1
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Higher mortality of the less suitable brown trout host compared to the principal Atlantic salmon host when infested with freshwater pearl mussel (Margaritifera margaritifera) glochidia. Parasitol Res 2021; 120:2401-2413. [PMID: 33844065 PMCID: PMC8263406 DOI: 10.1007/s00436-021-07145-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2020] [Accepted: 03/30/2021] [Indexed: 10/31/2022]
Abstract
The freshwater pearl mussel (Margaritifera margaritifera) is a highly host-specific parasite, with an obligate parasitic stage on salmonid fish. Atlantic salmon (Salmo salar) and brown trout (Salmo trutta f. trutta and Salmo trutta f. fario) are the only hosts in their European distribution. Some M. margaritifera populations exclusively infest either Atlantic salmon or brown trout, while others infest both hosts with one salmonid species typically being the principal host and the other a less suitable host. Glochidial abundance, prevalence and growth are often used as parameters to measure host suitability, with the most suitable host species displaying the highest parameters. However, it is not known if the degree of host specialisation will negatively influence host fitness (virulence) among different host species. In this study we examined the hypothesis that glochidial infestation would result in differential virulence in two salmonid host species and that lower virulence would be observed on the most suitable host. Atlantic salmon and brown trout were infested with glochidia from two M. margaritifera populations that use Atlantic salmon as their principal host, and the difference in host mortality among infested and control (sham infested) fish was examined. Higher mortality was observed in infested brown trout (the less suitable host) groups, compared to the other test groups. Genetic assignment was used to identify offspring from individual mother mussels. We found that glochidia from individual mothers can infest both the salmonid hosts; however, some mothers displayed a bias towards either salmon or trout. We believe that the differences in host-dependent virulence and the host bias displayed by individual mothers were a result of genotype × genotype interactions between the glochidia and their hosts, indicating that there is an underlying genetic component for this parasite-host interaction.
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2
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Callens M, De Meester L, Muylaert K, Mukherjee S, Decaestecker E. The bacterioplankton community composition and a host genotype dependent occurrence of taxa shape the Daphnia magna gut bacterial community. FEMS Microbiol Ecol 2021; 96:5861314. [PMID: 32573725 PMCID: PMC7360484 DOI: 10.1093/femsec/fiaa128] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2020] [Accepted: 06/22/2020] [Indexed: 12/21/2022] Open
Abstract
The assembly of host-associated bacterial communities is influenced by a multitude of biotic and abiotic factors. It is essential to gain insight in the impact and relative strength of these factors if we want to be able to predict the effects of environmental change on the assembly of host-associated bacterial communities, or deliberately modify them. The environmental pool of bacteria, from which the host is colonized, and the genetic background of the host are both considered to be important in determining the composition of host-associated bacterial communities. We experimentally assessed the relative importance of these two factors and their interaction on the composition of Daphnia magna gut bacterial communities. Bacterioplankton originating from natural ponds or a laboratory culture were used to inoculate germ-free Daphnia of different genotypes. We found that the composition of the environmental bacterial community has a major influence on the Daphnia gut bacterial community, both reflected by the presence or absence of specific taxa as well as by a correlation between abundances in the environment and on the host. Our data also indicate a consistent effect of host genotype on the occurrence of specific bacterial taxa in the gut of Daphnia over different environments.
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Affiliation(s)
- Martijn Callens
- Laboratory of Aquatic Biology, Department of Biology, University of Leuven - Campus KULAK, E. Sabbelaan 53, B-8500 Kortrijk, Belgium.,CEFE, Univ Montpellier, CNRS, EPHE, IRD, Univ Paul Valéry Montpellier 3, Montpellier, France
| | - Luc De Meester
- Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven, Charles Deberiotstraat 32, 3000 Leuven, Belgium.,Institute of Biology, Freie Universität Berlin, Köning-Luise-Strasse 1-3, 14195 Berlin, Germany.,Leibniz Institut für Gewasserökologie und Binnenfischerei (IGB), Müggelseedamm 310, 12587 Berlin, Germany
| | - Koenraad Muylaert
- Laboratory of Aquatic Biology, Department of Biology, University of Leuven - Campus KULAK, E. Sabbelaan 53, B-8500 Kortrijk, Belgium
| | - Shinjini Mukherjee
- Laboratory of Aquatic Ecology, Evolution and Conservation, University of Leuven, Charles Deberiotstraat 32, 3000 Leuven, Belgium
| | - Ellen Decaestecker
- Laboratory of Aquatic Biology, Department of Biology, University of Leuven - Campus KULAK, E. Sabbelaan 53, B-8500 Kortrijk, Belgium
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3
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Bulteel L, Houwenhuyse S, Declerck SAJ, Decaestecker E. The Role of Microbiome and Genotype in Daphnia magna upon Parasite Re-Exposure. Genes (Basel) 2021; 12:70. [PMID: 33430247 PMCID: PMC7825712 DOI: 10.3390/genes12010070] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Revised: 12/31/2020] [Accepted: 01/05/2021] [Indexed: 02/07/2023] Open
Abstract
Recently, it has been shown that the community of gut microorganisms plays a crucial role in host performance with respect to parasite tolerance. Knowledge, however, is lacking on the role of the gut microbiome in mediating host tolerance after parasite re-exposure, especially considering multiple parasite infections. We here aimed to fill this knowledge gap by studying the role of the gut microbiome on tolerance in Daphnia magna upon multiple parasite species re-exposure. Additionally, we investigated the role of the host genotype in the interaction between the gut microbiome and the host phenotypic performance. A microbiome transplant experiment was performed in which three germ-free D. magna genotypes were exposed to a gut microbial inoculum and a parasite community treatment. The gut microbiome inocula were pre-exposed to the same parasite communities or a control treatment. Daphnia performance was monitored, and amplicon sequencing was performed to characterize the gut microbial community. Our experimental results showed that the gut microbiome plays no role in Daphnia tolerance upon parasite re-exposure. We did, however, find a main effect of the gut microbiome on Daphnia body size reflecting parasite specific responses. Our results also showed that it is rather the Daphnia genotype, and not the gut microbiome, that affected parasite-induced host mortality. Additionally, we found a role of the genotype in structuring the gut microbial community, both in alpha diversity as in the microbial composition.
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Affiliation(s)
- Lore Bulteel
- Laboratory of Aquatic Biology, Department of Biology, University of Leuven-Campus Kulak, E. Sabbelaan 53, 8500 Kortrijk, Belgium; (S.H.); (E.D.)
| | - Shira Houwenhuyse
- Laboratory of Aquatic Biology, Department of Biology, University of Leuven-Campus Kulak, E. Sabbelaan 53, 8500 Kortrijk, Belgium; (S.H.); (E.D.)
| | - Steven A. J. Declerck
- Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6700 AB Wageningen, The Netherlands;
- Laboratory of Aquatic Ecology, Evolution and Conservation, Department of Biology, KULeuven, 3000 Leuven, Belgium
| | - Ellen Decaestecker
- Laboratory of Aquatic Biology, Department of Biology, University of Leuven-Campus Kulak, E. Sabbelaan 53, 8500 Kortrijk, Belgium; (S.H.); (E.D.)
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4
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Reyserhove L, Samaey G, Muylaert K, Coppé V, Van Colen W, Decaestecker E. A historical perspective of nutrient change impact on an infectious disease in Daphnia. Ecology 2018; 98:2784-2798. [PMID: 28845593 DOI: 10.1002/ecy.1994] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2017] [Revised: 06/18/2017] [Accepted: 07/10/2017] [Indexed: 01/01/2023]
Abstract
Changes in food quality can play a substantial role in the vulnerability of hosts to infectious diseases. In this study, we focused on the genetic differentiation of the water flea Daphnia magna towards food of different quality (by manipulating C:N:P ratios) and its impact on the interaction with a virulent infectious disease, "White Fat Cell Disease (WFCD)". Via a resurrection ecology approach, we isolated two Daphnia subpopulations from different depths in a sediment core, which were exposed to parasites and a nutrient ratio gradient in a common garden experiment. Our results showed a genetic basis for sensitivity towards food deprivation. Both fecundity and host survival was differently affected when fed with low-quality food. This strongly impacted the way both subpopulations interacted with this parasite. A historical reconstruction of nutrient changes in a sediment core reflected an increase in organic material and phosphorus concentration (more eutrophic conditions) over time in the studied pond. These results enable us to relate patterns of genetic differentiation in sensitivity towards food deprivation to an increasing level of eutrophication of the subpopulations, which ultimately impacts parasite virulence effects. This finding was confirmed via a dynamic energy budgets (DEB), in which energy was partitioned for the host and the parasite. The model was tailored to our study by integrating (1) increased growth and a fecundity shift in the host upon parasitism and (2) differences of food assimilation in the subpopulations showing that a reduced nutrient assimilation resulted in increased parasite virulence. The combination of our experiment with the DEB model shows that it is important to consider genetic diversity when studying the impact of nutritional stress on species interactions, especially in the context of changing environments and emerging infectious diseases.
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Affiliation(s)
- Lien Reyserhove
- KU Leuven, Interdisciplinary Research Facility Life Sciences, KULAK, Campus Kortrijk, Etienne Sabbelaan 53, Kortrijk, B-8500, Belgium
| | - Giovanni Samaey
- Department of Computer Science, KU Leuven, Celestijnenlaan 200A, Leuven, B-3001, Belgium
| | - Koenraad Muylaert
- KU Leuven, Interdisciplinary Research Facility Life Sciences, KULAK, Campus Kortrijk, Etienne Sabbelaan 53, Kortrijk, B-8500, Belgium
| | - Vincent Coppé
- Department of Computer Science, KU Leuven, Celestijnenlaan 200A, Leuven, B-3001, Belgium
| | - Willem Van Colen
- KU Leuven, Interdisciplinary Research Facility Life Sciences, KULAK, Campus Kortrijk, Etienne Sabbelaan 53, Kortrijk, B-8500, Belgium
| | - Ellen Decaestecker
- KU Leuven, Interdisciplinary Research Facility Life Sciences, KULAK, Campus Kortrijk, Etienne Sabbelaan 53, Kortrijk, B-8500, Belgium
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5
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Toenshoff ER, Fields PD, Bourgeois YX, Ebert D. The End of a 60-year Riddle: Identification and Genomic Characterization of an Iridovirus, the Causative Agent of White Fat Cell Disease in Zooplankton. G3 (BETHESDA, MD.) 2018; 8:1259-1272. [PMID: 29487186 PMCID: PMC5873915 DOI: 10.1534/g3.117.300429] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/28/2017] [Accepted: 02/08/2018] [Indexed: 12/11/2022]
Abstract
The planktonic freshwater crustacean of the genus Daphnia are a model system for biomedical research and, in particular, invertebrate-parasite interactions. Up until now, no virus has been characterized for this system. Here we report the discovery of an iridovirus as the causative agent of White Fat Cell Disease (WFCD) in Daphnia WFCD is a highly virulent disease of Daphnia that can easily be cultured under laboratory conditions. Although it has been studied from sites across Eurasia for more than 60 years, its causative agent had not been described, nor had an iridovirus been connected to WFCD before now. Here we find that an iridovirus-the Daphnia iridescent virus 1 (DIV-1)-is the causative agent of WFCD. DIV-1 has a genome sequence of about 288 kbp, with 39% G+C content and encodes 367 predicted open reading frames. DIV-1 clusters together with other invertebrate iridoviruses but has by far the largest genome among all sequenced iridoviruses. Comparative genomics reveal that DIV-1 has apparently recently lost a substantial number of unique genes but has also gained genes by horizontal gene transfer from its crustacean host. DIV-1 represents the first invertebrate iridovirus that encodes proteins to purportedly cap RNA, and it contains unique genes for a DnaJ-like protein, a membrane glycoprotein and protein of the immunoglobulin superfamily, which may mediate host-pathogen interactions and pathogenicity. Our findings end a 60-year search for the causative agent of WFCD and add to our knowledge of iridovirus genomics and invertebrate-virus interactions.
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Affiliation(s)
- Elena R Toenshoff
- Basel University, Department of Environmental Sciences, Zoology, Vesalgasse 1, CH-4051 Basel, Switzerland
| | - Peter D Fields
- Basel University, Department of Environmental Sciences, Zoology, Vesalgasse 1, CH-4051 Basel, Switzerland
| | - Yann X Bourgeois
- Basel University, Department of Environmental Sciences, Zoology, Vesalgasse 1, CH-4051 Basel, Switzerland
| | - Dieter Ebert
- Basel University, Department of Environmental Sciences, Zoology, Vesalgasse 1, CH-4051 Basel, Switzerland
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6
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Hite JL, Penczykowski RM, Shocket MS, Griebel KA, Strauss AT, Duffy MA, Cáceres CE, Hall SR. Allocation, not male resistance, increases male frequency during epidemics: a case study in facultatively sexual hosts. Ecology 2017; 98:2773-2783. [PMID: 28766698 DOI: 10.1002/ecy.1976] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2017] [Revised: 06/23/2017] [Accepted: 07/18/2017] [Indexed: 12/19/2022]
Abstract
Why do natural populations vary in the frequency of sexual reproduction? Virulent parasites may help explain why sex is favored during disease epidemics. To illustrate, we show a higher frequency of males and sexually produced offspring in natural populations of a facultative parthenogenetic host during fungal epidemics. In a multi-year survey of 32 lakes, the frequency of males (an index of sex) was higher in populations of zooplankton hosts with larger epidemics. A lake mesocosm experiment established causality: experimental epidemics produced a higher frequency of males relative to disease-free controls. One common explanation for such a pattern involves Red Queen (RQ) dynamics. However, this particular system lacks key genetic specificity mechanisms required for the RQ, so we evaluated two other hypotheses. First, individual females, when stressed by infection, could increase production of male offspring vs. female offspring (a tenant of the "Abandon Ship" theory). Data from a life table experiment supports this mechanism. Second, higher male frequency during epidemics could reflect a purely demographic process (illustrated with a demographic model): males could resist infection more than females (via size-based differences in resistance and mortality). However, we found no support for this resistance mechanism. A size-based model of resistance, parameterized with data, revealed why: higher male susceptibility negated the lower exposure (a size-based advantage) of males. These results suggest that parasite-mediated increases in allocation to sex by individual females, rather than male resistance, increased the frequency of sex during larger disease epidemics.
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Affiliation(s)
- Jessica L Hite
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | | | - Marta S Shocket
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | | | | | - Meghan A Duffy
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Carla E Cáceres
- School of Integrative Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Spencer R Hall
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
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7
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Martinez AJ, Kim KL, Harmon JP, Oliver KM. Specificity of Multi-Modal Aphid Defenses against Two Rival Parasitoids. PLoS One 2016; 11:e0154670. [PMID: 27135743 PMCID: PMC4852904 DOI: 10.1371/journal.pone.0154670] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2015] [Accepted: 04/18/2016] [Indexed: 12/02/2022] Open
Abstract
Insects are often attacked by multiple natural enemies, imposing dynamic selective pressures for the development and maintenance of enemy-specific resistance. Pea aphids (Acyrthosiphon pisum) have emerged as models for the study of variation in resistance against natural enemies, including parasitoid wasps. Internal defenses against their most common parasitoid wasp, Aphidius ervi, are sourced through two known mechanisms– 1) endogenously encoded resistance or 2) infection with the heritable bacterial symbiont, Hamiltonella defensa. Levels of resistance can range from nearly 0–100% against A. ervi but varies based on aphid genotype and the strain of toxin-encoding bacteriophage (called APSE) carried by Hamiltonella. Previously, other parasitoid wasps were found to commonly attack this host, but North American introductions of A. ervi have apparently displaced all other parasitoids except Praon pequodorum, a related aphidiine braconid wasp, which is still found attacking this host in natural populations. To explain P. pequodorum’s persistence, multiple studies have compared direct competition between both wasps, but have not examined specificity of host defenses as an indirectly mediating factor. Using an array of experimental aphid lines, we first examined whether aphid defenses varied in effectiveness toward either wasp species. Expectedly, both types of aphid defenses were effective against A. ervi, but unexpectedly, were completely ineffective against P. pequodorum. Further examination showed that P. pequodorum wasps suffered no consistent fitness costs from developing in even highly ‘resistant’ aphids. Comparison of both wasps’ egg-larval development revealed that P. pequodorum’s eggs have thicker chorions and hatch two days later than A. ervi’s, likely explaining their differing abilities to overcome aphid defenses. Overall, our results indicate that aphids resistant to A. ervi may serve as reservoirs for P. pequodorum, hence contributing to its persistence in field populations. We find that specificity of host defenses and defensive symbiont infections, may have important roles in influencing enemy compositions by indirectly mediating the interactions and abundance of rival natural enemies.
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Affiliation(s)
- Adam J. Martinez
- Department of Entomology, University of Georgia, Athens, Georgia, United States of America
- * E-mail:
| | - Kyungsun L. Kim
- Department of Entomology, University of Georgia, Athens, Georgia, United States of America
| | - Jason P. Harmon
- Department of Entomology, North Dakota State University, Fargo, North Dakota, United States of America
| | - Kerry M. Oliver
- Department of Entomology, University of Georgia, Athens, Georgia, United States of America
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8
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Metzger CMJA, Luijckx P, Bento G, Mariadassou M, Ebert D. The Red Queen lives: Epistasis between linked resistance loci. Evolution 2016; 70:480-7. [DOI: 10.1111/evo.12854] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 01/04/2016] [Accepted: 01/05/2016] [Indexed: 02/05/2023]
Affiliation(s)
| | - Pepijn Luijckx
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
- Department of Ecology & Evolutionary Biology; University of Toronto; M5S 3B2 Toronto Ontario Canada
| | - Gilberto Bento
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
| | - Mahendra Mariadassou
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
- INRA, UR1404 Unité Mathématique et Informatique Appliquées du Génome à l'Environnement; 78350 Jouy-en-Josas France
| | - Dieter Ebert
- Zoological Institute; University of Basel; CH-4051 Basel Switzerland
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9
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Ebert D, Duneau D, Hall MD, Luijckx P, Andras JP, Du Pasquier L, Ben-Ami F. A Population Biology Perspective on the Stepwise Infection Process of the Bacterial Pathogen Pasteuria ramosa in Daphnia. ADVANCES IN PARASITOLOGY 2015; 91:265-310. [PMID: 27015951 DOI: 10.1016/bs.apar.2015.10.001] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The infection process of many diseases can be divided into series of steps, each one required to successfully complete the parasite's life and transmission cycle. This approach often reveals that the complex phenomenon of infection is composed of a series of more simple mechanisms. Here we demonstrate that a population biology approach, which takes into consideration the natural genetic and environmental variation at each step, can greatly aid our understanding of the evolutionary processes shaping disease traits. We focus in this review on the biology of the bacterial parasite Pasteuria ramosa and its aquatic crustacean host Daphnia, a model system for the evolutionary ecology of infectious disease. Our analysis reveals tremendous differences in the degree to which the environment, host genetics, parasite genetics and their interactions contribute to the expression of disease traits at each of seven different steps. This allows us to predict which steps may respond most readily to selection and which steps are evolutionarily constrained by an absence of variation. We show that the ability of Pasteuria to attach to the host's cuticle (attachment step) stands out as being strongly influenced by the interaction of host and parasite genotypes, but not by environmental factors, making it the prime candidate for coevolutionary interactions. Furthermore, the stepwise approach helps us understanding the evolution of resistance, virulence and host ranges. The population biological approach introduced here is a versatile tool that can be easily transferred to other systems of infectious disease.
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Affiliation(s)
- Dieter Ebert
- Zoological Institute, University of Basel, Basel, Switzerland
| | - David Duneau
- Zoological Institute, University of Basel, Basel, Switzerland; Department Ecologie et Diversité Biologique, University Paul Sabatier-Toulouse III, Toulouse, France
| | - Matthew D Hall
- Zoological Institute, University of Basel, Basel, Switzerland; Monash University, School of Biological Sciences, Clayton Campus, Melbourne, VIC, Australia
| | - Pepijn Luijckx
- Zoological Institute, University of Basel, Basel, Switzerland; Department of Ecology & Evolutionary Biology, University of Toronto, Toronto, ON, Canada
| | - Jason P Andras
- Zoological Institute, University of Basel, Basel, Switzerland; Department of Biological Sciences, Mount Holyoke College, South Hadley, MA, USA
| | | | - Frida Ben-Ami
- Department of Zoology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, Israel
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10
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Clerc M, Ebert D, Hall MD. Expression of parasite genetic variation changes over the course of infection: implications of within-host dynamics for the evolution of virulence. Proc Biol Sci 2015; 282:20142820. [PMID: 25761710 DOI: 10.1098/rspb.2014.2820] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
How infectious disease agents interact with their host changes during the course of infection and can alter the expression of disease-related traits. Yet by measuring parasite life-history traits at one or few moments during infection, studies have overlooked the impact of variable parasite growth trajectories on disease evolution. Here we show that infection-age-specific estimates of host and parasite fitness components can reveal new insight into the evolution of parasites. We do so by characterizing the within-host dynamics over an entire infection period for five genotypes of the castrating bacterial parasite Pasteuria ramosa infecting the crustacean Daphnia magna. Our results reveal that genetic variation for parasite-induced gigantism, host castration and parasite spore loads increases with the age of infection. Driving these patterns appears to be variation in how well the parasite maintains control of host reproduction late in the infection process. We discuss the evolutionary consequences of this finding with regard to natural selection acting on different ages of infection and the mechanism underlying the maintenance of castration efficiency. Our results highlight how elucidating within-host dynamics can shed light on the selective forces that shape infection strategies and the evolution of virulence.
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Affiliation(s)
- Melanie Clerc
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Labs, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK Zoological Institute, University of Basel, Vesalgasse 1, Basel 4051, Switzerland
| | - Dieter Ebert
- Zoological Institute, University of Basel, Vesalgasse 1, Basel 4051, Switzerland
| | - Matthew D Hall
- Zoological Institute, University of Basel, Vesalgasse 1, Basel 4051, Switzerland School of Biological Sciences, Monash University, Melbourne 3800, Australia
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11
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Duffy MA, James TY, Longworth A. Ecology, Virulence, and Phylogeny of Blastulidium paedophthorum, a Widespread Brood Parasite of Daphnia spp. Appl Environ Microbiol 2015; 81:5486-96. [PMID: 26048938 PMCID: PMC4510196 DOI: 10.1128/aem.01369-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 05/28/2015] [Indexed: 11/20/2022] Open
Abstract
Parasitism is now recognized as a major factor impacting the ecology and evolution of plankton, including Daphnia. Parasites that attack the developing embryos of daphniids, known as brood parasites, were first described in the early 1900s but have received relatively little study. Here, we link previous morphological descriptions of the oomycete brood parasite Blastulidium paedophthorum with information on its phylogenetic placement, ecology, and virulence. Based on the morphology and phylogenetic relationship with other members of the Leptomitales, we show that a brood parasite observed in daphniids in the Midwestern United States is B. paedophthorum. We used morphology, DNA sequences, and laboratory infection experiments to show that B. paedophthorum is a multihost parasite that can be transmitted between species and genera. A field survey of six hosts in 15 lakes revealed that B. paedophthorum is common in all six host taxa (present on 38.3% of our host species-lake-sampling date combinations; the maximum infection prevalences were 8.7% of the population and 20% of the asexual adult female population). Although B. paedophthorum was observed in all 15 lakes, presence and infection prevalence varied among lakes. Infection with B. paedophthorum did not reduce host life span but significantly impacted host fecundity. Theory predicts that parasites that affect host fecundity without affecting host life span should have the strongest impact on host population dynamics. Based on its virulence and commonness in natural populations and on the central role of daphniids in freshwater food webs, we predict that B. paedophthorum will influence daphniid ecology and evolution, as well as the larger food web.
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Affiliation(s)
- Meghan A Duffy
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA
| | - Alan Longworth
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, USA
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12
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Asselman J, De Coninck DIM, Vandegehuchte MB, Jansen M, Decaestecker E, De Meester L, Vanden Bussche J, Vanhaecke L, Janssen CR, De Schamphelaere KAC. Global cytosine methylation in Daphnia magna depends on genotype, environment, and their interaction. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2015; 34:1056-1061. [PMID: 25639773 DOI: 10.1002/etc.2887] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 11/13/2014] [Accepted: 01/06/2015] [Indexed: 06/04/2023]
Abstract
The authors characterized global cytosine methylation levels in 2 different genotypes of the ecotoxicological model organism Daphnia magna after exposure to a wide array of biotic and abiotic environmental stressors. The present study aimed to improve the authors' understanding of the role of cytosine methylation in the organism's response to environmental conditions. The authors observed a significant genotype effect, an environment effect, and a genotype × environment effect. In particular, global cytosine methylation levels were significantly altered after exposure to Triops predation cues, Microcystis, and sodium chloride compared with control conditions. Significant differences between the 2 genotypes were observed when animals were exposed to Triops predation cues, Microcystis, Cryptomonas, and sodium chloride. Despite the low global methylation rate under control conditions (0.49-0.52%), global cytosine methylation levels upon exposure to Triops demonstrated a 5-fold difference between the genotypes (0.21% vs 1.02%). No effects were found in response to arsenic, cadmium, fish, lead, pH of 5.5, pH of 8, temperature, hypoxia, and white fat cell disease. The authors' results point to the potential role of epigenetic effects under changing environmental conditions such as predation (i.e., Triops), diet (i.e., Cryptomonas and Microcystis), and salinity. The results of the present study indicate that, despite global cytosine methylation levels being low, epigenetic effects may be important in environmental studies on Daphnia.
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Affiliation(s)
- Jana Asselman
- Laboratory for Environmental Toxicology and Aquatic Ecology (GhEnToxLab), Ghent University, Ghent, Belgium
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Aalto SL, Ketola T, Pulkkinen K. No uniform associations between parasite prevalence and environmental nutrients. Ecology 2014. [DOI: 10.1890/13-2007.1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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14
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Lange B, Reuter M, Ebert D, Muylaert K, Decaestecker E. Diet quality determines interspecific parasite interactions in host populations. Ecol Evol 2014; 4:3093-102. [PMID: 25247066 PMCID: PMC4161182 DOI: 10.1002/ece3.1167] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2014] [Revised: 06/17/2014] [Accepted: 06/19/2014] [Indexed: 11/08/2022] Open
Abstract
The widespread occurrence of multiple infections and the often vast range of nutritional resources for their hosts allow that interspecific parasite interactions in natural host populations might be determined by host diet quality. Nevertheless, the role of diet quality with respect to multispecies parasite interactions on host population level is not clear. We here tested the effect of host population diet quality on the parasite community in an experimental study using Daphnia populations. We studied the effect of diet quality on Daphnia population demography and the interactions in multispecies parasite infections of this freshwater crustacean host. The results of our experiment show that the fitness of a low-virulent microsporidian parasite decreased in low, but not in high-host-diet quality conditions. Interestingly, infections with the microsporidium protected Daphnia populations against a more virulent bacterial parasite. The observed interspecific parasite interactions are discussed with respect to the role of diet quality-dependent changes in host fecundity. This study reflects that exploitation competition in multispecies parasite infections is environmentally dependent, more in particular it shows that diet quality affects interspecific parasite competition within a single host and that this can be mediated by host population-level effects.
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Affiliation(s)
- Benjamin Lange
- Laboratory Aquatic Biology, Science & Technology-Kulak, KU LeuvenKortrijk, 8500, Belgium
| | - Max Reuter
- Department of Genetics, Evolution & Environment, University College LondonLondon, WC1E 6BT, UK
| | - Dieter Ebert
- Zoological Institute, University of BaselBasel, CH-4051, Switzerland
| | - Koenraad Muylaert
- Laboratory Aquatic Biology, Science & Technology-Kulak, KU LeuvenKortrijk, 8500, Belgium
| | - Ellen Decaestecker
- Laboratory Aquatic Biology, Science & Technology-Kulak, KU LeuvenKortrijk, 8500, Belgium
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15
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Rode NO, Lievens EJ, Segard A, Flaven E, Jabbour-Zahab R, Lenormand T. Cryptic microsporidian parasites differentially affect invasive and native Artemia spp. Int J Parasitol 2013; 43:795-803. [DOI: 10.1016/j.ijpara.2013.04.009] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2013] [Revised: 04/13/2013] [Accepted: 04/22/2013] [Indexed: 12/26/2022]
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16
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Bruns E, Carson M, May G. Pathogen and host genotype differently affect pathogen fitness through their effects on different life-history stages. BMC Evol Biol 2012; 12:135. [PMID: 22857005 PMCID: PMC3483255 DOI: 10.1186/1471-2148-12-135] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2012] [Accepted: 07/10/2012] [Indexed: 01/28/2023] Open
Abstract
BACKGROUND Adaptation of pathogens to their hosts depends critically on factors affecting pathogen reproductive rate. While pathogen reproduction is the end result of an intricate interaction between host and pathogen, the relative contributions of host and pathogen genotype to variation in pathogen life history within the host are not well understood. Untangling these contributions allows us to identify traits with sufficient genetic variation for selection to act and to identify mechanisms of coevolution between pathogens and their hosts. We investigated the effects of pathogen and host genotype on three life-history components of pathogen fitness; infection efficiency, latent period, and sporulation capacity, in the oat crown rust fungus, Puccinia coronata f.sp. avenae, as it infects oats (Avena sativa). RESULTS We show that both pathogen and host genotype significantly affect total spore production but do so through their effects on different life-history stages. Pathogen genotype has the strongest effect on the early stage of infection efficiency, while host genotype most strongly affects the later life-history stages of latent period and sporulation capacity. In addition, host genotype affected the relationship between pathogen density and the later life-history traits of latent period and sporulation capacity. We did not find evidence of pathogen-by-host genotypic (GxG) interactions. CONCLUSION Our results illustrate mechanisms by which variation in host populations will affect the evolution of pathogen life history. Results show that different pathogen life-history stages have the potential to respond differently to selection by host or pathogen genotype and suggest mechanisms of antagonistic coevolution. Pathogen populations may adapt to host genotypes through increased infection efficiency while their plant hosts may adapt by limiting the later stages of pathogen growth and spore production within the host.
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Affiliation(s)
- Emily Bruns
- Department of Ecology Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA
- Graduate Program in Ecology, Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA
| | - Martin Carson
- United States Department of Agriculture – Agriculture Research Service, Cereal Disease Laboratory, University of Minnesota, Saint Paul, 55108, USA
| | - Georgiana May
- Department of Ecology Evolution and Behavior, University of Minnesota, Saint Paul, MN, 55108, USA
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17
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Auld SKJR, Hall SR, Duffy MA. Epidemiology of a Daphnia-multiparasite system and its implications for the red queen. PLoS One 2012; 7:e39564. [PMID: 22761826 PMCID: PMC3382569 DOI: 10.1371/journal.pone.0039564] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2012] [Accepted: 05/28/2012] [Indexed: 12/02/2022] Open
Abstract
The Red Queen hypothesis can explain the maintenance of host and parasite diversity. However, the Red Queen requires genetic specificity for infection risk (i.e., that infection depends on the exact combination of host and parasite genotypes) and strongly virulent effects of infection on host fitness. A European crustacean (Daphnia magna)--bacterium (Pasteuria ramosa) system typifies such specificity and high virulence. We studied the North American host Daphnia dentifera and its natural parasite Pasteuria ramosa, and also found strong genetic specificity for infection success and high virulence. These results suggest that Pasteuria could promote Red Queen dynamics with D. dentifera populations as well. However, the Red Queen might be undermined in this system by selection from a more common yeast parasite (Metschnikowia bicuspidata). Resistance to the yeast did not correlate with resistance to Pasteuria among host genotypes, suggesting that selection by Metschnikowia should proceed relatively independently of selection by Pasteuria.
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Affiliation(s)
- Stuart K J R Auld
- School of Biology, Georgia Institute of Technology, Atlanta, Georgia, United States of America.
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18
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Who benefits from reduced reproduction in parasitized hosts? An experimental test using the Pasteuria ramosa-Daphnia magna system. Parasitology 2011; 138:1910-5. [PMID: 21854675 DOI: 10.1017/s0031182011001302] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
We investigated whether parasites or hosts benefit from reduced reproduction in infected hosts. When parasites castrate their hosts, the regain of host reproduction is necessary for castration to be a host adaptation. When infecting Daphnia magna with Pasteuria ramosa, in a lake water based medium, 49 2% of the castrated females regained reproduction. We investigated the relationship between castration level, and parasite and host fitness proxies to determine the adaptive value of host castration. Hosts which regained reproduction contained less spores and had a higher lifetime reproduction than permanently castrated hosts. We also found a negative correlation between parasite and host lifetime reproduction. For hosts which regained reproduction we found no optimal level of castration associated with lifetime reproduction. These results support the view that host castration only is adaptive to the parasite in this system. In addition, we suggest that permanent castration might not be the norm under natural conditions in this system. Finally, we argue that a reduction in host reproduction is more likely to evolve as a property favouring parasites rather than hosts. To our knowledge this is the only experimental study to investigate the adaptive value of reduced host reproduction when castrated hosts can regain reproduction.
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Jefferies JM, Clarke SC, Webb JS, Kraaijeveld AR. Risk of Red Queen dynamics in pneumococcal vaccine strategy. Trends Microbiol 2011; 19:377-81. [DOI: 10.1016/j.tim.2011.06.001] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2011] [Revised: 05/27/2011] [Accepted: 06/07/2011] [Indexed: 01/08/2023]
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20
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Refardt D, Ebert D. The impact of infection on host competition and its relationship to parasite persistence in a Daphnia microparasite system. Evol Ecol 2011. [DOI: 10.1007/s10682-011-9487-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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21
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Östman Ö. Interspecific competition affects genetic structure but not genetic diversity ofDaphnia magna. Ecosphere 2011. [DOI: 10.1890/es11-00039.1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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22
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Duneau D, Luijckx P, Ben-Ami F, Laforsch C, Ebert D. Resolving the infection process reveals striking differences in the contribution of environment, genetics and phylogeny to host-parasite interactions. BMC Biol 2011; 9:11. [PMID: 21342515 PMCID: PMC3052238 DOI: 10.1186/1741-7007-9-11] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2010] [Accepted: 02/22/2011] [Indexed: 11/30/2022] Open
Abstract
Background Infection processes consist of a sequence of steps, each critical for the interaction between host and parasite. Studies of host-parasite interactions rarely take into account the fact that different steps might be influenced by different factors and might, therefore, make different contributions to shaping coevolution. We designed a new method using the Daphnia magna - Pasteuria ramosa system, one of the rare examples where coevolution has been documented, in order to resolve the steps of the infection and analyse the factors that influence each of them. Results Using the transparent Daphnia hosts and fluorescently-labelled spores of the bacterium P. ramosa, we identified a sequence of infection steps: encounter between parasite and host; activation of parasite dormant spores; attachment of spores to the host; and parasite proliferation inside the host. The chances of encounter had been shown to depend on host genotype and environment. We tested the role of genetic and environmental factors in the newly described activation and attachment steps. Hosts of different genotypes, gender and species were all able to activate endospores of all parasite clones tested in different environments; suggesting that the activation cue is phylogenetically conserved. We next established that parasite attachment occurs onto the host oesophagus independently of host species, gender and environmental conditions. In contrast to spore activation, attachment depended strongly on the combination of host and parasite genotypes. Conclusions Our results show that different steps are influenced by different factors. Host-type-independent spore activation suggests that this step can be ruled out as a major factor in Daphnia-Pasteuria coevolution. On the other hand, we show that the attachment step is crucial for the pronounced genetic specificities of this system. We suggest that this one step can explain host population structure and could be a key force behind coevolutionary cycles. We discuss how different steps can explain different aspects of the coevolutionary dynamics of the system: the properties of the attachment step, explaining the rapid evolution of infectivity and the properties of later parasite proliferation explaining the evolution of virulence. Our study underlines the importance of resolving the infection process in order to better understand host-parasite interactions.
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Affiliation(s)
- David Duneau
- University of Basel, Zoological Institute, Vesalgasse 1, Basel, Switzerland.
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23
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Hall SR, Becker CR, Duffy MA, Cáceres CE. Variation in resource acquisition and use among host clones creates key epidemiological trade‐offs. Am Nat 2011; 176:557-65. [PMID: 20887188 DOI: 10.1086/656523] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Parasites can certainly harm host fitness. Given such virulence, hosts should evolve strategies to resist or tolerate infection. But what governs those strategies and the costs that they incur? This study illustrates how a fecundity‐susceptibility trade‐off among clonally reared genotypes of a zooplankton (Daphnia dentifera) infected by a fungal parasite (Metschnikowia) arises due to variation in resource acquisition and use by hosts. To make these connections, we used lab experiments and theoretical models that link feeding with susceptibility, energetics, and fecundity of hosts. These feeding‐based mechanisms also produced a fecundity‐survivorship trade‐off. Meanwhile, a parasite spore yield–fecundity trade‐off arose from variation in juvenile growth rate among host clones (another index of resource use), a result that was readily anticipated and explained by the models. Thus, several key epidemiological trade‐offs stem from variation in resource acquisition and use among clones. This connection should catalyze the creation of new theory that integrates resource‐ and gene‐based responses of hosts to disease.
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Affiliation(s)
- Spencer R Hall
- Department of Biology, Indiana University, Bloomington, IN 47405, USA.
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24
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Luijckx P, Ben-Ami F, Mouton L, Du Pasquier L, Ebert D. Cloning of the unculturable parasite Pasteuria ramosa and its Daphnia host reveals extreme genotype-genotype interactions. Ecol Lett 2010; 14:125-31. [PMID: 21091597 DOI: 10.1111/j.1461-0248.2010.01561.x] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The degree of specificity in host-parasite interactions has important implications for ecology and evolution. Unfortunately, specificity can be difficult to determine when parasites cannot be cultured. In such cases, studies often use isolates of unknown genetic composition, which may lead to an underestimation of specificity. We obtained the first clones of the unculturable bacterium Pasteuria ramosa, a parasite of Daphnia magna. Clonal genotypes of the parasite exhibited much more specific interactions with host genotypes than previous studies using isolates. Clones of P. ramosa infected fewer D. magna genotypes than isolates and host clones were either fully susceptible or fully resistant to the parasite. Our finding enhances our understanding of the evolution of virulence and coevolutionary dynamics in this system. We recommend caution when using P. ramosa isolates as the presence of multiple genotypes may influence the outcome and interpretation of some experiments.
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Affiliation(s)
- Pepijn Luijckx
- Institut of Zoology, Evolutionsbiologie, University of Basel, Basel, Switzerland.
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25
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Labbé P, Vale PF, Little TJ. Successfully resisting a pathogen is rarely costly in Daphnia magna. BMC Evol Biol 2010; 10:355. [PMID: 21083915 PMCID: PMC2998533 DOI: 10.1186/1471-2148-10-355] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2010] [Accepted: 11/17/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND A central hypothesis in the evolutionary ecology of parasitism is that trade-offs exist between resistance to parasites and other fitness components such as fecundity, growth, survival, and predator avoidance, or resistance to other parasites. These trade-offs are called costs of resistance. These costs fall into two broad categories: constitutive costs of resistance, which arise from a negative genetic covariance between immunity and other fitness-related traits, and inducible costs of resistance, which are the physiological costs incurred by hosts when mounting an immune response. We sought to study inducible costs in depth using the crustacean Daphnia magna and its bacterial parasite Pasteuria ramosa. RESULTS We designed specific experiments to study the costs induced by exposure to this parasite, and we re-analysed previously published data in an effort to determine the generality of such costs. However, despite the variety of genetic backgrounds of both hosts and parasites, and the different exposure protocols and environmental conditions used in these experiment, this work showed that costs of exposure can only rarely be detected in the D. magna-P. ramosa system. CONCLUSIONS We discuss possible reasons for this lack of detectable costs, including scenarios where costs of resistance to parasites might not play a major role in the co-evolution of hosts and parasites.
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Affiliation(s)
- Pierrick Labbé
- University of Edinburgh, Institute of Evolutionary Biology, King's Buildings, Edinburgh, EH9 3JT, UK.
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26
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Abstract
Host populations with high genetic diversity are predicted to have lower levels of infection prevalence. This theory assumes that host genetic diversity results in variation in susceptibility and that parasites exhibit variation in infectivity. Empirical studies on the effects of host heterogeneity typically neglect the role of parasite diversity. We conducted three laboratory experiments designed to test if genetic variation in Daphnia magna populations and genetic variation in its parasites together influence the course of parasite spread after introduction. We found that a natural D. magna population exhibited variation in susceptibility to infection by three parasite species and had strong host clone-parasite species interactions. There was no effect of host heterogeneity in experimental host populations (polycultures and monocultures) separately exposed to single strains of three parasite species. When we manipulated the genetic diversity of a single parasite species and exposed them to host monocultures and polycultures, we found that parasite prevalence increased with the number of parasite strains. Host monocultures exposed to several parasite strains had higher mean parasite prevalence and higher variance than polycultures. These results indicate that effect of host genetic diversity on the spread of infection depends on the level of genetic diversity in the parasite population.
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Affiliation(s)
- Holly H Ganz
- Département de Biology, Unité d'Ecologie et Evolution, Université de Fribourg, Chemin du Massé 10, 1700 Fribourg, Switzerland.
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27
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Molecular identification and hidden diversity of novel Daphnia parasites from European lakes. Appl Environ Microbiol 2009; 75:7051-9. [PMID: 19767459 DOI: 10.1128/aem.01306-09] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Parasites play important roles in local population dynamics and genetic structure. However, due to insufficient diagnostic tools, detailed host-parasite interactions may remain concealed by hidden parasite diversity in natural systems. Microscopic examination of 19 European lake Daphnia populations revealed the presence of three groups of parasites: fungi, microsporidia, and oomycetes. For most of these parasites no genetic markers have been described so far. Based on sequence similarities of the nuclear small-subunit and internal transcribed spacer (ITS) rRNA gene regions, one fungus, four microsporidian, and nine oomycete taxa were discovered in 147 infected Daphnia (and/or three other zooplankton crustaceans). Additionally, cloning of rRNA gene regions revealed parasite sequence variation within host individuals. This was most pronounced in the ITS region of one microsporidian taxon, where the within-host sequence variation ranged from 1.7% to 5.3% polymorphic sites for parasite isolates from 14 different geographical locations. Interestingly, the parasite isolates from close locations grouped together based on sequence similarities, suggesting that there was parasite dispersal. Taken together, the data obtained in this study revealed hidden diversity of parasite communities in Daphnia lake populations. Moreover, a higher level of resolution for identifying parasite strains makes it possible to test new hypotheses with respect to parasite dispersal, transmission routes, and coinfection.
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28
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Hall SR, Becker CR, Simonis JL, Duffy MA, Tessier AJ, Cáceres CE. Friendly competition: evidence for a dilution effect among competitors in a planktonic host-parasite system. Ecology 2009; 90:791-801. [PMID: 19341148 DOI: 10.1890/08-0838.1] [Citation(s) in RCA: 75] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The "dilution effect" concept in disease ecology offers the intriguing possibility that clever manipulation of less competent hosts could reduce disease prevalence in populations of more competent hosts. The basic concept is straightforward: host species vary in suitability (competence) for parasites, and disease transmission decreases when there are more incompetent hosts interacting with vectors or removing free-living stages of a parasite. However, host species also often interact with each other in other ecological ways, e.g., as competitors for resources. The net result of these simultaneous, multiple interactions (disease dilution and resource competition) is challenging to predict. Nonetheless, we see the signature of both roles operating concurrently in a planktonic host-parasite system. We document pronounced spatiotemporal variation in the size of epidemics of a virulent fungus (Metschnikowia bicuspidata) in Midwestern U.S. lake populations of a dominant crustacean grazer (Daphnia dentifera). We show that some of this variation is captured by changes in structure of Daphnia assemblages. Lake-years with smaller epidemics were characterized by assemblages dominated by less suitable hosts ("diluters," D. pulicaria and D. retrocurva, whose suitabilties were determined in lab experiments and field surveys) at the start of epidemics. Furthermore, within a season, less suitable hosts increased as epidemics declined. These observations are consistent with a dilution effect. However, more detailed time series analysis (using multivariate autoregressive models) of three intensively sampled epidemics show the signature of a likely interaction between dilution and resource competition between these Daphnia species. The net outcome of this interaction likely promoted termination of these fungal outbreaks. Should this outcome always arise in "friendly competition" systems where diluting hosts compete with more competent hosts? The answers to this question lie at a frontier of disease ecology.
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Affiliation(s)
- Spencer R Hall
- Department of Biology, Indiana University, Bloomington, Indiana 47405-3700, USA.
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29
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Gaba S, Ebert D. Time-shift experiments as a tool to study antagonistic coevolution. Trends Ecol Evol 2009; 24:226-32. [PMID: 19201504 DOI: 10.1016/j.tree.2008.11.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2008] [Revised: 11/06/2008] [Accepted: 11/10/2008] [Indexed: 11/16/2022]
Abstract
Although understanding natural selection in antagonistic host-parasite interactions has been a challenge for many years, direct evidence for the coevolutionary process is still scarce, particularly in relation to changes in antagonist populations over time. The underlying processes of coevolution thus remain difficult to characterise. Time-shift experiments can be used to test the performance of an antagonist population from a moment in time against the other from the same and different moments in time, revealing reciprocal adaptation in host-parasite relationships. Here we discuss how time-shift experiments together with modelling can shed new insights on the underlying processes of antagonistic coevolution.
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Affiliation(s)
- Sabrina Gaba
- Universität Basel, Zoologisches Institut, Evolutionsbiologie, Vesalgasse 1, 4051 Basel, Switzerland.
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30
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Abstract
Immune function is likely to be a critical determinant of an organism's fitness, yet most natural animal and plant populations exhibit tremendous genetic variation for immune traits. Accumulating evidence suggests that environmental heterogeneity may retard the long-term efficiency of natural selection and even maintain polymorphism, provided alternative host genotypes are favoured under different environmental conditions. 'Environment' in this context refers to abiotic factors such as ambient temperature or availability of nutrient resources, genetic diversity of pathogens or competing physiological demands on the host. These factors are generally controlled in laboratory experiments measuring immune performance, but variation in them is likely to be very important in the evolution of resistance to infection. Here, we review some of the literature emphasizing the complexity of natural selection on immunity. Our aim is to describe how environmental and genetic heterogeneities, often excluded from experimentation as 'noise', may determine the evolutionary potential of populations or the potential for interacting species to coevolve.
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Affiliation(s)
- Brian P Lazzaro
- Department of Entomology, Cornell University, Ithaca, NY 14850, USA.
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31
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Survival of the currently fittest: genetics of rainbow trout survival across time and space. Genetics 2008; 180:507-16. [PMID: 18757927 DOI: 10.1534/genetics.108.089896] [Citation(s) in RCA: 60] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
As a fitness trait, survival is assumed to exhibit low heritability due to strong selection eroding genetic variation and/or spatio-temporal variation in mortality agents reducing genetic and increasing residual variation. The latter phenomenon in particular may contribute to low heritability in multigeneration data, even if certain cohorts exhibit significant genetic variation. Analysis of survival data from 10 year classes of rainbow trout reared at three test stations showed that treating survival as a single trait across all generations resulted in low heritability (h2 = 0.08-0.17). However, when heritabilities were estimated from homogeneous generation and test station-specific cohorts, a wide range of heritability values was revealed (h2 = 0.04-0.71). Of 64 genetic correlations between different cohorts, 20 were positive, but 16 were significantly negative, confirming that genetic architecture of survival is not stable across generations and environments. These results reveal the existence of hidden genetic variation for survival and demonstrate that treating survival as one trait over several generations may not reveal its true genetic architecture. Negative genetic correlations between cohorts indicate that overall survival has limited potential to predict general resistance, and care should be taken when using it as selection criterion.
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32
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Ebert D. Host–parasite coevolution: Insights from the Daphnia–parasite model system. Curr Opin Microbiol 2008; 11:290-301. [DOI: 10.1016/j.mib.2008.05.012] [Citation(s) in RCA: 115] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2008] [Revised: 05/13/2008] [Accepted: 05/16/2008] [Indexed: 10/21/2022]
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Variable-number-of-tandem-repeats analysis of genetic diversity in Pasteuria ramosa. Curr Microbiol 2008; 56:447-52. [PMID: 18214600 DOI: 10.1007/s00284-008-9104-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Accepted: 11/30/2007] [Indexed: 10/22/2022]
Abstract
Variable-number-of-tandem-repeats (VNTR) markers are increasingly being used in population genetic studies of bacteria. They were recently developed for Pasteuria ramosa, an endobacterium that infects Daphnia species. In the present study, we genotyped P. ramosa in 18 infected hosts from the United Kingdom, Belgium, and two lakes in the United States using seven VNTR markers. Two Daphnia species were collected: D. magna and D. dentifera. Six loci showed length polymorphism, with as many as five alleles identified for a single locus. Similarity coefficient calculations showed that the extent of genetic variation between pairs of isolates within populations differed according to the population, but it was always less than the genetic distances among populations. Analysis of the genetic distances performed using principal component analysis revealed strong clustering by location of origin, but not by host Daphnia species. Our study demonstrated that the VNTR markers available for P. ramosa are informative in revealing genetic differences within and among populations and may therefore become an important tool for providing detailed analysis of population genetics and epidemiology.
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Decaestecker E, Gaba S, Raeymaekers JAM, Stoks R, Van Kerckhoven L, Ebert D, De Meester L. Host–parasite ‘Red Queen’ dynamics archived in pond sediment. Nature 2007; 450:870-3. [PMID: 18004303 DOI: 10.1038/nature06291] [Citation(s) in RCA: 417] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2007] [Accepted: 09/21/2007] [Indexed: 11/09/2022]
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35
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Soltanian S, Thai TQ, Dhont J, Sorgeloos P, Bossier P. The protective effect against Vibrio campbellii in Artemia nauplii by pure beta-glucan and isogenic yeast cells differing in beta-glucan and chitin content operated with a source-dependent time lag. FISH & SHELLFISH IMMUNOLOGY 2007; 23:1003-14. [PMID: 17827034 DOI: 10.1016/j.fsi.2007.04.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/15/2007] [Revised: 03/30/2007] [Accepted: 04/05/2007] [Indexed: 05/17/2023]
Abstract
In invertebrates the defence system to fight infectious diseases depends mainly on a non-specific or innate immune response, contrary to the vertebrate immune system. The use of natural immunostimulants that enhance the defence mechanism or the immune response of target organisms may be an excellent preventive tool against pathogens. Several strains of baker's yeast Saccharomyces cerevisiae have been found to be good immune enhancers. Previously, it was shown that small quantities of the mnn9 yeast cells and/or glucan particles could protect Artemia nauplii against the pathogenic bacterium Vibrio campbellii in the gnotobiotic Artemia challenge test. Apparently, the higher amount and/or availability of beta-glucans and/or chitin present in mnn9 yeast strain might play an essential role in such protection. The present study reveals that these compounds could only provide protection against the pathogen when they were supplied to Artemia well in advance of the challenge (8-48 h depending on the source). Also the putative immunostimulant did not have a curative action. Moreover, short-time exposure of Artemia to mnn9 strain (priming) did not provide protection against the pathogen longer than two days. Hence, it is hypothesized that the mere stimulation of known biochemical pathways, e.g. prophenoloxidase is not sufficient to explain the mechanisms involved in the observed immunostimulation obtained by beta-glucans and/or mnn9 yeast in Artemia nauplii.
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Affiliation(s)
- Siyavash Soltanian
- Laboratory of Aquaculture and Artemia Reference Center, Faculty of Bioscience Engineering, Ghent University, Rozier 44, 9000 Gent, Belgium.
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Pulkkinen K. Microparasite transmission to Daphnia magna decreases in the presence of conspecifics. Oecologia 2007; 154:45-53. [PMID: 17657511 DOI: 10.1007/s00442-007-0805-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2007] [Accepted: 06/20/2007] [Indexed: 10/23/2022]
Abstract
Single parasite species often have a range of different hosts which vary in their ability to sustain the parasite. When foraging for food, alternative hosts with similar feeding modes may compete for the infective stages of trophically transmitted parasites. If some of the infective stages end up in unsuitable hosts, transmission of the parasite to the focal host is decreased. I studied whether the presence of conspecifics alters the probability of an uninfected susceptible recipient Daphnia becoming infected by a microparasite and if this effect depends on whether the added conspecifics themselves are susceptible or resistant to infection. The presence of both susceptible and resistant conspecifics decreased the probability of infection in recipients. This effect was dependent on the density of the conspecifics but was not found to be related to their size. In addition, when Daphnia were placed in medium derived from crowded Daphnia populations, the probability of infection in recipients decreased as compared to that in standard medium. This implies that decreases in transmission probability are not caused by dilution of spores through food competition only, but also by indirect interference mediated through infochemicals released by Daphnia. Since Daphnia have been found to respond to crowding by decreasing their filtering rate, the decrease in transmission is probably caused by decreased intake of spores in crowded conditions. The presence of conspecifics can thus decrease microparasite transmission in Daphnia which may have important consequences for epidemiology and evolution of Daphnia parasites.
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Affiliation(s)
- Katja Pulkkinen
- Department of Biological and Environmental Science, University of Jyväskylä, P.O. Box 35, 40014, Jyväskylä, Finland.
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Zhang P, Sandland GJ, Feng Z, Xu D, Minchella DJ. Evolutionary implications for interactions between multiple strains of host and parasite. J Theor Biol 2007; 248:225-40. [PMID: 17585945 DOI: 10.1016/j.jtbi.2007.05.011] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2006] [Revised: 05/07/2007] [Accepted: 05/07/2007] [Indexed: 10/23/2022]
Abstract
The interaction between multiple parasite strains within different host types may influence the evolutionary trajectories of parasites. In this article, we formulate a deterministic model with two strains of parasites and two host types in order to investigate how heterogeneities in parasite virulence and host life-history may affect the persistence and spread of diseases in natural systems. We compute the reproductive number of strain i (R(i)) independently, as well as the (conditional) "invasion" reproductive number for strains i (R(i)(j), j not equal i) when strain j is at a positive equilibrium. We show that the disease-free equilibrium is locally asymptotically stable if R(i)<1 for both strains and is unstable if R(i)>1 for one stain. We establish the criterion R(i)(j)>1 for strain i to invade strain j. Subthreshold coexistence driven by coinfection is possible even when R(i) of one strain is below 1. We identify conditions that determine the evolution of parasite specialism or generalism based on the life-history strategies employed by hosts, and investigate how host strains may influence parasite persistence.
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Affiliation(s)
- Pei Zhang
- Department of Mathematics, Purdue University, West Lafayette, IN 47907, USA
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Mouton L, Nong G, Preston JF, Ebert D. Variable-number tandem repeats as molecular markers for biotypes of Pasteuria ramosa in Daphnia spp. Appl Environ Microbiol 2007; 73:3715-8. [PMID: 17400766 PMCID: PMC1932705 DOI: 10.1128/aem.02398-06] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Variable-number tandem repeats (VNTRs) have been identified in populations of Pasteuria ramosa, a castrating endobacterium of Daphnia species. The allelic polymorphisms at 14 loci in laboratory and geographically diverse soil samples showed that VNTRs may serve as biomarkers for the genetic characterization of P. ramosa isolates.
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Affiliation(s)
- Laurence Mouton
- Zoologisches Institut der Universität Basel, Evolutionsbiologie, Vesalgasse 1, 4051 Basel, Switzerland.
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Dugaw CJ, Preisser EL, Hastings A, Strong DR. Widening the window of persistence in seasonal pathogen–host systems. Theor Popul Biol 2005; 68:267-76. [PMID: 16085188 DOI: 10.1016/j.tpb.2005.05.003] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2005] [Revised: 05/25/2005] [Accepted: 05/31/2005] [Indexed: 11/18/2022]
Abstract
Local instability of exploiter-victim systems is well-known in both theory and in nature. Victims can be too sparse to support exploiter reproduction (under-exploitation) or they can be too readily driven to extinction (over-exploitation). Exploiters of seasonal resources face the additional challenge of surviving periods when victims are rare or unavailable. We formulate a fully stochastic model of highly seasonal pathogen-host dynamics and explore the interactions between an entomopathogenic nematode and its lepidopteran host. Our model suggests that if nematode populations experience the high rates of mortality predicted by short-term laboratory experiments, the paired threats of under- and over-exploitation should preclude the long-term persistence of this exploiter-victim system. We measured nematode mortality rates in the field and found that long-term mortality is lower than that predicted by short-term experiments. Incorporation of this new data into our model produces long-term persistence of local nematode populations across a range of initial nematode densities.
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Affiliation(s)
- Christopher J Dugaw
- Department of Mathematics, University of California Davis, One Shields Avenue, Davis, CA 95616, USA.
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Abstract
Rapid progress is being made in elucidating the molecular mechanisms involved in invertebrate immunity. This search for molecules runs the risk of missing important phenomena. In vertebrates, acquired protection and pathogen-specific responses were demonstrated experimentally long before the mechanisms responsible were elucidated. Without analogous experiments, mechanism-driven work may not demonstrate the full richness of invertebrate immunity.
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Decaestecker E, Declerck S, De Meester L, Ebert D. Ecological implications of parasites in natural Daphnia populations. Oecologia 2005; 144:382-90. [PMID: 15891825 DOI: 10.1007/s00442-005-0083-7] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2004] [Accepted: 02/24/2005] [Indexed: 10/25/2022]
Abstract
In natural host populations, parasitism is considered to be omnipresent and to play an important role in shaping host life history and population dynamics. Here, we study parasitism in natural populations of the zooplankton host Daphnia magna investigating their individual and population level effects during a 2-year field study. Our results revealed a rich and highly prevalent community of parasites, with eight endoparasite species (four microsporidia, one amoeba, two bacteria and one nematode) and six epibionts (belonging to five different taxa: Chlorophyta, Bacillariophyceae, Ciliata, Fungi and Rotifera). Several of the endoparasites were associated with a severe overall fecundity reduction of the hosts, while such effects were not seen for epibionts. In particular, infections by Pasteuria ramosa, White Fat Cell Disease and Flabelliforma magnivora were strongly associated with a reduction in overall D. magna fecundity. Across the sampling period, average population fecundity of D. magna was negatively associated with overall infection intensity and total endoparasite richness. Population density of D. magna was negatively correlated to overall endoparasite prevalence and positively correlated with epibiont richness. Finally, the reduction in host fecundity caused by different parasite species was negatively correlated to both parasite prevalence and the length of the time period during which the parasite persisted in the host population. Consistent with epidemiological models, these results indicate that parasite mediated host damages influence the population dynamics of both hosts and parasites.
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Affiliation(s)
- Ellen Decaestecker
- Laboratory of Aquatic Ecology, Catholic University of Leuven, Ch. De Bèriotstraat 32, 3000, Leuven, Belgium.
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Kilpimaa J, Van de Casteele T, Jokinen I, Mappes J, Alatalo RV. GENETIC AND ENVIRONMENTAL VARIATION IN ANTIBODY AND T-CELL MEDIATED RESPONSES IN THE GREAT TIT. Evolution 2005. [DOI: 10.1554/04-678.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Haag CR, Ebert D. Parasite-mediated selection in experimental metapopulations of Daphnia magna. Proc Biol Sci 2004; 271:2149-55. [PMID: 15475335 PMCID: PMC1691835 DOI: 10.1098/rspb.2004.2841] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
In metapopulations, only a fraction of all local host populations may be infected with a given parasite species, and limited dispersal of parasites suggests that colonization of host populations by parasites may involve only a small number of parasite strains. Using hosts and parasites obtained from a natural metapopulation, we studied the evolutionary consequences of invasion by single strains of parasites in experimental populations of the cyclical parthenogen Daphnia magna. In two experiments, each spanning approximately one season, we monitored clone frequency changes in outdoor container populations consisting of 13 and 19 D. magna clones, respectively. The populations were either infected with single strains of the microsporidian parasites Octosporea bayeri or Ordospora colligata or left unparasitized. In both experiments, infection changed the representation of clones over time significantly, indicating parasite-mediated evolution in the experimental populations. Furthermore, the two parasite species changed clone frequencies differently, suggesting that the interaction between infection and competitive ability of the hosts was specific to the parasite species. Taken together, our results suggest that parasite strains that invade local host populations can lead to evolutionary changes in the genetic composition of the host population and that this change is parasite-species specific.
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Affiliation(s)
- Christoph R Haag
- Université de Fribourg, Départment de Biologie, Unité d'Ecologie et d'Evolution, GH-1700 Fribourg, Switzerland.
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Jackson JA, Tinsley RC. Geographic and within-population structure in variable resistance to parasite species and strains in a vertebrate host. Int J Parasitol 2004; 35:29-37. [PMID: 15619513 DOI: 10.1016/j.ijpara.2004.10.017] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2004] [Revised: 10/01/2004] [Accepted: 10/08/2004] [Indexed: 11/30/2022]
Abstract
Host resistance to parasites and parasite infectivity may be subject to significant genetically determined variation within species. However, relatively little is known of how this variability is structured in natural vertebrate populations and their macroparasites. A laboratory experiment on host susceptibility-parasite infectivity variation in a wildlife host-parasite system (subspecies of the anuran X. laevis and their polystome flatworms), including 33 pairwise allopatric and sympatric host-parasite combinations (three parasite geographical isolates x 11 host full-sibling families, n=600), revealed a complex pattern of infection success. Results amongst host sibships from different localities suggested that infection success was subject to a highly significant locality x parasite isolate interaction. Within localities, a highly significant sibship x isolate interaction also occurred in one of two groups of sibships examined. The existence of such interactions suggests a potential for frequency-dependent, Red Queen-like selection. Interaction between locality and isolate was partly due to higher infection levels in sympatric combinations, consistent with a general pattern of host-specific adaptation. However, some allopatric combinations produced unpredictably high infection levels, resulting in very asymmetrical cross-infectivity patterns (where the reciprocal cross-infections produced negligible infection). This phylogeographically structured host-parasite system may, therefore, sometimes generate local parasite strains with high infectivity to allopatric hosts. Secondary contact between populations could thus result in significant, and unequal, transfer of parasites.
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Affiliation(s)
- Joseph A Jackson
- School of Biology, University of Nottingham, Nottingham NG7 2RD, UK.
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Puurtinen M, Hytönen M, Knott KE, Taskinen J, Nissinen K, Kaitala V. THE EFFECTS OF MATING SYSTEM AND GENETIC VARIABILITY ON SUSCEPTIBILITY TO TREMATODE PARASITES IN A FRESHWATER SNAIL, LYMNAEA STAGNALIS. Evolution 2004. [DOI: 10.1554/04-465] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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