahaemolyticus ATCC 43996 was used for comparison. At the 50:1 bacteria hemocyte ratio, only V. parahaemolyticus strains induced significant lysosomal membrane destabilisation. Stimulation of extracellular lysozyme release, total ROS, O 2 − and NO production were observed, although to different extents and with distinct time courses for different vibrios, V. vulnificus 509 in particular. Further comparisons between V. parahaemolyticus Conero and V. vulnificus 509 showed that only the latter induced dysregulation of the phosphorylation state of p38 MAP Kinase and apoptotic processes. The results indicate that mussel hemocytes can mount an efficient immune response towards V. parahaemolyticus and V. alginolyticus strains, whereas V. vulnificus 509 may affect the hemocyte function. This is the first report on immune responses of mussels to local environmental isolates of human pathogenic vibrios. These data reinforce the hypothesis that Mytilus hemocytes show specific responses to different vibrio species and strains. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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- View/download PDF
45. Functional responses can unify invasion ecology.
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Dick, Jaimie, Alexander, Mhairi, Ricciardi, Anthony, Laverty, Ciaran, Downey, Paul, Xu, Meng, Jeschke, Jonathan, Saul, Wolf-Christian, Hill, Matthew, Wasserman, Ryan, Barrios-O'Neill, Daniel, Weyl, Olaf, and Shaw, Richard
- Abstract
We contend that invasion ecology requires a universal, measurable trait of species and their interactions with resources that predicts key elements of invasibility and ecological impact; here, we advocate that functional responses can help achieve this across taxonomic and trophic groups, among habitats and contexts, and can hence help unify disparate research interests in invasion ecology. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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46. Functional responses can't unify invasion ecology.
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Vonesh, James, McCoy, Mike, Altwegg, Res, Landi, Pietro, and Measey, John
- Abstract
Dick et al. (Biol Invasions, 2017) propose that the comparative functional response framework provides a unifying approach for the study of invasive species. We agree that functional responses are an important and powerful quantitative description of consumer effects on resources, and co-opting classical ecological theory to better predict invasive species impacts is a laudable move for invasion biology. However, we fear that the early successes of select examples of the comparative functional response (CFR) approach has led Dick et al. to exaggerate the generality of its utility, and about its ability to unify the field. Further, they fail to provide a convincing argument why CFR is better than existing tools such as invasion history or impact indices, even when considering emerging or potential invaders. In this response we provide details of three conceptual issues stemming from classical ecological theoretical frameworks and two practical problems that Dick et al. and other CFR proponents need to address. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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47. Demography and feeding behavior of Stenostomum leucops (Dugés, 1828)
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Alma R. Núñez-Ortiz, Sarma Nandini, and S.S.S. Nandini
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Stenostomum ,functional responses ,population growth ,prey selection ,feeding behavior. ,Geography. Anthropology. Recreation ,Physical geography ,GB3-5030 ,Environmental sciences ,GE1-350 - Abstract
Freshwater turbellarians, despite their mainly benthic habits, interact with pelagic communities of rotifers and cladocerans. However, very little is known about their demographic characteristics, food preference and functional response. To fill that gap we studied one of the most widely spread species, Stenostomum leucops. We conducted population growth experiments using abundant food (several rotifer and cladocerans species). To evaluate possible impact of S. leucops on planktonic communities, we conducted prey preference experiments at two temperatures: 18 and 23°C. The number of rotifers and cladocerans consumed was calculated by the difference between the initial and final density. We found that diets supplemented with fresh algae achieved higher S. leucops densities than those with detritus supplements in their diets. In the case of animal diets, Euchlanis dilatata allowed S. leucops reach higher densities than the other zooplankton species; E. dilatata was positively selected for in the selectivity study at both 18 and 23°C. Stenostomum leucops showed a type II functional response on rotifers and the cladoceran Alona glabra. Our results suggest that S. leucops select their prey according to their vulnerability using different mechanisms, which optimize their food intake.
- Published
- 2016
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- View/download PDF
48. Density-dependent ecosystem service delivery under shifting temperatures by dung beetles
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Honest Machekano, Casper Nyamukondiwa, Nonofo Gotcha, and Ross N. Cuthbert
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0106 biological sciences ,Ecological services ,Nutrient cycle ,Environmental Engineering ,Seed dispersal ,Climate change ,Changing environments ,010603 evolutionary biology ,01 natural sciences ,Ecosystem services ,Functional responses ,Feces ,Seed Dispersal ,Environmental Chemistry ,Animals ,Waste Management and Disposal ,Scarabaeus ,Ecosystem ,biology ,Ecology ,Dung removal ,Temperature ,Biodiversity ,15. Life on land ,biology.organism_classification ,Pollution ,Coleoptera ,010602 entomology ,Coprophagic species ,13. Climate action ,Density dependent ,Environmental science ,Natural capital ,Bioturbation - Abstract
Highlights: • Temperature, dung mass and beetle density affected dung utilisation services. • Dung utilisation increased significantly with temperature and density. • Largest Khepher prodigiosus exhibited highest dung utilisation among species. • Emergent effects suggest species respond differently to warming and beetle density. • Ecosystem services provision requires surveillance under global climate change. Abstract: Increases in the frequency and magnitude of suboptimal temperatures as a result of climate change are subjecting insects to unprecedented stresses. This may negatively affect their fitness and the efficiency of their ecosystem service provision. Dung beetles are ecosystem service providers: through feeding on and burying dung, they facilitate nutrient recycling, secondary seed dispersal, parasite control, soil bioturbation and dung decomposition. As such, prediction of how dung beetles respond to multiple anthropogenic environmental changes is critical for the conservation of ecosystem services. Here, we quantified ecosystem services via dung utilisation and dung ball production in three telecoprid species: Allogymnopleurus indigaceous, Scarabaeus zambezianus and Khepher prodigiosus. We examined ecosystem service efficiency factorially under different beetle densities towards different dung masses and under three temperature treatments (21 °C, 28 °C and 35 °C). Khepher prodigiosus, exhibited greatest dung utilisation efficiency overall across dung masses, compared to both S. zambezianus and A. indigaceous. Dung removal was exhibited under all the tested temperatures by all tested species, and therefore the sub-optimal temperatures employed here did not fully inhibit ecosystem service delivery. However, emergent effects among temperatures, beetle species and beetle density further affected removal efficiency: S. zambezianus and A. indigaceous utilisation increased with both warming and beetle density, whereas K. prodigiosus performance was less temperature- and density-dependent. Beetles also tended to exhibit positive density-dependence as dung supply increased. The numbers of dung balls produced differed across species, and increased with temperature and densities, with S. zambezianus producing significantly most balls overall. Our study provides novel evidence for differential density-dependent ecosystem service delivery among species across stressful temperature regimes and emergent effects for dung mass utilisation. This information is essential for biodiversity-ecosystem-function and is critical for the conservation of functionally efficacious species, with implications for natural capital conservation policy in rapidly changing environments.
- Published
- 2022
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49. Necessary and sufficient conditions for the existence of periodic solutions in a predator-prey model on time scales
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Xingyong Liu and Xiuxiang Liu
- Subjects
Time scales ,periodic solutions ,predator-prey system ,functional responses ,Mathematics ,QA1-939 - Abstract
This article explores the existence of periodic solutions for non-autonomous impulsive semi-ratio-dependent predator-prey systems on time scales. Based on a continuous theorem in coincidence degree theory, sharp sufficient and necessary conditions are derived in which most popular monotonic, non-monotonic and predator functional responses are applicable. This article extends the work in [6,10,12,13,134,18,25].
- Published
- 2012
50. Warming mediates the relationship between plant nutritional properties and herbivore functional responses.
- Author
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Xu, Meng, Dick, Jaimie T. A., Ricciardi, Anthony, Fang, Miao, Zhang, Canyu, Gu, Dangen, Mu, Xidong, Luo, Du, Wei, Hui, and Hu, Yinchang
- Subjects
- *
STOICHIOMETRY , *TEMPERATURE effect , *PLANT nutrition , *PER capita , *POMACEA canaliculata - Abstract
Quantifying the per capita effects of invasive alien species is crucial for assessing their ecological impact. A major challenge to risk assessment of invasive species was to understand the factors that cause per capita effects to vary in different ecological contexts, particularly in a warming world. By conducting functional response experiments, we estimated the per capita effects (attack rate and maximum feeding rate) of an invasive herbivorous snail, Pomacea canaliculata, toward ten host plant species. We tested whether variation in these effects is related to plant nutritional and physical properties (total N and dry matter content ( DMC)) and examined how increasing temperature can shift these relationships. We observed stronger per capita effects (i.e., higher attack rate and maximum feeding rate) by the snail on plants with higher total N, but no direct relationship was found with DMC. A significant interaction effect of total N and DMC on the attack rate indicated that DMC probably adjusted the feeding indirectly. Warmer temperatures reduced correlations between snail functional responses and host plant nutritional properties (total N) by increasing maximum feeding rate for plants of low nutrition, but there was no such effect on attack rates. However, given the nonreplacement design used in our study, the nonsignificant effect of temperature on the attack rate should be caveated. Our result suggests that characterizing the per capita effects of herbivores using functional responses can reveal the mechanisms by which climate change may alter herbivore-plant interactions and, thus, the ecological impacts of introduced herbivores. [ABSTRACT FROM AUTHOR]
- Published
- 2016
- Full Text
- View/download PDF
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