1
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Hawley L, Smalling KL, Glaberman S. Critical review of the phytohemagglutinin assay for assessing amphibian immunity. CONSERVATION PHYSIOLOGY 2023; 11:coad090. [PMID: 38090122 PMCID: PMC10714196 DOI: 10.1093/conphys/coad090] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 09/15/2023] [Accepted: 10/26/2023] [Indexed: 04/26/2024]
Abstract
Infectious diseases are a major driver of the global amphibian decline. In addition, many factors, including genetics, stress, pollution, and climate change can influence the response to pathogens. Therefore, it is important to be able to evaluate amphibian immunity in the laboratory and in the field. The phytohemagglutinin (PHA) assay is an inexpensive and relatively non-invasive tool that has been used extensively to assess immunocompetence, especially in birds, and more recently in amphibians. However, there is substantial variation in experimental methodology among amphibian PHA studies in terms of species and life stages, PHA doses and injection sites, and use of experimental controls. Here, we compile and compare all known PHA studies in amphibians to identify knowledge gaps and develop best practices for future work. We found that research has only been conducted on a limited number of species, which may not reflect the diversity of amphibians. There is also a lack of validation studies in most species, so that doses and timing of PHA injection and subsequent swelling measurements may not effectively evaluate immunocompetence. Based on these and other findings, we put forward a set of recommendations to make future PHA studies more consistent and improve the ability to utilize this assay in wild populations, where immune surveillance is greatly needed.
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Affiliation(s)
- Lauren Hawley
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
| | - Kelly L Smalling
- New Jersey Water Science Center, U.S. Geological Survey, Lawrenceville, NJ, USA
| | - Scott Glaberman
- Department of Environmental Science and Policy, George Mason University, Fairfax, VA, USA
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2
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Goodman RM, Carman HR, Mahaffy RP, Cabrera NS. Trace Amounts of Ranavirus Detected in Common Musk Turtles ( Sternotherus odoratus) at a Site Where the Pathogen Was Previously Common. Animals (Basel) 2023; 13:2951. [PMID: 37760351 PMCID: PMC10526040 DOI: 10.3390/ani13182951] [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: 08/15/2023] [Revised: 09/07/2023] [Accepted: 09/14/2023] [Indexed: 09/29/2023] Open
Abstract
Ranaviruses are global multi-host pathogens that infect ectothermic vertebrates and cause mass mortality events in some species. In 2021-2022, we surveyed two species of aquatic turtles in a Virginia site where previous research found ranavirus in lizards (Sceloporus undulatus) and turtles (Chrysemys picta picta and Terrapene carolina carolina). We sampled tissues from 206 turtles and tested 249 samples (including recaptures) for ranavirus using qPCR. We detected trace amounts of ranavirus DNA in 2.8% of Common Musk Turtles (Sternotherus odoratus). We did not detect the virus in Eastern Painted Turtles (C. p. picta). The Ct values from animals carrying ranavirus corresponded to positive controls with a concentration of one copy of ranavirus DNA per microliter and likely reflect DNA in the environment rather than ranavirus infection in turtles. Turtles carrying ranavirus DNA came from only one pond in one year. The amount of ranavirus in our study site, as indicated by tissue samples from turtles, appears to have dropped dramatically since previous research conducted over a decade ago. This study represents the first report of ranavirus detected in S. odoratus and contributes to the scarce literature on longitudinal surveys of ranavirus in wild chelonians. We emphasize the need for large sample sizes and multi-year sampling to detect this pathogen in wild populations.
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Affiliation(s)
- Rachel M. Goodman
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA;
| | - Henry R. Carman
- The Watershed Research and Training Center, Hayfork, CA 96041, USA;
| | - R. Paul Mahaffy
- School of Physical Therapy, University of Lynchburg, Lynchburg, VA 24502, USA;
| | - Nathan S. Cabrera
- Department of Biology, Hampden-Sydney College, Hampden-Sydney, VA 23943, USA;
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3
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Assis VR, Robert J, Titon SCM. Introduction to the special issue Amphibian immunity: stress, disease and ecoimmunology. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220117. [PMID: 37305915 PMCID: PMC10258669 DOI: 10.1098/rstb.2022.0117] [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: 05/01/2023] [Accepted: 05/02/2023] [Indexed: 06/13/2023] Open
Abstract
Amphibian populations have been declining worldwide, with global climate changes and infectious diseases being among the primary causes of this scenario. Infectious diseases are among the primary drivers of amphibian declines, including ranavirosis and chytridiomycosis, which have gained more attention lately. While some amphibian populations are led to extinction, others are disease-resistant. Although the host's immune system plays a major role in disease resistance, little is known about the immune mechanisms underlying amphibian disease resistance and host-pathogen interactions. As ectotherms, amphibians are directly subjected to changes in temperature and rainfall, which modulate stress-related physiology, including immunity and pathogen physiology associated with diseases. In this sense, the contexts of stress, disease and ecoimmunology are essential for a better understanding of amphibian immunity. This issue brings details about the ontogeny of the amphibian immune system, including crucial aspects of innate and adaptive immunity and how ontogeny can influence amphibian disease resistance. In addition, the papers in the issue demonstrate an integrated view of the amphibian immune system associated with the influence of stress on immune-endocrine interactions. The collective body of research presented herein can provide valuable insights into the mechanisms underlying disease outcomes in natural populations, particularly in the context of changing environmental conditions. These findings may ultimately enhance our ability to forecast effective conservation strategies for amphibian populations. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
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Affiliation(s)
- Vania Regina Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, 05508-900 São Paulo, Brazil
- College of Public Health, University of South Florida, Tampa, FL 33612-9415, USA
| | - Jacques Robert
- Department of Microbiology and Immunology, University of Rochester, Rochester, NY 14642, USA
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4
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Bates KA, Friesen J, Loyau A, Butler H, Vredenburg VT, Laufer J, Chatzinotas A, Schmeller DS. Environmental and Anthropogenic Factors Shape the Skin Bacterial Communities of a Semi-Arid Amphibian Species. MICROBIAL ECOLOGY 2022:10.1007/s00248-022-02130-5. [PMID: 36445401 DOI: 10.1007/s00248-022-02130-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2022] [Accepted: 10/23/2022] [Indexed: 06/16/2023]
Abstract
The amphibian skin microbiome is important in maintaining host health, but is vulnerable to perturbation from changes in biotic and abiotic conditions. Anthropogenic habitat disturbance and emerging infectious diseases are both potential disrupters of the skin microbiome, in addition to being major drivers of amphibian decline globally. We investigated how host environment (hydrology, habitat disturbance), pathogen presence, and host biology (life stage) impact the skin microbiome of wild Dhofar toads (Duttaphrynus dhufarensis) in Oman. We detected ranavirus (but not Batrachochytrium dendrobatidis) across all sampling sites, constituting the first report of this pathogen in Oman, with reduced prevalence in disturbed sites. We show that skin microbiome beta diversity is driven by host life stage, water source, and habitat disturbance, but not ranavirus infection. Finally, although trends in bacterial diversity and differential abundance were evident in disturbed versus undisturbed sites, bacterial co-occurrence patterns determined through network analyses revealed high site specificity. Our results therefore provide support for amphibian skin microbiome diversity and taxa abundance being associated with habitat disturbance, with bacterial co-occurrence (and likely broader aspects of microbial community ecology) being largely site specific.
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Affiliation(s)
- K A Bates
- Department of Zoology, University of Oxford, Oxford, UK.
| | - J Friesen
- Centre for Environmental Biotechnology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - A Loyau
- Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Stechlin, Germany
- Laboratoire Écologie Fonctionnelle et Environnement, Université de Toulouse, INPT, UPS, Toulouse, France
| | - H Butler
- Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - V T Vredenburg
- Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - J Laufer
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
| | - A Chatzinotas
- Department of Environmental Microbiology, Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany
- Institute of Biology, Leipzig University, Leipzig, Germany
- German Centre for Integrative Biodiversity Research (iDiv), Halle-Jena-Leipzig, Leipzig, Germany
| | - D S Schmeller
- Laboratoire Écologie Fonctionnelle et Environnement, Université de Toulouse, INPT, UPS, Toulouse, France
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5
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Ford CE, Brookes LM, Skelly E, Sergeant C, Jordine T, Balloux F, Nichols RA, Garner TWJ. Non-Lethal Detection of Frog Virus 3-Like (RUK13) and Common Midwife Toad Virus-Like (PDE18) Ranaviruses in Two UK-Native Amphibian Species. Viruses 2022; 14:v14122635. [PMID: 36560639 PMCID: PMC9786228 DOI: 10.3390/v14122635] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Revised: 11/18/2022] [Accepted: 11/23/2022] [Indexed: 11/29/2022] Open
Abstract
Ranaviruses have been involved in amphibian mass mortality events worldwide. Effective screening to control this pathogen is essential; however, current sampling methods are unsuitable for the detection of subclinical infections. Non-lethal screening is needed to prevent both further spread of ranavirus and losses of at-risk species. To assess non-lethal sampling methods, we conducted two experiments: bath exposing common frogs to RUK13 ranavirus at three concentrations, and exposing common toads to RUK13 or PDE18. Non-lethal sampling included buccal, digit, body and tank swabs, along with toe clips and stool taken across three time-points post-exposure. The presence/load of ranavirus was examined using quantitative PCR in 11 different tissues obtained from the same euthanised animals (incl. liver, gastro-intestinal tract and kidney). Buccal swab screening had the highest virus detection rate in both species (62% frogs; 71% toads) and produced consistently high virus levels compared to other non-lethal assays. The buccal swab was effective across multiple stages of infection and differing infection intensities, though low levels of infection were more difficult to detect. Buccal swab assays competed with, and even outperformed, lethal sampling in frogs and toads, respectively. Successful virus detection in the absence of clinical signs was observed (33% frogs; 50% toads); we found no difference in detectability for RUK13 and PDE18. Our results suggest that buccal swabbing could replace lethal sampling for screening and be introduced as standard practice for ranavirus surveillance.
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Affiliation(s)
- Charlotte E. Ford
- School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
- Zoological Society of London, Institute of Zoology, Nuffield Building, Outer Circle, London NW8 7LS, UK
- UCL Genetics Institute, University College London, Gower Street, London WC1E 6BT, UK
- Correspondence: or
| | - Lola M. Brookes
- Zoological Society of London, Institute of Zoology, Nuffield Building, Outer Circle, London NW8 7LS, UK
- RVC Animal Welfare Science and Ethics, The Royal Veterinary College, Hawkshead Lane, Hatfield AL9 7TA, UK
| | - Emily Skelly
- Zoological Society of London, Institute of Zoology, Nuffield Building, Outer Circle, London NW8 7LS, UK
| | - Chris Sergeant
- Zoological Society of London, Institute of Zoology, Nuffield Building, Outer Circle, London NW8 7LS, UK
| | - Tresai Jordine
- Zoological Society of London, Institute of Zoology, Nuffield Building, Outer Circle, London NW8 7LS, UK
| | - Francois Balloux
- UCL Genetics Institute, University College London, Gower Street, London WC1E 6BT, UK
| | - Richard A. Nichols
- School of Biological and Behavioural Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | - Trenton W. J. Garner
- Zoological Society of London, Institute of Zoology, Nuffield Building, Outer Circle, London NW8 7LS, UK
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6
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Monk JD, Smith JA, Donadío E, Perrig PL, Crego RD, Fileni M, Bidder O, Lambertucci SA, Pauli JN, Schmitz OJ, Middleton AD. Cascading effects of a disease outbreak in a remote protected area. Ecol Lett 2022; 25:1152-1163. [PMID: 35175672 DOI: 10.1111/ele.13983] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/17/2022] [Accepted: 01/26/2022] [Indexed: 11/27/2022]
Abstract
Disease outbreaks induced by humans increasingly threaten wildlife communities worldwide. Like predators, pathogens can be key top-down forces in ecosystems, initiating trophic cascades that may alter food webs. An outbreak of mange in a remote Andean protected area caused a dramatic population decline in a mammalian herbivore (the vicuña), creating conditions to test the cascading effects of disease on the ecological community. By comparing a suite of ecological measurements to pre-disease baseline records, we demonstrate that mange restructured tightly linked trophic interactions previously driven by a mammalian predator (the puma). Following the mange outbreak, scavenger (Andean condor) occurrence in the ecosystem declined sharply and plant biomass and cover increased dramatically in predation refuges where herbivory was historically concentrated. The evidence shows that a disease-induced trophic cascade, mediated by vicuña density, could supplant the predator-induced trophic cascade, mediated by vicuña behaviour, thereby transforming the Andean ecosystem.
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Affiliation(s)
- Julia D Monk
- School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Justine A Smith
- Department of Wildlife, Fish, and Conservation Biology, University of California - Davis, Davis, California, USA
| | - Emiliano Donadío
- Fundación Rewilding Argentina, Los Antiguos, Santa Cruz, Argentina
| | - Paula L Perrig
- Grupo de Investigaciones en Biología de la Conservación, INIBIOMA - CONICET, Universidad Nacional del Comahue, Bariloche, Argentina.,Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Ramiro D Crego
- Conservation Ecology Center, Smithsonian National Zoo and Conservation Biology Institute, Front Royal, Virginia, USA
| | - Martin Fileni
- Facultad de Ciencias Naturales y Museo, Universidad Nacional de La Plata, La Plata, Buenos Aires, Argentina
| | - Owen Bidder
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, California, USA
| | - Sergio A Lambertucci
- Grupo de Investigaciones en Biología de la Conservación, INIBIOMA - CONICET, Universidad Nacional del Comahue, Bariloche, Argentina
| | - Jonathan N Pauli
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Oswald J Schmitz
- School of the Environment, Yale University, New Haven, Connecticut, USA
| | - Arthur D Middleton
- Department of Environmental Science, Policy, and Management, University of California - Berkeley, Berkeley, California, USA
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7
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Rubenina I, Kirjusina M, Ceirans A, Gravele E, Gavarane I, Pupins M, Krasnov BR. Environmental, anthropogenic, and spatial factors affecting species composition and species associations in helminth communities of water frogs (Pelophylax esculentus complex) in Latvia. Parasitol Res 2021; 120:3461-3474. [PMID: 34476585 DOI: 10.1007/s00436-021-07303-8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2021] [Accepted: 08/25/2021] [Indexed: 10/20/2022]
Abstract
We investigated factors affecting species composition and patterns of species associations in parasite communities of water frogs (Pelophylax esculentus complex), applying the distance-based redundancy analysis for component communities (assemblages harboured by host populations) and Markov random fields modelling for infracommunities (assemblages harboured by individual hosts), respectively. We asked (a) What are the relative effects of variation in environmental, land use (i.e., anthropogenic), and spatial factors on the variation in the species composition of component communities (i.e., in a locality)? and (b) What is the dominant pattern of species associations in infracommunities (in a host individual), and how do these associations vary along environmental and/or anthropogenic gradients? In component communities, the greatest portion of variation in helminth species composition was explained by the combined effects of space, anthropogenic pressure, and NDVI, with the pure effect of the spatial predictor being much stronger than the effects of the remaining predictors. In infracommunities, the probability of occurrence of some, but not all, helminth species depended on the occurrence of another species, with the numbers of negative and positive co-occurrences being equal. The strength and/or sign of associations of some species pairs were spatially stable, whereas interactions between other species pairs varied along the gradient of the amount of green vegetation, from negative to positive and vice versa. We conclude that the processes in parasite infracommunities and component communities in frogs are intertwined, with both bottom-up and top-down effects acting at different hierarchical scales.
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Affiliation(s)
- Ilze Rubenina
- Institute of Life Sciences and Technologies, Daugavpils University, Parades Street 1A, Daugavpils, 5401, Latvia.
| | - Muza Kirjusina
- Institute of Life Sciences and Technologies, Daugavpils University, Parades Street 1A, Daugavpils, 5401, Latvia
| | - Andris Ceirans
- Institute of Life Sciences and Technologies, Daugavpils University, Parades Street 1A, Daugavpils, 5401, Latvia
| | - Evita Gravele
- Institute of Life Sciences and Technologies, Daugavpils University, Parades Street 1A, Daugavpils, 5401, Latvia
| | - Inese Gavarane
- Institute of Life Sciences and Technologies, Daugavpils University, Parades Street 1A, Daugavpils, 5401, Latvia
| | - Mihails Pupins
- Institute of Life Sciences and Technologies, Daugavpils University, Parades Street 1A, Daugavpils, 5401, Latvia
| | - Boris R Krasnov
- Mitrani Department of Desert Ecology, Swiss Institute for Dryland Environmental and Energy Research, Jacob Blaustein Institutes for Desert Research, Ben-Gurion University of the Negev, Sede Boqer Campus, Midreshet Ben-Gurion, Israel
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8
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Gavel MJ, Young SD, Dalton RL, Soos C, McPhee L, Forbes MR, Robinson SA. Effects of two pesticides on northern leopard frog (Lithobates pipiens) stress metrics: Blood cell profiles and corticosterone concentrations. AQUATIC TOXICOLOGY (AMSTERDAM, NETHERLANDS) 2021; 235:105820. [PMID: 33819826 DOI: 10.1016/j.aquatox.2021.105820] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 02/12/2021] [Accepted: 03/22/2021] [Indexed: 06/12/2023]
Abstract
Amphibians are declining globally. Exposure to pesticides has been implicated in decreasing amphibian immune function, thus increasing their susceptibility to parasites and disease and thereby negatively affecting individuals and populations. Amphibians are likely exposed to neonicotinoids because these widely used insecticides are highly soluble in water and because amphibian freshwater habitats are often embedded in agroecosystems. Herein, we investigate the effects of long-term exposure to two individual neonicotinoids (clothianidin or thiamethoxam) at either low or high concentrations (2.5 or 250 µg/L) on northern leopard frog (Lithobates pipiens) blood cell profiles and concentrations of corticosterone, an energy-mediating hormone associated with stress. Larval frogs from Gosner stage 25 to 46 were exposed to pesticide and control treatments in outdoor mesocosms. Corticosterone concentrations were measured after 6 d of exposure, and blood cell profiles were assessed once frogs reached Gosner stage 46 (following 8 w of exposure). No significant changes were found in erythrocyte counts, leukocyte counts, monocyte to leukocyte ratios or corticosterone concentrations between treatments. However, exposure to either 2.5 or 250 µg/L of clothianidin, or 250 µg/L of thiamethoxam decreased neutrophil to lymphocyte ratios and neutrophil to leukocyte ratios, and exposure to 2.5 µg/L of clothianidin or 250 µg/L of thiamethoxam decreased eosinophil to leukocyte ratios. Our results indicate that long-term exposure to neonicotinoids can alter leukocyte profiles, indicative of a stress response. Future studies should investigate whether chronic exposure to neonicotinoids affect multiple measures of stress differently or influences the susceptibility of amphibians to parasites and pathogens. Our work underscores the importance of continued use of multiple measures of stress for different amphibian species when undertaking ecotoxicological assessments.
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Affiliation(s)
- Melody J Gavel
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Sarah D Young
- Department of Biology, Carleton University, Ottawa, Ontario, Canada; Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Science and Technology Branch, Environment and Climate Change Canada, Ottawa, Ontario, Canada
| | - Rebecca L Dalton
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Catherine Soos
- Department of Veterinary Pathology, University of Saskatchewan, Saskatoon, Canada; Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Science and Technology Branch, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
| | - Landon McPhee
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Science and Technology Branch, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
| | - Mark R Forbes
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Stacey A Robinson
- Ecotoxicology and Wildlife Health Division, Wildlife and Landscape Science Directorate, Science and Technology Branch, Environment and Climate Change Canada, Ottawa, Ontario, Canada.
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9
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Bielby J, Price SJ, Monsalve-CarcaÑo C, Bosch J. Host contribution to parasite persistence is consistent between parasites and over time, but varies spatially. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2021; 31:e02256. [PMID: 33164249 DOI: 10.1002/eap.2256] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2020] [Revised: 06/11/2020] [Accepted: 08/16/2020] [Indexed: 06/11/2023]
Abstract
Most parasites and pathogens infect multiple hosts, but a great deal of variation exists in the role of those hosts in persistence of infection. Understanding which hosts are most important in maintaining parasites can provide a clearer target for infection control. Recently developed empirical and theoretical approaches provide a way to quantify the relative contribution of hosts within a community and place them in a multi-host framework to better direct control efforts. Amphibians provide a framework for better understanding multi-host-multi-parasite dynamics. Two well-studied amphibian parasites, Batrachochytrium dendrobatidis (Bd) and Ranavirus, infect multiple host species and exhibit a great deal of heterogeneity in how they affect hosts. We used these two parasites and a community of five amphibian species to investigate the relative importance of hosts in parasite persistence, and how any patterns varied spatially and temporally. At two sites (Lake Ercina and Lake Lloroza in the Picos de Europa National Park, Spain) we collected data on the prevalence and shedding rate of parasite infection for both Bd and Ranavirus, and the abundance of each species' life stages. We used these data to parameterize a recently developed modeling framework, which was used to quantify the relative contribution of each host to the community reproductive number, R0 . By comparing each host-category over time and between sites we were able to identify consistencies in which host was responsible for the maintenance of these two parasites. Within a site one species consistently contributed the most to the persistence of both parasites. This consistency did not transfer between sites, the maintenance host species being different for each. At one site (Ercina), life stages of the common midwife toad, Alytes obstetricans, acted as the maintenance host for both Bd and Ranavirus. In contrast, at the second site, Lloroza, the alpine newt, Ichthyosaura alpestris, fulfilled that role. A single host species was responsible for infection persistence of both parasites at each lake. Attempts to control the infection levels and impacts of multiple parasites can benefit from a community epidemiology approach, and provide clarity on which hosts are the foci of mitigation efforts. However, at a small spatial scale, the target host may vary according to the physical qualities of those sites and the demographics of the host community.
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Affiliation(s)
- Jon Bielby
- School of Natural Sciences and Psychology, Liverpool John Moores University, James Parsons Building, Byrom Street, Liverpool, L3 3AF, United Kingdom
| | - Stephen J Price
- UCL Genetics Institute, Darwin Building, Gower Street, London, WC1E 6BT, United Kingdom
- Institute of Zoology, Zoological Society of London, Regents Park, London, NW1 4RY, United Kingdom
| | | | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, Madrid, 28006, Spain
- Research Unit of Biodiversity (CSIC, UO, PA), Oviedo University-Campus Mieres, Mieres, Spain
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10
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Abstract
Host-associated microbiomes contribute in many ways to the homeostasis of the metaorganism. The microbiome's contributions range from helping to provide nutrition and aiding growth, development, and behavior to protecting against pathogens and toxic compounds. Here we summarize the current knowledge of the diversity and importance of the microbiome to animals, using representative examples of wild and domesticated species. We demonstrate how the beneficial ecological roles of animal-associated microbiomes can be generally grouped into well-defined main categories and how microbe-based alternative treatments can be applied to mitigate problems for both economic and conservation purposes and to provide crucial knowledge about host-microbiota symbiotic interactions. We suggest a Customized Combination of Microbial-Based Therapies to promote animal health and contribute to the practice of sustainable husbandry. We also discuss the ecological connections and threats associated with animal biodiversity loss, microorganism extinction, and emerging diseases, such as the COVID-19 pandemic.
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Affiliation(s)
- Raquel S Peixoto
- Institute of Microbiology, Federal University of Rio de Janeiro, Rio de Janeiro 21941-901, Brazil; .,Current affiliation: Red Sea Research Center, Division of Biological and Environmental Science and Engineering, King Abdullah University of Science and Technology, Thuwal, 23955-6900 Saudia Arabia;
| | - Derek M Harkins
- J. Craig Venter Institute, Rockville, Maryland 20850, USA; ,
| | - Karen E Nelson
- J. Craig Venter Institute, Rockville, Maryland 20850, USA; ,
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11
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Bienentreu JF, Lesbarrères D. Amphibian Disease Ecology: Are We Just Scratching the Surface? HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - David Lesbarrères
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
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12
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Campbell LJ, Pawlik AH, Harrison XA. Amphibian ranaviruses in Europe: important directions for future research. Facets (Ott) 2020. [DOI: 10.1139/facets-2020-0007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Ranaviruses are an emerging group of pathogens capable of infecting all cold-blooded vertebrates. In Europe, ranaviruses pose a particularly potent threat to wild amphibian populations. Since the 1980s research on amphibian-infecting ranaviruses in Europe has been growing. The wide distribution of amphibian populations in Europe, the ease with which many are monitored, and the tractable nature of counterpart ex situ experimental systems have provided researchers with a unique opportunity to study many aspects of host–ranavirus interactions in the wild. These characteristics of European amphibian populations will also enable researchers to lead the way as the field of host–ranavirus interactions progresses. In this review, we provide a summary of the current key knowledge regarding amphibian infecting ranaviruses throughout Europe. We then outline important areas of further research and suggest practical ways each could be pursued. We address the study of potential interactions between the amphibian microbiome and ranaviruses, how pollution may exacerbate ranaviral disease either as direct stressors of amphibians or indirect modification of the amphibian microbiome. Finally, we discuss the need for continued surveillance of ranaviral emergence in the face of climate change.
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Affiliation(s)
- Lewis J. Campbell
- Department of Pathobiological Sciences, School of Veterinary Medicine, University of Wisconsin-Madison, Madison, WI 53711, USA
| | - Alice H. Pawlik
- Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall TR10 9FE, UK
| | - Xavier A. Harrison
- Centre for Ecology and Conservation, University of Exeter, Penryn, Cornwall TR10 9FE, UK
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13
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Harrison XA, Price SJ, Hopkins K, Leung WTM, Sergeant C, Garner TWJ. Diversity-Stability Dynamics of the Amphibian Skin Microbiome and Susceptibility to a Lethal Viral Pathogen. Front Microbiol 2019; 10:2883. [PMID: 31956320 PMCID: PMC6951417 DOI: 10.3389/fmicb.2019.02883] [Citation(s) in RCA: 43] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 11/29/2019] [Indexed: 12/20/2022] Open
Abstract
Variation among animals in their host-associated microbial communities is increasingly recognized as a key determinant of important life history traits including growth, metabolism, and resistance to disease. Quantitative estimates of the factors shaping the stability of host microbiomes over time at the individual level in non-model organisms are scarce. Addressing this gap in our knowledge is important, as variation among individuals in microbiome stability may represent temporal gain or loss of key microbial species and functions linked to host health and/or fitness. Here we use controlled experiments to investigate how both heterogeneity in microbial species richness of the environment and exposure to the emerging pathogen Ranavirus influence the structure and temporal dynamics of the skin microbiome in a vertebrate host, the European common frog (Rana temporaria). Our evidence suggests that altering the bacterial species richness of the environment drives divergent temporal microbiome dynamics of the amphibian skin. Exposure to ranavirus effects changes in skin microbiome structure irrespective of total microbial diversity, but individuals with higher pre-exposure skin microbiome diversity appeared to exhibit higher survival. Higher diversity skin microbiomes also appear less stable over time compared to lower diversity microbiomes, but stability of the 100 most abundant ("core") community members was similar irrespective of microbiome richness. Our study highlights the importance of extrinsic factors in determining the stability of host microbiomes over time, which may in turn have important consequences for the stability of host-microbe interactions and microbiome-fitness correlations.
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Affiliation(s)
- Xavier A Harrison
- Institute of Zoology, Zoological Society of London, London, United Kingdom.,Centre for Ecology and Conservation, University of Exeter, Exeter, United Kingdom
| | - Stephen J Price
- Institute of Zoology, Zoological Society of London, London, United Kingdom.,UCL Genetics Institute, University College London, London, United Kingdom
| | - Kevin Hopkins
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - William T M Leung
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - Chris Sergeant
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, London, United Kingdom
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14
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Groffen J, Oh SY, Kwon S, Jang Y, Borzée A. High mortality in Bufo gargarizans eggs associated with an undescribed Saprolegnia ferax strain in the Republic of Korea. DISEASES OF AQUATIC ORGANISMS 2019; 137:89-99. [PMID: 31854327 DOI: 10.3354/dao03434] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Pathogenic water molds have a significant impact on many species, especially amphibians. The genus Saprolegnia is a pathogenic oomycete restricted to aquatic and moist habitats, and its presence is strongly linked to the abundance of amphibians and fishes. We investigated the influence of Saprolegnia presence on egg mortality and egg occurrence under varying environmental conditions in the Asiatic toad Bufo gargarizans at 27 breeding sites in the Republic of Korea. We then assessed the impact of Saprolegnia on the presence of B. gargarizans at the 27 sites surveyed weekly during the B. gargarizans breeding season for 3 consecutive years. We used molecular tools to identify the water molds as belonging to an undescribed S. ferax strain. We demonstrated that the presence of S. ferax was positively associated with higher water conductivity and ponds. In addition, while S. ferax prevalence was associated with a reduction in B. gargarizans breeding activity and breeding success, we could not determine its impact on the subsequent breeding seasons. Our study highlights the potential negative effects of Saprolegnia on amphibian reproduction, although additional research is necessary to determine the relationship between Saprolegnia, its hosts and the impacts of habitat loss on amphibians.
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Affiliation(s)
- Jordy Groffen
- Department of Life Sciences and Division of EcoScience, Ewha Womans University, Seoul 04096, ROK
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15
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Rosa GM, Bosch J, Martel A, Pasmans F, Rebelo R, Griffiths RA, Garner TWJ. Sex‐biased disease dynamics increase extinction risk by impairing population recovery. Anim Conserv 2019. [DOI: 10.1111/acv.12502] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- G. M. Rosa
- Durrell Institute of Conservation and Ecology School of Anthropology and Conservation University of Kent CanterburyKent UK
- Institute of Zoology Zoological Society of London Regent's ParkLondon UK
- Centre for Ecology, Evolution and Environmental Changes (CE3C)Faculdade de Ciências da Universidade de LisboaLisboa Portugal
| | - J. Bosch
- Museo Nacional de Ciencias NaturalesCSIC Madrid Spain
| | - A. Martel
- Department of Pathology, Bacteriology and Avian Diseases Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - F. Pasmans
- Department of Pathology, Bacteriology and Avian Diseases Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - R. Rebelo
- Centre for Ecology, Evolution and Environmental Changes (CE3C)Faculdade de Ciências da Universidade de LisboaLisboa Portugal
| | - R. A. Griffiths
- Durrell Institute of Conservation and Ecology School of Anthropology and Conservation University of Kent CanterburyKent UK
| | - T. W. J. Garner
- Institute of Zoology Zoological Society of London Regent's ParkLondon UK
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16
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Price SJ, Leung WTM, Owen CJ, Puschendorf R, Sergeant C, Cunningham AA, Balloux F, Garner TWJ, Nichols RA. Effects of historic and projected climate change on the range and impacts of an emerging wildlife disease. GLOBAL CHANGE BIOLOGY 2019; 25:2648-2660. [PMID: 31074105 DOI: 10.1111/gcb.14651] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
The global trend of increasing environmental temperatures is often predicted to result in more severe disease epidemics. However, unambiguous evidence that temperature is a driver of epidemics is largely lacking, because it is demanding to demonstrate its role among the complex interactions between hosts, pathogens, and their shared environment. Here, we apply a three-pronged approach to understand the effects of temperature on ranavirus epidemics in UK common frogs, combining in vitro, in vivo, and field studies. Each approach suggests that higher temperatures drive increasing severity of epidemics. In wild populations, ranavirosis incidents were more frequent and more severe at higher temperatures, and their frequency increased through a period of historic warming in the 1990s. Laboratory experiments using cell culture and whole animal models showed that higher temperature increased ranavirus propagation, disease incidence, and mortality rate. These results, combined with climate projections, predict severe ranavirosis outbreaks will occur over wider areas and an extended season, possibly affecting larval recruitment. Since ranaviruses affect a variety of ectothermic hosts (amphibians, reptiles, and fish), wider ecological damage could occur. Our three complementary lines of evidence present a clear case for direct environmental modulation of these epidemics and suggest management options to protect species from disease.
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Affiliation(s)
- Stephen J Price
- UCL Genetics Institute, London, United Kingdom
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - William T M Leung
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | | | - Robert Puschendorf
- School of Biological and Marine Sciences, University of Plymouth, Devon, United Kingdom
| | - Chris Sergeant
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | | | | | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, London, United Kingdom
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17
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Oertli B, Parris KM. Review: Toward management of urban ponds for freshwater biodiversity. Ecosphere 2019. [DOI: 10.1002/ecs2.2810] [Citation(s) in RCA: 54] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Affiliation(s)
- Beat Oertli
- HEPIA, HES‐SO University of Applied Sciences and Arts Western Switzerland 150 Route de Presinge 1254 Jussy‐Geneva Switzerland
| | - Kirsten M. Parris
- School of Ecosystem and Forest Sciences The University of Melbourne Parkville Victoria 3010 Australia
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18
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Duffus ALJ, Garner TWJ, Nichols RA, Standridge JP, Earl JE. Modelling Ranavirus Transmission in Populations of Common Frogs ( Rana temporaria) in the United Kingdom. Viruses 2019; 11:v11060556. [PMID: 31208063 PMCID: PMC6630962 DOI: 10.3390/v11060556] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2019] [Revised: 05/31/2019] [Accepted: 06/04/2019] [Indexed: 12/13/2022] Open
Abstract
Ranaviruses began emerging in common frogs (Rana temporaria) in the United Kingdom in the late 1980s and early 1990s, causing severe disease and declines in the populations of these animals. Herein, we explored the transmission dynamics of the ranavirus(es) present in common frog populations, in the context of a simple susceptible-infected (SI) model, using parameters derived from the literature. We explored the effects of disease-induced population decline on the dynamics of the ranavirus. We then extended the model to consider the infection dynamics in populations exposed to both ulcerative and hemorrhagic forms of the ranaviral disease. The preliminary investigation indicated the important interactions between the forms. When the ulcerative form was present in a population and the hemorrhagic form was later introduced, the hemorrhagic form of the disease needed to be highly contagious, to persist. We highlighted the areas where further research and experimental evidence is needed and hope that these models would act as a guide for further research into the amphibian disease dynamics.
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Affiliation(s)
- Amanda L J Duffus
- Department of Mathematics and Natural Sciences, Gordon State College, Barnesville, GA 30204, USA.
| | | | - Richard A Nichols
- School of Biological and Chemical Sciences, Queen Mary, University of London, London E1 4NS, UK.
| | - Joshua P Standridge
- Department of Mathematics and Natural Sciences, Gordon State College, Barnesville, GA 30204, USA.
| | - Julia E Earl
- School of Biological Sciences, Louisiana Tech University, Ruston, LA 71272, USA.
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19
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Gavel MJ, Richardson SD, Dalton RL, Soos C, Ashby B, McPhee L, Forbes MR, Robinson SA. Effects of 2 Neonicotinoid Insecticides on Blood Cell Profiles and Corticosterone Concentrations of Wood Frogs (Lithobates sylvaticus). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2019; 38:1273-1284. [PMID: 30901102 DOI: 10.1002/etc.4418] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2018] [Revised: 01/19/2019] [Accepted: 03/14/2019] [Indexed: 06/09/2023]
Abstract
Neonicotinoids are widely used insecticides that are detectable in agricultural waterways. These insecticides are of concern due to their potential impacts on nontarget organisms. Pesticides can affect development of amphibians and suppress the immune system, which could impact disease susceptibility and tolerance. No previous studies on amphibians have examined the effects of these insecticides on differential blood cell proportions or concentrations of corticosterone (a general stress hormone). We investigated the effects of chronic exposure to 2 neonicotinoids, thiamethoxam and clothianidin, on immunometrics of wood frogs (Lithobates sylvaticus). Frogs were exposed to single, chronic treatments of 2.5 or 250 µg/L of clothianidin or thiamethoxam for 7 wk from Gosner stages 25 to 46. The juvenile frogs were then maintained for 3 wk post metamorphosis without exposure to neonicotinoids. We measured water-borne corticosterone twice: at 6 d and 8 wk after exposure in larval and juvenile frogs, respectively. We assessed differential blood cell profiles from juvenile frogs. Corticosterone was significantly lower in tadpoles exposed to 250 µg/L of thiamethoxam compared with other tadpole treatments, but no significant differences in corticosterone concentrations were found in treatments using juvenile frogs. Anemia was detected in all treatments compared with controls with the exception of tadpoles exposed to 2.5 µg/L of clothianidin. Neutrophil-to-leukocyte and neutrophil-to-lymphocyte ratios were elevated in frogs exposed to 250 µg/L of thiamethoxam. Collectively, these results indicate that chronic exposure to neonicotinoids has varied impacts on blood cell profiles and corticosterone concentrations of developing wood frogs, which are indicative of stress. Future studies should investigate whether exposure to neonicotinoids increases susceptibility to infection by parasites in both larval and adult wood frogs. Environ Toxicol Chem 2019;38:1273-1284. © 2019 Crown in the right of Canada. Published by Wiley Periodicals Inc. on behalf of SETAC.
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Affiliation(s)
- Melody J Gavel
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | | | - Rebecca L Dalton
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
- Science and Technology Branch, Science and Risk Assessment Directorate, Ecological Assessment Division, Environment and Climate Change Canada, Gatineau, Quebec, Canada
| | - Catherine Soos
- Science and Technology Branch, Wildlife and Landscape Science Directorate, Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
- Department of Veterinary Pathology, University of Saskatchewan, Saskatoon, Canada
| | - Brendan Ashby
- Science and Technology Branch, Wildlife and Landscape Science Directorate, Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
| | - Landon McPhee
- Science and Technology Branch, Wildlife and Landscape Science Directorate, Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, Saskatoon, Saskatchewan, Canada
| | - Mark R Forbes
- Department of Biology, Carleton University, Ottawa, Ontario, Canada
| | - Stacey A Robinson
- Science and Technology Branch, Wildlife and Landscape Science Directorate, Ecotoxicology and Wildlife Health Division, Environment and Climate Change Canada, Ottawa, Ontario, Canada
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20
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Campbell LJ, Garner TWJ, Tessa G, Scheele BC, Griffiths AGF, Wilfert L, Harrison XA. An emerging viral pathogen truncates population age structure in a European amphibian and may reduce population viability. PeerJ 2018; 6:e5949. [PMID: 30479902 PMCID: PMC6241393 DOI: 10.7717/peerj.5949] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2018] [Accepted: 10/17/2018] [Indexed: 11/20/2022] Open
Abstract
Infectious diseases can alter the demography of their host populations, reducing their viability even in the absence of mass mortality. Amphibians are the most threatened group of vertebrates globally, and emerging infectious diseases play a large role in their continued population declines. Viruses belonging to the genus Ranavirus are responsible for one of the deadliest and most widespread of these diseases. To date, no work has used individual level data to investigate how ranaviruses affect population demographic structure. We used skeletochronology and morphology to evaluate the impact of ranaviruses on the age structure of populations of the European common frog (Rana temporaria) in the UK. We compared ecologically similar populations that differed most notably in their historical presence or absence of ranavirosis (the acute syndrome caused by ranavirus infection). Our results suggest that ranavirosis may truncate the age structure of R. temporaria populations. One potential explanation for such a shift might be increased adult mortality and subsequent shifts in the life history of younger age classes that increase reproductive output earlier in life. Additionally, we constructed population projection models which indicated that such increased adult mortality could heighten the vulnerability of frog populations to stochastic environmental challenges.
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Affiliation(s)
- Lewis J Campbell
- Environment and Sustainability Institute, University of Exeter, Penryn, UK.,Institute of Zoology, Zoological Society of London, London, UK.,Department of Pathobiological Sciences, University of Wisconsin-Madison, Madison, WI, USA
| | | | - Giulia Tessa
- Life Sciences and Systems Biology, University of Turin, Turin, Italy
| | - Benjamin C Scheele
- Fenner School of Environment and Society, Australian National University, Canberra, ACT, Australia
| | | | - Lena Wilfert
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK.,Institute of Evolutionary Ecology and Conservation Genomics, Universität Ulm, Ulm, Germany
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21
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Youker-Smith TE, Boersch-Supan PH, Whipps CM, Ryan SJ. Environmental Drivers of Ranavirus in Free-Living Amphibians in Constructed Ponds. ECOHEALTH 2018; 15:608-618. [PMID: 30094775 PMCID: PMC6245063 DOI: 10.1007/s10393-018-1350-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 06/18/2018] [Accepted: 06/22/2018] [Indexed: 06/08/2023]
Abstract
Amphibian ranaviruses occur globally, but we are only beginning to understand mechanisms for emergence. Ranaviruses are aquatic pathogens which can cause > 90% mortality in larvae of many aquatic-breeding amphibians, making them important focal host taxa. Host susceptibilities and virulence of ranaviruses have been studied extensively in controlled laboratory settings, but research is needed to identify drivers of infection in natural environments. Constructed ponds, essential components of wetland restoration, have been associated with higher ranavirus prevalence than natural ponds, posing a conundrum for conservation efforts, and emphasizing the need to understand potential drivers. In this study, we analyzed 4 years of Frog virus 3 prevalence and associated environmental parameters in populations of wood frogs (Lithobates sylvaticus) and green frogs (Lithobates clamitans) in a constructed pond system. High prevalence was best predicted by low temperature, high host density, low zooplankton concentrations, and Gosner stages approaching metamorphosis. This study identified important variables to measure in assessments of ranaviral infection risk in newly constructed ponds, including effects of zooplankton, which have not been previously quantified in natural settings. Examining factors mediating diseases in natural environments, particularly in managed conservation settings, is important to both validate laboratory findings in situ, and to inform future conservation planning, particularly in the context of adaptive management.
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Affiliation(s)
- Tess E Youker-Smith
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY, 13210, USA
| | - Philipp H Boersch-Supan
- Quantitative Disease Ecology and Conservation (QDEC) Lab, Department of Geography, University of Florida, 3128 Turlington Hall, Gainesville, FL, 32601, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA
| | - Christopher M Whipps
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry, Syracuse, NY, 13210, USA
| | - Sadie J Ryan
- Quantitative Disease Ecology and Conservation (QDEC) Lab, Department of Geography, University of Florida, 3128 Turlington Hall, Gainesville, FL, 32601, USA.
- Emerging Pathogens Institute, University of Florida, Gainesville, FL, 32610, USA.
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22
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Effects of Emerging Infectious Diseases on Amphibians: A Review of Experimental Studies. DIVERSITY-BASEL 2018. [DOI: 10.3390/d10030081] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Numerous factors are contributing to the loss of biodiversity. These include complex effects of multiple abiotic and biotic stressors that may drive population losses. These losses are especially illustrated by amphibians, whose populations are declining worldwide. The causes of amphibian population declines are multifaceted and context-dependent. One major factor affecting amphibian populations is emerging infectious disease. Several pathogens and their associated diseases are especially significant contributors to amphibian population declines. These include the fungi Batrachochytrium dendrobatidis and B. salamandrivorans, and ranaviruses. In this review, we assess the effects of these three pathogens on amphibian hosts as found through experimental studies. Such studies offer valuable insights to the causal factors underpinning broad patterns reported through observational studies. We summarize key findings from experimental studies in the laboratory, in mesocosms, and from the field. We also summarize experiments that explore the interactive effects of these pathogens with other contributors of amphibian population declines. Though well-designed experimental studies are critical for understanding the impacts of disease, inconsistencies in experimental methodologies limit our ability to form comparisons and conclusions. Studies of the three pathogens we focus on show that host susceptibility varies with such factors as species, host age, life history stage, population and biotic (e.g., presence of competitors, predators) and abiotic conditions (e.g., temperature, presence of contaminants), as well as the strain and dose of the pathogen, to which hosts are exposed. Our findings suggest the importance of implementing standard protocols and reporting for experimental studies of amphibian disease.
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23
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Tornabene BJ, Blaustein AR, Briggs CJ, Calhoun DM, Johnson PTJ, McDevitt-Galles T, Rohr JR, Hoverman JT. The influence of landscape and environmental factors on ranavirus epidemiology in a California amphibian assemblage. FRESHWATER BIOLOGY 2018; 63:639-651. [PMID: 30127540 PMCID: PMC6097636 DOI: 10.1111/fwb.13100] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 02/16/2018] [Indexed: 06/08/2023]
Abstract
A fundamental goal of disease ecology is to determine the landscape and environmental processes that drive disease dynamics at different biological levels to guide management and conservation. Although ranaviruses (family Iridoviridae) are emerging amphibian pathogens, few studies have conducted comprehensive field surveys to assess potential drivers of ranavirus disease dynamics.We examined the factors underlying patterns in site-level ranavirus presence and individual-level ranavirus infection in 76 ponds and 1,088 individuals representing 5 amphibian species within the East Bay region of California.Based on a competing-model approach followed by variance partitioning, landscape and biotic variables explained the most variation in site-level presence. However, biotic and individual-level variables explained the most variation in individual-level infection.Distance to nearest ranavirus-infected pond (the landscape factor) was more important than biotic factors at the site-level; however, biotic factors were most influential at the individual-level. At the site level, the probability of ranavirus presence correlated negatively with distance to nearest ranavirus-positive pond, suggesting that the movement of water or mobile taxa (e.g., adult amphibians, birds, reptiles) may facilitate the movement of ranavirus between ponds and across the landscape.Taxonomic richness associated positively with ranavirus presence at the site-level, but vertebrate richness associated negatively with infection prevalence in the host population. This might reflect the contrasting influences of diversity on pathogen colonization versus transmission among hosts.Amphibian host species differed in their likelihood of ranavirus infection: American bullfrogs (Rana catesbeiana) had the weakest association with infection while rough-skinned newts (Taricha granulosa) had the strongest. After accounting for host species effects, hosts with greater snout-vent length had a lower probability of infection.Our study demonstrates the array of landscape, environmental, and individual-level factors associated with ranavirus epidemiology. Moreover, our study helps illustrate that the importance of these factors varies with biological level.
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Affiliation(s)
- Brian J Tornabene
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2061
| | - Andrew R Blaustein
- Integrative Biology, 3029 Cordley Hall, Oregon State University, Corvallis, OR 97331-2914
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9610
| | - Dana M Calhoun
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334
| | - Pieter T J Johnson
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334
| | - Travis McDevitt-Galles
- Department of Ecology and Evolutionary Biology, University of Colorado at Boulder, Boulder, CO 80309-0334
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620
| | - Jason T Hoverman
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN 47907-2061
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24
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Campbell LJ, Hammond SA, Price SJ, Sharma MD, Garner TWJ, Birol I, Helbing CC, Wilfert L, Griffiths AGF. A novel approach to wildlife transcriptomics provides evidence of disease-mediated differential expression and changes to the microbiome of amphibian populations. Mol Ecol 2018; 27:1413-1427. [PMID: 29420865 DOI: 10.1111/mec.14528] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2017] [Revised: 01/31/2018] [Accepted: 02/01/2018] [Indexed: 01/01/2023]
Abstract
Ranaviruses are responsible for a lethal, emerging infectious disease in amphibians and threaten their populations throughout the world. Despite this, little is known about how amphibian populations respond to ranaviral infection. In the United Kingdom, ranaviruses impact the common frog (Rana temporaria). Extensive public engagement in the study of ranaviruses in the UK has led to the formation of a unique system of field sites containing frog populations of known ranaviral disease history. Within this unique natural field system, we used RNA sequencing (RNA-Seq) to compare the gene expression profiles of R. temporaria populations with a history of ranaviral disease and those without. We have applied a RNA read-filtering protocol that incorporates Bloom filters, previously used in clinical settings, to limit the potential for contamination that comes with the use of RNA-Seq in nonlaboratory systems. We have identified a suite of 407 transcripts that are differentially expressed between populations of different ranaviral disease history. This suite contains genes with functions related to immunity, development, protein transport and olfactory reception among others. A large proportion of potential noncoding RNA transcripts present in our differentially expressed set provide first evidence of a possible role for long noncoding RNA (lncRNA) in amphibian response to viruses. Our read-filtering approach also removed significantly more bacterial reads from libraries generated from positive disease history populations. Subsequent analysis revealed these bacterial read sets to represent distinct communities of bacterial species, which is suggestive of an interaction between ranavirus and the host microbiome in the wild.
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Affiliation(s)
- Lewis J Campbell
- Environment and Sustainability Institute, University of Exeter, Penryn, UK.,Institute of Zoology, Zoological Society of London, London, UK
| | - Stewart A Hammond
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Stephen J Price
- Institute of Zoology, Zoological Society of London, London, UK.,UCL Genetics Institute, University College London, London, UK
| | - Manmohan D Sharma
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
| | | | - Inanc Birol
- Canada's Michael Smith Genome Sciences Centre, British Columbia Cancer Agency, Vancouver, BC, Canada
| | - Caren C Helbing
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Lena Wilfert
- Centre for Ecology and Conservation, University of Exeter, Penryn, UK
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25
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Kwon S, Park J, Choi WJ, Koo KS, Lee JG, Park D. First case of ranavirus-associated mass mortality in a natural population of the Huanren frog (Rana huanrenensis) tadpoles in South Korea. Anim Cells Syst (Seoul) 2017. [DOI: 10.1080/19768354.2017.1376706] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Affiliation(s)
- Sera Kwon
- Department of Biology, Kangwon National University, Chuncheon, South Korea
| | - Jaejin Park
- Department of Biology, Kangwon National University, Chuncheon, South Korea
| | - Woo-Jin Choi
- Department of Biology, Kangwon National University, Chuncheon, South Korea
| | - Kyo-Soung Koo
- Department of Biology, Kangwon National University, Chuncheon, South Korea
| | - Jin-Gu Lee
- Gyeonggido Agricultural Research and Extension Services, Hwaseong, South Korea
| | - Daesik Park
- Division of Science Education, Kangwon National University, Chuncheon, South Korea
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26
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Price SJ, Wadia A, Wright ON, Leung WTM, Cunningham AA, Lawson B. Screening of a long-term sample set reveals two Ranavirus lineages in British herpetofauna. PLoS One 2017; 12:e0184768. [PMID: 28931029 PMCID: PMC5607163 DOI: 10.1371/journal.pone.0184768] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2017] [Accepted: 08/30/2017] [Indexed: 11/18/2022] Open
Abstract
Reports of severe disease outbreaks in amphibian communities in mainland Europe due to strains of the common midwife toad virus (CMTV)-like clade of Ranavirus are increasing and have created concern due to their considerable population impacts. In Great Britain, viruses in another clade of Ranavirus-frog virus 3 (FV3)-like-have caused marked declines of common frog (Rana temporaria) populations following likely recent virus introductions. The British public has been reporting mortality incidents to a citizen science project since 1992, with carcasses submitted for post-mortem examination, resulting in a long-term tissue archive spanning 25 years. We screened this archive for ranavirus (458 individuals from 228 incidents) using molecular methods and undertook preliminary genotyping of the ranaviruses detected. In total, ranavirus was detected in 90 individuals from 41 incidents focused in the north and south of England. The majority of detections involved common frogs (90%) but also another anuran, a caudate and a reptile. Most incidents were associated with FV3-like viruses but two, separated by 300 km and 16 years, involved CMTV-like viruses. These British CMTV-like viruses were more closely related to ranaviruses from mainland Europe than to each other and were estimated to have diverged at least 458 years ago. This evidence of a CMTV-like virus in Great Britain in 1995 represents the earliest confirmed case of a CMTV associated with amphibians and raises important questions about the history of ranavirus in Great Britain and the epidemiology of CMTV-like viruses. Despite biases present in the opportunistic sample used, this study also demonstrates the role of citizen science projects in generating resources for research and the value of maintaining long-term wildlife tissue archives.
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Affiliation(s)
- Stephen J. Price
- UCL Genetics Institute, Gower Street, London, United Kingdom
- Institute of Zoology, ZSL, Regents Park, London, United Kingdom
- * E-mail:
| | - Alexandra Wadia
- Institute of Zoology, ZSL, Regents Park, London, United Kingdom
- University of York, York, United Kingdom
| | - Owen N. Wright
- Institute of Zoology, ZSL, Regents Park, London, United Kingdom
- School of Biosciences, Cardiff University, Cardiff, Wales, United Kingdom
| | | | | | - Becki Lawson
- Institute of Zoology, ZSL, Regents Park, London, United Kingdom
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From fish to frogs and beyond: Impact and host range of emergent ranaviruses. Virology 2017; 511:272-279. [PMID: 28860047 DOI: 10.1016/j.virol.2017.08.001] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 07/29/2017] [Accepted: 08/01/2017] [Indexed: 11/21/2022]
Abstract
Ranaviruses are pathogens of ectothermic vertebrates, including amphibians. We reviewed patterns of host range and virulence of ranaviruses in the context of virus genotype and postulate that patterns reflect significant variation in the historical and current host range of three groups of Ranavirus: FV3-like, CMTV-like and ATV-like ranaviruses. Our synthesis supports previous hypotheses about host range and jumps: FV3s are amphibian specialists, while ATVs are predominantly fish specialists that switched once to caudate amphibians. The most recent common ancestor of CMTV-like ranaviruses and FV3-like forms appears to have infected amphibians but CMTV-like ranaviruses may circulate in both amphibian and fish communities independently. While these hypotheses are speculative, we hope that ongoing efforts to describe ranavirus genetics, increased surveillance of host species and targeted experimental assays of susceptibility to infection and/or disease will facilitate better tests of the importance of hypothetical evolutionary drivers of ranavirus virulence and host range.
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DETECTION AND REPORTING OF RANAVIRUS IN AMPHIBIANS: EVALUATION OF THE ROLES OF THE WORLD ORGANISATION FOR ANIMAL HEALTH AND THE PUBLISHED LITERATURE. J Wildl Dis 2017; 53:509-520. [PMID: 28402726 DOI: 10.7589/2016-08-176] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Pathogens of wildlife can have direct impacts on human and livestock health as well as on biodiversity, as causative factors in population declines and extinctions. The World Organization for Animal Health (OIE) seeks to facilitate rapid sharing of information about animal diseases to enable up-to-date risk assessments of translocations of animals and animal products. The OIE also produces manuals of recommended methods to standardize diagnostic testing. Ranaviruses are important amphibian pathogens that may have spread through international trade, and infections became notifiable to OIE in 2009. We surveyed and reviewed published literature for data on sampling, diagnostic testing, and reporting of ranavirus during 2009-14. We also investigated attitudes and awareness of the OIE and its recommendations for best practice. We found that sampling effort is uneven and concentrated in the northern hemisphere. We also identified citizen science projects that have the potential to improve the quantity and quality of data on the incidence of ranavirus infection and the circumstances surrounding disease outbreaks. We found reporting of infection to be inconsistent: reporting was split between the published literature (where it was subject to a 2-yr lag) and the OIE with little overlap, results of negative diagnostic tests were underreported, and scientific researchers lacked awareness of the role of the OIE. Approaches to diagnostic screening were poorly harmonized and heavily reliant on molecular methods. These flaws in the mechanisms of ranavirus detection and reporting hamper the construction of a comprehensive disease information database.
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Campbell LJ, Head ML, Wilfert L, Griffiths AGF. An ecological role for assortative mating under infection? CONSERV GENET 2017; 18:983-994. [PMID: 32009857 PMCID: PMC6961493 DOI: 10.1007/s10592-017-0951-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2016] [Accepted: 03/01/2017] [Indexed: 11/29/2022]
Abstract
Wildlife diseases are emerging at a higher rate than ever before meaning that understanding their potential impacts is essential, especially for those species and populations that may already be of conservation concern. The link between population genetic structure and the resistance of populations to disease is well understood: high genetic diversity allows populations to better cope with environmental changes, including the outbreak of novel diseases. Perhaps following this common wisdom, numerous empirical and theoretical studies have investigated the link between disease and disassortative mating patterns, which can increase genetic diversity. Few however have looked at the possible link between disease and the establishment of assortative mating patterns. Given that assortative mating can reduce genetic variation within a population thus reducing the adaptive potential and long-term viability of populations, we suggest that this link deserves greater attention, particularly in those species already threatened by a lack of genetic diversity. Here, we summarise the potential broad scale genetic implications of assortative mating patterns and outline how infection by pathogens or parasites might bring them about. We include a review of the empirical literature pertaining to disease-induced assortative mating. We also suggest future directions and methodological improvements that could advance our understanding of how the link between disease and mating patterns influences genetic variation and long-term population viability.
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Affiliation(s)
- L. J. Campbell
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
- Institute of Zoology, Zoological Society of London, Regent’s Park, London, NW1 4RY UK
| | - M. L. Head
- Division of Evolution, Ecology and Genetics, Research School of Biology, Australian National University, Canberra, ACT Australia
| | - L. Wilfert
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
| | - A. G. F. Griffiths
- Environment and Sustainability Institute, University of Exeter, Penryn Campus, Penryn, Cornwall TR10 9FE UK
- FoAM Kernow, Studio E, Jubilee Warehouse, Commercial Road, Penryn, Cornwall TR10 8FG UK
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Soto-Azat C, Peñafiel-Ricaurte A, Price SJ, Sallaberry-Pincheira N, García MP, Alvarado-Rybak M, Cunningham AA. Xenopus laevis and Emerging Amphibian Pathogens in Chile. ECOHEALTH 2016; 13:775-783. [PMID: 27682604 DOI: 10.1007/s10393-016-1186-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/23/2016] [Revised: 08/31/2016] [Accepted: 09/08/2016] [Indexed: 06/06/2023]
Abstract
Amphibians face an extinction crisis with no precedence. Two emerging infectious diseases, ranaviral disease caused by viruses within the genus Ranavirus and chytridiomycosis due to Batrachochytrium dendrobatidis (Bd), have been linked with amphibian mass mortalities and population declines in many regions of the globe. The African clawed frog (Xenopus laevis) has been indicated as a vector for the spread of these pathogens. Since the 1970s, this species has been invasive in central Chile. We collected X. laevis and dead native amphibians in Chile between 2011 and 2013. We conducted post-mortem examinations and molecular tests for Ranavirus and Bd. Eight of 187 individuals (4.3 %) tested positive for Ranavirus: seven X. laevis and a giant Chilean frog (Calyptocephallela gayi). All positive cases were from the original area of X. laevis invasion. Bd was found to be more prevalent (14.4 %) and widespread than Ranavirus, and all X. laevis Bd-positive animals presented low to moderate levels of infection. Sequencing of a partial Ranavirus gene revealed 100 % sequence identity with Frog Virus 3. This is the first report of Ranavirus in Chile, and these preliminary results are consistent with a role for X. laevis as an infection reservoir for both Ranavirus and Bd.
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Affiliation(s)
- Claudio Soto-Azat
- Facultad de Ecología y Recursos Naturales, Centro de Investigación Para la Sustentabilidad, Universidad Andres Bello, Republica 440, Santiago, Chile.
| | - Alexandra Peñafiel-Ricaurte
- Facultad de Ecología y Recursos Naturales, Centro de Investigación Para la Sustentabilidad, Universidad Andres Bello, Republica 440, Santiago, Chile
| | - Stephen J Price
- UCL Genetics Institute, Gower Street, London, WC1E 6BT, UK
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
| | - Nicole Sallaberry-Pincheira
- Facultad de Ecología y Recursos Naturales, Centro de Investigación Para la Sustentabilidad, Universidad Andres Bello, Republica 440, Santiago, Chile
| | - María Pía García
- Facultad de Ecología y Recursos Naturales, Centro de Investigación Para la Sustentabilidad, Universidad Andres Bello, Republica 440, Santiago, Chile
- Molecular Virology Laboratory, Fundación Ciencia & Vida, Av. Zañartu 1482, Ñuñoa, Chile
| | - Mario Alvarado-Rybak
- Facultad de Ecología y Recursos Naturales, Centro de Investigación Para la Sustentabilidad, Universidad Andres Bello, Republica 440, Santiago, Chile
| | - Andrew A Cunningham
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
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Price SJ, Garner TWJ, Cunningham AA, Langton TES, Nichols RA. Reconstructing the emergence of a lethal infectious disease of wildlife supports a key role for spread through translocations by humans. Proc Biol Sci 2016; 283:rspb.2016.0952. [PMID: 27683363 PMCID: PMC5046891 DOI: 10.1098/rspb.2016.0952] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Accepted: 08/31/2016] [Indexed: 12/22/2022] Open
Abstract
There have been few reconstructions of wildlife disease emergences, despite their extensive impact on biodiversity and human health. This is in large part attributable to the lack of structured and robust spatio-temporal datasets. We overcame logistical problems of obtaining suitable information by using data from a citizen science project and formulating spatio-temporal models of the spread of a wildlife pathogen (genus Ranavirus, infecting amphibians). We evaluated three main hypotheses for the rapid increase in disease reports in the UK: that outbreaks were being reported more frequently, that climate change had altered the interaction between hosts and a previously widespread pathogen, and that disease was emerging due to spatial spread of a novel pathogen. Our analysis characterized localized spread from nearby ponds, consistent with amphibian dispersal, but also revealed a highly significant trend for elevated rates of additional outbreaks in localities with higher human population density—pointing to human activities in also spreading the virus. Phylogenetic analyses of pathogen genomes support the inference of at least two independent introductions into the UK. Together these results point strongly to humans repeatedly translocating ranaviruses into the UK from other countries and between UK ponds, and therefore suggest potential control measures.
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Affiliation(s)
- Stephen J Price
- UCL Genetics Institute, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK Institute of Zoology, Zoological Society of London, London NW1 4RY, UK School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
| | | | | | - Tom E S Langton
- Herpetofauna Consultants International, Triton House, Bramfield, Halesworth, Suffolk IP19 9AE, UK
| | - Richard A Nichols
- School of Biological and Chemical Sciences, Queen Mary University of London, Mile End Road, London E1 4NS, UK
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32
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Bell BD. A review of potential alpine newt (Ichthyosaura alpestris) impacts on native frogs in New Zealand. J R Soc N Z 2016. [DOI: 10.1080/03036758.2016.1216455] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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MONITORING RANAVIRUS-ASSOCIATED MORTALITY IN A DUTCH HEATHLAND IN THE AFTERMATH OF A RANAVIRUS DISEASE OUTBREAK. J Wildl Dis 2016; 52:817-827. [PMID: 27455198 DOI: 10.7589/2015-04-104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ranaviruses are an emerging group of viruses that infect amphibians, fish, and reptiles. Although ranaviruses have not been linked to extinctions, emergence in amphibian communities has resulted in population declines for some species. We present the results of ranavirus-associated mortality in a Dutch national park in the aftermath of an outbreak associated with a common midwife toad virus (CMTV)-like ranavirus. We monitored five bodies of water across Dwingelderveld National Park, the Netherlands, in 2011-13. Dead and live amphibians were counted weekly July-September and every 2 wk in June and October. Dead amphibians were collected and tested for ranavirus infection. In addition, we measured biologic, chemical, and physical site characteristics to test for a correlation with ranavirus-associated mortality. Ranavirus infection was widespread in our study area and we observed nearly continuous presence of dead, ranavirus-infected amphibians in the presence of asymptomatic, live amphibians throughout our study. Fatalities occurred in larval, subadult, and adult amphibians. Ranavirus infection prevalence (based on fatal cases) was significantly associated with increasing fractions of adults and subadults compared to juveniles and larvae in the population, but was unrelated to any other measured site characteristics. Our findings showed that a CMTV-like ranavirus can persist long term in an ecosystem, affecting a diversity of amphibian species and life stages for a prolonged period. This study illustrates the importance of monitoring the modes of spread for ranaviruses and their impact on amphibian populations.
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Rijks JM, Saucedo B, Spitzen-van der Sluijs A, Wilkie GS, van Asten AJAM, van den Broek J, Boonyarittichaikij R, Stege M, van der Sterren F, Martel A, Pasmans F, Hughes J, Gröne A, van Beurden SJ, Kik MJL. Investigation of Amphibian Mortality Events in Wildlife Reveals an On-Going Ranavirus Epidemic in the North of the Netherlands. PLoS One 2016; 11:e0157473. [PMID: 27315226 PMCID: PMC4912076 DOI: 10.1371/journal.pone.0157473] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Accepted: 05/30/2016] [Indexed: 12/15/2022] Open
Abstract
In the four years following the first detection of ranavirus (genus Ranavirus, family Iridoviridae) infection in Dutch wildlife in 2010, amphibian mortality events were investigated nationwide to detect, characterize and map ranaviruses in amphibians over time, and to establish the affected host species and the clinico-pathological presentation of the disease in these hosts. The ultimate goal was to obtain more insight into ranavirus disease emergence and ecological risk. In total 155 dead amphibians from 52 sites were submitted between 2011 and 2014, and examined using histopathology, immunohistochemistry, virus isolation and molecular genetic characterization. Ranavirus-associated amphibian mortality events occurred at 18 sites (35%), initially only in proximity of the 2010 index site. Specimens belonging to approximately half of the native amphibian species were infected, including the threatened Pelobates fuscus (spadefoot toad). Clustered massive outbreaks involving dead adult specimens and ranavirus genomic identity indicated that one common midwife toad virus (CMTV)-like ranavirus strain is emerging in provinces in the north of the Netherlands. Modelling based on the spatiotemporal pattern of spread showed a high probability that this emerging virus will continue to be detected at new sites (the discrete reproductive power of this outbreak is 0.35). Phylogenetically distinct CMTV-like ranaviruses were found in the south of the Netherlands more recently. In addition to showing that CMTV-like ranaviruses threaten wild amphibian populations not only in Spain but also in the Netherlands, the current spread and risk of establishment reiterate that understanding the underlying causes of CMTV-like ranavirus emergence requires international attention.
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Affiliation(s)
- Jolianne M. Rijks
- Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands
- * E-mail:
| | - Bernardo Saucedo
- Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands
- Department of Pathobiology, Utrecht University, Utrecht, The Netherlands
| | | | - Gavin S. Wilkie
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Alphons J. A. M. van Asten
- Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands
- Department of Pathobiology, Utrecht University, Utrecht, The Netherlands
| | - Jan van den Broek
- Department of Farm Animal Health, Utrecht University, Utrecht, The Netherlands
| | | | - Marisca Stege
- Department of Pathobiology, Utrecht University, Utrecht, The Netherlands
| | | | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Merelbeke, Belgium
| | - Joseph Hughes
- MRC-University of Glasgow Centre for Virus Research, Glasgow, United Kingdom
| | - Andrea Gröne
- Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands
- Department of Pathobiology, Utrecht University, Utrecht, The Netherlands
| | | | - Marja J. L. Kik
- Dutch Wildlife Health Centre, Utrecht University, Utrecht, The Netherlands
- Department of Pathobiology, Utrecht University, Utrecht, The Netherlands
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