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Krasnov BR, Shenbrot GI, Khokhlova IS, López Berrizbeitia MF, Matthee S, Sanchez JP, VAN DER Mescht L. Environment and traits affect parasite and host species positions but not roles in flea-mammal networks. Integr Zool 2024. [PMID: 38263720 DOI: 10.1111/1749-4877.12799] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2024]
Abstract
We studied spatial variation in the effects of environment and network size on species positions and roles in multiple flea-mammal networks from four biogeographic realms. We asked whether species positions (measured as species strength [SS], the degree of interaction specialization [d'], and the eigenvector centrality [C]) or the roles of fleas and their hosts in the interaction networks: (a) are repeatable/conserved within a flea or a host species; (b) vary in dependence on environmental variables and/or network size; and (c) the effects of environment and network size on species positions or roles in the networks depend on species traits. The repeatability analysis of species position indices for 441 flea and 429 host species, occurring in at least two networks, demonstrated that the repeatability of SS, d', and C within a species was significant, although not especially high, suggesting that the indices' values were affected by local factors. The majority of flea and host species in the majority of networks demonstrated a peripheral role. A value of at least one index of species position was significantly affected by environmental variables or network size in 41 and 36, respectively, of the 52 flea and 52 host species that occurred in multiple networks. In both fleas and hosts, the occurrence of the significant effect of environment or network size on at least one index of species position, but not on a species' role in a network, was associated with some species traits.
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Affiliation(s)
- Boris R Krasnov
- Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Georgy I Shenbrot
- Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - Irina S Khokhlova
- French Associates Institute for Agriculture and Biotechnology of Drylands, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
| | - M Fernanda López Berrizbeitia
- Programa de Conservación de los Murciélagos de Argentina (PCMA) and Instituto de Investigaciones de Biodiversidad Argentina (PIDBA)-CCT CONICET Noa Sur (Consejo Nacional de Investigaciones Científicas y Técnicas), Facultad de Ciencias Naturales e IML, UNT, and Fundación Miguel Lillo, San Miguel de Tucumán, Argentina
| | - Sonja Matthee
- Department of Conservation Ecology and Entomology, Stellenbosch University, Matieland, South Africa
| | - Juliana P Sanchez
- Centro de Investigaciones y Transferencia del Noroeste de la Provincia de Buenos Aires-CITNOBA (CONICET-UNNOBA), Pergamino, Argentina
| | - Luther VAN DER Mescht
- Clinvet International (Pty) Ltd, Bloemfontein, South Africa
- Department of Zoology and Entomology, University of the Free State, Bloemfontein, South Africa
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2
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Vagnon C, Rohr RP, Bersier LF, Cattanéo F, Guillard J, Frossard V. Combining food web theory and population dynamics to assess the impact of invasive species. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.913954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The impacts of invasive species on resident communities are driven by a tangle of ecological interactions difficult to quantify empirically. Combining a niche model with a population dynamic model, both allometrically parametrized, may represent a consistent framework to investigate invasive species impacts on resident communities in a food web context when empirical data are scarce. We used this framework to assess the ecological consequences of an invasive apex predator (Silurus glanis) in peri-Alpine lake food webs. Both increases and decreases of resident species abundances were highlighted and differed when accounting for different S. glanis body sizes. Complementarily, the prominence of indirect effects, such as trophic cascades, suggested that common approaches may only capture a restricted fraction of invasion consequences through direct predation or competition. By leveraging widely available biodiversity data, our approach may provide relevant insights for a comprehensive assessment and management of invasive species impacts on aquatic ecosystems.
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3
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Functional Responses and Additive Multiple Predator Effects of Two Common Wetland Fish. WATER 2022. [DOI: 10.3390/w14050699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Understanding trophic interactions is essential for the prediction and measurement of structure and function in aquatic environments. Communities in these ecosystems may be shaped by variables such as predator diversity, prey density and emergent multiple predator effects (MPEs), which are likely to influence trophic dynamics. In this study, we examined the effect of key predatory fish in floodplain wetlands, namely Oreochromis mossambicus and Enteromius paludinosus, towards Chironomidae prey, using a comparative functional response (FR) approach. We used single predator species as well as intra- and interspecific paired species to contrast FRs under multiple predator scenarios. Attack rate and handling time estimates from single predator FRs were used to predict multiple predators’ feeding rates, which were compared to observe multiple predators’ feeding rates to quantify potential MPEs. From single fish trials, each species displayed a significant Type II FR, characterized by high feeding rates at low prey densities. Oreochromis mossambicus had a steeper (initial slope, i.e., higher attack rate) and higher (asymptote of curve, i.e., shorter handling time and higher maximum feeding rate) FR, whereas E. paludinosus exhibited lower-magnitude FRs (i.e., lower attack rate, longer handling time and lower feeding rate). In multiple predator scenarios, feeding rates were well-predicted by those of single predators, both in conspecific and interspecific pairs, and thus we did not find evidence for antagonistic or synergistic MPEs. Predator–prey interactions in wetland systems can have significant consequences on the structure and dynamics of ecological communities. In turn, this could have destabilizing effects on resources in tropical wetlands. These results, although experimental, help us understand how trophic interaction among conspecific or interspecific fish species in Austral tropical wetlands might influence their aquatic prey species. This will help us to understand food web dynamics better.
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Cuthbert RN, Dalu T, Wasserman RJ, Sentis A, Weyl OLF, Froneman PW, Callaghan A, Dick JTA. Prey and predator density-dependent interactions under different water volumes. Ecol Evol 2021; 11:6504-6512. [PMID: 34141235 PMCID: PMC8207356 DOI: 10.1002/ece3.7503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 03/09/2021] [Accepted: 03/15/2021] [Indexed: 01/28/2023] Open
Abstract
Predation is a critical ecological process that directly and indirectly mediates population stabilities, as well as ecosystem structure and function. The strength of interactions between predators and prey may be mediated by multiple density dependences concerning numbers of predators and prey. In temporary wetland ecosystems in particular, fluctuating water volumes may alter predation rates through differing search space and prey encounter rates. Using a functional response approach, we examined the influence of predator and prey densities on interaction strengths of the temporary pond specialist copepod Lovenula raynerae preying on cladoceran prey, Daphnia pulex, under contrasting water volumes. Further, using a population dynamic modeling approach, we quantified multiple predator effects across differences in prey density and water volume. Predators exhibited type II functional responses under both water volumes, with significant antagonistic multiple predator effects (i.e., antagonisms) exhibited overall. The strengths of antagonistic interactions were, however, enhanced under reduced water volumes and at intermediate prey densities. These findings indicate important biotic and abiotic contexts that mediate predator-prey dynamics, whereby multiple predator effects are contingent on both prey density and search area characteristics. In particular, reduced search areas (i.e., water volumes) under intermediate prey densities could enhance antagonisms by heightening predator-predator interference effects.
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Affiliation(s)
- Ross N. Cuthbert
- GEOMAR Helmholtz‐Zentrum für Ozeanforschung KielKielGermany
- Institute for Global Food Security, School of Biological SciencesQueen's University BelfastBelfastUK
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
| | - Tatenda Dalu
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- School of Biology and Environmental SciencesUniversity of MpumalangaNelspruitSouth Africa
| | - Ryan J. Wasserman
- South African Institute for Aquatic BiodiversityMakhandaSouth Africa
- Department of Zoology and EntomologyRhodes UniversityMakhandaSouth Africa
| | - Arnaud Sentis
- INRAEAix Marseille University, UMR RECOVERAix‐en‐ProvenceFrance
| | - Olaf L. F. Weyl
- DSI/NRF Research Chair in Inland Fisheries and Freshwater EcologySouth African Institute for Aquatic BiodiversityMakhandaSouth Africa
| | | | - Amanda Callaghan
- Ecology and Evolutionary Biology, School of Biological SciencesUniversity of ReadingReadingUK
| | - Jaimie T. A. Dick
- Institute for Global Food Security, School of Biological SciencesQueen's University BelfastBelfastUK
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5
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Buxton M, Cuthbert RN, Dalu T, Nyamukondiwa C, Wasserman RJ. Predator density modifies mosquito regulation in increasingly complex environments. PEST MANAGEMENT SCIENCE 2020; 76:2079-2086. [PMID: 31943746 DOI: 10.1002/ps.5746] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 12/16/2019] [Accepted: 01/13/2020] [Indexed: 06/10/2023]
Abstract
BACKGROUND Predation plays a pivotal role in the composition and functioning of ecosystems. Both habitat complexity and predator density are important contexts which may determine the strength of trophic and non-trophic interactions. In aquatic systems, the efficacy of natural enemies in regulating vector pest species could be modified by such context dependencies. Here, we use a functional response (FR) approach to experimentally quantify conspecific multiple predator effects across a habitat complexity gradient of two notonectids, Anisops sardea and Enithares chinai, towards larvae of the vector mosquito Culex pipiens pipiens. RESULTS E. chinai exhibited significantly greater consumption rates than A. sardea across habitat complexities, both as individuals and conspecific pairs. Each predator type displayed Type II FRs across experimental treatments, with synergistic multiple predator effects (i.e. prey risk enhancement) displayed in the absence of habitat complexity. Effects of increasing habitat complexity modified multiple predator effects differentially between species given behavioral differences, with habitat complexity causing significant antagonism (i.e. prey risk reduction) with multiple A. sardea compared to E. chinai. CONCLUSION Habitat complexity effects on multiple predator interactions can manifest differently at the species level, suggesting emergent effects which complicate predictions of natural enemy impact in heterogenous environments. Considerations of density, diversity and habitat effects on efficacies of natural enemies should thus be considered by pest management practitioners to better explain biocontrol efficacies in increasingly diverse environments. © 2020 Society of Chemical Industry.
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Affiliation(s)
- Mmabaledi Buxton
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
| | - Ross N Cuthbert
- School of Biological Sciences, Queen's University Belfast, Belfast, UK
| | - Tatenda Dalu
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, South Africa
| | - Casper Nyamukondiwa
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
| | - Ryan J Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, Palapye, Botswana
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6
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Cuthbert RN, Callaghan A, Dick JTA. A novel metric reveals biotic resistance potential and informs predictions of invasion success. Sci Rep 2019; 9:15314. [PMID: 31653905 PMCID: PMC6814831 DOI: 10.1038/s41598-019-51705-9] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2019] [Accepted: 10/07/2019] [Indexed: 11/10/2022] Open
Abstract
Invasive species continue to proliferate and detrimentally impact ecosystems on a global scale. Whilst impacts are well-documented for many invaders, we lack tools to predict biotic resistance and invasion success. Biotic resistance from communities may be a particularly important determinant of the success of invaders. The present study develops traditional ecological concepts to better understand and quantify biotic resistance. We quantified predation towards the highly invasive Asian tiger mosquito Aedes albopictus and a representative native mosquito Culex pipiens by three native and widespread cyclopoid copepods, using functional response and prey switching experiments. All copepods demonstrated higher magnitude type II functional responses towards the invasive prey over the analogous native prey, aligned with higher attack and maximum feeding rates. All predators exhibited significant, frequency-independent prey preferences for the invader. With these results, we developed a novel metric for biotic resistance which integrates predator numerical response proxies, revealing differential biotic resistance potential among predators. Our results are consistent with field patterns of biotic resistance and invasion success, illustrating the predictive capacity of our methods. We thus propose the further development of traditional ecological concepts, such as functional responses, numerical responses and prey switching, in the evaluation of biotic resistance and invasion success.
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Affiliation(s)
- Ross N Cuthbert
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5DL, UK. .,Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, RG6 6AS, UK.
| | - Amanda Callaghan
- Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, RG6 6AS, UK
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Belfast, BT9 5DL, UK
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7
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Sheath DJ, Dick JTA, Dickey JWE, Guo Z, Andreou D, Britton JR. Winning the arms race: host-parasite shared evolutionary history reduces infection risks in fish final hosts. Biol Lett 2019; 14:rsbl.2018.0363. [PMID: 30045905 PMCID: PMC6083226 DOI: 10.1098/rsbl.2018.0363] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2018] [Accepted: 06/27/2018] [Indexed: 12/18/2022] Open
Abstract
Parasite manipulation of intermediate hosts evolves to increase parasite trophic transmission to final hosts, yet counter selection should act on the final host to reduce infection risk and costs. However, determining who wins this arms race and to what extent is challenging. Here, for the first time, comparative functional response analysis quantified final host consumption patterns with respect to intermediate host parasite status. Experiments used two evolutionarily experienced fish hosts and two naive hosts, and their amphipod intermediate hosts of the acanthocephalan parasite Pomphorhynchus tereticollis. The two experienced fish consumed significantly fewer infected than non-infected prey, with lower attack rates and higher handling times towards the former. Conversely, the two naive fish consumed similar numbers of infected and non-infected prey at most densities, with similar attack rates and handling times towards both. Thus, evolutionarily experienced final hosts can reduce their infection risks and costs via reduced intermediate host consumption, with this not apparent in naive hosts.
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Affiliation(s)
- Danny J Sheath
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK.,Institute of Global Health, University of Geneva, Geneva, Switzerland
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - James W E Dickey
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK
| | - Zhiqiang Guo
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK.,State Key Laboratory of Marine Resource Utilization in South China Sea, College of Oceanology, Hainan University, Haikou 570228, People's Republic of China
| | - Demetra Andreou
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK
| | - J Robert Britton
- Department of Life and Environmental Sciences, Faculty of Science and Technology, Bournemouth University, Poole, UK
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8
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Effect of prey size and structural complexity on the functional response in a nematode- nematode system. Sci Rep 2019; 9:5696. [PMID: 30952927 PMCID: PMC6451004 DOI: 10.1038/s41598-019-42213-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 03/25/2019] [Indexed: 11/09/2022] Open
Abstract
The functional response of a predatory nematode and the influence of different prey sizes and habitat structure on the concerning parameters were analyzed. We hypothesized that the handling of small prey would be less time-consuming, whereas feeding on larger prey would be more efficient. Therefore, type II functional response curves were expected for large prey and a trend towards type III curves for small prey. We expected the introduction of prey refuges to shift the functional response curves from hyperbolic to sigmoidal and that the effect would be even more pronounced with smaller prey. P. muscorum consumed large amounts of small and large C. elegans, with daily per capita ingestion of prey reaching a maximum of 19.8 µg fresh weight, which corresponds to 4.8 times the predator’s biomass. Regardless of prey size and habitat structure, P. muscorum exhibit a type III functional response. Overall, the allometric effect of prey size had a greater effect on the predator’s functional response than did the addition of substrate, presumably due to the similar body shape and mobility of the two nematode species. Our results demonstrate that individual factors such as feeding behavior are important determinants of functional responses and therefore of ecosystem stability.
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9
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Delmas E, Besson M, Brice MH, Burkle LA, Dalla Riva GV, Fortin MJ, Gravel D, Guimarães PR, Hembry DH, Newman EA, Olesen JM, Pires MM, Yeakel JD, Poisot T. Analysing ecological networks of species interactions. Biol Rev Camb Philos Soc 2019; 94:16-36. [PMID: 29923657 DOI: 10.1111/brv.12433] [Citation(s) in RCA: 180] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2017] [Revised: 05/08/2018] [Accepted: 05/14/2018] [Indexed: 01/24/2023]
Abstract
Network approaches to ecological questions have been increasingly used, particularly in recent decades. The abstraction of ecological systems - such as communities - through networks of interactions between their components indeed provides a way to summarize this information with single objects. The methodological framework derived from graph theory also provides numerous approaches and measures to analyze these objects and can offer new perspectives on established ecological theories as well as tools to address new challenges. However, prior to using these methods to test ecological hypotheses, it is necessary that we understand, adapt, and use them in ways that both allow us to deliver their full potential and account for their limitations. Here, we attempt to increase the accessibility of network approaches by providing a review of the tools that have been developed so far, with - what we believe to be - their appropriate uses and potential limitations. This is not an exhaustive review of all methods and metrics, but rather, an overview of tools that are robust, informative, and ecologically sound. After providing a brief presentation of species interaction networks and how to build them in order to summarize ecological information of different types, we then classify methods and metrics by the types of ecological questions that they can be used to answer from global to local scales, including methods for hypothesis testing and future perspectives. Specifically, we show how the organization of species interactions in a community yields different network structures (e.g., more or less dense, modular or nested), how different measures can be used to describe and quantify these emerging structures, and how to compare communities based on these differences in structures. Within networks, we illustrate metrics that can be used to describe and compare the functional and dynamic roles of species based on their position in the network and the organization of their interactions as well as associated new methods to test the significance of these results. Lastly, we describe potential fruitful avenues for new methodological developments to address novel ecological questions.
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Affiliation(s)
- Eva Delmas
- Département de Sciences Biologiques, Université de Montréal, Montréal, H2V 2J7, Canada.,Québec Centre for Biodiversity Sciences, McGill University, Montréal, H3A 1B1, Canada
| | - Mathilde Besson
- Département de Sciences Biologiques, Université de Montréal, Montréal, H2V 2J7, Canada.,Québec Centre for Biodiversity Sciences, McGill University, Montréal, H3A 1B1, Canada
| | - Marie-Hélène Brice
- Département de Sciences Biologiques, Université de Montréal, Montréal, H2V 2J7, Canada.,Québec Centre for Biodiversity Sciences, McGill University, Montréal, H3A 1B1, Canada
| | - Laura A Burkle
- Department of Ecology, Montana State University, Bozeman, MT 59715, U.S.A
| | - Giulio V Dalla Riva
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, V6T 1Z4, Canada
| | - Marie-Josée Fortin
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, M5S 3B2, Canada
| | - Dominique Gravel
- Québec Centre for Biodiversity Sciences, McGill University, Montréal, H3A 1B1, Canada.,Département de Biologie, Université de Sherbrooke, Sherbrooke, J1K 2R1, Canada
| | - Paulo R Guimarães
- Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo, 05508-090, Brazil
| | - David H Hembry
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ 85721, U.S.A
| | - Erica A Newman
- School of Natural Resources and Environment, University of Arizona, Tucson, AZ 85721, U.S.A.,Pacific Wildland Fire Sciences Laboratory, USDA Forest Service, Seattle, WA 98103, U.S.A
| | - Jens M Olesen
- Department of Bioscience, Aarhus University, Aarhus, 8000, Denmark
| | - Mathias M Pires
- Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas (UNICAMP), Campinas, 13083-862, Brazil
| | - Justin D Yeakel
- Life & Environmental Sciences, University of California Merced, Merced, CA 95343, U.S.A.,Santa Fe Institute, Santa Fe, NM 87501, U.S.A
| | - Timothée Poisot
- Département de Sciences Biologiques, Université de Montréal, Montréal, H2V 2J7, Canada.,Québec Centre for Biodiversity Sciences, McGill University, Montréal, H3A 1B1, Canada
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10
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Cuthbert RN, Dalu T, Wasserman RJ, Callaghan A, Weyl OL, Dick JT. Using functional responses to quantify notonectid predatory impacts across increasingly complex environments. ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY 2019. [DOI: 10.1016/j.actao.2018.11.004] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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11
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Cuthbert RN, Dalu T, Wasserman RJ, Dick JTA, Mofu L, Callaghan A, Weyl OLF. Intermediate predator naïveté and sex-skewed vulnerability predict the impact of an invasive higher predator. Sci Rep 2018; 8:14282. [PMID: 30250163 PMCID: PMC6155278 DOI: 10.1038/s41598-018-32728-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 09/14/2018] [Indexed: 12/03/2022] Open
Abstract
The spread of invasive species continues to reduce biodiversity across all regions and habitat types globally. However, invader impact prediction can be nebulous, and approaches often fail to integrate coupled direct and indirect invader effects. Here, we examine the ecological impacts of an invasive higher predator on lower trophic groups, further developing methodologies to more holistically quantify invader impact. We employ functional response (FR, resource use under different densities) and prey switching experiments to examine the trait- and density-mediated impacts of the invasive mosquitofish Gambusia affinis on an endemic intermediate predator Lovenula raynerae (Copepoda). Lovenula raynerae effectively consumed larval mosquitoes, but was naïve to mosquitofish cues, with attack rates and handling times of the intermediate predator unaffected by mosquitofish cue-treated water. Mosquitofish did not switch between male and female prey, consistently displaying a strong preference for female copepods. We thus demonstrate a lack of risk-reduction activity in the presence of invasive fish by L. raynerae and, in turn, high susceptibility of such intermediate trophic groups to invader impact. Further, we show that mosquitofish demonstrate sex-skewed predator selectivity towards intermediate predators of mosquito larvae, which may affect predator population demographics and, perversely, increase disease vector proliferations. We advocate the utility of FRs and prey switching combined to holistically quantify invasive species impact potential on native organisms at multiple trophic levels.
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Affiliation(s)
- Ross N Cuthbert
- Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK. .,DST/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa. .,Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, RG6 6AS, England, UK.
| | - Tatenda Dalu
- Department of Ecology and Resource Management, University of Venda, Thohoyandou, 0950, South Africa.,South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
| | - Ryan J Wasserman
- Department of Biological Sciences and Biotechnology, Botswana International University of Science and Technology, P. Bag 16, Palapye, Botswana.,South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Medical Biology Centre, Queen's University Belfast, Belfast, BT9 7BL, Northern Ireland, UK
| | - Lubabalo Mofu
- South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
| | - Amanda Callaghan
- Ecology and Evolutionary Biology, School of Biological Sciences, University of Reading, Harborne Building, Reading, RG6 6AS, England, UK
| | - Olaf L F Weyl
- DST/NRF Research Chair in Inland Fisheries and Freshwater Ecology, South African Institute for Aquatic Biodiversity (SAIAB), Grahamstown, 6140, South Africa
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12
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McIntire KM, Juliano SA. How can mortality increase population size? A test of two mechanistic hypotheses. Ecology 2018; 99:1660-1670. [PMID: 29722433 DOI: 10.1002/ecy.2375] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2017] [Revised: 03/11/2018] [Accepted: 04/12/2018] [Indexed: 11/05/2022]
Abstract
Overcompensation occurs when added mortality increases survival to the next life-cycle stage. Overcompensation can contribute to the Hydra effect, wherein added mortality increases equilibrium population size. One hypothesis for overcompensation is that added mortality eases density dependence, increasing survival to adulthood ("temporal separation of mortality and density dependence"). Mortality early in the life cycle is therefore predicted to cause overcompensation, whereas mortality later in the life cycle is not. Another hypothesis for overcompensation is that threat of mortality (e.g., from predation) causes behavioral changes that reduce overexploitation of resources, allowing resource recovery, and increasing production of adults ("prudent resource exploitation"). Behaviorally active predation cues alone are therefore predicted to cause overcompensation. We tested these predictions in two experiments with larvae of two species of Aedes. As predicted, early mortality yielded greater production of adults, and of adult females, and greater estimated rate of population increase than did later mortality. Addition of water-borne predation cues usually reduced browsing on surfaces in late-stage larvae, but contrary to prediction, resulted in neither significantly greater production of adult mosquitoes nor significantly greater estimated rate of increase. Thus we have strong evidence that timing of mortality contributes to overcompensation and the Hydra effect in mosquitoes. Evidence that predation cues alone can result in overcompensation via prudent resource exploitation is lacking. We expect the overcompensation in response to early mortality will be common in organisms with complex life cycles, density dependence among juveniles, and developmental control of populations.
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Affiliation(s)
- Kristina M McIntire
- School of Biological Sciences, Illinois State University, Normal, Illinois, 61790-4120, USA
| | - Steven A Juliano
- School of Biological Sciences, Illinois State University, Normal, Illinois, 61790-4120, USA
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13
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Beermann J, Boos K, Gutow L, Boersma M, Peralta AC. Combined effects of predator cues and competition define habitat choice and food consumption of amphipod mesograzers. Oecologia 2018; 186:645-654. [PMID: 29335795 PMCID: PMC5829112 DOI: 10.1007/s00442-017-4056-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Accepted: 12/24/2017] [Indexed: 12/01/2022]
Abstract
Predation has direct impact on prey populations by reducing prey abundance. In addition, predator presence alone can also have non-consumptive effects on prey species, potentially influencing their interspecific interactions and thus the structure of entire assemblages. The performance of potential prey species may, therefore, depend on both the presence of predators and competitors. We studied habitat use and food consumption of a marine mesograzer, the amphipod Echinogammarus marinus, in the presence/absence of a fish mesopredator and/or an amphipod competitor. The presence of the predator affected both habitat choice and food consumption of the grazer, indicating a trade-off between the use of predator-free space and food acquisition. Without the predator, E. marinus were distributed equally over different microhabitats, whereas in the presence of the predator, most individuals chose a sheltered microhabitat and reduced their food consumption. Furthermore, habitat choice of the amphipods changed in the presence of interspecific competitors, also resulting in reduced feeding rates. The performance of E. marinus is apparently driven by trait-mediated direct and indirect effects caused by the interplay of predator avoidance and competition. This highlights the importance of potential non-consumptive impacts of predators on their prey organisms. The flexible responses of small invertebrate consumers to the combined effects of predation and competition potentially lead to changes in the structure of coastal ecosystems and the multiple species interactions therein.
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Affiliation(s)
- Jan Beermann
- Department of Functional Ecology, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PO Box 120161, 27515, Bremerhaven, Germany.
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, Postbox 180, 27483, Helgoland, Germany.
- Helmholtz Institute for Functional Marine Biodiversity, Oldenburg, Germany.
| | - Karin Boos
- MARUM-Center for Marine Environmental Sciences, University of Bremen, Leobener Straße 8, 28359, Bremen, Germany
| | - Lars Gutow
- Department of Functional Ecology, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, PO Box 120161, 27515, Bremerhaven, Germany
| | - Maarten Boersma
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, Postbox 180, 27483, Helgoland, Germany
- FB2, University of Bremen, Bremen, Germany
| | - Ana Carolina Peralta
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Biologische Anstalt Helgoland, Postbox 180, 27483, Helgoland, Germany
- Marine Biology Laboratory, Simon Bolivar University, Caracas, Venezuela
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14
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Médoc V, Thuillier L, Spataro T. Opportunistic omnivory impairs our ability to predict invasive species impacts from functional response comparisons. Biol Invasions 2017. [DOI: 10.1007/s10530-017-1628-5] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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15
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Terry JCD, Morris RJ, Bonsall MB. Trophic interaction modifications: an empirical and theoretical framework. Ecol Lett 2017; 20:1219-1230. [PMID: 28921859 PMCID: PMC6849598 DOI: 10.1111/ele.12824] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/01/2017] [Accepted: 07/17/2017] [Indexed: 12/01/2022]
Abstract
Consumer-resource interactions are often influenced by other species in the community. At present these 'trophic interaction modifications' are rarely included in ecological models despite demonstrations that they can drive system dynamics. Here, we advocate and extend an approach that has the potential to unite and represent this key group of non-trophic interactions by emphasising the change to trophic interactions induced by modifying species. We highlight the opportunities this approach brings in comparison to frameworks that coerce trophic interaction modifications into pairwise relationships. To establish common frames of reference and explore the value of the approach, we set out a range of metrics for the 'strength' of an interaction modification which incorporate increasing levels of contextual information about the system. Through demonstrations in three-species model systems, we establish that these metrics capture complimentary aspects of interaction modifications. We show how the approach can be used in a range of empirical contexts; we identify as specific gaps in current understanding experiments with multiple levels of modifier species and the distributions of modifications in networks. The trophic interaction modification approach we propose can motivate and unite empirical and theoretical studies of system dynamics, providing a route to confront ecological complexity.
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Affiliation(s)
| | - Rebecca J. Morris
- Department of ZoologyUniversity of OxfordOxfordOX1 3PSUK
- Biological Sciences, Faculty of Natural and Environmental SciencesUniversity of SouthamptonLife Sciences Building 85Highfield CampusSouthamptonSO17 1BJUK
| | - Michael B. Bonsall
- Department of ZoologyUniversity of OxfordOxfordOX1 3PSUK
- St. Peter's CollegeNew Inn Hall StreetOxfordOX1 2DLUK
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16
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Penk M, Saul W, Dick JT, Donohue I, Alexander ME, Linzmaier S, Jeschke JM. A trophic interaction framework for identifying the invasive capacity of novel organisms. Methods Ecol Evol 2017. [DOI: 10.1111/2041-210x.12817] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Marcin Penk
- School of Natural SciencesTrinity College Dublin Dublin Ireland
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
| | - Wolf‐Christian Saul
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
- Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin Germany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany
- Centre for Invasion Biology (CIB)Department of Botany and Zoology & Department of Mathematical SciencesStellenbosch University Matieland South Africa
| | - Jaimie T.A. Dick
- Institute for Global Food SecuritySchool of Biological SciencesQueen's University Belfast Belfast UK
| | - Ian Donohue
- School of Natural SciencesTrinity College Dublin Dublin Ireland
| | - Mhairi E. Alexander
- Institute for Biomedical and Environmental Health Research (IBEHR)School of Science and SportUniversity of the West of Scotland Paisley UK
| | - Stefan Linzmaier
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
- Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin Germany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany
| | - Jonathan M. Jeschke
- Department of Biology, Chemistry, PharmacyInstitute of BiologyFreie Universität Berlin Berlin Germany
- Leibniz‐Institute of Freshwater Ecology and Inland Fisheries (IGB) Berlin Germany
- Berlin‐Brandenburg Institute of Advanced Biodiversity Research (BBIB) Berlin Germany
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17
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Wada Y, Iwasaki K, Ida TY, Yusa Y. Roles of the seasonal dynamics of ecosystem components in fluctuating indirect interactions on a rocky shore. Ecology 2017; 98:1093-1103. [PMID: 28112400 DOI: 10.1002/ecy.1743] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/22/2016] [Revised: 12/14/2016] [Accepted: 01/04/2017] [Indexed: 11/06/2022]
Abstract
Accurately evaluating the strengths of direct (i.e., consumptive and non-consumptive) effects and indirect (density- and trait-mediated) interactions is crucial for understanding the mechanisms of the maintenance and dynamics of an ecosystem. However, an in situ evaluation has not been conducted for a long enough period of time to fully consider the seasonality and life histories of the community components. We conducted a 9-month (from summer to spring) field experiment in an intertidal rocky shore ecosystem involving the carnivorous snail, Thais clavigera, its prey, the limpet Siphonaria sirius, and their resources, the cyanobacterium (blue-green alga) Lithoderma sp. and the green algae Ulva spp. From summer to autumn, the predation pressure was high, and the consumptive and non-consumptive effects of the predator had opposite (positive and negative, respectively) effects on the prey. Both the density- and trait-mediated indirect interactions decreased the coverage of Lithoderma and increased the coverage of Ulva. As the predation pressure decreased in autumn, the predator affected both the adults and the new recruits of the prey. The trait-mediated interactions still existed, but the density-mediated interactions were not detected. From winter to spring, no direct effects or indirect interactions were detected because of the low predation pressure. Our investigation highlights previously unnoticed processes-showing that the strengths of the direct effects and indirect interactions fluctuate greatly with the seasonality of the ecosystem components.
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Affiliation(s)
- Yoko Wada
- Faculty of Science, Nara Women's University, Kitauoya-nishi, Nara, 6308506 Japan
| | - Keiji Iwasaki
- Institute for Natural Science, Nara University, 1500 Misasagi-cho, Nara, 6318502 Japan
| | - Takashi Y Ida
- Faculty of Science, Nara Women's University, Kitauoya-nishi, Nara, 6308506 Japan
| | - Yoichi Yusa
- Faculty of Science, Nara Women's University, Kitauoya-nishi, Nara, 6308506 Japan
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18
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Martinez-Haro M, Acevedo P, Pais-Costa AJ, Taggart MA, Martins I, Ribeiro R, Marques JC. Assessing estuarine quality: A cost-effective in situ assay with amphipods. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2016; 212:382-391. [PMID: 26874320 DOI: 10.1016/j.envpol.2016.01.071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2015] [Revised: 01/19/2016] [Accepted: 01/25/2016] [Indexed: 06/05/2023]
Abstract
In situ assays based on feeding depression can be powerful ecotoxicological tools that can link physiological organism-level responses to population and/or community-level effects. Amphipods are traditional target species for toxicity tests due to their high sensitivity to contaminants, availability in the field and ease of handling. However, cost-effective in situ assays based on feeding depression are not yet available for amphipods that inhabit estuarine ecosystems. The aim of this work was to assess a short-term in situ assay based on postexposure feeding rates on easily quantifiable food items with an estuarine amphipod. Experiments were carried out under laboratory conditions using juvenile Echinogammarus marinus as the target individual. When 60 Artemia franciscana nauplii (as prey) were provided per individual for a period of 30 min in dark conditions, feeding rates could be easily quantified. As an endpoint, postexposure feeding inhibition in E. marinus was more sensitive to cadmium contamination than mortality. Assay calibration under field conditions demonstrated the relevance of sediment particle size in explaining individual feeding rates in uncontaminated water bodies. An evaluation of the 48-h in situ bioassay based on postexposure feeding rates indicated that it is able to discriminate between unpolluted and polluted estuarine sites. Using the harmonized protocol described here, the in situ postexposure feeding assay with E. marinus was found to be a potentially useful, cost-effective tool for assessing estuarine sediment and water quality.
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Affiliation(s)
- Monica Martinez-Haro
- MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Portugal; Instituto de Investigación en Recursos Cinegéticos (IREC-CSIC-UCLM-JCCM), Ronda de Toledo 12, Ciudad Real, Spain.
| | - Pelayo Acevedo
- Instituto de Investigación en Recursos Cinegéticos (IREC-CSIC-UCLM-JCCM), Ronda de Toledo 12, Ciudad Real, Spain
| | - Antónia Juliana Pais-Costa
- MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Portugal
| | - Mark A Taggart
- Environmental Research Institute, University of the Highlands and Islands, Castle Street, Thurso, Caithness, Scotland, KW14 7JD, UK
| | - Irene Martins
- MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Portugal
| | - Rui Ribeiro
- Centre for Functional Ecology, Department of Life Sciences, University of Coimbra, Calçada Martim de Freitas, 3000-456, Coimbra, Portugal
| | - João Carlos Marques
- MARE - Marine and Environmental Sciences Centre, Department of Life Sciences, University of Coimbra, Portugal
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19
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Paterson RA, Dick JTA, Pritchard DW, Ennis M, Hatcher MJ, Dunn AM. Predicting invasive species impacts: a community module functional response approach reveals context dependencies. J Anim Ecol 2015; 84:453-63. [PMID: 25265905 PMCID: PMC4354255 DOI: 10.1111/1365-2656.12292] [Citation(s) in RCA: 65] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2013] [Accepted: 08/21/2014] [Indexed: 11/28/2022]
Abstract
Predatory functional responses play integral roles in predator-prey dynamics, and their assessment promises greater understanding and prediction of the predatory impacts of invasive species. Other interspecific interactions, however, such as parasitism and higher-order predation, have the potential to modify predator-prey interactions and thus the predictive capability of the comparative functional response approach. We used a four-species community module (higher-order predator; focal native or invasive predators; parasites of focal predators; native prey) to compare the predatory functional responses of native Gammarus duebeni celticus and invasive Gammarus pulex amphipods towards three invertebrate prey species (Asellus aquaticus, Simulium spp., Baetis rhodani), thus, quantifying the context dependencies of parasitism and a higher-order fish predator on these functional responses. Our functional response experiments demonstrated that the invasive amphipod had a higher predatory impact (lower handling time) on two of three prey species, which reflects patterns of impact observed in the field. The community module also revealed that parasitism had context-dependent influences, for one prey species, with the potential to further reduce the predatory impact of the invasive amphipod or increase the predatory impact of the native amphipod in the presence of a higher-order fish predator. Partial consumption of prey was similar for both predators and occurred increasingly in the order A. aquaticus, Simulium spp. and B. rhodani. This was associated with increasing prey densities, but showed no context dependencies with parasitism or higher-order fish predator. This study supports the applicability of comparative functional responses as a tool to predict and assess invasive species impacts incorporating multiple context dependencies.
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Affiliation(s)
- Rachel A Paterson
- Institute for Global Food Security, School of Biological Sciences, Queen's University BelfastBelfast, UK
- School of Biology, University of LeedsLeeds, UK
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University BelfastBelfast, UK
| | - Daniel W Pritchard
- School of Planning, Architecture and Civil Engineering, Queen's University BelfastBelfast, UK
| | - Marilyn Ennis
- Institute for Global Food Security, School of Biological Sciences, Queen's University BelfastBelfast, UK
| | - Melanie J Hatcher
- School of Biology, University of LeedsLeeds, UK
- School of Biological Sciences, University of BristolBristol, UK
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20
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Nonconsumptive Effects of Predation and Impaired Chemosensory Risk Assessment on an Aquatic Prey Species. INTERNATIONAL JOURNAL OF ECOLOGY 2015. [DOI: 10.1155/2015/894579] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Weak levels of acidity impair chemosensory risk assessment by aquatic species which may result in increased predator mortalities in the absence of compensatory avoidance mechanisms. Using replicate populations of wild juvenile Atlantic salmon (Salmo salar) in neutral and acidic streams, we conducted a series of observational studies and experiments to identify differences in behaviours that may compensate for the loss of chemosensory information on predation risk. Comparing the behavioural strategies of fish between neutral and acidic streams may elucidate the influence of environmental degradation on nonconsumptive effects (NCEs) of predation. Salmon in acidic streams are more active during the day than their counterparts in neutral streams, and are more likely to avoid occupying territories offering fewer physical refugia from predators. Captive cross-population transplant experiments indicate that at equal densities, salmon in acidic streams do not demonstrate relative decreases in growth rate as a result of their different behavioural strategies. Instead, altering diel activity patterns to maximize visual information use and occupying relatively safer territories appear sufficient to offset increased predation risk in acidic streams. Additional strategies such as elevated foraging rates during active periods or adopting riskier foraging tactics are necessary to account for the observed similarities in growth rates.
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21
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Abdala-Roberts L, Mooney KA. Ecological and evolutionary consequences of plant genotype diversity in a tri-trophic system. Ecology 2014. [DOI: 10.1890/13-2029.1] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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22
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MacNeil C, Dick JTA. The enemy of my enemy is my friend: intraguild predation between invaders and natives facilitates coexistence with shared invasive prey. Biol Lett 2014; 10:rsbl.2014.0398. [PMID: 25122739 DOI: 10.1098/rsbl.2014.0398] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Understanding and predicting the outcomes of biological invasions is challenging where multiple invader and native species interact. We hypothesize that antagonistic interactions between invaders and natives could divert their impact on subsequent invasive species, thus facilitating coexistence. From field data, we found that, when existing together in freshwater sites, the native amphipod Gammarus duebeni celticus and a previous invader G. pulex appear to facilitate the establishment of a second invader, their shared prey Crangonyx pseudogracilis. Indeed, the latter species was rarely found at sites where each Gammarus species was present on its own. Experiments indicated that this may be the result of G. d. celticus and G. pulex engaging in more intraguild predation (IGP) than cannibalism; when the 'enemy' of either Gammarus species was present, that is, the other Gammarus species, C. pseudogracilis significantly more often escaped predation. Thus, the presence of mutual enemies and the stronger inter- than intraspecific interactions they engage in can facilitate other invaders. With some invasive species such as C. pseudogracilis having no known detrimental effects on native species, and indeed having some positive ecological effects, we also conclude that some invasions could promote biodiversity and ecosystem functioning.
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Affiliation(s)
- Calum MacNeil
- Department of Environment, Food and Agriculture, The Isle of Man Government, Thie Slieau Whallian, Foxdale Road, St. Johns IM4 3AS, The Isle of Man, The British Isles
| | - Jaimie T A Dick
- Institute for Global Food Security, School of Biological Sciences, Queen's University Belfast, MBC, 97 Lisburn Road, Belfast BT9 7BL, UK
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23
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Toscano BJ, Griffen BD. Trait-mediated functional responses: predator behavioural type mediates prey consumption. J Anim Ecol 2014; 83:1469-77. [PMID: 24749626 DOI: 10.1111/1365-2656.12236] [Citation(s) in RCA: 75] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2014] [Accepted: 04/11/2014] [Indexed: 11/29/2022]
Abstract
The predator functional response (i.e. per capita consumption rate as a function of prey density) is central to our understanding of predator-prey population dynamics. This response is behavioural, depending on the rate of attack and time it takes to handle prey. Consistent behavioural differences among conspecific individuals, termed behavioural types, are a widespread feature of predator and prey populations but the effects of behavioural types on the functional response remain unexplored. We tested the effects of crab (Panopeus herbstii) behavioural type, specifically individual activity level, on the crab functional response to mussel (Brachidontes exustus) prey. We further tested whether the effects of activity level on the response are mediated by the presence of toadfish (Opsanus tau) predation threat in the form of waterborne chemical cues known to reduce crab activity level. The effects of crab activity level on the functional response were dependent on crab body size. Individual activity level increased the magnitude (i.e. slope and asymptote) of the type II functional response of small crabs, potentially through an increase in time spent foraging, but had no effect on the functional response of large crabs. Predation threat did not interact with activity level to influence mussel consumption, but independently reduced the slope of the type II functional response. Overall, this study demonstrates size-specific effects of a behavioural type on a predator-prey interaction, as well as a general pathway (modification of the functional response) by which the effects of individual behavioural types can scale up to influence predator-prey population dynamics.
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Affiliation(s)
- Benjamin J Toscano
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA
| | - Blaine D Griffen
- Department of Biological Sciences, University of South Carolina, Columbia, SC, 29208, USA.,Marine Science Program, University of South Carolina, Columbia, SC, 29208, USA
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24
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Predator cue studies reveal strong trait-mediated effects in communities despite variation in experimental designs. Anim Behav 2013. [DOI: 10.1016/j.anbehav.2013.09.036] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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