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A Sterility-Mortality Tolerance Trade-Off Leads to Within-Population Variation in Host Tolerance. Bull Math Biol 2023; 85:16. [PMID: 36670241 DOI: 10.1007/s11538-023-01119-6] [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: 11/05/2022] [Accepted: 01/02/2023] [Indexed: 01/21/2023]
Abstract
While experimental studies have demonstrated within-population variation in host tolerance to parasitism, theoretical studies rarely predict for polymorphism to arise. However, most theoretical models do not consider the crucial distinction between tolerance to the effects of infection-induced deaths (mortality tolerance) and tolerance to the parasite-induced reduction in the reproduction of infected hosts (sterility tolerance). While some studies have examined trade-offs between host tolerance and resistance mechanisms, none has considered a correlation within different tolerance mechanisms. We assume that sterility tolerance and mortality tolerance are directly traded-off in a host population subjected to a pathogen and use adaptive dynamics to study their evolutionary behaviour. We find that such a trade-off between the two tolerance strategies can drive the host population to branch into dimorphic strains, leading to coexistence of strains with sterile hosts that have low mortality and fully fertile with high mortality rates. Further, we find that a wider range of trade-off shapes allows branching at intermediate- or high-infected population size. Our other significant finding is that sterility tolerance is maximised (and mortality tolerance minimised) at an intermediate disease-induced mortality rate. Additionally, evolution entirely reverses the disease prevalence pattern corresponding to the recovery rate, compared to when no strategies evolve. We provide novel predictions on the evolutionary behaviour of two tolerance strategies concerning such a trade-off.
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2
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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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3
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Bartlett LJ, Boots M. The central role of host reproduction in determining the evolution of virulence in spatially structured populations. J Theor Biol 2021; 523:110717. [PMID: 33862089 DOI: 10.1016/j.jtbi.2021.110717] [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: 05/18/2020] [Revised: 04/05/2021] [Accepted: 04/09/2021] [Indexed: 10/21/2022]
Abstract
A substantial body of work has shown that local transmission selects for less acute, 'prudent' parasites that have lower virulence and transmission rates. This is because parasite strains with higher transmission rates 'self-shade' due to a combination of genetic correlations (self: clustered related parasite strains compete for susceptible individuals) and ecological correlations (shade: infected individuals clustering and blocking transmission). However, the interaction of ecological and genetic correlations alongside higher order ecological effects such as patch extinctions means that spatial evolutionary effects can be nuanced; theory has predicted that a relatively small proportion of local infection can select for highest virulence, such that there is a humped relationship between the degree of local infection and the harm that parasites are selected to cause. Here, we examine the separate roles of the interaction scales of reproduction and infection in the context of different degrees of pathogenic castration in determining virulence evolution outcomes. Our key result is that, as long as there is significant reproduction from infected individuals, local infection always selects for lower virulence, and that the prediction that a small proportion of local infection can select for higher virulence only occurs for highly castrating pathogens. The results emphasize the importance of demography for evolutionary outcomes in spatially structured populations, but also show that the core prediction that parasites are prudent in space is reasonable for the vast majority of host-parasite interactions and mixing patterns in nature.
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Affiliation(s)
- Lewis J Bartlett
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK; Center for the Ecology of Infectious Diseases, University of Georgia, Athens, GA 30602, USA.
| | - Mike Boots
- Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Penryn Campus, Penryn TR10 9FE, UK; Department of Integrative Biology, University of California, Berkeley, CA 94720, USA
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4
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Magallanes S, Møller AP, Luján-Vega C, Fong E, Vecco D, Flores-Saavedra W, García-Longoriaa L, de Lope F, Iannacone JA, Marzal A. Exploring the adjustment to parasite pressure hypothesis: differences in uropygial gland volume and haemosporidian infection in palearctic and neotropical birds. Curr Zool 2020; 67:147-156. [PMID: 33854532 PMCID: PMC8026150 DOI: 10.1093/cz/zoaa037] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 07/02/2020] [Indexed: 11/29/2022] Open
Abstract
Parasites are globally widespread pathogenic organisms, which impose important selective forces upon their hosts. Thus, in accordance with the Adjustment to parasite pressure hypothesis, it is expected that defenses among hosts vary relative to the selective pressure imposed by parasites. According to the latitudinal gradient in diversity, species richness and abundance of parasites peak near the equator. The uropygial gland is an important defensive exocrine gland against pathogens in birds. Size of the uropygial gland has been proposed to vary among species of birds because of divergent selection by pathogens on their hosts. Therefore, we should expect that bird species from the tropics should have relatively larger uropygial glands for their body size than species from higher latitudes. However, this hypothesis has not yet been explored. Here, we analyze the size of the uropygial gland of 1719 individual birds belonging to 36 bird species from 3 Neotropical (Peru) and 3 temperate areas (Spain). Relative uropygial gland volume was 12.52% larger in bird species from the tropics than from temperate areas. This finding is consistent with the relative size of this defensive organ being driven by selective pressures imposed by parasites. We also explored the potential role of this gland as a means of avoiding haemosporidian infection, showing that species with large uropygial glands for their body size tend to have lower mean prevalence of haemosporidian infection, regardless of their geographical origin. This result provides additional support for the assumption that secretions from the uropygial gland reduce the likelihood of becoming infected with haemosporidians.
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Affiliation(s)
- Sergio Magallanes
- Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, Avda. de Elvas S/N, Badajoz ES-06006, Spain
| | - Anders Pape Møller
- Ecologie Systématique Evolution, Université Paris-Sud, Orsay 91400, France.,Key Laboratory for Biodiversity Science and Ecological Engineering of Ministry of Education, College of Life Sciences, Beijing Normal University, Beijing 100875, China
| | - Charlene Luján-Vega
- Pharmacology and Toxicology Graduate Group, University of California, Davis, Davis, CA 95616, USA
| | - Esteban Fong
- EverGreen Institute-San Rafael, Distrito de Indiana, Loreto 16200, Perú
| | - Daniel Vecco
- Centro Urku de Estudios Amazónicos, Tarapoto 22202, Perú
| | | | - Luz García-Longoriaa
- Molecular Ecology and Evolution Lab, Department of Biology, Lund University, Lund 221 00, Sweden.,Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, Avda. de Elvas S/N, Badajoz ES-06006, Spain
| | - Florentino de Lope
- Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, Avda. de Elvas S/N, Badajoz ES-06006, Spain
| | - José A Iannacone
- Laboratorio de Ingeniería Ambiental, Universidad Científica del Sur-Villa el Salvador, Lima 15067, Perú.,Laboratorio de Invertebrados, Universidad Ricardo Palma, Santiago de Surco 15039, Perú
| | - Alfonso Marzal
- Department of Anatomy, Cellular Biology and Zoology, University of Extremadura, Avda. de Elvas S/N, Badajoz ES-06006, Spain
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5
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Host-Induced Genome Instability Rapidly Generates Phenotypic Variation across Candida albicans Strains and Ploidy States. mSphere 2020; 5:5/3/e00433-20. [PMID: 32493724 PMCID: PMC7273350 DOI: 10.1128/msphere.00433-20] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
Candida albicans is an opportunistic fungal pathogen of humans. The ability to generate genetic variation is essential for adaptation and is a strategy that C. albicans and other fungal pathogens use to change their genome size. Stressful environments, including the host, induce C. albicans genome instability. Here, we investigated how C. albicans genetic background and ploidy state impact genome instability, both in vitro and in a host environment. We show that the host environment induces genome instability, but the magnitude depends on C. albicans genetic background. Furthermore, we show that tetraploid C. albicans is highly unstable in host environments and rapidly reduces in genome size. These reductions in genome size often resulted in reduced virulence. In contrast, diploid C. albicans displayed modest host-induced genome size changes, yet these frequently resulted in increased virulence. Such studies are essential for understanding how opportunistic pathogens respond and potentially adapt to the host environment. Candida albicans is an opportunistic fungal pathogen of humans that is typically diploid yet has a highly labile genome tolerant of large-scale perturbations including chromosomal aneuploidy and loss-of-heterozygosity events. The ability to rapidly generate genetic variation is crucial for C. albicans to adapt to changing or stressful environments, like those encountered in the host. Genetic variation occurs via stress-induced mutagenesis or can be generated through its parasexual cycle, in which tetraploids arise via diploid mating or stress-induced mitotic defects and undergo nonmeiotic ploidy reduction. However, it remains largely unknown how genetic background contributes to C. albicans genome instability in vitro or in the host environment. Here, we tested how genetic background, ploidy, and the host environment impacts C. albicans genome stability. We found that host association induced both loss-of-heterozygosity events and genome size changes, regardless of genetic background or ploidy. However, the magnitude and types of genome changes varied across C. albicans strain background and ploidy state. We then assessed if host-induced genomic changes resulted in fitness consequences on growth rate and nonlethal virulence phenotypes and found that many host-derived isolates significantly changed relative to their parental strain. Interestingly, diploid host-associated C. albicans predominantly decreased host reproductive fitness, whereas tetraploid host-associated C. albicans increased host reproductive fitness. Together, these results are important for understanding how host-induced genomic changes in C. albicans alter its relationship with the host. IMPORTANCECandida albicans is an opportunistic fungal pathogen of humans. The ability to generate genetic variation is essential for adaptation and is a strategy that C. albicans and other fungal pathogens use to change their genome size. Stressful environments, including the host, induce C. albicans genome instability. Here, we investigated how C. albicans genetic background and ploidy state impact genome instability, both in vitro and in a host environment. We show that the host environment induces genome instability, but the magnitude depends on C. albicans genetic background. Furthermore, we show that tetraploid C. albicans is highly unstable in host environments and rapidly reduces in genome size. These reductions in genome size often resulted in reduced virulence. In contrast, diploid C. albicans displayed modest host-induced genome size changes, yet these frequently resulted in increased virulence. Such studies are essential for understanding how opportunistic pathogens respond and potentially adapt to the host environment.
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6
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Janoušková E, Berec L. Fecundity-Longevity Trade-Off, Vertical Transmission, and Evolution of Virulence in Sterilizing Pathogens. Am Nat 2019; 195:95-106. [PMID: 31868533 DOI: 10.1086/706182] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Sterilizing pathogens are common, yet studies focused on how such pathogens respond adaptively to fecundity reductions caused in their hosts are rare. Here we assume that the infected hosts, as a result of redistributing energy resources saved by reduced fecundity, have increased longevity and focus on exploring the consequences of such a fecundity-longevity trade-off on sterility virulence evolution in the pathogens. We find that the trade-off itself cannot prevent the evolution of full sterilization. Therefore, we allow for vertical transmission and reveal that the fecundity-longevity trade-off strongly determines the threshold efficiency of vertical transmission above which partial host sterilization evolves. Partial sterilization may appear as an intermediate level of sterility virulence or as a stable dimorphism at which avirulent and highly virulent strains coexist. The fecundity-longevity trade-off significantly contributes to determining the actual outcome, in many cases countering predictions made in the absence of this trade-off. It is known that in well-mixed populations, partial sterilization may evolve in pathogens under a combination of horizontal and vertical transmission. Our study highlights that this is independent of the form of horizontal transmission and the type of density dependence in host demography and that the fecundity-longevity trade-off is an important player in sterility virulence evolution.
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7
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A Novel Virulence Phenotype Rapidly Assesses Candida Fungal Pathogenesis in Healthy and Immunocompromised Caenorhabditis elegans Hosts. mSphere 2019; 4:4/2/e00697-18. [PMID: 30971447 PMCID: PMC6458437 DOI: 10.1128/msphere.00697-18] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
Opportunistic pathogens are commensals capable of causing disease and are serious threats to human health. It is critical to understand the mechanisms and host contexts under which opportunistic pathogens become virulent. In this work, we present a novel assay to quickly and quantitatively measure pathogen virulence in healthy and immunocompromised nematode hosts. We found that Candida species, one of the most prominent fungal opportunistic pathogens of humans, decrease host fitness by reducing survival and impacting host reproduction. Most importantly, by measuring virulence in hosts that have intact or compromised immune function, we can reveal the pathogenic potential of opportunistic fungal pathogens. The yeast Candida albicans is an opportunistic pathogen of humans, meaning that despite commensal interactions with its host, it can transition to a harmful pathogen. While C. albicans is the predominant species isolated in the human gastrointestinal mycobiome and is implicated in fungal infection, infections due to non-albicans Candida species are rapidly rising. Studying the factors that contribute to virulence is often challenging and frequently depends on many contexts, including host immune status and pathogen genetic background. Here, we utilize the nematode Caenorhabditis elegans as a perspicuous and efficient model host system to study fungal infections of Candida pathogens. We find that, in addition to reducing lifetime host survival, exposure to C. albicans results in delayed reproduction, which significantly reduced lineage growth over multiple generations. Furthermore, we assessed fungal pathogen virulence in C. elegans hosts compromised for innate immune function and detected increased early mortality, reduced brood sizes, and delayed reproduction relative to infected healthy hosts. Importantly, by assessing virulence in both healthy and immunocompromised host backgrounds, we reveal the pathogen potential in non-albicans Candida species. Taken together, we present a novel lineage growth assay to measure reduction in host fitness associated with fungal infection and demonstrate significant interactions between pathogen and host immune function that contribute to virulence. IMPORTANCE Opportunistic pathogens are commensals capable of causing disease and are serious threats to human health. It is critical to understand the mechanisms and host contexts under which opportunistic pathogens become virulent. In this work, we present a novel assay to quickly and quantitatively measure pathogen virulence in healthy and immunocompromised nematode hosts. We found that Candida species, one of the most prominent fungal opportunistic pathogens of humans, decrease host fitness by reducing survival and impacting host reproduction. Most importantly, by measuring virulence in hosts that have intact or compromised immune function, we can reveal the pathogenic potential of opportunistic fungal pathogens.
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8
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McLeod DV, Day T. Why is sterility virulence most common in sexually transmitted infections? Examining the role of epidemiology. Evolution 2019; 73:872-882. [PMID: 30859562 DOI: 10.1111/evo.13718] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 02/06/2019] [Indexed: 11/29/2022]
Abstract
Sterility virulence, or the reduction in host fecundity due to infection, occurs in many host-pathogen systems. Notably, sterility virulence is more common for sexually transmitted infections (STIs) than for directly transmitted pathogens, while other forms of virulence tend to be limited in STIs. This has led to the suggestion that sterility virulence may have an adaptive explanation. By focusing upon finite population models, we show that the observed patterns of sterility virulence can be explained by consideration of the epidemiological differences between STIs and directly transmitted pathogens. In particular, when pathogen transmission is predominantly density invariant (as for STIs), and mortality is density dependent, sterility virulence can be favored by demographic stochasticity, whereas if pathogen transmission is predominantly density dependent, as is common for most directly transmitted pathogens, sterility virulence is disfavored. We show these conclusions can hold even if there is a weak selective advantage to sterilizing.
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Affiliation(s)
- David V McLeod
- Institute of Integrative Biology, ETH Zürich, Zürich, Switzerland
| | - Troy Day
- Department of Mathematics and Statistics, Department of Biology Queen's University, Kingston, Ontario, Canada
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9
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Murall CL, Jackson R, Zehbe I, Boulle N, Segondy M, Alizon S. Epithelial stratification shapes infection dynamics. PLoS Comput Biol 2019; 15:e1006646. [PMID: 30673699 PMCID: PMC6361466 DOI: 10.1371/journal.pcbi.1006646] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 02/04/2019] [Accepted: 11/16/2018] [Indexed: 02/07/2023] Open
Abstract
Infections of stratified epithelia contribute to a large group of common diseases, such as dermatological conditions and sexually transmitted diseases. To investigate how epithelial structure affects infection dynamics, we develop a general ecology-inspired model for stratified epithelia. Our model allows us to simulate infections, explore new hypotheses and estimate parameters that are difficult to measure with tissue cell cultures. We focus on two contrasting pathogens: Chlamydia trachomatis and Human papillomaviruses (HPV). Using cervicovaginal parameter estimates, we find that key infection symptoms can be explained by differential interactions with the layers, while clearance and pathogen burden appear to be bottom-up processes. Cell protective responses to infections (e.g. mucus trapping) generally lowered pathogen load but there were specific effects based on infection strategies. Our modeling approach opens new perspectives for 3D tissue culture experimental systems of infections and, more generally, for developing and testing hypotheses related to infections of stratified epithelia.
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Affiliation(s)
| | - Robert Jackson
- Probe Development and Biomarker Exploration, Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
- Biotechnology Program, Lakehead University, Thunder Bay, Ontario, Canada
| | - Ingeborg Zehbe
- Probe Development and Biomarker Exploration, Thunder Bay Regional Health Research Institute, Thunder Bay, Ontario, Canada
- Department of Biology, Lakehead University, Thunder Bay, Ontario, Canada
| | - Nathalie Boulle
- Pathogenesis and Control of Chronic Infections, INSERM, EFS, Université de Montpellier, Montpellier, France
| | - Michel Segondy
- Pathogenesis and Control of Chronic Infections, INSERM, EFS, Université de Montpellier, Montpellier, France
| | - Samuel Alizon
- Laboratoire MIVEGEC (UMR CNRS 5290, IRD, UM), Montpellier, France
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10
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Ritter M, Kalbe M, Henrich T. Virulence in the three-spined stickleback specific parasite Schistocephalus solidus is inherited additively. Exp Parasitol 2017; 180:133-140. [DOI: 10.1016/j.exppara.2017.02.016] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 02/14/2017] [Accepted: 02/23/2017] [Indexed: 10/20/2022]
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11
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Luu H, Tate AT. Recovery and immune priming modulate the evolutionary trajectory of infection-induced reproductive strategies. J Evol Biol 2017; 30:1748-1762. [PMID: 28667661 DOI: 10.1111/jeb.13138] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2016] [Revised: 06/09/2017] [Accepted: 06/16/2017] [Indexed: 12/29/2022]
Abstract
In response to parasite exposure, organisms from a variety of taxa undergo a shift in reproductive investment that may trade off with other life-history traits including survival and immunity. By suppressing reproduction in favour of somatic and immunological maintenance, hosts can enhance the probability of survival and recovery from infection. By plastically enhancing reproduction through terminal investment, on the other hand, hosts under the threat of disease-induced mortality could enhance their lifetime reproductive fitness through reproduction rather than survival. However, we know little about the evolution of these strategies, particularly when hosts can recover and even bequeath protection to their offspring. In this study, we develop a stochastic agent-based model that competes somatic maintenance and terminal investment strategies as they trade off differentially with lifespan, parasite resistance, recovery and transgenerational immune priming. Our results suggest that a trade-off between reproduction and recovery can drive directional selection for either terminal investment or somatic maintenance, depending on the cost of reproduction to lifespan. However, some conditions, such as low virulence with a high cost of reproduction to lifespan, can favour diversifying selection for the coexistence of both strategies. The introduction of transgenerational priming into the model favours terminal investment when all strategies are equally likely to produce primed offspring, but favours somatic maintenance if it confers even a slight priming advantage over terminal investment. Our results suggest that both immune priming and recovery may modulate the evolution of reproductive shift diversity and magnitude upon exposure to parasites.
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Affiliation(s)
- H Luu
- Department of Biology and Biochemistry, University of Houston, Houston, USA
| | - A T Tate
- Department of Biology and Biochemistry, University of Houston, Houston, USA
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12
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Bankers L, Fields P, McElroy KE, Boore JL, Logsdon JM, Neiman M. Genomic evidence for population-specific responses to co-evolving parasites in a New Zealand freshwater snail. Mol Ecol 2017; 26:3663-3675. [PMID: 28429458 DOI: 10.1111/mec.14146] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2016] [Revised: 03/27/2017] [Accepted: 03/29/2017] [Indexed: 01/13/2023]
Abstract
Reciprocal co-evolving interactions between hosts and parasites are a primary source of strong selection that can promote rapid and often population- or genotype-specific evolutionary change. These host-parasite interactions are also a major source of disease. Despite their importance, very little is known about the genomic basis of co-evolving host-parasite interactions in natural populations, especially in animals. Here, we use gene expression and sequence evolution approaches to take critical steps towards characterizing the genomic basis of interactions between the freshwater snail Potamopyrgus antipodarum and its co-evolving sterilizing trematode parasite, Microphallus sp., a textbook example of natural coevolution. We found that Microphallus-infected P. antipodarum exhibit systematic downregulation of genes relative to uninfected P. antipodarum. The specific genes involved in parasite response differ markedly across lakes, consistent with a scenario where population-level co-evolution is leading to population-specific host-parasite interactions and evolutionary trajectories. We also used an FST -based approach to identify a set of loci that represent promising candidates for targets of parasite-mediated selection across lakes as well as within each lake population. These results constitute the first genomic evidence for population-specific responses to co-evolving infection in the P. antipodarum-Microphallus interaction and provide new insights into the genomic basis of co-evolutionary interactions in nature.
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Affiliation(s)
- Laura Bankers
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Peter Fields
- Zoologisches Institut, Universität Basel, Basel, Switzerland
| | - Kyle E McElroy
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Jeffrey L Boore
- Department of Integrative Biology, University of California, Berkeley, CA, USA
| | - John M Logsdon
- Department of Biology, University of Iowa, Iowa City, IA, USA
| | - Maurine Neiman
- Department of Biology, University of Iowa, Iowa City, IA, USA
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13
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Pradeu T. Mutualistic viruses and the heteronomy of life. STUDIES IN HISTORY AND PHILOSOPHY OF BIOLOGICAL AND BIOMEDICAL SCIENCES 2016; 59:80-8. [PMID: 26972872 PMCID: PMC7108282 DOI: 10.1016/j.shpsc.2016.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 02/27/2016] [Indexed: 05/04/2023]
Abstract
Though viruses have generally been characterized by their pathogenic and more generally harmful effects, many examples of mutualistic viruses exist. Here I explain how the idea of mutualistic viruses has been defended in recent virology, and I explore four important conceptual and practical consequences of this idea. I ask to what extent this research modifies the way scientists might search for new viruses, our notion of how the host immune system interacts with microbes, the development of new therapeutic approaches, and, finally, the role played by the criterion of autonomy in our understanding of living things. Overall, I suggest that the recognition of mutualistic viruses plays a major role in a wider ongoing revision of our conception of viruses.
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Affiliation(s)
- Thomas Pradeu
- ImmunoConcept, UMR5164, CNRS, University of Bordeaux, France.
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14
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Magallanes S, Møller AP, García-Longoria L, de Lope F, Marzal A. Volume and antimicrobial activity of secretions of the uropygial gland are correlated with malaria infection in house sparrows. Parasit Vectors 2016; 9:232. [PMID: 27114098 PMCID: PMC4845389 DOI: 10.1186/s13071-016-1512-7] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 04/14/2016] [Indexed: 11/18/2022] Open
Abstract
Background Animals have developed a wide range of defensive mechanisms against parasites to reduce the likelihood of infection and its negative fitness costs. The uropygial gland is an exocrine gland that produces antimicrobial and antifungal secretions with properties used as a defensive barrier on skin and plumage. This secretion has been proposed to affect the interaction between avian hosts and their ectoparasites. Because uropygial secretions may constitute a defense mechanism against ectoparasites, this may result in a reduction in prevalence of blood parasites that are transmitted by ectoparasitic vectors. Furthermore, other studies pointed out that vectors could be attracted by uropygial secretions and hence increase the probability of becoming infected. Here we explored the relationship between uropygial gland size, antimicrobial activity of uropygial secretions and malaria infection in house sparrows Passer domesticus. Methods A nested-PCR was used to identify blood parasites infection. Flow cytometry detecting absolute cell counting assessed antimicrobial activity of the uropygial gland secretion Results Uninfected house sparrows had larger uropygial glands and higher antimicrobial activity in uropygial secretions than infected individuals. We found a positive association between uropygial gland size and scaled body mass index, but only in uninfected sparrows. Female house sparrows had larger uropygial glands and higher antimicrobial activity of gland secretions than males. Conclusion These findings suggest that uropygial gland secretions may play an important role as a defensive mechanism against malaria infection.
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Affiliation(s)
- Sergio Magallanes
- Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain
| | - Anders Pape Møller
- Laboratoire d'Ecologie, Systématique et Evolution, CNRS UMR 8079, Université Paris-Sud, Bâtiment 362, F-91405, Orsay Cedex, France
| | - Luz García-Longoria
- Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain
| | - Florentino de Lope
- Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain
| | - Alfonso Marzal
- Departamento de Anatomía Biología Celular y Zoología, Universidad de Extremadura, Avda. de Elvas s/n, E-06006, Badajoz, Spain.
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