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Schulz NK, Asgari D, Liu S, Birnbaum SS, Williams AM, Prakash A, Tate AT. Resources modulate developmental shifts but not infection tolerance upon coinfection in an insect system. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.08.01.606236. [PMID: 39149267 PMCID: PMC11326177 DOI: 10.1101/2024.08.01.606236] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 08/17/2024]
Abstract
Energetic resources fuel immune responses and parasite growth within organisms, but it is unclear whether energy allocation is sufficient to explain changes in infection outcomes under the threat of multiple parasites. We manipulated diet in flour beetles (Tribolium confusum) infected with two natural parasites to investigate the role of resources in shifting metabolic and immune responses after single and co-infection. Our results suggest that gregarine parasites alter the within-host energetic environment, and by extension juvenile development time, in a diet-dependent manner. Gregarines do not affect host resistance to acute bacterial infection but do stimulate the expression of an alternative set of immune genes and promote damage to the gut, ultimately contributing to reduced survival regardless of diet. Thus, energy allocation is not sufficient to explain the immunological contribution to coinfection outcomes, emphasizing the importance of mechanistic insight for predicting the impact of coinfection across levels of biological organization.
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Affiliation(s)
- Nora K.E. Schulz
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37232
| | - Danial Asgari
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37232
| | - Siqin Liu
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37232
| | | | - Alissa M. Williams
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37232
| | - Arun Prakash
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37232
| | - Ann T. Tate
- Department of Biological Sciences, Vanderbilt University, Nashville TN 37232
- Evolutionary Studies Initiative, Vanderbilt University, Nashville TN 37232
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2
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Narr CF, Binger S, Sedlacek E, Anderson B, Shoemaker G, Stanley A, Stokoski M, Hall E. Evaluating host diet effects on microparasites by measuring the stoichiometry of infrapopulations one cell at a time. Ecol Evol 2024; 14:e11645. [PMID: 39026962 PMCID: PMC11255380 DOI: 10.1002/ece3.11645] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 05/23/2024] [Accepted: 06/16/2024] [Indexed: 07/20/2024] Open
Abstract
Progress in the field of ecological stoichiometry has demonstrated that the outcome of ecological interactions can often be predicted a priori based on the nutrient ratios (e.g., carbon: nitrogen: phosphorus, C:N:P) of interacting organisms. However, the challenges of accurately measuring the nutrient content of active parasites within hosts has limited our ability to rigorously apply ecological stoichiometry to host-parasite systems. Traditional nutrient analyses require high parasite biomasses, often preventing individual-level analyses. This prevents researchers from estimating variation in the nutrient content of individual parasites within a single host infrapopulation, a critical factor that could define how the ecology of the parasite affects the host-parasite interaction. Here, we explain how energy dispersive technology, a technique currently used to measure the elemental content of free-living microbes, can be adapted for parasitic microbial infrapopulations. We demonstrate the power of accurately quantifying the biomass stoichiometry of individual microbial parasites sampled directly from individual hosts. Using this approach, we show that the stoichiometric composition of two microbial parasites capable of infecting the same host are stoichiometrically distinct and respond to host diet quality differently. We also demonstrate that characteristics of the stoichiometric trait distributions of these infrapopulations were important predictors of host fecundity, a proxy for virulence in this system, and better predictors of parasite load than the mean parasite stoichiometry or our parasite and diet treatments alone. EDS provides a rigorous tool for applying ecological stoichiometry to host-parasite systems and enables researchers to explore the nutritional physiology of host-parasite interactions at a scale that is more relevant to the ecology and evolution of the system than traditional nutrient analyses. Here we demonstrate that this level of resolution provides useful insights into the diet-dependent physiology of microbial parasites and their hosts. We anticipate that this improved level of resolution has the potential to elucidate a range of eco-evo interactions in host-parasite systems that were previously unobservable.
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Affiliation(s)
- Charlotte F. Narr
- School of Biological SciencesSouthern Illinois University in CarbondaleCarbondaleIllinoisUSA
| | - Scott Binger
- School of Biological SciencesSouthern Illinois University in CarbondaleCarbondaleIllinoisUSA
| | - Erin Sedlacek
- School of Biological SciencesSouthern Illinois University in CarbondaleCarbondaleIllinoisUSA
| | - Bianca Anderson
- Environmental Sciences and SustainabilityFort CollinsColoradoUSA
| | - Grace Shoemaker
- Environmental Sciences and SustainabilityFort CollinsColoradoUSA
| | - Adrienne Stanley
- School of Biological SciencesSouthern Illinois University in CarbondaleCarbondaleIllinoisUSA
| | - Madison Stokoski
- School of Biological SciencesSouthern Illinois University in CarbondaleCarbondaleIllinoisUSA
| | - Ed Hall
- Environmental Sciences and SustainabilityFort CollinsColoradoUSA
- Graduate Degree Program in EcologyColorado State UniversityFort CollinsColoradoUSA
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3
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Stanley A, Valentine S, Narr CF. Divvying up the pie: Tissue nutrient content is related to its parasite load. Ecol Evol 2024; 14:e11122. [PMID: 38774141 PMCID: PMC11106516 DOI: 10.1002/ece3.11122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 02/19/2024] [Accepted: 02/23/2024] [Indexed: 05/24/2024] Open
Abstract
The nutrient content of host resources can influence the abundance of parasites within an ecosystem, but linking specific nutrients in a host to the abundance of different parasite taxa remains a challenge. Here, we work to forge this link by quantifying the relationship between the nutrient content of specific infection sites and the abundance of multiple parasite taxa within the digestive tract of largemouth bass (Micropterus salmoides) collected from the Mississippi River. To generate a mechanistic understanding of these relationships, we tested four basic predictions: (1) the nutrient content of different host tissues (infection sites) varies within and across hosts, (2) the nutrient content of parasite genera differs from that of their host tissue(s), (3) the nutrient content of parasite genera differ from one another and (4) the nutrient content of host tissues is related to the nutrient content and abundance of parasite genera. We found support for each of these predictions. We found stoichiometric differences between the digestive tissues we examined. We also found that across hosts, intestine and pyloric caeca C:N ratios increased and %N decreased with fish condition factor. Both of the actively feeding parasitic genera we measured had lower C:N ratios compared to both their host tissue and other encysted/non-reproductive genera, suggesting the potential for N limitation of these parasites in the intestines or pyloric caeca of hosts. Consistent with this possibility, we found that the total number of actively feeding parasitic worms in the pyloric caeca increased with that tissue's N:P ratio (but was not related to host condition factor). Our results suggest that parasites encounter significant variation in nutrient content within and across hosts and that this variation may influence the abundance of actively feeding parasites. This work highlights the need for additional empirical comparisons of parasite stoichiometry across tissues and individual hosts.
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Affiliation(s)
- Adrienne Stanley
- School of Biological SciencesSouthern Illinois UniversityCarbondaleILUSA
| | - Shaley Valentine
- Illinois River Biological StationIllinois Natural History SurveyHavanaILUSA
| | - Charlotte F. Narr
- School of Biological SciencesSouthern Illinois UniversityCarbondaleILUSA
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4
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Grunberg RL, Braat M, Bolnick DI. Elemental content of a host-parasite relationship in the threespine stickleback. Oecologia 2024; 204:427-437. [PMID: 37358647 DOI: 10.1007/s00442-023-05405-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 06/12/2023] [Indexed: 06/27/2023]
Abstract
Parasite infections are ubiquitous and their effects on hosts could play a role in ecosystem processes. Ecological stoichiometry provides a framework to study linkages between consumers and their resource, such as parasites and their host, and ecosystem process; however, the stoichiometric traits of host-parasite associations are rarely quantified. Specifically, it is unclear whether parasites' elemental ratios closely resemble those of their host or if infection is related to host stoichiometry, especially in vertebrate hosts. To answer such questions, we measured the elemental content (%C, %N, and %P) and molar ratios (C:N, C:P, and N:P) of parasitized and unparasitized Gasterosteus aculeatus (three-spined stickleback) and their cestode parasite, Schistocephalus solidus. Host and parasite elemental content were distinct from each other, and parasites were generally higher in %C and lower in %N and %P. Parasite infections were related to host C:N, with infected hosts being lower in C:N. Parasite elemental content was independent of their host, but parasite body mass and parasite density were important drivers of parasite stoichiometry. Overall, these potential effects of parasite infections on host stoichiometry along with parasites' distinct elemental compositions suggest parasites may further contribute to differences in how individual hosts store and recycle nutrients.
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Affiliation(s)
- Rita L Grunberg
- Department of Biology, University of North Carolina, Chapel Hill, NC, USA.
| | - Megan Braat
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA
| | - Daniel I Bolnick
- Department of Ecology and Evolutionary Biology, University of Connecticut, Storrs, CT, 06269, USA
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5
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Gsell AS, Biere A, de Boer W, de Bruijn I, Eichhorn G, Frenken T, Geisen S, van der Jeugd H, Mason-Jones K, Meisner A, Thakur MP, van Donk E, Zwart MP, Van de Waal DB. Environmental refuges from disease in host-parasite interactions under global change. Ecology 2023; 104:e4001. [PMID: 36799146 DOI: 10.1002/ecy.4001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2021] [Revised: 12/04/2022] [Accepted: 12/08/2022] [Indexed: 02/18/2023]
Abstract
The physiological performance of organisms depends on their environmental context, resulting in performance-response curves along environmental gradients. Parasite performance-response curves are generally expected to be broader than those of their hosts due to shorter generation times and hence faster adaptation. However, certain environmental conditions may limit parasite performance more than that of the host, thereby providing an environmental refuge from disease. Thermal disease refuges have been extensively studied in response to climate warming, but other environmental factors may also provide environmental disease refuges which, in turn, respond to global change. Here, we (1) showcase laboratory and natural examples of refuges from parasites along various environmental gradients, and (2) provide hypotheses on how global environmental change may affect these refuges. We strive to synthesize knowledge on potential environmental disease refuges along different environmental gradients including salinity and nutrients, in both natural and food-production systems. Although scaling up from single host-parasite relationships along one environmental gradient to their interaction outcome in the full complexity of natural environments remains difficult, integrating host and parasite performance-response can serve to formulate testable hypotheses about the variability in parasitism outcomes and the occurrence of environmental disease refuges under current and future environmental conditions.
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Affiliation(s)
- Alena S Gsell
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Ecosystem Research Department, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Arjen Biere
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Wietse de Boer
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Soil Biology Group, Wageningen University & Research, Wageningen, The Netherlands
| | - Irene de Bruijn
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Koppert, Berkel en Rodenrijs, The Netherlands
| | - Götz Eichhorn
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Centre for Avian Migration and Demography, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Thijs Frenken
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Great Lakes Institute for Environmental Research (GLIER), University of Windsor, Windsor, Ontario, Canada
| | - Stefan Geisen
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Department of Nematology, Wageningen University and Research, Wageningen, The Netherlands
| | - Henk van der Jeugd
- Department of Animal Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Centre for Avian Migration and Demography, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Kyle Mason-Jones
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Annelein Meisner
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Wageningen University & Research, Wageningen Research, Wageningen, The Netherlands.,Microbial Ecology Group, Department of Biology, Lund University, Lund, Sweden
| | - Madhav P Thakur
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Terrestrial Ecology Group, Institute of Ecology and Evolution, University of Bern, Bern, Switzerland
| | - Ellen van Donk
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Mark P Zwart
- Department of Microbial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands
| | - Dedmer B Van de Waal
- Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Wageningen, The Netherlands.,Department of Freshwater and Marine Ecology, Institute for Biodiversity and Ecosystem Dynamics, University of Amsterdam, Amsterdam, The Netherlands
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6
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Vannatta JT, Minchella DJ. The influence of parasitism on producers and nutrients in mesocosm ecosystems. FOOD WEBS 2021. [DOI: 10.1016/j.fooweb.2021.e00204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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7
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Clark NF, Taylor-Robinson AW. An Ecologically Framed Comparison of The Potential for Zoonotic Transmission of Non-Human and Human-Infecting Species of Malaria Parasite. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2021; 94:361-373. [PMID: 34211355 PMCID: PMC8223545] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
The threats, both real and perceived, surrounding the development of new and emerging infectious diseases of humans are of critical concern to public health and well-being. Among these risks is the potential for zoonotic transmission to humans of species of the malaria parasite, Plasmodium, that have been considered historically to infect exclusively non-human hosts. Recently observed shifts in the mode, transmission, and presentation of malaria among several species studied are evidenced by shared vectors, atypical symptoms, and novel host-seeking behavior. Collectively, these changes indicate the presence of environmental and ecological pressures that are likely to influence the dynamics of these parasite life cycles and physiological make-up. These may be further affected and amplified by such factors as increased urban development and accelerated rate of climate change. In particular, the extended host-seeking behavior of what were once considered non-human malaria species indicates the specialist niche of human malaria parasites is not a limiting factor that drives the success of blood-borne parasites. While zoonotic transmission of non-human malaria parasites is generally considered to not be possible for the vast majority of Plasmodium species, failure to consider the feasibility of its occurrence may lead to the emergence of a potentially life-threatening blood-borne disease of humans. Here, we argue that recent trends in behavior among what were hitherto considered to be non-human malaria parasites to infect humans call for a cross-disciplinary, ecologically-focused approach to understanding the complexities of the vertebrate host/mosquito vector/malaria parasite triangular relationship. This highlights a pressing need to conduct a multi-species investigation for which we recommend the construction of a database to determine ecological differences among all known Plasmodium species, vectors, and hosts. Closing this knowledge gap may help to inform alternative means of malaria prevention and control.
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Affiliation(s)
- Nicole F. Clark
- Institute for Applied Ecology, University of Canberra,
Bruce, Australia,College of Medicine and Public Health, Flinders
University, Australia
| | - Andrew W. Taylor-Robinson
- Infectious Diseases Research Group, School of Health,
Medical & Applied Sciences, Central Queensland University, Brisbane,
Australia,College of Health & Human Sciences, Charles Darwin
University, Casuarina, Australia,To whom all correspondence should be addressed:
Prof Andrew W. Taylor-Robinson, Infectious Diseases Research Group, School of
Health, Medical & Applied Sciences, Central Queensland University, 160 Ann
Street, Brisbane, QLD 4000, Australia; Tel: +61 7 3295 1185;
; ORCID iD: https://orcid.org/0000-0001-7342-8348
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8
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Frenken T, Paseka R, González AL, Asik L, Seabloom EW, White LA, Borer ET, Strauss AT, Peace A, Van de Waal DB. Changing elemental cycles, stoichiometric mismatches, and consequences for pathogens of primary producers. OIKOS 2021. [DOI: 10.1111/oik.08253] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
- Thijs Frenken
- Dept of Aquatic Ecology, Netherlands Inst. of Ecology (NIOO‐KNAW) Wageningen the Netherlands
- Great Lakes Inst. for Environmental Research (GLIER), Univ. of Windsor Windsor ON Canada
| | - Rachel Paseka
- Dept of Ecology, Evolution and Behavior, Univ. of Minnesota St. Paul MN USA
| | | | - Lale Asik
- Dept of Biology and Center for Computational and Integrative Biology, Rutgers Univ. Camden NJ USA
| | - Eric W. Seabloom
- Great Lakes Inst. for Environmental Research (GLIER), Univ. of Windsor Windsor ON Canada
| | - Lauren A. White
- National Socio‐Environmental Synthesis Center (SESYNC), Univ. of Maryland Annapolis MD USA
| | - Elizabeth T. Borer
- Great Lakes Inst. for Environmental Research (GLIER), Univ. of Windsor Windsor ON Canada
| | - Alex T. Strauss
- Great Lakes Inst. for Environmental Research (GLIER), Univ. of Windsor Windsor ON Canada
- Dept of Ecology, Evolution and Behavior, Univ. of Minnesota St. Paul MN USA
| | - Angela Peace
- Dept of Mathematics and Statistics, Texas Tech Univ. Lubbock TX USA
| | - Dedmer B. Van de Waal
- Dept of Aquatic Ecology, Netherlands Inst. of Ecology (NIOO‐KNAW) Wageningen the Netherlands
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9
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The contributions of a trematode parasite infectious stage to carbon cycling in a model freshwater system. Parasitol Res 2021; 120:1743-1754. [PMID: 33792814 DOI: 10.1007/s00436-021-07142-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 03/24/2021] [Indexed: 10/21/2022]
Abstract
Parasites remainunderstudied members of most ecosystems, especially free-living infectious stages, such as the aquatic cercariae of trematodes (flatworms). Recent studies are shedding more light on their roles, particularly as prey for a diverse array of aquatic predators, but the possible fates of cercariae remain unclear. While this is critical to elucidate because cercariae represent a large potential source of energy and nutrients, determining the fate of cercariae-derived organic matter involves many logistical challenges. Previous studies utilized elemental and stable isotope analysis when examining host-parasite interactions, but none has used such approaches to track the movement of cercariae biomass within food webs. Here we report that Plagiorchis sp. cercariae were effectively labelled with 13C by introducing this compound in the food of their snail host. We then added 13C-labelled cercariae as a potential food source to experimental mesocosms containing a simplified model freshwater food web represented by diving beetles (Dytiscidae sp.), dragonfly larvae (Leucorrhinia intacta), oligochaete worms (Lumbriculus variegatus), and a zooplankton community dominated by Daphnia pulex. The oligochaetes had the highest ratio of 13C to 12C, suggesting benthic detritivores are substantial, but previously unrecognized, consumers of cercariae biomass. In an experiment where L. variegatus were fed mass equivalents of dead D. pulex or cercariae, growth was greater with the latter diet, supporting the importance of cercariae as food source for benthic organisms. Given the substantial cercariae biomass possible in natural settings, understanding their contributions to energy flow and nutrient cycling is important, along with developing methods to do so.
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10
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Timi JT, Poulin R. Why ignoring parasites in fish ecology is a mistake. Int J Parasitol 2020; 50:755-761. [PMID: 32592807 DOI: 10.1016/j.ijpara.2020.04.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 04/08/2020] [Accepted: 04/18/2020] [Indexed: 12/14/2022]
Abstract
Parasites are ubiquitous components of biological systems that have evolved in multiple independent lineages during the history of life, resulting in a diversity of taxa greater than that of their free-living counterparts. Extant host-parasite associations are the result of tight reciprocal adaptations that allow parasites to exploit specific biological features of their hosts to ensure their transmission, survival, and maintenance of viable populations. As a result, parasites may affect host physiology, morphology, reproduction or behaviour, and they are increasingly recognized as having significant impacts on host individuals, populations, communities and even ecosystems. Although this is usually acknowledged by parasite ecologists, fish ecologists often ignore parasitism in their studies, often acting as though their systems are free of parasites. However, the effects of parasites on their hosts can alter variables routinely used in fish ecology, ranging from the level of individual fish (e.g. condition factors) to populations (e.g. estimates of mortality and reproductive success) or communities (e.g. measures of interspecific competition or the structure and functioning of food webs). By affecting fish physiology, parasites can also interfere with measurements of trophic levels by means of stable isotope composition, or have antagonistic or synergistic effects with host parameters normally used as indicators of different sources of pollution. Changes in host behaviour induced by parasites can also modify host distribution patterns, habitat selection, diet composition, sexual behaviour, etc., with implications for the ecology of fish and of their predators and prey. In this review, we summarise and illustrate the likely biases and erroneous conclusions that one may expect from studies of fish ecology that ignore parasites, from the individual to the community level. Given the impact of parasites across all levels of biological organisation, we show that their omission from the design and analyses of ecological studies poses real risks of flawed interpretations for those patterns and processes that ecologists seek to uncover.
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Affiliation(s)
- Juan T Timi
- Laboratorio de Ictioparasitología, Instituto de Investigaciones Marinas y Costeras (IIMyC), Facultad de Ciencias Exactas y Naturales, Universidad Nacional de Mar del Plata- Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET). Funes 3350, (7600) Mar del Plata, Argentina.
| | - Robert Poulin
- Zoology Department, University of Otago, PO Box 56, Dunedin 9054, New Zealand
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11
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Llopis-Belenguer C, Balbuena JA, Lange K, de Bello F, Blasco-Costa I. Towards a Unified Functional Trait Framework for Parasites. Trends Parasitol 2019; 35:972-982. [DOI: 10.1016/j.pt.2019.09.003] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 09/01/2019] [Accepted: 09/06/2019] [Indexed: 11/28/2022]
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12
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Schultz B, Koprivnikar J. Free-living parasite infectious stages promote zooplankton abundance under the risk of predation. Oecologia 2019; 191:411-420. [PMID: 31501977 DOI: 10.1007/s00442-019-04503-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2019] [Accepted: 09/04/2019] [Indexed: 11/30/2022]
Abstract
Free-living parasite infectious stages, such as the cercariae of trematodes (flatworms), can represent substantial biomass in aquatic ecosystems, yet their interactions with other planktonic fauna are poorly understood. Given that cercariae are consumed by various aquatic predators, sometimes even preferentially over zooplankton, their presence may decrease predation pressure on free-living organisms within similar trophic niches by serving as alternate prey. Here, we experimentally examined how the presence of cercariae (Plagiorchis sp.) affected the population dynamics of common freshwater zooplankton (Daphnia sp.) in the presence of a predator (the larval dragonfly, Leucorrhinia intacta) known to consume both. After seeding 48 mesocosms with starting populations of Daphnia, we used four treatments (12 replicates each) representing a factorial combination of the absence/presence of both cercariae and dragonfly larvae and tracked Daphnia populations over 4 weeks. We found a significant interaction between the presence of cercariae and predators on Daphnia population size. When faced with predation pressure, Daphnia reached ~ 50% higher numbers when accompanied by cercariae than without, suggesting a "protective" effect of the latter by acting as substitute prey. Within aquatic ecosystems, an abundance of trematodes may prove advantageous for zooplankton communities that share common predators, but further studies will be needed to determine how this varies depending on the predator, trematode, and zooplankton taxa involved.
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Affiliation(s)
- Ben Schultz
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada
| | - Janet Koprivnikar
- Department of Chemistry and Biology, Ryerson University, 350 Victoria Street, Toronto, ON, M5B 2K3, Canada.
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13
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High food quality increases infection of Gammarus pulex (Crustacea: Amphipoda) by the acanthocephalan parasite Pomphorhynchus laevis. Int J Parasitol 2019; 49:805-817. [PMID: 31348961 DOI: 10.1016/j.ijpara.2019.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 04/29/2019] [Accepted: 05/22/2019] [Indexed: 12/14/2022]
Abstract
Parasitism is an important process in ecosystems, but has been largely neglected in ecosystem research. However, parasites are involved in most trophic links in food webs with, in turn, a major role in community structure and ecosystem processes. Several studies have shown that higher nutrient availability in ecosystems tends to increase the prevalence of parasites. Yet, most of these studies focused on resource availability, whereas studies investigating resource quality remain scarce. In this study, we tested the impact of the quality of host food resources on infection by parasites, as well as on the consequences for the host. Three resources were used to individually feed Gammarus pulex (Crustacea: Amphipoda) experimentally infected or not infected with the acanthocephalan species Pomphorhynchus laevis: microbially conditioned leaf litter without phosphorus input (standard resource); microbially conditioned leaf litter enriched in phosphorus; and microbially conditioned leaf litter without phosphorus input but complemented with additional inputs of benthic diatoms rich in both phosphorus and eicosapentaenoic acid. During the 110 day experiment, infection rate, parasite load, host survival, and parasite-mediated behavioral traits implicated in trophic transmission were measured (refuge use, geotaxis and locomotor activity). The resources of higher quality, regardless of the infection status, reduced gammarid mortality and increased gammarid growth. In addition, higher quality resources increased the proportion of infected gammarids, and led to more cases of multi-infections. While slightly modifying the geotaxis behavior of uninfected gammarids, resource quality did not modulate the impact of parasites on host behavior. Finally, for most parameters, consumption of algal resources had a greater impact than did phosphorus-enriched leaf litter. Therefore, manipulation of resource quality significantly affected host-parasite relationships, which stressed the need for future research to investigate in natura the relationships between resource availability, resource quality and parasite prevalence.
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