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Ismail S, Farner J, Couper L, Mordecai E, Lyberger K. Temperature and intraspecific variation affect host-parasite interactions. Oecologia 2024; 204:389-399. [PMID: 38006450 DOI: 10.1007/s00442-023-05481-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Accepted: 11/06/2023] [Indexed: 11/27/2023]
Abstract
Parasites play key roles in regulating aquatic ecosystems, yet the impact of climate warming on their ecology and disease transmission remains poorly understood. Isolating the effect of warming is challenging as transmission involves multiple interacting species and potential intraspecific variation in temperature responses of one or more of these species. Here, we leverage a wide-ranging mosquito species and its facultative parasite as a model system to investigate the impact of temperature on host-parasite interactions and disease transmission. We conducted a common garden experiment measuring parasite growth and infection rates at seven temperatures using 12 field-collected parasite populations and a single mosquito population. We find that both free-living growth rates and infection rates varied with temperature, which were highest at 18-24.5 °C and 13 °C, respectively. Further, we find intraspecific variation in peak performance temperature reflecting patterns of local thermal adaptation-parasite populations from warmer source environments typically had higher thermal optima for free-living growth rates. For infection rates, we found a significant interaction between parasite population and nonlinear effects of temperature. These findings underscore the need to consider both host and parasite thermal responses, as well as intraspecific variation in thermal responses, when predicting the impacts of climate change on disease in aquatic ecosystems.
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Affiliation(s)
- Sherine Ismail
- Department of Biology, Stanford University, Stanford, USA
| | | | - Lisa Couper
- Department of Biology, Stanford University, Stanford, USA
| | - Erin Mordecai
- Department of Biology, Stanford University, Stanford, USA
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2
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Ismail S, Farner J, Couper L, Mordecai E, Lyberger K. Temperature and intraspecific variation affect host-parasite interactions. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.24.554680. [PMID: 37662401 PMCID: PMC10473705 DOI: 10.1101/2023.08.24.554680] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
Parasites play key roles in regulating aquatic ecosystems, yet the impact of climate warming on their ecology and disease transmission remains poorly understood. Isolating the effect of warming is challenging as transmission involves multiple interacting species and potential intraspecific variation in temperature responses of one or more of these species. Here, we leverage a wide-ranging mosquito species and its facultative parasite as a model system to investigate the impact of temperature on host-parasite interactions and disease transmission. We conducted a common garden experiment measuring parasite growth and infection rates at seven temperatures using 12 field-collected parasite populations and a single mosquito population. We find that both free-living growth rates and infection rates varied with temperature, which were highest at 18-24.5°C and 13°C, respectively. Further, we find intraspecific variation in peak performance temperature reflecting patterns of local thermal adaptation-parasite populations from warmer source environments typically had higher thermal optima for free-living growth rates. For infection rates, we found a significant interaction between parasite population and nonlinear effects of temperature. These findings underscore the need to consider both host and parasite thermal responses, as well as intraspecific variation in thermal responses, when predicting the impacts of climate change on disease in aquatic ecosystems.
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3
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Sun SJ, Dziuba MK, Jaye RN, Duffy MA. Temperature modifies trait-mediated infection outcomes in a Daphnia-fungal parasite system. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220009. [PMID: 36744571 PMCID: PMC9900708 DOI: 10.1098/rstb.2022.0009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2022] [Accepted: 10/24/2022] [Indexed: 02/07/2023] Open
Abstract
One major concern related to climate change is that elevated temperatures will drive increases in parasite outbreaks. Increasing temperature is known to alter host traits and host-parasite interactions, but we know relatively little about how these are connected mechanistically-that is, about how warmer temperatures impact the relationship between epidemiologically relevant host traits and infection outcomes. Here, we used a zooplankton-fungus (Daphnia dentifera-Metschnikowia bicuspidata) disease system to experimentally investigate how temperature impacted physical barriers to infection and cellular immune responses. We found that Daphnia reared at warmer temperatures had more robust physical barriers to infection but decreased cellular immune responses during the initial infection process. Infected hosts at warmer temperatures also suffered greater reductions in fecundity and lifespan. Furthermore, the relationship between a key trait-gut epithelium thickness, a physical barrier-and the likelihood of terminal infection reversed at warmer temperatures. Together, our results highlight the complex ways that temperatures can modulate host-parasite interactions and show that different defense components can have qualitatively different responses to warmer temperatures, highlighting the importance of considering key host traits when predicting disease dynamics in a warmer world. This article is part of the theme issue 'Infectious disease ecology and evolution in a changing world'.
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Affiliation(s)
- Syuan-Jyun Sun
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
- International Degree Program in Climate Change and Sustainable Development, National Taiwan University, Taipei 10617, Taiwan
| | - Marcin K. Dziuba
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Riley N. Jaye
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Meghan A. Duffy
- Department of Ecology & Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
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4
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Sun S, Dziuba MK, Jaye RN, Duffy MA. Transgenerational plasticity in a zooplankton in response to elevated temperature and parasitism. Ecol Evol 2023; 13:e9767. [PMID: 36760704 PMCID: PMC9897957 DOI: 10.1002/ece3.9767] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2022] [Revised: 01/05/2023] [Accepted: 01/09/2023] [Indexed: 02/05/2023] Open
Abstract
Organisms are increasingly facing multiple stressors, which can simultaneously interact to cause unpredictable impacts compared with a single stressor alone. Recent evidence suggests that phenotypic plasticity can allow for rapid responses to altered environments, including biotic and abiotic stressors, both within a generation and across generations (transgenerational plasticity). Parents can potentially "prime" their offspring to better cope with similar stressors or, alternatively, might produce offspring that are less fit because of energetic constraints. At present, it remains unclear exactly how biotic and abiotic stressors jointly mediate the responses of transgenerational plasticity and whether this plasticity is adaptive. Here, we test the effects of biotic and abiotic environmental changes on within- and transgenerational plasticity using a Daphnia-Metschnikowia zooplankton-fungal parasite system. By exposing parents and their offspring consecutively to the single and combined effects of elevated temperature and parasite infection, we showed that transgenerational plasticity induced by temperature and parasite stress influenced host fecundity and lifespan; offsprings of mothers who were exposed to one of the stressors were better able to tolerate elevated temperature, compared with the offspring of mothers who were exposed to neither or both stressors. Yet, the negative effects caused by parasite infection were much stronger, and this greater reduction in host fitness was not mitigated by transgenerational plasticity. We also showed that elevated temperature led to a lower average immune response, and that the relationship between immune response and lifetime fecundity reversed under elevated temperature: the daughters of exposed mothers showed decreased fecundity with increased hemocyte production at ambient temperature but the opposite relationship at elevated temperature. Together, our results highlight the need to address questions at the interface of multiple stressors and transgenerational plasticity and the importance of considering multiple fitness-associated traits when evaluating the adaptive value of transgenerational plasticity under changing environments.
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Affiliation(s)
- Syuan‐Jyun Sun
- Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
- International Degree Program in Climate Change and Sustainable DevelopmentNational Taiwan UniversityTaipeiTaiwan
| | - Marcin K. Dziuba
- Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Riley N. Jaye
- Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
| | - Meghan A. Duffy
- Department of Ecology and Evolutionary BiologyUniversity of MichiganAnn ArborMichiganUSA
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5
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Litchman E, Thomas MK. Are we underestimating the ecological and evolutionary effects of warming? Interactions with other environmental drivers may increase species vulnerability to high temperatures. OIKOS 2022. [DOI: 10.1111/oik.09155] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Elena Litchman
- Kellogg Biological Station, Michigan State Univ. Hickory Corners MI USA
- Dept of Global Ecology, Carnegie Inst. for Science Stanford CA USA
| | - Mridul K. Thomas
- Dept F.‐A. Forel for Environmental and Aquatic Sciences, Univ. of Geneva Geneva Switzerland
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6
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Ameline C, Voegtli F, Andras J, Dexter E, Engelstädter J, Ebert D. Genetic slippage after sex maintains diversity for parasite resistance in a natural host population. SCIENCE ADVANCES 2022; 8:eabn0051. [PMID: 36399570 PMCID: PMC9674289 DOI: 10.1126/sciadv.abn0051] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2021] [Accepted: 10/04/2022] [Indexed: 06/16/2023]
Abstract
Although parasite-mediated selection is a major driver of host evolution, its influence on genetic variation for parasite resistance is not yet well understood. We monitored resistance in a large population of the planktonic crustacean Daphnia magna over 8 years, as it underwent yearly epidemics of the bacterial pathogen Pasteuria ramosa. We observed cyclic dynamics of resistance: Resistance increased throughout the epidemics, but susceptibility was restored each spring when hosts hatched from sexual resting stages. Host resting stages collected across the year showed that largely resistant host populations can produce susceptible sexual offspring. A genetic model of resistance developed for this host-parasite system, based on multiple loci and strong epistasis, is in partial agreement with our findings. Our results reveal that, despite strong selection for resistance in a natural host population, genetic slippage after sexual reproduction can be a strong factor for the maintenance of genetic diversity of host resistance.
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Affiliation(s)
- Camille Ameline
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Felix Voegtli
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Jason Andras
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Eric Dexter
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Australia
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, University of Basel, Vesalgasse 1, 4051 Basel, Switzerland
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7
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Kim SK, Choi JY. Behavioral Avoidance Response of Daphnia to Fungal Infection Caused by Metschnikowia Species in a Temperate Reservoir. BIOLOGY 2022; 11:1409. [PMID: 36290312 PMCID: PMC9598222 DOI: 10.3390/biology11101409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 09/22/2022] [Accepted: 09/24/2022] [Indexed: 06/16/2023]
Abstract
Morphological or behavioral defense mechanisms are important evolutionary strategies for the survival of prey. Studies have focused on predation and competition, but infection has been overlooked, despite being a determining factor of distribution and species diversity of prey. We hypothesized that the winter migration of Daphnia pulicaria is a community defense strategy to avoid fungal infection. To test this hypothesis, environmental variables and the Cladocera community, including D. pulicaria, were monitored in three study sections of the Anri Reservoir in the Republic of Korea during September 2010-August 2015. During three winter seasons, the density of infected D. pulicaria increased in all study sections, and they migrated from the central to the littoral area. Most of the infected individuals had dormant eggs in sexually reproducing mothers. However, when the proportion of non-infected individuals was higher than that of infected individuals, winter migration was not observed. Additional microcosm experiments showed that dormant eggs of D. pulicaria obtained from ice crystals in the littoral area had lower hatching and infection rates than those obtained from mothers moving from other zones. Therefore, the migration of D. pulicaria during winter is an active response to avoid intergenerational fungal infection.
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8
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Transgenerational plasticity alters parasite fitness in changing environments. Parasitology 2022; 149:1515-1520. [PMID: 36043359 PMCID: PMC10090760 DOI: 10.1017/s0031182022001056] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Transgenerational plasticity can help organisms respond rapidly to changing environments. Most prior studies of transgenerational plasticity in host–parasite interactions have focused on the host, leaving us with a limited understanding of transgenerational plasticity of parasites. We tested whether exposure to elevated temperatures while spores are developing can modify the ability of those spores to infect new hosts, as well as the growth and virulence of the next generation of parasites in the new host. We exposed Daphnia dentifera to its naturally co-occurring fungal parasite Metschnikowia bicuspidata, rearing the parasite at cooler (20°C) or warmer (24°C) temperatures and then, factorially, using those spores to infect at 20 and 24°C. Infections by parasites reared at warmer past temperatures produced more mature spores, but only when the current infections were at cooler temperatures. Moreover, the percentage of mature spores was impacted by both rearing and current temperatures, and was highest for infections with spores reared in a warmer environment that infected hosts in a cooler environment. In contrast, virulence was influenced only by current temperatures. These results demonstrate transgenerational plasticity of parasites in response to temperature changes, with fitness impacts that are dependent on both past and current environments.
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9
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Hector TE, Hoang KL, Li J, King KC. Symbiosis and host responses to heating. Trends Ecol Evol 2022; 37:611-624. [PMID: 35491290 DOI: 10.1016/j.tree.2022.03.011] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2021] [Revised: 03/22/2022] [Accepted: 03/28/2022] [Indexed: 12/31/2022]
Abstract
Virtually all organisms are colonized by microbes. Average temperatures are rising because of global climate change - accompanied by increases in extreme climatic events and heat shock - and symbioses with microbes may determine species persistence in the 21st century. Although parasite infection typically reduces host upper thermal limits, interactions with beneficial microbes can facilitate host adaptation to warming. The effects of warming on the ecology and evolution of the microbial symbionts remain understudied but are important for understanding how climate change might affect host health and disease. We present a framework for untangling the contributions of symbiosis to predictions of host persistence in the face of global change.
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Affiliation(s)
- Tobias E Hector
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Kim L Hoang
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Jingdi Li
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK
| | - Kayla C King
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford OX1 3SZ, UK.
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10
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Schampera C, Agha R, Manzi F, Wolinska J. Parasites do not adapt to elevated temperature, as evidenced from experimental evolution of a phytoplankton-fungus system. Biol Lett 2022; 18:20210560. [PMID: 35168375 PMCID: PMC8847893 DOI: 10.1098/rsbl.2021.0560] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Global warming is predicted to impact the prevalence and severity of infectious diseases. However, empirical data supporting this statement usually stem from experiments in which parasite fitness and disease outcome are measured directly after temperature increase. This might exclude the possibility of parasite adaptation. To incorporate the adaptive response of parasites into predictions of disease severity in a warmer world, we undertook an experimental evolution assay in which a fungal parasite of phytoplankton was maintained at elevated or control temperatures for six months, corresponding to 100–200 parasite generations. Host cultures were maintained at the respective temperatures and provided as substrate, but were not under parasite pressure. A reciprocal infection experiment conducted after six-month serial passages revealed no evidence of parasite adaptation. In fact, parasite fitness at elevated temperatures was inferior in parasite populations reared at elevated temperatures compared with those maintained under control temperature. However, this effect was reversed after parasites were returned to control temperatures for a few (approx. 10) generations. The absence of parasite adaptation to elevated temperatures suggests that, in phytoplankton–fungus systems, disease outcome under global warming will be largely determined by both host and parasite thermal ecology.
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Affiliation(s)
- Charlotte Schampera
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Ramsy Agha
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany
| | - Florent Manzi
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany.,Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität (FU) Berlin, Berlin, Germany
| | - Justyna Wolinska
- Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), Berlin, Germany.,Department of Biology, Chemistry, Pharmacy, Institute of Biology, Freie Universität (FU) Berlin, Berlin, Germany
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11
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Hector TE, Sgrò CM, Hall MD. Thermal limits in the face of infectious disease: How important are pathogens? GLOBAL CHANGE BIOLOGY 2021; 27:4469-4480. [PMID: 34170603 DOI: 10.1111/gcb.15761] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Revised: 06/14/2021] [Accepted: 06/18/2021] [Indexed: 06/13/2023]
Abstract
The frequency and severity of both extreme thermal events and disease outbreaks are predicted to continue to shift as a consequence of global change. As a result, species persistence will likely be increasingly dependent on the interaction between thermal stress and pathogen exposure. Missing from the intersection between studies of infectious disease and thermal ecology, however, is the capacity for pathogen exposure to directly disrupt a host's ability to cope with thermal stress. Common sources of variation in host thermal performance, which are likely to interact with infection, are also often unaccounted for when assessing either the vulnerability of species or the potential for disease spread during extreme thermal events. Here, we describe how infection can directly alter host thermal limits, to a degree that exceeds the level of variation commonly seen across species large geographic distributions and that equals the detrimental impact of other ecologically relevant stressors. We then discuss various sources of heterogeneity within and between populations that are likely to be important in mediating the impact that infection has on variation in host thermal limits. In doing so we highlight how infection is a widespread and important source of variation in host thermal performance, which will have implications for both the persistence and vulnerability of species and the dynamics and transmission of disease in a more thermally extreme world.
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Affiliation(s)
- Tobias E Hector
- School of Biological Sciences, Monash University, Melbourne, Vic., Australia
| | - Carla M Sgrò
- School of Biological Sciences, Monash University, Melbourne, Vic., Australia
| | - Matthew D Hall
- School of Biological Sciences, Monash University, Melbourne, Vic., Australia
- Centre of Geometric Biology, Monash University, Melbourne, Vic., Australia
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12
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Hector TE, Sgrò CM, Hall MD. Temperature and pathogen exposure act independently to drive host phenotypic trajectories. Biol Lett 2021; 17:20210072. [PMID: 34129797 PMCID: PMC8205525 DOI: 10.1098/rsbl.2021.0072] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Natural populations are experiencing an increase in the occurrence of both thermal stress and disease outbreaks. How these two common stressors interact to determine host phenotypic shifts will be important for population persistence, yet a myriad of different traits and pathways are a target of both stressors, making generalizable predictions difficult to obtain. Here, using the host Daphnia magna and its bacterial pathogen Pasteuria ramosa, we tested how temperature and pathogen exposure interact to drive shifts in multivariate host phenotypes. We found that these two stressors acted mostly independently to shape host phenotypic trajectories, with temperature driving a faster pace of life by favouring early development and increased intrinsic population growth rates, while pathogen exposure impacted reproductive potential through reductions in lifetime fecundity. Studies focussed on extreme thermal stress are increasingly showing how pathogen exposure can severely hamper the thermal tolerance of a host. However, our results suggest that under milder thermal stress, and in terms of life-history traits, increases in temperature might not exacerbate the impact of pathogen exposure on host performance, and vice versa.
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Affiliation(s)
- Tobias E Hector
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Carla M Sgrò
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Matthew D Hall
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia.,Centre for Geometric Biology, Monash University, Melbourne, VIC 3800, Australia
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13
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Turner WC, Kamath PL, van Heerden H, Huang YH, Barandongo ZR, Bruce SA, Kausrud K. The roles of environmental variation and parasite survival in virulence-transmission relationships. ROYAL SOCIETY OPEN SCIENCE 2021; 8:210088. [PMID: 34109041 PMCID: PMC8170194 DOI: 10.1098/rsos.210088] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Disease outbreaks are a consequence of interactions among the three components of a host-parasite system: the infectious agent, the host and the environment. While virulence and transmission are widely investigated, most studies of parasite life-history trade-offs are conducted with theoretical models or tractable experimental systems where transmission is standardized and the environment controlled. Yet, biotic and abiotic environmental factors can strongly affect disease dynamics, and ultimately, host-parasite coevolution. Here, we review research on how environmental context alters virulence-transmission relationships, focusing on the off-host portion of the parasite life cycle, and how variation in parasite survival affects the evolution of virulence and transmission. We review three inter-related 'approaches' that have dominated the study of the evolution of virulence and transmission for different host-parasite systems: (i) evolutionary trade-off theory, (ii) parasite local adaptation and (iii) parasite phylodynamics. These approaches consider the role of the environment in virulence and transmission evolution from different angles, which entail different advantages and potential biases. We suggest improvements to how to investigate virulence-transmission relationships, through conceptual and methodological developments and taking environmental context into consideration. By combining developments in life-history evolution, phylogenetics, adaptive dynamics and comparative genomics, we can improve our understanding of virulence-transmission relationships across a diversity of host-parasite systems that have eluded experimental study of parasite life history.
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Affiliation(s)
- Wendy C. Turner
- US Geological Survey, Wisconsin Cooperative Wildlife Research Unit, Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Pauline L. Kamath
- School of Food and Agriculture, University of Maine, Orono, ME 04469, USA
| | - Henriette van Heerden
- Faculty of Veterinary Science, Department of Veterinary Tropical Diseases, University of Pretoria, Onderstepoort, South Africa
| | - Yen-Hua Huang
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Zoe R. Barandongo
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Spencer A. Bruce
- Department of Biological Sciences, University at Albany, State University of New York, Albany, NY 12222, USA
| | - Kyrre Kausrud
- Section for Epidemiology, Norwegian Veterinary Institute, Ullevålsveien 68, 0454 Oslo, Norway
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14
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Comeault AA, Matute DR. Temperature-Dependent Competitive Outcomes between the Fruit Flies Drosophila santomea and Drosophila yakuba. Am Nat 2021; 197:312-323. [DOI: 10.1086/712781] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Ferris C, Wright R, Brockhurst MA, Best A. The evolution of host resistance and parasite infectivity is highest in seasonal resource environments that oscillate at intermediate amplitudes. Proc Biol Sci 2020; 287:20200787. [PMID: 32453992 PMCID: PMC7287369 DOI: 10.1098/rspb.2020.0787] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 05/01/2020] [Indexed: 12/31/2022] Open
Abstract
Seasonal environments vary in their amplitude of oscillation but the effects of this temporal heterogeneity for host-parasite coevolution are poorly understood. Here, we combined mathematical modelling and experimental evolution of a coevolving bacteria-phage interaction to show that the intensity of host-parasite coevolution peaked in environments that oscillate in their resource supply with intermediate amplitude. Our experimentally parameterized mathematical model explains that this pattern is primarily driven by the ecological effects of resource oscillations on host growth rates. Our findings suggest that in host-parasite systems where the host's but not the parasite's population growth dynamics are subject to seasonal forcing, the intensity of coevolution will peak at intermediate amplitudes but be constrained at extreme amplitudes of environmental oscillation.
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Affiliation(s)
- Charlotte Ferris
- School of Mathematics and Statistics, University of Sheffield, Hicks Building, 226 Hounsfield Road, Sheffield S3 7RH, UK
| | - Rosanna Wright
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Michael A. Brockhurst
- Department of Animal and Plant Sciences, University of Sheffield, Sheffield S10 2TN, UK
| | - Alex Best
- School of Mathematics and Statistics, University of Sheffield, Hicks Building, 226 Hounsfield Road, Sheffield S3 7RH, UK
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16
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González R, Butković A, Elena SF. From foes to friends: Viral infections expand the limits of host phenotypic plasticity. Adv Virus Res 2020; 106:85-121. [PMID: 32327149 DOI: 10.1016/bs.aivir.2020.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Phenotypic plasticity enables organisms to survive in the face of unpredictable environmental stress. Intimately related to the notion of phenotypic plasticity is the concept of the reaction norm that places phenotypic plasticity in the context of a genotype-specific response to environmental gradients. Whether reaction norms themselves evolve and which factors might affect their shape has been the object of intense debates among evolutionary biologists along the years. Since their discovery, viruses have been considered as pathogens. However, new viromic techniques and a shift in conceptual paradigms are showing that viruses are mostly non-pathogenic ubiquitous entities. Recent studies have shown how viral infections can even be beneficial for their hosts. This may happen especially in the context of stressed hosts, where the virus infection can induce beneficial changes in the host's physiological homeostasis, hence changing the shape of the reaction norm. Despite the fact that underlying physiological mechanisms and evolutionary dynamics are still not well understood, such beneficial interactions are being discovered in a growing number of plant-virus systems. Here, we aim to review these disperse studies and place them into the context of phenotypic plasticity and the evolution of reaction norms. This is an emerging field that is posing many questions that still need to be properly answered. The answers would clearly interest virologists, plant pathologists and evolutionary biologists and likely they will suggest possible future biotechnological applications, including the development of crops with higher survival rates and yield under adverse environmental situations.
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Affiliation(s)
- Rubén González
- Instituto de Biología Integrativa de Sistemas, CSIC-Universitat de València, Valencia, Spain.
| | - Anamarija Butković
- Instituto de Biología Integrativa de Sistemas, CSIC-Universitat de València, Valencia, Spain
| | - Santiago F Elena
- Instituto de Biología Integrativa de Sistemas, CSIC-Universitat de València, Valencia, Spain; The Santa Fe Institute, Santa Fe, NM, United States.
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17
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Sadler DE, Brunner FS, Plaistow SJ. Temperature and clone-dependent effects of microplastics on immunity and life history in Daphnia magna. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2019; 255:113178. [PMID: 31520904 DOI: 10.1016/j.envpol.2019.113178] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Revised: 09/03/2019] [Accepted: 09/04/2019] [Indexed: 06/10/2023]
Abstract
Microplastic (MP) pollution is potentially a major threat to many aquatic organisms. Yet we currently know very little about the mechanisms responsible for the effects of small MPs on phenotypes, and the extent to which effects of MPs are modified by genetic and environmental factors. Using a multivariate approach, we studied the effects of 500 nm polystyrene microspheres on the life history and immunity of eight clones of the freshwater cladoceran Daphnia magna reared at two temperatures (18 °C/24 °C). MP exposure altered multivariate phenotypes in half of the clones we studied but had no effect on others. In the clones that were affected, individuals exposed to MPs had smaller offspring at both temperatures, and more offspring at high temperature. Differences in response to MP exposure were unrelated to differences in particle uptake, but were instead linked to an upregulation of haemocytes, particularly at high temperature. The clone-specific, context-dependent nature of our results demonstrates the importance of incorporating genetic variation and environmental context into assessments of the impact of plastic particle exposure. Our results identify immunity as an important mechanism underpinning genetically variable responses to MP pollution and may have major implications for predicting consequences of MP pollution.
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Affiliation(s)
- Daniel E Sadler
- Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, L69 7ZB Liverpool, United Kingdom
| | - Franziska S Brunner
- Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, L69 7ZB Liverpool, United Kingdom.
| | - Stewart J Plaistow
- Institute of Integrative Biology, University of Liverpool, Biosciences Building, Crown Street, L69 7ZB Liverpool, United Kingdom
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18
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Hector TE, Sgrò CM, Hall MD. Pathogen exposure disrupts an organism's ability to cope with thermal stress. GLOBAL CHANGE BIOLOGY 2019; 25:3893-3905. [PMID: 31148326 DOI: 10.1111/gcb.14713] [Citation(s) in RCA: 25] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/21/2019] [Indexed: 06/09/2023]
Abstract
As a result of global climate change, species are experiencing an escalation in the severity and regularity of extreme thermal events. With patterns of disease distribution and transmission predicted to undergo considerable shifts in the coming years, the interplay between temperature and pathogen exposure will likely determine the capacity of a population to persist under the dual threat of global change and infectious disease. In this study, we investigated how exposure to a pathogen affects an individual's ability to cope with extreme temperatures. Using experimental infections of Daphnia magna with its obligate bacterial pathogen Pasteuria ramosa, we measured upper thermal limits of multiple host and pathogen genotype combinations across the dynamic process of infection and under various forms (static and ramping) of thermal stress. We find that pathogens substantially limit the thermal tolerance of their host, with the reduction in upper thermal limits on par with the breadth of variation seen across similar species entire geographical ranges. The precise magnitude of any reduction, however, was specific to the host and pathogen genotype combination. In addition, as thermal ramping rate slowed, upper thermal limits of both healthy and infected individuals were reduced. Our results suggest that the capacity of a population to evolve new thermal limits, when also faced with the threat of infection, will depend not only on a host's genetic variability in warmer environments, but also on the frequency of host and pathogen genotypes. We suggest that pathogen-induced alterations of host thermal performance should be taken into account when assessing the resilience of any population and its potential for adaptation to global change.
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Affiliation(s)
- Tobias E Hector
- School of Biological Sciences and Centre for Geometric Biology, Monash University, Melbourne, Victoria, Australia
| | - Carla M Sgrò
- School of Biological Sciences and Centre for Geometric Biology, Monash University, Melbourne, Victoria, Australia
| | - Matthew D Hall
- School of Biological Sciences and Centre for Geometric Biology, Monash University, Melbourne, Victoria, Australia
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19
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Shocket MS, Magnante A, Duffy MA, Cáceres CE, Hall SR. Can hot temperatures limit disease transmission? A test of mechanisms in a zooplankton–fungus system. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
| | | | - Meghan A. Duffy
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor MI USA
| | - Carla E. Cáceres
- School of Integrative Biology University of Illinois at Urbana‐Champaign Urbana IL USA
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20
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Savola E, Ebert D. Assessment of parasite virulence in a natural population of a planktonic crustacean. BMC Ecol 2019; 19:14. [PMID: 30871516 PMCID: PMC6419459 DOI: 10.1186/s12898-019-0230-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Accepted: 02/28/2019] [Indexed: 02/05/2023] Open
Abstract
Background Understanding the impact of disease in natural populations requires an understanding of infection risk and the damage that parasites cause to their hosts (= virulence). However, because these disease traits are often studied and quantified under controlled laboratory conditions and with reference to healthy control hosts, we have little knowledge about how they play out in natural conditions. In the Daphnia–Pasteuria host–parasite system, field assessments often show very low estimates of virulence, while controlled laboratory experiments indicate extremely high virulence. Results To examine this discrepancy, we sampled Daphnia magna hosts from the field during a parasite epidemic and recorded disease traits over a subsequent 3-week period in the laboratory. As predicted for chronic disease where infections in older (larger) hosts are also, on average, older, we found that larger D. magna females were infected more often, had fewer offspring prior to the onset of castration and showed signs of infection sooner than smaller hosts. Also consistent with laboratory experiments, infected animals were found in both sexes and in all sizes of hosts. Infected females were castrated at capture or became castrated soon after. As most females in the field carried no eggs in their brood pouch at the time of sampling, virulence estimates of infected females relative to uninfected females were low. However, with improved feeding conditions in the laboratory, only uninfected females resumed reproduction, resulting in very high relative virulence estimates. Conclusions Overall, our study shows that the disease manifestation of P. ramosa, as expressed under natural conditions, is consistent with what we know from laboratory experiments. However, parasite induced fecundity reduction of infected, relative to uninfected hosts depended strongly on the environmental conditions. We argue that this effect is particularly strong for castrating parasites, because infected hosts have low fecundity under all conditions.
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Affiliation(s)
- Eevi Savola
- Department of Environmental Sciences, Zoology, Basel University, Vesalgasse 1, 4051, Basel, Switzerland.,Institute of Evolutionary Biology, School of Biological Sciences, The University of Edinburgh, Ashworth Laboratories, Edinburgh, EH9 3FL, UK
| | - Dieter Ebert
- Department of Environmental Sciences, Zoology, Basel University, Vesalgasse 1, 4051, Basel, Switzerland.
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21
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Penczykowski RM, Parratt SR, Barrès B, Sallinen SK, Laine AL. Manipulating host resistance structure reveals impact of pathogen dispersal and environmental heterogeneity on epidemics. Ecology 2018; 99:2853-2863. [PMID: 30289567 DOI: 10.1002/ecy.2526] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2018] [Accepted: 08/20/2018] [Indexed: 11/08/2022]
Abstract
Understanding how variation in hosts, parasites, and the environment shapes patterns of disease is key to predicting ecological and evolutionary outcomes of epidemics. Yet in spatially structured populations, variation in host resistance may be spatially confounded with variation in parasite dispersal and environmental factors that affect disease processes. To tease apart these disease drivers, we paired surveys of natural epidemics with experiments manipulating spatial variation in host susceptibility to infection. We mapped epidemics of the wind-dispersed powdery mildew pathogen Podosphaera plantaginis in five populations of its plant host, Plantago lanceolata. At 15 replicate sites within each population, we deployed groups of healthy potted 'sentinel' plants from five allopatric host lines. By tracking which sentinels became infected in the field and measuring pathogen connectivity and microclimate at those sites, we could test how variation in these factors affected disease when spatial variation in host resistance and soil conditions was minimized. We found that the prevalence and severity of sentinel infection varied over small spatial scales in the field populations, largely due to heterogeneity in pathogen prevalence on wild plants and unmeasured environmental factors. Microclimate was critical for disease spread only at the onset of epidemics, where humidity increased infection risk. Sentinels were more likely to become infected than initially healthy wild plants at a given field site. However, in a follow-up laboratory inoculation study we detected no significant differences between wild and sentinel plant lines in their qualitative susceptibility to pathogen isolates from the field populations, suggesting that primarily non-genetic differences between sentinel and wild hosts drove their differential infection rates in the field. Our study leverages a multi-faceted experimental approach to disentangle important biotic and abiotic drivers of disease patterns within wild populations.
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Affiliation(s)
- Rachel M Penczykowski
- Research Centre for Ecological Change, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
| | - Steven R Parratt
- Research Centre for Ecological Change, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
| | - Benoit Barrès
- Research Centre for Ecological Change, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
| | - Suvi K Sallinen
- Research Centre for Ecological Change, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
| | - Anna-Liisa Laine
- Research Centre for Ecological Change, University of Helsinki, PO Box 65 (Viikinkaari 1), FI-00014, Helsinki, Finland
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22
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Shocket MS, Vergara D, Sickbert AJ, Walsman JM, Strauss AT, Hite JL, Duffy MA, Cáceres CE, Hall SR. Parasite rearing and infection temperatures jointly influence disease transmission and shape seasonality of epidemics. Ecology 2018; 99:1975-1987. [PMID: 29920661 DOI: 10.1002/ecy.2430] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Revised: 04/03/2018] [Accepted: 05/19/2018] [Indexed: 11/07/2022]
Abstract
Seasonal epidemics erupt commonly in nature and are driven by numerous mechanisms. Here, we suggest a new mechanism that could determine the size and timing of seasonal epidemics: rearing environment changes the performance of parasites. This mechanism arises when the environmental conditions in which a parasite is produced impact its performance-independently from the current environment. To illustrate the potential for "rearing effects", we show how temperature influences infection risk (transmission rate) in a Daphnia-fungus disease system through both parasite rearing temperature and infection temperature. During autumnal epidemics, zooplankton hosts contact (eat) fungal parasites (spores) reared in a gradually cooling environment. To delineate the effect of rearing temperature from temperature at exposure and infection, we used lab experiments to parameterize a mechanistic model of transmission rate. We also evaluated the rearing effect using spores collected from epidemics in cooling lakes. We found that fungal spores were more infectious when reared at warmer temperatures (in the lab and in two of three lakes). Additionally, the exposure (foraging) rate of hosts increased with warmer infection temperatures. Thus, both mechanisms cause transmission rate to drop as temperature decreases over the autumnal epidemic season (from summer to winter). Simulations show how these temperature-driven changes in transmission rate can induce waning of epidemics as lakes cool. Furthermore, via thermally dependent transmission, variation in environmental cooling patterns can alter the size and shape of epidemics. Thus, the thermal environment drives seasonal epidemics through effects on hosts (exposure rate) and the infectivity of parasites (a rearing effect). Presently, the generality of parasite rearing effects remains unknown. Our results suggest that they may provide an important but underappreciated mechanism linking temperature to the seasonality of epidemics.
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Affiliation(s)
- Marta S Shocket
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | - Daniela Vergara
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | - Andrew J Sickbert
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | - Jason M Walsman
- Department of Biology, Indiana University, Bloomington, Indiana, 47405, USA
| | | | - Jessica L Hite
- 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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23
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Lievens EJP, Perreau J, Agnew P, Michalakis Y, Lenormand T. Decomposing parasite fitness reveals the basis of specialization in a two-host, two-parasite system. Evol Lett 2018; 2:390-405. [PMID: 30283690 PMCID: PMC6121826 DOI: 10.1002/evl3.65] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2018] [Revised: 06/07/2018] [Accepted: 06/11/2018] [Indexed: 11/29/2022] Open
Abstract
The ecological specialization of parasites–whether they can obtain high fitness on very few or very many different host species–is a determining feature of their ecology. In order to properly assess specialization, it is imperative to measure parasite fitness across host species; to understand its origins, fitness must be decomposed into the underlying traits. Despite the omnipresence of parasites with multiple hosts, very few studies assess and decompose their specialization in this way. To bridge this gap, we quantified the infectivity, virulence, and transmission rate of two parasites, the horizontally transmitted microsporidians Anostracospora rigaudi and Enterocytospora artemiae, in their natural hosts, the brine shrimp Artemia parthenogenetica and Artemia franciscana. Our results demonstrate that each parasite performs well on one of the two host species (A. rigaudi on A. parthenogenetica, and E. artemiae on A. franciscana), and poorly on the other. This partial specialization is driven by high infectivity and transmission rates in the preferred host, and is associated with maladaptive virulence and large costs of resistance in the other. Our study represents a rare empirical contribution to the study of parasite evolution in multihost systems, highlighting the negative effects of under‐ and overexploitation when adapting to multiple hosts.
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Affiliation(s)
- Eva J P Lievens
- UMR 5175 CEFE CNRS-Université de Montpellier-Université P. Valéry-EPHE 34293 Montpellier Cedex 5 France.,UMR 5290 MIVEGEC CNRS-IRD-Université de Montpellier 34394 Montpellier Cedex 5 France
| | - Julie Perreau
- UMR 5175 CEFE CNRS-Université de Montpellier-Université P. Valéry-EPHE 34293 Montpellier Cedex 5 France
| | - Philip Agnew
- UMR 5290 MIVEGEC CNRS-IRD-Université de Montpellier 34394 Montpellier Cedex 5 France
| | - Yannis Michalakis
- UMR 5290 MIVEGEC CNRS-IRD-Université de Montpellier 34394 Montpellier Cedex 5 France
| | - Thomas Lenormand
- UMR 5175 CEFE CNRS-Université de Montpellier-Université P. Valéry-EPHE 34293 Montpellier Cedex 5 France
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24
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Gibson AK, Stoy KS, Lively CM. Bloody-minded parasites and sex: the effects of fluctuating virulence. J Evol Biol 2018; 31:611-620. [PMID: 29460507 PMCID: PMC5882519 DOI: 10.1111/jeb.13252] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Revised: 02/12/2018] [Accepted: 02/14/2018] [Indexed: 12/18/2022]
Abstract
Asexual lineages can grow at a faster rate than sexual lineages. Why then is sexual reproduction so widespread? Much empirical evidence supports the Red Queen hypothesis. Under this hypothesis, coevolving parasites favour sexual reproduction by adapting to infect common asexual clones and driving them down in frequency. One limitation, however, seems to challenge the generality of the Red Queen: in theoretical models, parasites must be very virulent to maintain sex. Moreover, experiments show virulence to be unstable, readily shifting in response to environmental conditions. Does variation in virulence further limit the ability of coevolving parasites to maintain sex? To address this question, we simulated temporal variation in virulence and evaluated the outcome of competition between sexual and asexual females. We found that variation in virulence did not limit the ability of coevolving parasites to maintain sex. In fact, relatively high variation in virulence promoted parasite-mediated maintenance of sex. With sufficient variation, sexual females persisted even when mean virulence fell well below the threshold virulence required to maintain sex under constant conditions. We conclude that natural variation in virulence does not limit the relevance of the Red Queen hypothesis for natural populations; on the contrary, it could expand the range of conditions over which coevolving parasites can maintain sex.
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Affiliation(s)
- Amanda K Gibson
- Department of Biology, Indiana University, Bloomington, IN, USA
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Kayla S Stoy
- Department of Biology, Emory University, Atlanta, GA, USA
| | - Curtis M Lively
- Department of Biology, Indiana University, Bloomington, IN, USA
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25
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Fitness and eco-physiological response of a chytrid fungal parasite infecting planktonic cyanobacteria to thermal and host genotype variation. Parasitology 2018; 145:1279-1286. [DOI: 10.1017/s0031182018000215] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
AbstractUnderstanding how individual parasite traits contribute to overall fitness, and how they are modulated by both external and host environment, is crucial for predicting disease outcome. Fungal (chytrid) parasites of phytoplankton are important yet poorly studied pathogens with the potential to modulate the abundance and composition of phytoplankton communities and to drive their evolution. Here, we studied life-history traits of a chytrid parasite infecting the planktonic, bloom-forming cyanobacterium Planktothrix spp. under host genotype and thermal variation. When expressing parasite fitness in terms of transmission success, disease outcome was largely modulated by temperature alone. Yet, a closer examination of individual parasite traits linked to different infection phases, such as (i) the establishment of the infection (i.e. intensity of infection) and (ii) the exploitation of host resources (i.e. size of reproductive structures and propagules), revealed differential host genotype and temperature × host genotype modulation, respectively. This illustrates how parasite fitness results from the interplay of individual parasite traits that are differentially controlled by host and external environment, and stresses the importance of combining multiple traits to gain insights into underlying infection mechanisms.
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26
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Shocket MS, Strauss AT, Hite JL, Šljivar M, Civitello DJ, Duffy MA, Cáceres CE, Hall SR. Temperature Drives Epidemics in a Zooplankton-Fungus Disease System: A Trait-Driven Approach Points to Transmission via Host Foraging. Am Nat 2018; 191:435-451. [PMID: 29570399 DOI: 10.1086/696096] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Climatic warming will likely have idiosyncratic impacts on infectious diseases, causing some to increase while others decrease or shift geographically. A mechanistic framework could better predict these different temperature-disease outcomes. However, such a framework remains challenging to develop, due to the nonlinear and (sometimes) opposing thermal responses of different host and parasite traits and due to the difficulty of validating model predictions with observations and experiments. We address these challenges in a zooplankton-fungus (Daphnia dentifera-Metschnikowia bicuspidata) system. We test the hypothesis that warmer temperatures promote disease spread and produce larger epidemics. In lakes, epidemics that start earlier and warmer in autumn grow much larger. In a mesocosm experiment, warmer temperatures produced larger epidemics. A mechanistic model parameterized with trait assays revealed that this pattern arose primarily from the temperature dependence of transmission rate (β), governed by the increasing foraging (and, hence, parasite exposure) rate of hosts (f). In the trait assays, parasite production seemed sufficiently responsive to shape epidemics as well; however, this trait proved too thermally insensitive in the mesocosm experiment and lake survey to matter much. Thus, in warmer environments, increased foraging of hosts raised transmission rate, yielding bigger epidemics through a potentially general, exposure-based mechanism for ectotherms. This mechanistic approach highlights how a trait-based framework will enhance predictive insight into responses of infectious disease to a warmer world.
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27
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Gipson SAY, Hall MD. Interactions between host sex and age of exposure modify the virulence-transmission trade-off. J Evol Biol 2018; 31:428-437. [DOI: 10.1111/jeb.13237] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2017] [Accepted: 12/17/2017] [Indexed: 01/04/2023]
Affiliation(s)
- S. A. Y. Gipson
- School of Biological Sciences and Centre for Geometric Biology; Monash University; Melbourne Vic. Australia
| | - M. D. Hall
- School of Biological Sciences and Centre for Geometric Biology; Monash University; Melbourne Vic. Australia
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28
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Auld SKJR, Brand J. Simulated climate change, epidemic size, and host evolution across host-parasite populations. GLOBAL CHANGE BIOLOGY 2017; 23:5045-5053. [PMID: 28544153 DOI: 10.1111/gcb.13769] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Accepted: 05/15/2017] [Indexed: 06/07/2023]
Abstract
Climate change is causing warmer and more variable temperatures as well as physical flux in natural populations, which will affect the ecology and evolution of infectious disease epidemics. Using replicate seminatural populations of a coevolving freshwater invertebrate-parasite system (host: Daphnia magna, parasite: Pasteuria ramosa), we quantified the effects of ambient temperature and population mixing (physical flux within populations) on epidemic size and population health. Each population was seeded with an identical suite of host genotypes and dose of parasite transmission spores. Biologically reasonable increases in environmental temperature caused larger epidemics, and population mixing reduced overall epidemic size. Mixing also had a detrimental effect on host populations independent of disease. Epidemics drove parasite-mediated selection, leading to a loss of host genetic diversity, and mixed populations experienced greater evolution due to genetic drift over the season. These findings further our understanding of how diversity loss will reduce the host populations' capacity to respond to changes in selection, therefore stymying adaptation to further environmental change.
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Affiliation(s)
- Stuart K J R Auld
- Biological & Environmental Sciences, University of Stirling, Stirling, UK
| | - June Brand
- Biological & Environmental Sciences, University of Stirling, Stirling, UK
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29
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Temperature modulates the interaction between fungicide pollution and disease: evidence from a Daphnia-microparasitic yeast model. Parasitology 2017; 145:939-947. [PMID: 29160185 DOI: 10.1017/s0031182017002062] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Temperature is expected to modulate the responses of organisms to stress. Here, we aimed to assess the influence of temperature on the interaction between parasitism and fungicide contamination. Specifically, using the cladoceran Daphnia as a model system, we explored the isolated and interactive effects of parasite challenge (yeast Metschnikowia bicuspidata) and exposure to fungicides (copper sulphate and tebuconazole) at two temperatures (17 and 20 °C), in a fully factorial design. Confirming a previous study, M. bicuspidata infection and copper exposure caused independent effects on Daphnia life history, whereas infection was permanently suppressed with tebuconazole exposure. Here, we show that higher temperature generally increased the virulence of the parasite, with the hosts developing signs of infection earlier, reproducing less and dying at an earlier age. These effects were consistent across copper concentrations, whereas the joint effects of temperature (which enhanced the difference between non-infected and infected hosts) and the anti-parasitic action of tebuconazole resulted in a more pronounced parasite × tebuconazole interaction at the higher temperature. Thus, besides independently influencing parasite and contaminant effects, the temperature can act as a modulator of interactions between pollution and disease.
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30
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Abstract
Molecular and cellular studies reveal that the resistance of hosts to parasites and pathogens is a cascade-like process with multiple steps required to be passed for successful infection. By contrast, much of evolutionary reasoning is based on strongly simplified, one- or two-step infection processes with simple genetics or on resistance being a quantitative trait. Here we attempt a conceptual unification of these two perspectives with the aim of cross-fostering research and filling some of the gaps in our concepts of the ecology and evolution of disease. This conceptual unification has a profound impact on the way we understand the genetics and evolution of host resistance, ecological immunity, evolution of virulence, defence portfolios, and host-pathogen coevolution.
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Affiliation(s)
- Matthew D Hall
- School of Biological Sciences, Monash University, Melbourne, VIC 3800, Australia
| | - Gilberto Bento
- Zoological Institute, University of Basel, Basel 4051, Switzerland
| | - Dieter Ebert
- Zoological Institute, University of Basel, Basel 4051, Switzerland; Wissenschaftskolleg zu Berlin, Wallotstrasse 19, 14193 Berlin, Germany.
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31
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Pintar MR, Resetarits WJ. Persistence of an egg mass polymorphism in Ambystoma maculatum: differential performance under high and low nutrients. Ecology 2017; 98:1349-1360. [PMID: 28247910 DOI: 10.1002/ecy.1789] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 01/14/2017] [Accepted: 02/16/2017] [Indexed: 11/09/2022]
Abstract
Polymorphisms play critical roles in allowing organisms to adapt to novel environments while enabling ecological speciation under divergent selection. Ambystoma maculatum, the spotted salamander, exhibits a unique polymorphism in the structure and appearance of its egg masses with two common morphs, white and clear. Amphibian egg jelly layers mediate interactions between embryos and the environment and are more responsive to ecological pressures of natural selection than other egg coat components. The A. maculatum egg mass polymorphism was hypothesized to be adaptive with regard to varying dissolved nutrient levels in ponds. We conducted two mesocosm experiments, collected field data, and constructed a population projection model to determine how dissolved nutrient levels affect embryonic and larval development and relate to the distribution of the morphs in natural ponds. We found that upon hatching there was an interaction between nutrient level and egg mass morph wherein individuals from white morphs were larger in low nutrient habitats. This interaction persisted throughout the larval stage, and along with the higher abundance of white morphs in ponds with low conductivity, we demonstrate that the white morph is advantageous in low nutrient environments. Our findings provide evidence for the role of environmental heterogeneity in enabling the persistence of a structural egg mass polymorphism, with maintenance occurring across multiple scales and persistence across its range. This indicates that polymorphisms can maximize performance in heterogeneous environments, while persisting over long timescales without leading to sympatric speciation.
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Affiliation(s)
- Matthew R Pintar
- Department of Biology, University of Mississippi, University, Mississippi, 38677, USA
| | - William J Resetarits
- Department of Biology, University of Mississippi, University, Mississippi, 38677, USA
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32
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Shragai T, Tesla B, Murdock C, Harrington LC. Zika and chikungunya: mosquito-borne viruses in a changing world. Ann N Y Acad Sci 2017; 1399:61-77. [PMID: 28187236 DOI: 10.1111/nyas.13306] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2016] [Revised: 11/21/2016] [Accepted: 12/02/2016] [Indexed: 12/16/2022]
Abstract
The reemergence and growing burden of mosquito-borne virus infections have incited public fear and growing research efforts to understand the mechanisms of infection-associated health outcomes and to provide better approaches for mosquito vector control. While efforts to develop therapeutics, vaccines, and novel genetic mosquito-control technologies are underway, many important underlying ecological questions remain that could significantly enhance our understanding and ability to predict and prevent transmission. Here, we review the current knowledge about the transmission ecology of two recent arbovirus invaders, the chikungunya and Zika viruses. We introduce the viruses and mosquito vectors, highlighting viral biology, historical routes of transmission, and viral mechanisms facilitating rapid global invasion. In addition, we review factors contributing to vector global invasiveness and transmission efficiency. We conclude with a discussion of how human-induced biotic and abiotic environmental changes facilitate mosquito-borne virus transmission, emphasizing critical gaps in understanding. These knowledge gaps are tremendous; much of our data on basic mosquito ecology in the field predate 1960, and the mosquitoes themselves, as well as the world they live in, have substantially changed. A concerted investment in understanding the basic ecology of these vectors, which serve as the main drivers of pathogen transmission in both wildlife and human populations, is now more important than ever.
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Affiliation(s)
- Talya Shragai
- Department of Entomology, Cornell University, Ithaca, New York
| | - Blanka Tesla
- Department of Infectious Diseases and Odum School of Ecology, University of Georgia, Athens, Georgia
| | - Courtney Murdock
- Department of Infectious Diseases and Odum School of Ecology, University of Georgia, Athens, Georgia
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Klemme I, Karvonen A. Vertebrate defense against parasites: Interactions between avoidance, resistance, and tolerance. Ecol Evol 2016; 7:561-571. [PMID: 28116053 PMCID: PMC5243791 DOI: 10.1002/ece3.2645] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 11/08/2016] [Accepted: 11/13/2016] [Indexed: 12/03/2022] Open
Abstract
Hosts can utilize different types of defense against the effects of parasitism, including avoidance, resistance, and tolerance. Typically, there is tremendous heterogeneity among hosts in these defense mechanisms that may be rooted in the costs associated with defense and lead to trade‐offs with other life‐history traits. Trade‐offs may also exist between the defense mechanisms, but the relationships between avoidance, resistance, and tolerance have rarely been studied. Here, we assessed these three defense traits under common garden conditions in a natural host–parasite system, the trematode eye‐fluke Diplostomum pseudospathaceum and its second intermediate fish host. We looked at host individuals originating from four genetically distinct populations of two closely related salmonid species (Atlantic salmon, Salmo salar and sea trout, Salmo trutta trutta) to estimate the magnitude of variation in these defense traits and the relationships among them. We show species‐specific variation in resistance and tolerance and population‐specific variation in resistance. Further, we demonstrate evidence for a trade‐off between resistance and tolerance. Our results suggest that the variation in host defense can at least partly result from a compromise between different interacting defense traits, the relative importance of which is likely to be shaped by environmental components. Overall, this study emphasizes the importance of considering different components of the host defense system when making predictions on the outcome of host–parasite interactions.
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Affiliation(s)
- Ines Klemme
- Department of Biological and Environmental Science University of Jyvaskyla Jyvaskyla Finland
| | - Anssi Karvonen
- Department of Biological and Environmental Science University of Jyvaskyla Jyvaskyla Finland
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Michel J, Ebert D, Hall MD. The trans-generational impact of population density signals on host-parasite interactions. BMC Evol Biol 2016; 16:254. [PMID: 27887563 PMCID: PMC5123254 DOI: 10.1186/s12862-016-0828-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2016] [Accepted: 11/16/2016] [Indexed: 11/20/2022] Open
Abstract
Background The density of a host population is a key parameter underlying disease transmission, but it also has implications for the expression of disease through its effect on host physiology. In response to higher densities, individuals are predicted to either increase their immune investment in response to the elevated risk of parasitism, or conversely to decrease their immune capacity as a consequence of the stress of a crowded environment. However, an individual’s health is shaped by many different factors, including their genetic background, current environmental conditions, and maternal effects. Indeed, population density is often sensed through the presence of info-chemicals in the environment, which may influence a host’s interaction with parasites, and also those of its offspring. All of which may alter the expression of disease, and potentially uncouple the presumed link between changes in host density and disease outcomes. Results In this study, we used the water flea Daphnia magna and its obligate bacterial parasite Pasteuria ramosa, to investigate how signals of high host density impact on host-parasite interactions over two consecutive generations. We found that the chemical signals from crowded treatments induced phenotypic changes in both the parental and offspring generations. In the absence of a pathogen, life-history changes were genotype-specific, but consistent across generations, even when the signal of density was removed. In contrast, the influence of density on infected animals depended on the trait and generation of exposure. When directly exposed to signals of high-density, host genotypes responded differently in how they minimised the severity of disease. Yet, in the subsequent generation, the influence of density was rarely genotype-specific and instead related to ability of the host to minimise the onset of infection. Conclusion Our findings reveal that population level correlations between host density and infection capture only part of the complex relationship between crowding and the severity of disease. We suggest that besides its role in horizontal transmission, signals of density can influence parasite epidemiology by modifying mechanisms of resistance across multiple generations, and elevating variability via genotype-by-environment interactions. Our results help resolve why some studies are able to find a positive correlation between high density and resistance, while others uncover a negative correlation, or even no direct relationship at all. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0828-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Jessica Michel
- University of Basel, Zoological Institute, Vesalgasse 1, 4051, Basel, Switzerland
| | - Dieter Ebert
- University of Basel, Zoological Institute, Vesalgasse 1, 4051, Basel, Switzerland
| | - Matthew D Hall
- School of Biological Sciences, Monash University, Melbourne, VIC, 3800, Australia.
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Mazé-Guilmo E, Blanchet S, Rey O, Canto N, Loot G. Local adaptation drives thermal tolerance among parasite populations: a common garden experiment. Proc Biol Sci 2016; 283:20160587. [PMID: 27170717 PMCID: PMC4874721 DOI: 10.1098/rspb.2016.0587] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2016] [Accepted: 04/18/2016] [Indexed: 01/07/2023] Open
Abstract
Understanding the evolutionary responses of organisms to thermal regimes is of prime importance to better predict their ability to cope with ongoing climate change. Although this question has attracted interest in free-living organisms, whether or not infectious diseases have evolved heterogeneous responses to climate is still an open question. Here, we ran a common garden experiment using the fish ectoparasite Tracheliastes polycolpus, (i) to test whether parasites living in thermally heterogeneous rivers respond differently to an experimental thermal gradient and (ii) to determine the evolutionary processes (natural selection or genetic drift) underlying these responses. We demonstrated that the reaction norms involving the survival rate of the parasite larvae (i.e. the infective stage) across a temperature gradient significantly varied among six parasite populations. Using a Qst/Fst approach and phenotype-environment associations, we further showed that the evolution of survival rate partly depended upon temperature regimes experienced in situ, and was mostly underlined by diversifying selection, but also-to some extent-by stabilizing selection and genetic drift. This evolutionary response led to population divergences in thermal tolerance across the landscape, which has implications for predicting the effects of future climate change.
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Affiliation(s)
- Elise Mazé-Guilmo
- Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France
| | - Simon Blanchet
- Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France CNRS, UPS, École Nationale de Formation Agronomique (ENFA); UMR5174 EDB (Laboratoire Évolution and Diversité Biologique), 118 route de Narbonne, Toulouse cedex 4 31062, France
| | - Olivier Rey
- Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France Department of Biosciences, College of Science, University of Swansea, Swansea SA2 8PP, UK
| | - Nicolas Canto
- Centre National de la Recherche Scientifique (CNRS), Université Paul Sabatier (UPS), Station d'Ecologie Théorique et Expérimentale, UMR 5321, Moulis 09200, France
| | - Géraldine Loot
- CNRS, UPS, École Nationale de Formation Agronomique (ENFA); UMR5174 EDB (Laboratoire Évolution and Diversité Biologique), 118 route de Narbonne, Toulouse cedex 4 31062, France Université de Toulouse, UPS, UMR 5174 (EDB), 118 route de Narbonne, Toulouse cedex 4 31062, France
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36
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Gipson SAY, Hall MD. The evolution of sexual dimorphism and its potential impact on host-pathogen coevolution. Evolution 2016; 70:959-68. [DOI: 10.1111/evo.12922] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 03/14/2016] [Accepted: 04/06/2016] [Indexed: 12/25/2022]
Affiliation(s)
- Stephen A. Y. Gipson
- School of Biological Sciences; Monash University; Melbourne Victoria 3800 Australia
| | - Matthew D. Hall
- School of Biological Sciences; Monash University; Melbourne Victoria 3800 Australia
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37
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Brunner FS, Eizaguirre C. Can environmental change affect host/parasite-mediated speciation? ZOOLOGY 2016; 119:384-94. [PMID: 27210289 DOI: 10.1016/j.zool.2016.04.001] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/16/2016] [Accepted: 04/13/2016] [Indexed: 12/21/2022]
Abstract
Parasitism can be a driver of species divergence and thereby significantly alter species formation processes. While we still need to better understand how parasite-mediated speciation functions, it is even less clear how this process is affected by environmental change. Both rapid and gradual changes of the environment can modify host immune responses, parasite virulence and the specificity of their interactions. They will thereby change host-parasite evolutionary trajectories and the potential for speciation in both hosts and parasites. Here, we summarise mechanisms of host-parasite interactions affecting speciation and subsequently consider their susceptibility to environmental changes. We mainly focus on the effects of temperature change and nutrient input to ecosystems as they are major environmental stressors. There is evidence for both disruptive and accelerating effects of those pressures on speciation that seem to be context-dependent. A prerequisite for parasite-driven host speciation is that parasites significantly alter the host's Darwinian fitness. This can rapidly lead to divergent selection and genetic adaptation; however, it is likely preceded by more short-term plastic and transgenerational effects. Here, we also consider how these first responses and their susceptibility to environmental changes could lead to alterations of the species formation process and may provide alternative pathways to speciation.
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Affiliation(s)
- Franziska S Brunner
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom.
| | - Christophe Eizaguirre
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, United Kingdom
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38
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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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39
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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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40
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Hesse E, Best A, Boots M, Hall AR, Buckling A. Spatial heterogeneity lowers rather than increases host-parasite specialization. J Evol Biol 2015; 28:1682-90. [PMID: 26135011 PMCID: PMC4973826 DOI: 10.1111/jeb.12689] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2015] [Revised: 06/19/2015] [Accepted: 06/24/2015] [Indexed: 11/26/2022]
Abstract
Abiotic environmental heterogeneity can promote the evolution of diverse resource specialists, which in turn may increase the degree of host-parasite specialization. We coevolved Pseudomonas fluorescens and lytic phage ϕ2 in spatially structured populations, each consisting of two interconnected subpopulations evolving in the same or different nutrient media (homogeneous and heterogeneous environments, respectively). Counter to the normal expectation, host-parasite specialization was significantly lower in heterogeneous compared with homogeneous environments. This result could not be explained by dispersal homogenizing populations, as this would have resulted in the heterogeneous treatments having levels of specialization equal to or greater than that of the homogeneous environments. We argue that selection for costly generalists is greatest when the coevolving species are exposed to diverse environmental conditions and that this can provide an explanation for our results. A simple coevolutionary model of this process suggests that this can be a general mechanism by which environmental heterogeneity can reduce rather than increase host-parasite specialization.
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Affiliation(s)
- E Hesse
- ESI, Biosciences, University of Exeter, Penryn, UK
| | - A Best
- School of Mathematics and Statistics, University of Sheffield, Sheffield, UK
| | - M Boots
- CLES, Biosciences, University of Exeter, Penryn, UK
| | | | - A Buckling
- ESI, Biosciences, University of Exeter, Penryn, UK
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41
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Laine AL, Burdon JJ, Nemri A, Thrall PH. Host ecotype generates evolutionary and epidemiological divergence across a pathogen metapopulation. Proc Biol Sci 2015; 281:rspb.2014.0522. [PMID: 24870042 DOI: 10.1098/rspb.2014.0522] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The extent and speed at which pathogens adapt to host resistance varies considerably. This presents a challenge for predicting when--and where--pathogen evolution may occur. While gene flow and spatially heterogeneous environments are recognized to be critical for the evolutionary potential of pathogen populations, we lack an understanding of how the two jointly shape coevolutionary trajectories between hosts and pathogens. The rust pathogen Melampsora lini infects two ecotypes of its host plant Linum marginale that occur in close proximity yet in distinct populations and habitats. In this study, we found that within-population epidemics were different between the two habitats. We then tested for pathogen local adaptation at host population and ecotype level in a reciprocal inoculation study. Even after controlling for the effect of spatial structure on infection outcome, we found strong evidence of pathogen adaptation at the host ecotype level. Moreover, sequence analysis of two pathogen infectivity loci revealed strong genetic differentiation by host ecotype but not by distance. Hence, environmental variation can be a key determinant of pathogen population genetic structure and coevolutionary dynamics and can generate strong asymmetry in infection risks through space.
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Affiliation(s)
- Anna-Liisa Laine
- Metapopulation Research Group, Department of Biosciences, University of Helsinki, PO Box 65, Helsinki 00014, Finland
| | - Jeremy J Burdon
- CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia
| | - Adnane Nemri
- CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia
| | - Peter H Thrall
- CSIRO Plant Industry, GPO Box 1600, Canberra, Australian Capital Territory 2601, Australia
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42
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Culumber ZW, Schumer M, Monks S, Tobler M. Environmental heterogeneity generates opposite gene-by-environment interactions for two fitness-related traits within a population. Evolution 2015; 69:541-50. [PMID: 25496554 DOI: 10.1111/evo.12574] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/27/2014] [Indexed: 12/17/2022]
Abstract
Theory predicts that environmental heterogeneity offers a potential solution to the maintenance of genetic variation within populations, but empirical evidence remains sparse. The live-bearing fish Xiphophorus variatus exhibits polymorphism at a single locus, with different alleles resulting in up to five distinct melanistic "tailspot" patterns within populations. We investigated the effects of heterogeneity in two ubiquitous environmental variables (temperature and food availability) on two fitness-related traits (upper thermal limits and body condition) in two different tailspot types (wild-type and upper cut crescent). We found gene-by-environment (G × E) interactions between tailspot type and food level affecting upper thermal limits (UTL), as well as between tailspot type and thermal environment affecting body condition. Exploring mechanistic bases underlying these G × E patterns, we found no differences between tailspot types in hsp70 gene expression despite significant overall increases in expression under both thermal and food stress. Similarly, there was no difference in routine metabolic rates between the tailspot types. The reversal of relative performance of the two tailspot types under different environmental conditions revealed a mechanism by which environmental heterogeneity can balance polymorphism within populations through selection on different fitness-related traits.
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Affiliation(s)
- Zachary W Culumber
- Centro de Investigaciones Cientificas de las Huastecas "Aguazarca", 392 Colonia Aguazarca, Calnali, Hidalgo, 43230, Mexico; Division of Biology, Kansas State University, Manhattan, Kansas, 66506.
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43
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Murdock CC, Blanford S, Luckhart S, Thomas MB. Ambient temperature and dietary supplementation interact to shape mosquito vector competence for malaria. JOURNAL OF INSECT PHYSIOLOGY 2014; 67:37-44. [PMID: 24911425 PMCID: PMC4107084 DOI: 10.1016/j.jinsphys.2014.05.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/06/2014] [Revised: 05/22/2014] [Accepted: 05/24/2014] [Indexed: 05/23/2023]
Abstract
The extent to which environmental factors influence the ability of Anopheles mosquitoes to transmit malaria parasites remains poorly explored. Environmental variation, such as change in ambient temperature, will not necessarily influence the rates of host and parasite processes equivalently, potentially resulting in complex effects on infection outcomes. As proof of principle, we used Anopheles stephensi and the rodent malaria parasite, Plasmodium yoelii, to examine the effects of a range of constant temperatures on one aspect of host defense (detected as alterations in expression of nitric oxide synthase gene - NOS) to parasite infection. We experimentally boosted mosquito midgut immunity to infection through dietary supplementation with the essential amino acid l-Arginine (l-Arg), which increases midgut nitric oxide (NO) levels by infection-induced NOS catalysis in A. stephensi. At intermediate temperatures, supplementation reduced oocyst prevalence, oocyst intensity, and sporozoite prevalence suggesting that the outcome of parasite infection was potentially dependent upon the rate of NOS-mediated midgut immunity. At low and high temperature extremes, however, infection was severely constrained irrespective of supplementation. The effects of l-Arg appeared to be mediated by NO-dependent negative feedback on NOS expression, as evidenced by depressed NOS expression in l-Arg treated groups at temperatures where supplementation decreased parasite infection. These results suggest the need to consider the direct (e.g. effects of mosquito body temperature on parasite physiology) and indirect effects (e.g. mediated through changes in mosquito physiology/immunity) of environmental factors on mosquito-malaria interactions in order to understand natural variation in vector competence.
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Affiliation(s)
- Courtney C Murdock
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, Merkle Lab, Orchard Road, University Park, PA 16802, United States.
| | - Simon Blanford
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, Merkle Lab, Orchard Road, University Park, PA 16802, United States.
| | - Shirley Luckhart
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA 95616, United States.
| | - Matthew B Thomas
- Center for Infectious Disease Dynamics, Department of Entomology, Pennsylvania State University, Merkle Lab, Orchard Road, University Park, PA 16802, United States.
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44
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Garbutt JS, Scholefield JA, Vale PF, Little TJ. Elevated maternal temperature enhances offspring disease resistance inDaphnia magna. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12197] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jennie S. Garbutt
- Institute of Evolutionary Biology; University of Edinburgh; Kings Buildings, Ashworth Laboratories, West Mains Road Edinburgh EH9 3JT UK
| | - Jennifer A. Scholefield
- Institute of Evolutionary Biology; University of Edinburgh; Kings Buildings, Ashworth Laboratories, West Mains Road Edinburgh EH9 3JT UK
| | - Pedro F. Vale
- Centre for Immunity, Infection and Evolution; Institute of Evolutionary Biology; School of Biological Sciences; University of Edinburgh; Ashworth Laboratories, West Mains Road Edinburgh EH9 3JT UK
| | - Tom J. Little
- Institute of Evolutionary Biology; University of Edinburgh; Kings Buildings, Ashworth Laboratories, West Mains Road Edinburgh EH9 3JT UK
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45
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Vale PF. Killing them softly: managing pathogen polymorphism and virulence in spatially variable environments. Trends Parasitol 2013; 29:417-22. [PMID: 23928098 PMCID: PMC3764335 DOI: 10.1016/j.pt.2013.07.002] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 07/04/2013] [Accepted: 07/05/2013] [Indexed: 11/30/2022]
Abstract
Understanding why pathogen populations are genetically variable is vital because genetic variation fuels evolution, which often hampers disease control efforts. Here I argue that classical models of evolution in spatially variable environments - specifically, models of hard and soft selection - provide a useful framework to understand the maintenance of pathogen polymorphism and the evolution of virulence. First, the similarities between models of hard and soft selection and pathogen life cycles are described, highlighting how the type and timing of pathogen control measures impose density regulation that may affect both the level of pathogen polymorphism and virulence. The article concludes with an outline of potential lines of future theoretical and experimental work.
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Affiliation(s)
- Pedro F Vale
- Centre for Immunity, Infection, and Evolution and Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Ashworth Laboratories, West Mains Road, Edinburgh EH9 3JT, UK.
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46
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Harrison E, Laine AL, Hietala M, Brockhurst MA. Rapidly fluctuating environments constrain coevolutionary arms races by impeding selective sweeps. Proc Biol Sci 2013; 280:20130937. [PMID: 23760864 PMCID: PMC3712419 DOI: 10.1098/rspb.2013.0937] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Although pervasive, the impact of temporal environmental heterogeneity on coevolutionary processes is poorly understood. Productivity is a key temporally heterogeneous variable, and increasing productivity has been shown to increase rates of antagonistic arms race coevolution, and lead to the evolution of more broadly resistant hosts and more broadly infectious parasites. We investigated the effects of the grain of environmental heterogeneity, in terms of fluctuations in productivity, on bacteria–phage coevolution. Our findings demonstrate that environmental heterogeneity could constrain antagonistic coevolution, but that its effect was dependent upon the grain of heterogeneity, such that both the rate and extent of coevolution were most strongly limited in fine-grained, rapidly fluctuating heterogeneous environments. We further demonstrate that rapid environmental fluctuations were likely to have impeded selective sweeps of resistance alleles, which occurred over longer durations than the fastest, but not the slowest, frequency of fluctuations used. Taken together our results suggest that fine-grained environmental heterogeneity constrained the coevolutionary arms race by impeding selective sweeps.
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Affiliation(s)
- Ellie Harrison
- Department of Biology, University of York, York YO10 5DD, UK
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47
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Hall MD, Vettiger A, Ebert D. Interactions between environmental stressors: the influence of salinity on host-parasite interactions between Daphnia magna and Pasteuria ramosa. Oecologia 2012; 171:789-96. [PMID: 23001624 DOI: 10.1007/s00442-012-2452-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2012] [Accepted: 08/24/2012] [Indexed: 11/26/2022]
Abstract
Interactions between environmental stressors play an important role in shaping the health of an organism. This is particularly true in terms of the prevalence and severity of infectious disease, as stressors in combination will not always act to simply decrease the immune function of a host, but may instead interact to compound or even oppose the influence of parasitism on the health of an organism. Here, we explore the impact of environmental stress on host-parasite interactions using the water flea Daphnia magna and it is obligate parasite Pasteuria ramosa. Utilising an ecologically relevant stressor, we focus on the combined effect of salinity and P. ramosa on the fecundity and survival of the host, as well as on patterns of infectivity and the proliferation of the parasite. We show that in the absence of the parasite, host fecundity and survival was highest in the low salinity treatments. Once a parasite was introduced into the environment, however, salinity and parasitism acted antagonistically to influence both host survival and fecundity, and these patterns of disease were unrelated to infection rates or parasite spore loads. By summarising the form of interactions found in the broader Daphnia literature, we highlight how the combined effect of stress and parasitism will vary with the type of stressor, the trait used to describe the health of Daphnia and the host-parasite combination under observation. Our results highlight how the context-dependent nature of interactions between stress and parasitism inevitably complicates the link between environmental factors and the prevalence and severity of disease.
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Affiliation(s)
- Matthew D Hall
- Zoologisches Institut, Evolutionsbiologie, University of Basel, Basel, Switzerland.
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Rocha FB, Klaczko LB. CONNECTING THE DOTS OF NONLINEAR REACTION NORMS UNRAVELS THE THREADS OF GENOTYPE-ENVIRONMENT INTERACTION INDROSOPHILA. Evolution 2012; 66:3404-16. [DOI: 10.1111/j.1558-5646.2012.01702.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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49
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Hall MD, Ebert D. Disentangling the influence of parasite genotype, host genotype and maternal environment on different stages of bacterial infection in Daphnia magna. Proc Biol Sci 2012; 279:3176-83. [PMID: 22593109 DOI: 10.1098/rspb.2012.0509] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Individuals naturally vary in the severity of infectious disease when exposed to a parasite. Dissecting this variation into genetic and environmental components can reveal whether or not this variation depends on the host genotype, parasite genotype or a range of environmental conditions. Complicating this task, however, is that the symptoms of disease result from the combined effect of a series of events, from the initial encounter between a host and parasite, through to the activation of the host immune system and the exploitation of host resources. Here, we use the crustacean Daphnia magna and its parasite Pasteuria ramosa to show how disentangling genetic and environmental factors at different stages of infection improves our understanding of the processes shaping infectious disease. Using compatible host-parasite combinations, we experimentally exclude variation in the ability of a parasite to penetrate the host, from measures of parasite clearance, the reduction in host fecundity and the proliferation of the parasite. We show how parasite resistance consists of two components that vary in environmental sensitivity, how the maternal environment influences all measured aspects of the within-host infection process and how host-parasite interactions following the penetration of the parasite into the host have a distinct temporal component.
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Affiliation(s)
- Matthew D Hall
- Zoologisches Institut, Evolutionsbiologie, University of Basel, Basel 4051, Switzerland.
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50
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Cisarovsky G, Schmid-Hempel P, Sadd BM. Robustness of the outcome of adult bumblebee infection with a trypanosome parasite after varied parasite exposures during larval development. J Evol Biol 2012; 25:1053-9. [PMID: 22487556 DOI: 10.1111/j.1420-9101.2012.02507.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The outcome of defence by the invertebrate immunity has recently been shown to be more complex than previously thought. In particular, the outcome is affected by biotic and abiotic environmental variation, host genotype, parasite genotype and their interaction. Knowledge of conditions under which environmental variation affects the outcome of an infection is one important question that relates to this complexity. We here use the model system of the bumblebee, Bombus terrestris, infected by the trypanosome, Crithidia bombi, combined with a split-colony design to test the influence of the parasite environment during larval rearing on adult resistance. We find that genotype-specific interactions are maintained and adult resistance is not influenced. This demonstrates that environmental dependence of bumblebee-trypanosome interactions is not ubiquitous, and yet unknown constraints will maintain standard coevolutionary dynamics under such environmental deviations.
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Affiliation(s)
- G Cisarovsky
- ETH Zürich, Institute of Integrative Biology, Universitätstrasse 16, Zürich, Switzerland.
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