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Orlansky S, Ben-Ami F. The parasites of my rival are my friends. Front Microbiol 2023; 14:1135252. [PMID: 37323892 PMCID: PMC10264602 DOI: 10.3389/fmicb.2023.1135252] [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: 12/31/2022] [Accepted: 04/04/2023] [Indexed: 06/17/2023] Open
Abstract
The competitive exclusion principle asserts that two species cannot stably coexist in the same habitat. However, the presence of a parasite can facilitate temporary coexistence between two host species occupying the same habitat. Studies of parasite-mediated interspecific competition typically use two host species that are both susceptible to a single parasite species, as it is rare to find a resistant host species that requires a parasite to enable coexistence with a competitively superior susceptible host. We therefore investigated how two host species characterized by different susceptibility profiles affect each other when they coexist in the same habitat, by conducting two long-term mesocosm experiments in the laboratory. We followed populations of Daphnia similis coexisting with Daphnia magna, in either the presence or absence of the microsporidium Hamiltosporidium tvaerminnensis and then the bacterium Pasteuria ramosa. We found that in the absence of parasites, D. magna competitively excluded D. similis within a short period of time. However, in the presence of either parasites, the competitive ability of D. magna decreased dramatically. Our results emphasize the importance of parasites in shaping community structure and composition, by allowing coexistence of a resistant host species that would otherwise become extinct.
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Ebert D. Daphnia as a versatile model system in ecology and evolution. EvoDevo 2022; 13:16. [PMID: 35941607 PMCID: PMC9360664 DOI: 10.1186/s13227-022-00199-0] [Citation(s) in RCA: 30] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2021] [Accepted: 06/20/2022] [Indexed: 11/10/2022] Open
Abstract
Water fleas of the genus Daphnia have been a model system for hundreds of years and is among the best studied ecological model organisms to date. Daphnia are planktonic crustaceans with a cyclic parthenogenetic life-cycle. They have a nearly worldwide distribution, inhabiting standing fresh- and brackish water bodies, from small temporary pools to large lakes. Their predominantly asexual reproduction allows for the study of phenotypes excluding genetic variation, enabling us to separate genetic from non-genetic effects. Daphnia are often used in studies related to ecotoxicology, predator-induced defence, host–parasite interactions, phenotypic plasticity and, increasingly, in evolutionary genomics. The most commonly studied species are Daphnia magna and D. pulex, for which a rapidly increasing number of genetic and genomic tools are available. Here, I review current research topics, where the Daphnia model system plays a critical role.
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Affiliation(s)
- Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, CH-4051, Basel, Switzerland.
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Willis AR, Reinke AW. Factors That Determine Microsporidia Infection and Host Specificity. EXPERIENTIA SUPPLEMENTUM (2012) 2022; 114:91-114. [PMID: 35544000 DOI: 10.1007/978-3-030-93306-7_4] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Microsporidia are a large phylum of obligate intracellular parasites that infect an extremely diverse range of animals and protists. In this chapter, we review what is currently known about microsporidia host specificity and what factors influence microsporidia infection. Extensive sampling in nature from related hosts has provided insight into the host range of many microsporidia species. These field studies have been supported by experiments conducted in controlled laboratory environments which have helped to demonstrate host specificity. Together, these approaches have revealed that, while examples of generalist species exist, microsporidia specificity is often narrow, and species typically infect one or several closely related hosts. For microsporidia to successfully infect and complete their life cycle within a compatible host, several steps must occur, including spore germination, host cell invasion, and proliferation of the parasite within the host tissue. Many factors influence infection, including temperature, seasonality, nutrient availability, and the presence or absence of microbes, as well as the developmental stage, sex, and genetics of the host. Several studies have identified host genomic regions that influence resistance to microsporidia, and future work is likely to uncover molecular mechanisms of microsporidia host specificity in more detail.
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Affiliation(s)
- Alexandra R Willis
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada
| | - Aaron W Reinke
- Department of Molecular Genetics, University of Toronto, Toronto, ON, Canada.
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Keiser CN, Pinter-Wollman N, Ziemba MJ, Kothamasu KS, Pruitt JN. The primary case is not enough: Variation among individuals, groups and social networks modify bacterial transmission dynamics. J Anim Ecol 2018; 87:369-378. [PMID: 28692130 PMCID: PMC5871623 DOI: 10.1111/1365-2656.12729] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Accepted: 06/13/2017] [Indexed: 12/26/2022]
Abstract
The traits of the primary case of an infectious disease outbreak, and the circumstances for their aetiology, potentially influence the trajectory of transmission dynamics. However, these dynamics likely also depend on the traits of the individuals with whom the primary case interacts. We used the social spider Stegodyphus dumicola to test how the traits of the primary case, group phenotypic composition and group size interact to facilitate the transmission of a GFP-labelled cuticular bacterium. We also compared bacterial transmission across experimentally generated "daisy-chain" vs. "star" networks of social interactions. Finally, we compared social network structure across groups of different sizes. Groups of 10 spiders experienced more bacterial transmission events compared to groups of 30 spiders, regardless of groups' behavioural composition. Groups containing only one bold spider experienced the lowest levels of bacterial transmission regardless of group size. We found no evidence for the traits of the primary case influencing any transmission dynamics. In a second experiment, bacteria were transmitted to more individuals in experimentally induced star networks than in daisy-chains, on which transmission never exceeded three steps. In both experimental network types, transmission success depended jointly on the behavioural traits of the interacting individuals; however, the behavioural traits of the primary case were only important for transmission on star networks. Larger social groups exhibited lower interaction density (i.e. had a low ratio of observed to possible connections) and were more modular, i.e. they had more connections between nodes within a subgroup and fewer connections across subgroups. Thus, larger groups may restrict transmission by forming fewer interactions and by isolating subgroups that interacted with the primary case. These findings suggest that accounting for the traits of single exposed hosts has less power in predicting transmission dynamics compared to the larger scale factors of the social groups in which they reside. Factors like group size and phenotypic composition appear to alter social interaction patterns, which leads to differential transmission of microbes.
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Affiliation(s)
- Carl N. Keiser
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
- Biosciences Department, Rice University, Academy of Fellows, Rice University, Houston, TX, USA
| | - Noa Pinter-Wollman
- Department of Ecology and Evolutionary Biology, University of California, Los Angeles, CA, USA
| | - Michael J. Ziemba
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Krishna S. Kothamasu
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Jonathan N. Pruitt
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
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Linking host traits, interactions with competitors and disease: Mechanistic foundations for disease dilution. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13066] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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Decaestecker E, Verreydt D, De Meester L, Declerck SAJ. Parasite and nutrient enrichment effects on Daphnia interspecific competition. Ecology 2015; 96:1421-30. [PMID: 26236854 DOI: 10.1890/14-1167.1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Increased productivity due to nutrient enrichment is hypothesized to affect density-dependent processes, such as transmission success of horizontally transmitting parasites. Changes in nutrient availability can also modify the stoichiometry and condition of individual hosts, which may affect their susceptibility for parasites as well as the growth conditions for parasites within the host. Consequently, if not balanced by increased host immuno-competence or life history responses, changes in the magnitude of parasite effects with increasing nutrient availability are expected. If these parasite effects are host-species specific, this may lead to shifts in the host community structure. We here used the Daphnia- parasite model system to study the effect of nutrient enrichment on parasite-mediated competition in experimental mesocosms. In the absence of parasites, D. magna was competitively dominant to D. pulex at both low and high nutrient levels. Introduction of parasites resulted in infections of D. magna, but not of D. pulex and, as such, reversed the competitive hierarchy between these two species. Nutrient addition resulted in an increased prevalence and infection intensity of some of the parasites on D. magna. However, there was no evidence that high nutrient levels enhanced negative effects of parasites on the hosts. Costs associated with parasite infections may have been compensated by better growth conditions for D. magna in the presence of high nutrient levels.
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Pulkkinen K, Wojewodzic MW, Hessen DO. Phosphorus limitation enhances parasite impact: feedback effects at the population level. BMC Ecol 2014; 14:29. [PMID: 25366521 PMCID: PMC4223164 DOI: 10.1186/s12898-014-0029-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 10/16/2014] [Indexed: 12/19/2022] Open
Abstract
Background Nutrient deficiency affects the growth and population dynamics of consumers. Endoparasites can be seen as consumers that drain carbon (C) or energy from their host while simultaneously competing for limiting resources such as phosphorus (P). Depending on the relative demands of the host and the parasite for the limiting nutrient, intensified resource competition under nutrient limitation can either reduce the parasite’s effect on the host or further reduce the fitness of the nutrient-limited host. So far, knowledge of how nutrient limitation affects parasite performance at the host population level and how this affects the host populations is limited. Results We followed the population growth of Daphnia magna that were uninfected or experimentally infected with a microsporidian, Glugoides intestinalis. The Daphnia were fed either P-sufficient or P-limited algae. The P-limited diet decreased the population density and biomass compared with the populations fed with the P-sufficient algae. In the P-sufficient populations, infection with the parasite reduced the population density but not the biomass of Daphnia, while in the P-limited populations, both the density and biomass of Daphnia decreased toward the end of the 32 day experiment compared with the uninfected controls. The infected animals from the P-limited populations had higher parasite spore cluster counts, while, in a separate experiment, host diet quality did not affect the number of parasites in individually kept Daphnia. Conclusions Because host diet quality did not affect parasite numbers at the individual level, we suggest that the higher parasite load in the P-limited populations is a result of feedback effects arising at the population level. Because of the density-dependent transmission of the parasite and the time lag between exposure and transmission, the lower host population density in the P-limited populations led to a higher spore:host ratio. This effect may have been further reinforced by decreases in filtration rates caused by crowding in the P-sufficient populations and/or increases in filtration rates as a response to poor food quality in the P-limited populations. The increases in exposure led to a higher parasite load and aggravated the negative effects of parasite infection at the population level. Electronic supplementary material The online version of this article (doi:10.1186/s12898-014-0029-1) contains supplementary material, which is available to authorized users.
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Jalal M, Shala NK, Wojewodzic MW, Andersen T, Hessen DO. Multigenerational genomic responses to dietary phosphorus and temperature in Daphnia. Genome 2014; 57:439-48. [DOI: 10.1139/gen-2014-0047] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Temperature and nutrient availability are both hypothesized to affect organisms at the cellular and genomic levels. In this multigenerational study, Daphnia magna (D. magna) and Daphnia pulex (D. pulex) were maintained at high (20 °C) and low (10 °C) temperatures and nourished with phosphorus (P)-sufficient (50 μmol/L) and P-deficient (2 μmol/L) algae for up to 35 generations to assess the multigenerational impacts on genome size and nucleus size. Analysis by flow cytometry revealed significant increases in nucleus size for both species as well as genome size for D. magna in response to a low temperature. The degree of endoreplication, measured as cycle value, was species specific and responded to temperature and dietary composition. Under dietary P deficiency, D. magna, but not D. pulex, showed an apparent reduction in haploid genome size (C-value). These genomic responses are unlikely to reflect differences in nucleotide numbers, but rather structural changes affecting fluorochrome binding. While the ultimate and proximate causes of these responses are unknown, they suggest an intriguing potential for genomic responses that merits further research.
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Affiliation(s)
- Marwa Jalal
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Nita K. Shala
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Marcin W. Wojewodzic
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Tom Andersen
- Section for Aquatic Biology and Toxicology, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Dag O. Hessen
- Centre for Ecological and Evolutionary Synthesis, Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
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Jalal M, Wojewodzic MW, Laane CMM, Hessen DO. Larger Daphnia at lower temperature: a role for cell size and genome configuration? Genome 2013; 56:511-9. [DOI: 10.1139/gen-2013-0004] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Experiments with Daphnia magna and Daphnia pulex raised at 10 and 20 °C yielded larger adult size at the lower temperature. This must reflect increased cell size, increased cell numbers, or a combination of both. As it is difficult to achieve good estimates on cell size in crustaceans, we, therefore, measured nucleus and genome size using flow cytometry at 10 and 20 °C. DNA was stained with propidium iodide, ethidium bromide, and DAPI. Both nucleus and genome size estimates were elevated at 10 °C compared with 20 °C, suggesting that larger body size at low temperature could partly be accredited to an enlarged nucleus and thus cell size. Confocal microscopy observations confirmed the staining properties of fluorochromes. As differences in nucleotide numbers in response of growth temperature within a life span is unlikely, these results seem accredited to changed DNA–fluorochrome binding properties, presumably reflecting increased DNA condensation at low temperature. This implies that genome size comparisons may be impacted by ambient temperature in ectotherms. It also suggests that temperature-induced structural changes in the genome could affect cell size and for some species even body size.
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Affiliation(s)
- Marwa Jalal
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Marcin W. Wojewodzic
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Carl Morten M. Laane
- Department of Biosciences, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
| | - Dag O. Hessen
- Centre for Ecological and Evolutionary Synthesis, Department of Biology, University of Oslo, P.O. Box 1066 Blindern, N-0316 Oslo, Norway
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King KC, Auld SKJR, Wilson PJ, James J, Little TJ. The bacterial parasite Pasteuria ramosa is not killed if it fails to infect: implications for coevolution. Ecol Evol 2012; 3:197-203. [PMID: 23467806 PMCID: PMC3586630 DOI: 10.1002/ece3.438] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2012] [Revised: 10/18/2012] [Accepted: 10/29/2012] [Indexed: 12/02/2022] Open
Abstract
Strong selection on parasites, as well as on hosts, is crucial for fueling coevolutionary dynamics. Selection will be especially strong if parasites that encounter resistant hosts are destroyed and diluted from the local environment. We tested whether spores of the bacterial parasite Pasteuria ramosa were passed through the gut (the route of infection) of their host, Daphnia magna, and whether passaged spores remained viable for a “second chance” at infecting a new host. In particular, we tested if this viability (estimated via infectivity) depended on host genotype, whether or not the genotype was susceptible, and on initial parasite dose. Our results show that Pasteuria spores generally remain viable after passage through both susceptible and resistant Daphnia. Furthermore, these spores remained infectious even after being frozen for several weeks. If parasites can get a second chance at infecting hosts in the wild, selection for infection success in the first instance will be reduced. This could also weaken reciprocal selection on hosts and slow the coevolutionary process.
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Affiliation(s)
- Kayla C King
- Institute of Integrative Biology, University of Liverpool Crown Street, Liverpool, L69 7ZB, UK
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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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Ecological and genetic determinants of multiple infection and aggregation in a microbial host-parasite system. Parasitology 2008; 135:1373-83. [DOI: 10.1017/s0031182008004940] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
SUMMARYThe number of parasites colonizing a host (termed ‘multiple infection’) is an important determinant of host-parasite interactions. In theory, multiple infection is determined by random mass action in genetically and spatially homogeneous populations of host and parasite. In real populations, deviations from these assumptions may strongly influence levels of multiple infection. We carried out inoculation experiments in microcosms of the freshwater protozoanParamecium caudatumand its bacterial parasiteHolospora undulata. Increasing parasite dose produced higher levels of (multiple) infection; more susceptible host genotypes also were more multiply infected. An overall pattern of parasite aggregation (excess of uninfected individuals and of individuals carrying larger numbers of parasites) indicated deviations from random mass-action transmission. Homogenizing spatial distributions of parasite and host in our microcosms did not affect aggregation, whereas aggregation was more pronounced in old than in new host clones. Thus, variation in susceptibility may arise over time within clonal populations. When sequentially inoculated, already established infections increased the probability of additional infection in generally resistant host clones, but decreased it in more susceptible clones. Hence, the role of multiple infection as a driver of epidemiological or evolutionary processes may vary among populations, depending on their precise genetic composition or infection history.
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