1
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Zilio G, Deshpande JN, Duncan AB, Fronhofer EA, Kaltz O. Dispersal evolution and eco-evolutionary dynamics in antagonistic species interactions. Trends Ecol Evol 2024; 39:666-676. [PMID: 38637209 DOI: 10.1016/j.tree.2024.03.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2023] [Revised: 03/04/2024] [Accepted: 03/20/2024] [Indexed: 04/20/2024]
Abstract
Dispersal evolution modifies diverse spatial processes, such as range expansions or biological invasions of single species, but we are currently lacking a realistic vision for metacommunities. Focusing on antagonistic species interactions, we review existing theory of dispersal evolution between natural enemies, and explain how this might be relevant for classic themes in host-parasite evolutionary ecology, namely virulence evolution or local adaptation. Specifically, we highlight the importance of considering the simultaneous (co)evolution of dispersal and interaction traits. Linking such multi-trait evolution with reciprocal demographic and epidemiological feedbacks might change basic predictions about coevolutionary processes and spatial dynamics of interacting species. Future challenges concern the integration of system-specific disease ecology or spatial modifiers, such as spatial network structure or environmental heterogeneity.
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Affiliation(s)
- Giacomo Zilio
- Institut des Sciences de l'Evolution - Montpellier (ISEM), University of Montpellier, CNRS, IRD, Montpellier, France; Centre d'Ecologie Fonctionelle et Evolutive (CEFE), University of Montpellier, CNRS, Montpellier, France.
| | - Jhelam N Deshpande
- Institut des Sciences de l'Evolution - Montpellier (ISEM), University of Montpellier, CNRS, IRD, Montpellier, France
| | - Alison B Duncan
- Institut des Sciences de l'Evolution - Montpellier (ISEM), University of Montpellier, CNRS, IRD, Montpellier, France
| | - Emanuel A Fronhofer
- Institut des Sciences de l'Evolution - Montpellier (ISEM), University of Montpellier, CNRS, IRD, Montpellier, France
| | - Oliver Kaltz
- Institut des Sciences de l'Evolution - Montpellier (ISEM), University of Montpellier, CNRS, IRD, Montpellier, France.
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2
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Griette Q, Alfaro M, Raoul G, Gandon S. Evolution and spread of multiadapted pathogens in a spatially heterogeneous environment. Evol Lett 2024; 8:427-436. [PMID: 38818414 PMCID: PMC11134468 DOI: 10.1093/evlett/qrad073] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2023] [Revised: 12/13/2023] [Accepted: 01/08/2024] [Indexed: 06/01/2024] Open
Abstract
Pathogen adaptation to multiple selective pressures challenges our ability to control their spread. Here we analyze the evolutionary dynamics of pathogens spreading in a heterogeneous host population where selection varies periodically in space. We study both the transient dynamics taking place at the front of the epidemic and the long-term evolution far behind the front. We identify five types of epidemic profiles arising for different levels of spatial heterogeneity and different costs of adaptation. In particular, we identify the conditions where a generalist pathogen carrying multiple adaptations can outrace a coalition of specialist pathogens. We also show that finite host populations promote the spread of generalist pathogens because demographic stochasticity enhances the extinction of locally maladapted pathogens. But higher mutation rates between genotypes can rescue the coalition of specialists and speed up the spread of epidemics for intermediate levels of spatial heterogeneity. Our work provides a comprehensive analysis of the interplay between migration, local selection, mutation, and genetic drift on the spread and on the evolution of pathogens in heterogeneous environments. This work extends our fundamental understanding of the outcome of the competition between two specialists and a generalist strategy (single- vs. multiadapted pathogens). These results have practical implications for the design of more durable control strategies against multiadapted pathogens in agriculture and in public health.
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Affiliation(s)
- Quentin Griette
- Université Le Havre Normandie, Normandie Université, LMAH, 76600 Le Havre, France
| | | | - Gaël Raoul
- CMAP, CNRS, Ecole polytechnique, I.P. Paris, 91128 Palaiseau, France
| | - Sylvain Gandon
- CEFE, CNRS, Univ Montpellier, EPHE, IRD, Montpellier, France
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3
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Greenrod STE, Cazares D, Johnson S, Hector TE, Stevens EJ, MacLean RC, King KC. Warming alters life-history traits and competition in a phage community. Appl Environ Microbiol 2024; 90:e0028624. [PMID: 38624196 PMCID: PMC11107170 DOI: 10.1128/aem.00286-24] [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: 02/17/2024] [Accepted: 03/26/2024] [Indexed: 04/17/2024] Open
Abstract
Host-parasite interactions are highly susceptible to changes in temperature due to mismatches in species thermal responses. In nature, parasites often exist in communities, and responses to temperature are expected to vary between host-parasite pairs. Temperature change thus has consequences for both host-parasite dynamics and parasite-parasite interactions. Here, we investigate the impact of warming (37°C, 40°C, and 42°C) on parasite life-history traits and competition using the opportunistic bacterial pathogen Pseudomonas aeruginosa (host) and a panel of three genetically diverse lytic bacteriophages (parasites). We show that phages vary in their responses to temperature. While 37°C and 40°C did not have a major effect on phage infectivity, infection by two phages was restricted at 42°C. This outcome was attributed to disruption of different phage life-history traits including host attachment and replication inside hosts. Furthermore, we show that temperature mediates competition between phages by altering their competitiveness. These results highlight phage trait variation across thermal regimes with the potential to drive community dynamics. Our results have important implications for eukaryotic viromes and the design of phage cocktail therapies.IMPORTANCEMammalian hosts often elevate their body temperatures through fevers to restrict the growth of bacterial infections. However, the extent to which fever temperatures affect the communities of phages with the ability to parasitize those bacteria remains unclear. In this study, we investigate the impact of warming across a fever temperature range (37°C, 40°C, and 42°C) on phage life-history traits and competition using a bacterium (host) and bacteriophage (parasite) system. We show that phages vary in their responses to temperature due to disruption of different phage life-history traits. Furthermore, we show that temperature can alter phage competitiveness and shape phage-phage competition outcomes. These results suggest that fever temperatures have the potential to restrict phage infectivity and drive phage community dynamics. We discuss implications for the role of temperature in shaping host-parasite interactions more widely.
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Affiliation(s)
| | - Daniel Cazares
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Serena Johnson
- Department of Biology, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of British Columbia, Vancouver, Canada
| | - Tobias E. Hector
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Emily J. Stevens
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - R. Craig MacLean
- Department of Biology, University of Oxford, Oxford, United Kingdom
| | - Kayla C. King
- Department of Biology, University of Oxford, Oxford, United Kingdom
- Department of Zoology, University of British Columbia, Vancouver, Canada
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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4
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Kürschner T, Scherer C, Radchuk V, Blaum N, Kramer‐Schadt S. Resource asynchrony and landscape homogenization as drivers of virulence evolution: The case of a directly transmitted disease in a social host. Ecol Evol 2024; 14:e11065. [PMID: 38380064 PMCID: PMC10877554 DOI: 10.1002/ece3.11065] [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: 07/25/2023] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 02/22/2024] Open
Abstract
Throughout the last decades, the emergence of zoonotic diseases and the frequency of disease outbreaks have increased substantially, fuelled by habitat encroachment and vectors overlapping with more hosts due to global change. The virulence of pathogens is one key trait for successful invasion. In order to understand how global change drivers such as habitat homogenization and climate change drive pathogen virulence evolution, we adapted an established individual-based model of host-pathogen dynamics. Our model simulates a population of social hosts affected by a directly transmitted evolving pathogen in a dynamic landscape. Pathogen virulence evolution results in multiple strains in the model that differ in their transmission capability and lethality. We represent the effects of global change by simulating environmental changes both in time (resource asynchrony) and space (homogenization). We found an increase in pathogenic virulence and a shift in strain dominance with increasing landscape homogenization. Our model further indicated that lower virulence is dominant in fragmented landscapes, although pulses of highly virulent strains emerged under resource asynchrony. While all landscape scenarios favoured co-occurrence of low- and high-virulent strains, the high-virulence strains capitalized on the possibility for transmission when host density increased and were likely to become dominant. With asynchrony likely to occur more often due to global change, our model showed that a subsequent evolution towards lower virulence could lead to some diseases becoming endemic in their host populations.
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Affiliation(s)
- Tobias Kürschner
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Cédric Scherer
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Viktoriia Radchuk
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
| | - Niels Blaum
- Plant Ecology and Nature ConservationUniversity of PotsdamPotsdamGermany
| | - Stephanie Kramer‐Schadt
- Department of Ecological DynamicsLeibniz Institute for Zoo and Wildlife ResearchBerlinGermany
- Institute of EcologyTechnische Universität BerlinBerlinGermany
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5
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Azizi A, Kazanci C, Komarova NL, Wodarz D. Effect of Human Behavior on the Evolution of Viral Strains During an Epidemic. Bull Math Biol 2022; 84:144. [PMID: 36334172 PMCID: PMC9638455 DOI: 10.1007/s11538-022-01102-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2022] [Accepted: 10/17/2022] [Indexed: 11/08/2022]
Abstract
It is well known in the literature that human behavior can change as a reaction to disease observed in others, and that such behavioral changes can be an important factor in the spread of an epidemic. It has been noted that human behavioral traits in disease avoidance are under selection in the presence of infectious diseases. Here, we explore a complementary trend: the pathogen itself might experience a force of selection to become less “visible,” or less “symptomatic,” in the presence of such human behavioral trends. Using a stochastic SIR agent-based model, we investigated the co-evolution of two viral strains with cross-immunity, where the resident strain is symptomatic while the mutant strain is asymptomatic. We assumed that individuals exercised self-regulated social distancing (SD) behavior if one of their neighbors was infected with a symptomatic strain. We observed that the proportion of asymptomatic carriers increased over time with a stronger effect corresponding to higher levels of self-regulated SD. Adding mandated SD made the effect more significant, while the existence of a time-delay between the onset of infection and the change of behavior reduced the advantage of the asymptomatic strain. These results were consistent under random geometric networks, scale-free networks, and a synthetic network that represented the social behavior of the residents of New Orleans.
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Affiliation(s)
- Asma Azizi
- Department of Mathematics, Kennesaw State University, Marietta, GA, 30060, USA.
| | - Caner Kazanci
- Department of Mathematics, University of Georgia, Athens, GA, 30602, USA.,College of Engineering, University of Georgia, Athens, GA, 30602, USA
| | - Natalia L Komarova
- Department of Mathematics, University of California Irvine, Irvine, CA, 92697, USA
| | - Dominik Wodarz
- Department of Population Health and Disease Prevention Program in Public Health, Susan and Henry Samueli College of Health Sciences, University of California, Irvine, CA, 92697, USA
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6
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Fofana AM, Hurford A. Parasite-induced shifts in host movement may explain the transient coexistence of high- and low-pathogenic disease strains. J Evol Biol 2022; 35:1072-1086. [PMID: 35789020 DOI: 10.1111/jeb.14053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/30/2022] [Accepted: 06/02/2022] [Indexed: 11/27/2022]
Abstract
Many parasites induce decreased host movement, known as lethargy, which can impact disease spread and the evolution of virulence. Mathematical models have investigated virulence evolution when parasites cause host death, but disease-induced decreased host movement has received relatively less attention. Here, we consider a model where, due to the within-host parasite replication rate, an infected host can become lethargic and shift from a moving to a resting state, where it can die. We find that when the lethargy and disease-induced mortality costs to the parasites are not high, then evolutionary bistability can arise, and either moderate or high virulence can evolve depending on the initial virulence and the magnitude of mutation. These results suggest, firstly, the coexistence of strains with different virulence, which may explain the transient coexistence of low- and high-pathogenic strains of avian influenza viruses, and secondly, that medical interventions to treat the symptoms of lethargy or prevent disease-induced host deaths can result in a large jump in virulence and the rapid evolution of high virulence. In complement to existing results that show bistability when hosts are heterogeneous at the population level, we show that evolutionary bistability may arise due to transmission heterogeneity at the individual host level.
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Affiliation(s)
- Abdou Moutalab Fofana
- Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
| | - Amy Hurford
- Biology, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada.,Mathematics and Statistics, Memorial University of Newfoundland, St. John's, Newfoundland and Labrador, Canada
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7
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Warburton EM, Blanar CA. Life in the margins: host-parasite relationships in ecological edges. Parasitol Res 2021; 120:3965-3977. [PMID: 34694518 DOI: 10.1007/s00436-021-07355-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2021] [Accepted: 10/18/2021] [Indexed: 11/24/2022]
Abstract
Transitional zones, such as edge habitat, are key landscapes for investigating biodiversity. "Soft edges" are permeable corridors that hosts can cross, while "hard edges" are impermeable borders that hosts cannot pass. Although pathogen transmission in the context of edges is vital to species conservation, drivers of host-parasite relationships in ecological edges remain poorly understood. Thus, we defined a framework for testing hypotheses of host-parasite interactions in hard and soft edges by (1) characterizing hard and soft edges from both the host and parasite perspectives, (2) predicting the types of parasites that would be successful in each type of edge, and (3) applying our framework to species invasion fronts as an example of host-parasite relationships in a soft edge. Generally, we posited that parasites in soft edges are more likely to be negatively affected by habitat fragmentation than their hosts because they occupy higher trophic levels but parasite transmission would benefit from increased host connectivity. Parasites along hard edges, however, are at higher risk of local extinction due to host population perturbations with limited opportunity for parasite recolonization. We then used these characteristics to predict functional traits that would lead to parasite success along soft and hard edges. Finally, we applied our framework to invasive species fronts to highlight predictions regarding host connectivity and parasite traits in soft edges. We anticipate that our work will promote a more complete discussion of habitat connectivity using a common framework and stimulate empirical research into host-parasite relationships within ecological edges and transitional zones.
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Affiliation(s)
- Elizabeth M Warburton
- Center for the Ecology of Infectious Diseases, Odum School of Ecology, University of Georgia, Athens, GA, 30606, USA.
| | - Christopher A Blanar
- Department of Biological Sciences, Halmos College of Arts and Sciences, Nova Southeastern University, Davie, FL, 33314, USA
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8
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Visher E, Evensen C, Guth S, Lai E, Norfolk M, Rozins C, Sokolov NA, Sui M, Boots M. The three Ts of virulence evolution during zoonotic emergence. Proc Biol Sci 2021; 288:20210900. [PMID: 34375554 PMCID: PMC8354747 DOI: 10.1098/rspb.2021.0900] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2021] [Accepted: 07/16/2021] [Indexed: 12/21/2022] Open
Abstract
There is increasing interest in the role that evolution may play in current and future pandemics, but there is often also considerable confusion about the actual evolutionary predictions. This may be, in part, due to a historical separation of evolutionary and medical fields, but there is a large, somewhat nuanced body of evidence-supported theory on the evolution of infectious disease. In this review, we synthesize this evolutionary theory in order to provide a framework for clearer understanding of the key principles. Specifically, we discuss the selection acting on zoonotic pathogens' transmission rates and virulence at spillover and during emergence. We explain how the direction and strength of selection during epidemics of emerging zoonotic disease can be understood by a three Ts framework: trade-offs, transmission, and time scales. Virulence and transmission rate may trade-off, but transmission rate is likely to be favoured by selection early in emergence, particularly if maladapted zoonotic pathogens have 'no-cost' transmission rate improving mutations available to them. Additionally, the optimal virulence and transmission rates can shift with the time scale of the epidemic. Predicting pathogen evolution, therefore, depends on understanding both the trade-offs of transmission-improving mutations and the time scales of selection.
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Affiliation(s)
- Elisa Visher
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Claire Evensen
- Mathematical Institute, University of Oxford, Oxford OX2 6GG, UK
| | - Sarah Guth
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Edith Lai
- College of Natural Resources, University of California, Berkeley, CA 94720, USA
| | - Marina Norfolk
- College of Letters and Sciences, University of California, Berkeley, CA 94720, USA
| | - Carly Rozins
- Department of Science and Technology Studies, Division of Natural Science, York University, Toronto, Ontario, Canada M3J 1P3
| | - Nina A. Sokolov
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
| | - Melissa Sui
- College of Letters and Sciences, University of California, Berkeley, CA 94720, USA
| | - Michael Boots
- Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK
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9
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Nørgaard LS, Zilio G, Saade C, Gougat‐Barbera C, Hall MD, Fronhofer EA, Kaltz O. An evolutionary trade‐off between parasite virulence and dispersal at experimental invasion fronts. Ecol Lett 2021; 24:739-750. [DOI: 10.1111/ele.13692] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Revised: 11/30/2020] [Accepted: 12/23/2020] [Indexed: 11/29/2022]
Affiliation(s)
- Louise S. Nørgaard
- School of Biological Sciences Centre for Geometric Biology Monash University Melbourne3800Australia
- ISEMUniversity of MontpellierCNRSIRDEPHE Montpellier France
| | - Giacomo Zilio
- ISEMUniversity of MontpellierCNRSIRDEPHE Montpellier France
| | - Camille Saade
- ISEMUniversity of MontpellierCNRSIRDEPHE Montpellier France
| | | | - Matthew D. Hall
- School of Biological Sciences Centre for Geometric Biology Monash University Melbourne3800Australia
| | | | - Oliver Kaltz
- ISEMUniversity of MontpellierCNRSIRDEPHE Montpellier France
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10
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Keenan VA, Cornell SJ. Anomalous invasion dynamics due to dispersal polymorphism and dispersal-reproduction trade-offs. Proc Biol Sci 2021; 288:20202825. [PMID: 33434455 PMCID: PMC7892423 DOI: 10.1098/rspb.2020.2825] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Dispersal polymorphism and mutation play significant roles during biological invasions, potentially leading to evolution and complex behaviour such as accelerating or decelerating invasion fronts. However, life-history theory predicts that reproductive fitness-another key determinant of invasion dynamics-may be lower for more dispersive strains. Here, we use a mathematical model to show that unexpected invasion dynamics emerge from the combination of heritable dispersal polymorphism, dispersal-fitness trade-offs, and mutation between strains. We show that the invasion dynamics are determined by the trade-off relationship between dispersal and population growth rates of the constituent strains. We find that invasion dynamics can be 'anomalous' (i.e. faster than any of the strains in isolation), but that the ultimate invasion speed is determined by the traits of, at most, two strains. The model is simple but generic, so we expect the predictions to apply to a wide range of ecological, evolutionary, or epidemiological invasions.
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Affiliation(s)
- Vincent A Keenan
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
| | - Stephen J Cornell
- Institute of Integrative Biology, University of Liverpool, Crown Street, Liverpool L69 7ZB, UK
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11
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Nørgaard LS, Phillips BL, Hall MD. Infection in patchy populations: Contrasting pathogen invasion success and dispersal at varying times since host colonization. Evol Lett 2019; 3:555-566. [PMID: 31636946 PMCID: PMC6791296 DOI: 10.1002/evl3.141] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2018] [Revised: 07/01/2019] [Accepted: 09/03/2019] [Indexed: 12/02/2022] Open
Abstract
Repeated extinction and recolonization events generate a landscape of host populations that vary in their time since colonization. Within this dynamic landscape, pathogens that excel at invading recently colonized host populations are not necessarily those that perform best in host populations at or near their carrying capacity, potentially giving rise to divergent selection for pathogen traits that mediate the invasion process. Rarely, however, has this contention been empirically tested. Using Daphnia magna, we explored how differences in the colonization history of a host population influence the invasion success of different genotypes of the pathogen Pasteuria ramosa. By partitioning the pathogen invasion process into a series of individual steps, we show that each pathogen optimizes invasion differently when encountering host populations that vary in their time since colonization. All pathogen genotypes were more likely to establish successfully in recently colonized host populations, but the production of transmission spores was typically maximized in either the subsequent growth or stationary phase of host colonization. Integrating across the first three pathogen invasion steps (initial establishment, proliferation, and secondary infection) revealed that overall pathogen invasion success (and its variance) was, nonetheless, highest in recently colonized host populations. However, only pathogens that were slow to kill their host were able to maximize host‐facilitated dispersal. This suggests that only a subset of pathogen genotypes—the less virulent and more dispersive—are more likely to encounter newly colonized host populations at the front of a range expansion or in metapopulations with high extinction rates. Our results suggest a fundamental trade‐off for a pathogen between dispersal and virulence, and evidence for higher invasion success in younger host populations, a finding with clear implications for pathogen evolution in spatiotemporally dynamic settings.
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Affiliation(s)
- Louise S. Nørgaard
- School of Biological SciencesMonash UniversityClaytonMelbourne3800Australia
| | - Ben L. Phillips
- School of BioSciencesUniversity of MelbourneParkvilleVictoria3010Australia
| | - Matthew D. Hall
- School of Biological SciencesMonash UniversityClaytonMelbourne3800Australia
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12
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Pulkkinen K, Pekkala N, Ashrafi R, Hämäläinen DM, Nkembeng AN, Lipponen A, Hiltunen T, Valkonen JK, Taskinen J. Effect of resource availability on evolution of virulence and competition in an environmentally transmitted pathogen. FEMS Microbiol Ecol 2019; 94:4962392. [PMID: 29659817 DOI: 10.1093/femsec/fiy060] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2018] [Accepted: 04/04/2018] [Indexed: 01/21/2023] Open
Abstract
Understanding ecological and epidemiological factors driving pathogen evolution in contemporary time scales is a major challenge in modern health management. Pathogens that replicate outside the hosts are subject to selection imposed by ambient environmental conditions. Increased nutrient levels could increase pathogen virulence by pre-adapting for efficient use of resources upon contact to a nutrient rich host or by favouring transmission of fast-growing virulent strains. We measured changes in virulence and competition in Flavobacterium columnare, a bacterial pathogen of freshwater fish, under high and low nutrient levels. To test competition between strains in genotype mixtures, we developed a quantitative real-time PCR assay. We found that a virulent strain maintained its virulence and outcompeted less virulent strains independent of the nutrient level and resource renewal rate while a less virulent strain further lost virulence in chemostats under low nutrient level and over long-term serial culture under high nutrient level. Our results suggest that increased outside-host nutrient levels might maintain virulence in less virulent strains and increase their contribution to epidemics in aquaculture. The results highlight a need to further explore the role of resource in the outside-host environment in maintaining strain diversity and driving evolution of virulence among environmentally growing pathogens.
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Affiliation(s)
- Katja Pulkkinen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Nina Pekkala
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Roghaieh Ashrafi
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland.,Centre of Excellence in Biological Interactions, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä,Finland
| | - Dorrit M Hämäläinen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Aloysius N Nkembeng
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
| | - Anssi Lipponen
- A. I. Virtanen Institute for Molecular Sciences, P. O. Box 1627, (Neulaniementie 2), University of Eastern Finland, Kuopio, Finland
| | - Teppo Hiltunen
- Department of Microbiology, P. O. Box 56, (Viikinkaari 9), University of Helsinki, Helsinki, Finland
| | - Janne K Valkonen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland.,Centre of Excellence in Biological Interactions, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä,Finland
| | - Jouni Taskinen
- Department of Biological and Environmental Science, P. O. Box 35, (Survontie 9), University of Jyväskylä, Jyväskylä, Finland
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13
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Lion S, Gandon S. Spatial evolutionary epidemiology of spreading epidemics. Proc Biol Sci 2017; 283:rspb.2016.1170. [PMID: 27798295 DOI: 10.1098/rspb.2016.1170] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 09/19/2016] [Indexed: 01/04/2023] Open
Abstract
Most spatial models of host-parasite interactions either neglect the possibility of pathogen evolution or consider that this process is slow enough for epidemiological dynamics to reach an equilibrium on a fast timescale. Here, we propose a novel approach to jointly model the epidemiological and evolutionary dynamics of spatially structured host and pathogen populations. Starting from a multi-strain epidemiological model, we use a combination of spatial moment equations and quantitative genetics to analyse the dynamics of mean transmission and virulence in the population. A key insight of our approach is that, even in the absence of long-term evolutionary consequences, spatial structure can affect the short-term evolution of pathogens because of the build-up of spatial differentiation in mean virulence. We show that spatial differentiation is driven by a balance between epidemiological and genetic effects, and this quantity is related to the effect of kin competition discussed in previous studies of parasite evolution in spatially structured host populations. Our analysis can be used to understand and predict the transient evolutionary dynamics of pathogens and the emergence of spatial patterns of phenotypic variation.
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Affiliation(s)
- S Lion
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919, route de Mende, 34293 Montpellier Cedex 5, France
| | - S Gandon
- CEFE UMR 5175, CNRS - Université de Montpellier - Université Paul-Valéry Montpellier - EPHE, 1919, route de Mende, 34293 Montpellier Cedex 5, France
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Ecological and evolutionary approaches to managing honeybee disease. Nat Ecol Evol 2017; 1:1250-1262. [PMID: 29046562 PMCID: PMC5749923 DOI: 10.1038/s41559-017-0246-z] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2017] [Accepted: 06/20/2017] [Indexed: 12/12/2022]
Abstract
Honeybee declines are a serious threat to global agricultural security and productivity. Although multiple factors contribute to these declines, parasites are a key driver. Disease problems in honeybees have intensified in recent years, despite increasing attention to addressing them. Here we argue that we must focus on the principles of disease ecology and evolution to understand disease dynamics, assess the severity of disease threats, and control these threats via honeybee management. We cover the ecological context of honeybee disease, including both host and parasite factors driving current transmission dynamics, and then discuss evolutionary dynamics including how beekeeping management practices may drive selection for more virulent parasites. We then outline how ecological and evolutionary principles can guide disease mitigation in honeybees, including several practical management suggestions for addressing short- and long-term disease dynamics and consequences. Multiple interacting factors have contributed to the rapid decline of honeybee populations worldwide. Here, the authors review the impact of parasites and pathogens, and how ecological and evolutionary principles can guide management practices.
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15
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Short Rotations in Forest Plantations Accelerate Virulence Evolution in Root-Rot Pathogenic Fungi. FORESTS 2017. [DOI: 10.3390/f8060205] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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16
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Herbeck JT, Mittler JE, Gottlieb GS, Goodreau SM, Murphy JT, Cori A, Pickles M, Fraser C. Evolution of HIV virulence in response to widespread scale up of antiretroviral therapy: a modeling study. Virus Evol 2016; 2:vew028. [PMID: 29492277 PMCID: PMC5822883 DOI: 10.1093/ve/vew028] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
There are global increases in the use of HIV antiretroviral therapy (ART), guided by clinical benefits of early ART initiation and the efficacy of treatment as prevention of transmission. Separately, it has been shown theoretically and empirically that HIV virulence can evolve over time; observed virulence levels may reflect an adaptive balance between infected lifespan and per-contact transmission rate. However, the potential effects of widespread ART usage on HIV virulence are unknown. To predict these effects, we used an agent-based stochastic model to simulate evolutionary trends in HIV virulence, using set point viral load as a proxy for virulence. We calibrated our model to prevalence and incidence trends of South Africa. We explored two distinct ART scenarios: (1) ART initiation based on HIV-infected individuals reaching a CD4 count threshold; and (2) ART initiation based on individual time elapsed since HIV infection (a scenario that mimics "universal testing and treatment" (UTT) aspirations). In each case, we considered a range in population uptake of ART. We found that HIV virulence is generally unchanged in scenarios of CD4-based initiation. However, with ART initiation based on time since infection, virulence can increase moderately within several years of ART rollout, under high coverage levels and early treatment initiation (albeit within the context of epidemics that are rapidly decreasing in size). Sensitivity analyses suggested the impact of ART on virulence is relatively insensitive to model calibration. Our modeling study suggests that increasing HIV virulence driven by UTT is likely not a major public health concern, but should be monitored in sentinel surveillance, in a manner similar to transmitted resistance to antiretroviral drugs.
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Affiliation(s)
- Joshua T Herbeck
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - John E Mittler
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - Geoffrey S Gottlieb
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - Steven M Goodreau
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - James T Murphy
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - Anne Cori
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - Michael Pickles
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
| | - Christophe Fraser
- International Clinical Research Center, Department of Global Health, University of Washington, Seattle, WA 98104, USA
- Department of Microbiology, University of Washington, Seattle, WA 98195, USA
- Departments of Medicine, University of Washington, Seattle, WA 98195, USA
- Department of Anthropology, University of Washington, Seattle, WA 98195, USA
- Department of Infectious Disease Epidemiology, Imperial College London, London W2 1PG, UK
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