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Ujszegi J, Ujhegyi N, Balogh E, Mikó Z, Kásler A, Hettyey A, Bókony V. No sex-dependent mortality in an amphibian upon infection with the chytrid fungus, Batrachochytrium dendrobatidis. Ecol Evol 2024; 14:e70219. [PMID: 39219568 PMCID: PMC11362217 DOI: 10.1002/ece3.70219] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2024] [Revised: 08/07/2024] [Accepted: 08/09/2024] [Indexed: 09/04/2024] Open
Abstract
One of the major factors driving the currently ongoing biodiversity crisis is the anthropogenic spread of infectious diseases. Diseases can have conspicuous consequences, such as mass mortality events, but may also exert covert but similarly severe effects, such as sex ratio distortion via sex-biased mortality. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) is among the most important threats to amphibian biodiversity. Yet, whether Bd infection can skew sex ratios in amphibians is currently unknown, although such a hidden effect may cause the already dwindling amphibian populations to collapse. To investigate this possibility, we collected common toad (Bufo bufo) tadpoles from a natural habitat in Hungary and continuously treated them until metamorphosis with sterile Bd culture medium (control), or a liquid culture of a Hungarian or a Spanish Bd isolate. Bd prevalence was high in animals that died during the experiment but was almost zero in individuals that survived until the end of the experiment. Both Bd treatments significantly reduced survival after metamorphosis, but we did not observe sex-dependent mortality in either treatment. However, a small number of genotypically female individuals developed male phenotype (testes) in the Spanish Bd isolate treatment. Therefore, future research is needed to ascertain if larval Bd infection can affect sex ratio in common toads through female-to-male sex reversal.
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Affiliation(s)
- János Ujszegi
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of Systematic Zoology and EcologyELTE Eötvös Loránd UniversityBudapestHungary
| | - Nikolett Ujhegyi
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
| | - Emese Balogh
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of ZoologyUniversity of Veterinary Medicine BudapestBudapestHungary
| | - Zsanett Mikó
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
| | - Andrea Kásler
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of Systematic Zoology and EcologyELTE Eötvös Loránd UniversityBudapestHungary
- Doctoral School of Biology, Institute of BiologyELTE Eötvös Loránd UniversityBudapestHungary
| | - Attila Hettyey
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
- Department of Systematic Zoology and EcologyELTE Eötvös Loránd UniversityBudapestHungary
| | - Veronika Bókony
- Department of Evolutionary Ecology, HUN‐REN Centre for Agricultural ResearchPlant Protection InstituteBudapestHungary
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Thumsová B, Alarcos G, Ayres C, Rosa GM, Bosch J. Relationship between two pathogens in an amphibian community that experienced mass mortalities. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2024; 38:e14196. [PMID: 37811718 DOI: 10.1111/cobi.14196] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 08/28/2023] [Accepted: 09/28/2023] [Indexed: 10/10/2023]
Abstract
Because host species tend to harbor multiple parasitic species, coinfection in a host is common. The chytrid fungus Batrachochytrium dendrobatidis (Bd) and the viruses in the genus Ranavirus (Rv) are responsible for the decline of amphibians worldwide. Despite wide geographical co-occurrence and the serious conservation problem that coinfection with these pathogens could represent, little is known about their possible synergistic interactions and effects in a host community. We investigated the occurrence and associations between these two pathogens in an amphibian community after Rv-driven disease outbreaks were detected in four populations of the Iberian ribbed newt (Pleurodeles waltl) in northwestern Spain. We collected tissue samples from amphibians and fish and estimated Bd and Rv infection loads by qPCR. A few months after the most recent mass mortality event, Rv infection parameters at the affected sites decreased significantly or were lower than such registered at the sites where no outbreaks were recorded. Both pathogens were simultaneously present in almost all sites, but coinfection in a single host was rare. Our findings suggest that the co-occurrence of Bd and Rv does not predict adverse outcomes (e.g., enhanced susceptibility of hosts to one pathogen due to the presence or infection intensity of the other) following an outbreak. Other variables (such as species identity or site) were more important than infection with a pathogen in predicting the infection status and severity of infection with the other pathogen. Our results highlight the importance of host-specific and environmental characteristics in the dynamics of infections, coinfection patterns, and their impacts.
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Affiliation(s)
- Barbora Thumsová
- Asociación Herpetológica Española (AHE), Madrid, Spain
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
- IMIB-Research Unit of Biodiversity (University of Oviedo, CSIC, Principality of Asturias), Mieres, Spain
| | | | - Cesar Ayres
- Asociación Herpetológica Española (AHE), Madrid, Spain
| | - Gonçalo M Rosa
- Institute of Zoology, Zoological Society of London, London, UK
- Centre for Ecology, Evolution and Environmental Changes (cE3c), Faculdade de Ciências, Universidade de Lisboa, Lisboa, Portugal
| | - Jaime Bosch
- IMIB-Research Unit of Biodiversity (University of Oviedo, CSIC, Principality of Asturias), Mieres, Spain
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Meurling S, Siljestam M, Cortazar-Chinarro M, Åhlen D, Rödin-Mörch P, Ågren E, Höglund J, Laurila A. Body size mediates latitudinal population differences in the response to chytrid fungus infection in two amphibians. Oecologia 2024; 204:71-81. [PMID: 38097779 PMCID: PMC10830819 DOI: 10.1007/s00442-023-05489-5] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2021] [Accepted: 11/14/2023] [Indexed: 02/02/2024]
Abstract
Factors behind intraspecific variation in sensitivity to pathogens remain poorly understood. We investigated how geographical origin in two North European amphibians affects tolerance to infection by the chytrid fungus Batrachochytrium dendrobatidis (Bd), a generalist pathogen which has caused amphibian population declines worldwide. We exposed newly metamorphosed individuals of moor frog Rana arvalis and common toad Bufo bufo from two latitudinal regions to two different BdGPL strains. We measured survival and growth as infections may cause sub-lethal effects in fitness components even in the absence of mortality. Infection loads were higher in B. bufo than in R. arvalis, and smaller individuals had generally higher infection loads. B. bufo had high mortality in response to Bd infection, whereas there was little mortality in R. arvalis. Bd-mediated mortality was size-dependent and high-latitude individuals were smaller leading to high mortality in the northern B. bufo. Bd exposure led to sub-lethal effects in terms of reduced growth suggesting that individuals surviving the infection may have reduced fitness mediated by smaller body size. In both host species, the Swedish Bd strain caused stronger sublethal effects than the British strain. We suggest that high-latitude populations can be more vulnerable to chytrids than those from lower latitudes and discuss the possible mechanisms how body size and host geographical origin contribute to the present results.
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Affiliation(s)
- Sara Meurling
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Mattias Siljestam
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Maria Cortazar-Chinarro
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
- MEMEG/Department of Biology, Lund University, Lund, Sweden
- Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, Vancouver, Canada
| | - David Åhlen
- Department of Ecology, Environment and Plant Sciences, Stockholm University, Uppsala, Sweden
| | - Patrik Rödin-Mörch
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Erik Ågren
- Department of Pathology and Wildlife Diseases, National Veterinary Institute, Uppsala, Sweden
| | - Jacob Höglund
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden
| | - Anssi Laurila
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Uppsala, Sweden.
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4
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Vicente-Santos A, Willink B, Nowak K, Civitello DJ, Gillespie TR. Host-pathogen interactions under pressure: A review and meta-analysis of stress-mediated effects on disease dynamics. Ecol Lett 2023; 26:2003-2020. [PMID: 37804128 PMCID: PMC10874615 DOI: 10.1111/ele.14319] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2023] [Revised: 09/07/2023] [Accepted: 09/12/2023] [Indexed: 10/08/2023]
Abstract
Human activities have increased the intensity and frequency of natural stressors and created novel stressors, altering host-pathogen interactions and changing the risk of emerging infectious diseases. Despite the ubiquity of such anthropogenic impacts, predicting the directionality of outcomes has proven challenging. Here, we conduct a review and meta-analysis to determine the primary mechanisms through which stressors affect host-pathogen interactions and to evaluate the impacts stress has on host fitness (survival and fecundity) and pathogen infectivity (prevalence and intensity). We assessed 891 effect sizes from 71 host species (representing seven taxonomic groups) and 78 parasite taxa from 98 studies. We found that infected and uninfected hosts had similar sensitivity to stressors and that responses varied according to stressor type. Specifically, limited resources compromised host fecundity and decreased pathogen intensity, while abiotic environmental stressors (e.g., temperature and salinity) decreased host survivorship and increased pathogen intensity, and pollution increased mortality but decreased pathogen prevalence. We then used our meta-analysis results to develop susceptible-infected theoretical models to illustrate scenarios where infection rates are expected to increase or decrease in response to resource limitations or environmental stress gradients. Our results carry implications for conservation and disease emergence and reveal areas for future work.
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Affiliation(s)
- Amanda Vicente-Santos
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
| | - Beatriz Willink
- Department of Zoology, Stockholm University, Stockholm 106-91, Sweden
- Department of Biological Sciences, National University of Singapore, Singapore 117558, Singapore
- School of Biology, University of Costa Rica, San José 11501-2060, Costa Rica
| | - Kacy Nowak
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
| | - David J. Civitello
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Thomas R. Gillespie
- Population Biology, Ecology, and Evolution Program, Emory University, Atlanta, GA 30322, USA
- Department of Environmental Health, Rollins School of Public Health, Emory University, Atlanta, GA 30322, USA
- Department of Environmental Sciences, Emory University, Atlanta, GA 30322, USA
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5
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Ujszegi J, Boros Z, Fodor A, Vajna B, Hettyey A. Metabolites of Xenorhabdus bacteria are potent candidates for mitigating amphibian chytridiomycosis. AMB Express 2023; 13:88. [PMID: 37615904 PMCID: PMC10449739 DOI: 10.1186/s13568-023-01585-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2023] [Accepted: 07/20/2023] [Indexed: 08/25/2023] Open
Abstract
Chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has caused extreme losses in amphibian biodiversity. Finding bacteria that produce metabolites with antifungal properties may turn out to be invaluable in the fight against this devastating disease. The entomopathogenic bacteria, Xenorhabdus szentirmaii and X. budapestensis produce secondary metabolites that are effective against a wide range of fungal plant pathogens. To assess whether they may also be effective against Bd, we extracted cell-free culture media (CFCM) from liquid cultures of X. szentirmaii and X. budapestensis and tested their ability to inhibit Bd growth in vitro. As a second step, using juvenile common toads (Bufo bufo) experimentally infected with Bd we also tested the in vivo antifungal efficacy of X. szentirmaii CFCM diluted to 2 and 10% (v/v), while also assessing possible malign side effects on amphibians. Results of the in vitro experiment documented highly effective growth inhibition by CFCMs of both Xenorhabdus species. The in vivo experiment showed that treatment with CFCM of X. szentirmaii applied at a dilution of 10% resulted in infection intensities reduced by ca. 73% compared to controls and to juvenile toads treated with CFCM applied at a dilution of 2%. At the same time, we detected no negative side effects of treatment with CFCM on toad survival and development. Our results clearly support the idea that metabolites of X. szentirmaii, and perhaps of several other Xenorhabdus species as well, may prove highly useful for the treatment of Bd infected amphibians.
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Affiliation(s)
- János Ujszegi
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary.
- Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary.
| | - Zsófia Boros
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary
- Department of Genetics, Eötvös Loránd University, Budapest, Hungary
- Department of Microbiology, Eötvös Loránd University, Budapest, Hungary
| | - András Fodor
- Department of Genetics, Eötvös Loránd University, Budapest, Hungary
| | - Balázs Vajna
- Department of Microbiology, Eötvös Loránd University, Budapest, Hungary
| | - Attila Hettyey
- Department of Evolutionary Ecology, Plant Protection Institute, Centre for Agricultural Research, Eötvös Loránd Research Network, Budapest, Hungary
- Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest, Hungary
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Paetow LJ, Cue RI, Pauli BD, Marcogliese DJ. Effects of Herbicides and the Chytrid Fungus Batrachochytrium dendrobatidis on the growth, development and survival of Larval American Toads (Anaxyrus americanus). ECOTOXICOLOGY AND ENVIRONMENTAL SAFETY 2023; 259:115021. [PMID: 37216860 DOI: 10.1016/j.ecoenv.2023.115021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 05/08/2023] [Accepted: 05/14/2023] [Indexed: 05/24/2023]
Abstract
Pesticides and pathogens adversely affect amphibian health, but their interactive effects are not well known. We assessed independent and combined effects of two agricultural herbicides and the fungal pathogen Batrachochytrium dendrobatidis (Bd) on the growth, development and survival of larval American toads (Anaxyrus americanus). Wild-caught tadpoles were exposed to four concentrations of atrazine (0.18, 1.8, 18.0, 180 μg/L) or glyphosate (7, 70, 700, 7000 µg a.e./L), respectively contained in Aatrex® Liquid 480 (Syngenta) or Vision® Silviculture Herbicide (Monsanto) for 14 days, followed by two doses of Bd. At day 14, atrazine had not affected survival, but it non-monotonically affected growth. Exposure to the highest concentration of glyphosate caused 100% mortality within 4 days, while lower doses had an increasing monotonic effect on growth. At day 65, tadpole survival was unaffected by atrazine and the lower doses of glyphosate. Neither herbicide demonstrated an interaction effect with Bd on survival, but exposure to Bd increased survival among both herbicide-exposed and herbicide-control tadpoles. At day 60, tadpoles exposed to the highest concentration of atrazine remained smaller than controls, indicating longer-term effects of atrazine on growth, but effects of glyphosate on growth disappeared. Growth was unaffected by any herbicide-fungal interaction but was positively affected by exposure to Bd following exposure to atrazine. Atrazine exhibited a slowing and non-monotonic effect on Gosner developmental stage, while exposure to Bd tended to speed up development and act antagonistically toward the observed effect of atrazine. Overall, atrazine, glyphosate and Bd all showed a potential to modulate larval toad growth and development.
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Affiliation(s)
- Linda J Paetow
- Department of Biology, Concordia University, 7141 Sherbrooke St. W, Montreal, Quebec H4B 1R6, Canada.
| | - Roger I Cue
- Department of Animal Science, McGill University, 21111 Lakeshore Rd., Ste. Anne-de-Bellevue, Quebec H9X 3V9, Canada
| | - Bruce D Pauli
- Environment and Climate Change Canada, National Wildlife Research Centre, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario K1A 0H3, Canada
| | - David J Marcogliese
- Aquatic Contaminants Research Division, Water Science and Technology Directorate, Science and Technology Branch, St. Lawrence Centre, Environment and Climate Change Canada, 105 McGill, 7th Floor, Montreal, Quebec H2Y 2E7, Canada
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Bosch J, Thumsová B, Puschendorf R, Bielby J. Drivers of Batrachochytrium dendrobatidis infection load, with evidence of infection tolerance in adult male toads (Bufo spinosus). Oecologia 2023; 202:165-174. [PMID: 37147397 DOI: 10.1007/s00442-023-05380-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 04/25/2023] [Indexed: 05/07/2023]
Abstract
Chytridiomycosis is affecting hundreds of amphibian species worldwide, but while in tropical areas, adult individuals have been the focus of most investigations, the exact role played by infection intensity of breeding adults is not well understood in temperate areas. We conducted mark-recapture-capture surveys during spiny common toad breeding seasons from 2006 to 2018 at the site of the first recorded outbreak of chytridiomycosis in Europe, the Peñalara Massif (Sierra de Guadarrama National Park, central Spain), and collected infection samples and several variables related to the reproductive effort of male individuals. We used general linear mixed models to evaluate the contribution of study variables on the infection loads of adult male toads exhibited at their capturing date. We also analysed the differences on several male characteristics between the pond with the largest breeding population against the rest of the ponds. We found that the duration of time spent in the waterbody and the condition of the host predicted infection loads. Animals of good physical condition, that spent longer in water, have higher infection levels than individuals with the opposite set of traits. The pond supporting the largest breeding population housed smaller male toads and in poorer condition. Our results are consistent with a shift in reproductive strategy in response to infection and potentially a strategy of tolerance, rather than resistance to infection. These findings have applications for disease mitigation and theoretical implications related to the trade-offs made and the evolution of traits in response to the disease.
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Affiliation(s)
- Jaime Bosch
- Biodiversity Research Institute (IMIB), CSIC-University of Oviedo-Principality of Asturias, Mieres, Spain.
- Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Rascafría, Spain.
| | - Barbora Thumsová
- Asociación Herpetológica Española (AHE), Madrid, Spain
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
| | - Robert Puschendorf
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | - Jon Bielby
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
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Alonso A, Monroy S, Bosch J, Pérez J, Boyero L. Amphibian loss alters periphyton structure and invertebrate growth in montane streams. J Anim Ecol 2022; 91:2329-2337. [PMID: 36177539 PMCID: PMC9828351 DOI: 10.1111/1365-2656.13818] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Accepted: 09/23/2022] [Indexed: 01/12/2023]
Abstract
Amphibians are declining worldwide due to a combination of stressors such as climate change, invasive species, habitat loss, pollution and emergent diseases. Although their losses are likely to have important ecological consequences on the structure and functioning of freshwater ecosystems, this issue has been scarcely explored. We conducted an experiment in three montane streams-where primary production is the main source of energy and carbon-to assess the effects of amphibian disappearance (i.e. presence or absence of the common midwife toad Alytes obstetricans, a common species found in pools of these streams) on several aspects of ecosystem functioning and structure: periphyton biomass and chlorophyll a concentration, algal assemblage structure, and growth of macroinvertebrate grazers. We compared four types of experimental enclosures: (i) without macroinvertebrates or amphibians; (ii) with larvae of the caddisfly Allogamus laureatus; (iii) with A. obstetricans tadpoles; and (iv) with both A. laureatus larvae and A. obstetricans tadpoles. The absence of tadpoles increased periphyton biomass, but did not cause differences on inorganic sediment accrual. The algal assemblage had a higher diversity in the absence of tadpoles, and their characteristic taxa differed from the assemblages in presence of tadpoles. A. laureatus presented higher mass in presence of tadpoles; however, tadpole length was not affected by presence of macroinvertebrates. Our results suggest that presence of tadpoles is a driver of periphyton accrual and assemblage structure, acting as top-down control and with key potential consequences on the functioning of montane stream ecosystems.
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Affiliation(s)
- Alberto Alonso
- Department of Plant Biology and Ecology, Faculty of Science and TechnologyUniversity of the Basque Country (UPV/EHU)LeioaSpain
| | - Silvia Monroy
- Department of Plant Biology and Ecology, Faculty of Science and TechnologyUniversity of the Basque Country (UPV/EHU)LeioaSpain
| | - Jaime Bosch
- IMIB‐Research Unit of Biodiversity (CSIC, UO, PA)Oviedo University‐Campus MieresMieresSpain,Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de GuadarramaRascafríaSpain
| | - Javier Pérez
- Department of Plant Biology and Ecology, Faculty of Science and TechnologyUniversity of the Basque Country (UPV/EHU)LeioaSpain
| | - Luz Boyero
- Department of Plant Biology and Ecology, Faculty of Science and TechnologyUniversity of the Basque Country (UPV/EHU)LeioaSpain,IKERBASQUE, Basque Foundation for ScienceBilbaoSpain
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Humphries JE, Lanctôt CM, Robert J, McCallum HI, Newell DA, Grogan LF. Do immune system changes at metamorphosis predict vulnerability to chytridiomycosis? An update. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2022; 136:104510. [PMID: 35985564 DOI: 10.1016/j.dci.2022.104510] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2022] [Revised: 06/20/2022] [Accepted: 07/15/2022] [Indexed: 06/15/2023]
Abstract
Amphibians are among the vertebrate groups suffering great losses of biodiversity due to a variety of causes including diseases, such as chytridiomycosis (caused by the fungal pathogens Batrachochytrium dendrobatidis and B. salamandrivorans). The amphibian metamorphic period has been identified as being particularly vulnerable to chytridiomycosis, with dramatic physiological and immunological reorganisation likely contributing to this vulnerability. Here, we overview the processes behind these changes at metamorphosis and then perform a systematic literature review to capture the breadth of empirical research performed over the last two decades on the metamorphic immune response. We found that few studies focused specifically on the immune response during the peri-metamorphic stages of amphibian development and fewer still on the implications of their findings with respect to chytridiomycosis. We recommend future studies consider components of the immune system that are currently under-represented in the literature on amphibian metamorphosis, particularly pathogen recognition pathways. Although logistically challenging, we suggest varying the timing of exposure to Bd across metamorphosis to examine the relative importance of pathogen evasion, suppression or dysregulation of the immune system. We also suggest elucidating the underlying mechanisms of the increased susceptibility to chytridiomycosis at metamorphosis and the associated implications for population persistence. For species that overlap a distribution where Bd/Bsal are now endemic, we recommend a greater focus on management strategies that consider the important peri-metamorphic period.
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Affiliation(s)
- Josephine E Humphries
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland, 4222, Australia; Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, 2480, Australia.
| | - Chantal M Lanctôt
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Australian Rivers Institute, Griffith University, Southport, Queensland, 4222, Australia
| | - Jacques Robert
- Department of Microbiology and Immunology, University of Rochester Medical Center, 14642, Rochester, NY, United States
| | - Hamish I McCallum
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland, 4222, Australia
| | - David A Newell
- Faculty of Science and Engineering, Southern Cross University, Lismore, New South Wales, 2480, Australia
| | - Laura F Grogan
- School of Environment and Science, Griffith University, Southport, Queensland, 4222, Australia; Centre for Planetary Health and Food Security, Griffith University, Southport, Queensland, 4222, Australia
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Fu M, Waldman B. Novel chytrid pathogen variants and the global amphibian pet trade. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2022; 36:e13938. [PMID: 35561039 DOI: 10.1111/cobi.13938] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Accepted: 02/25/2022] [Indexed: 06/15/2023]
Abstract
Global wildlife trade spreads emerging infectious diseases that threaten biodiversity. The amphibian chytrid pathogen Batrachochytrium dendrobatidis (Bd) has caused population declines and species extinctions worldwide except in Asia. Fire-bellied toads (Bombina orientalis), exported in large numbers from Asia, are tolerant of Bd and carry hypervirulent ancestral chytrid BdAsia-1 variants. We assayed the virulence of a new isolate of BdAsia-1 on the model Australasian frog host Litoria caerulea. Infected individuals (n = 15) all showed rapid disease progression culminating in death, whereas sham-inoculated individuals (n = 10) presented no clinical signs of disease and all survived (log rank test, χ2 = 15.6, df = 1, p < 0.0001). The virulence of the new isolate of BdAsia-1 is comparable to the one we assayed previously (χ2 = 0.0, df = 1, p = 0.91). Internationally traded wildlife, even when they appear healthy, can carry hypervirulent variants of pathogens. Once new pathogen variants escape into the environment, native species that have had no opportunity to evolve resistance to them may perish. Our study suggests that hypervirulent pathogens are being spread by the international pet trade. Notifiable wildlife diseases attributable to locally endemic pathogens often fail to generate conservation concern so are rarely subject to border surveillance or import controls. Because of the danger novel variants pose, national border control agencies need to implement disease screening and quarantine protocols to ensure the safety of their endemic fauna.
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Affiliation(s)
- Minjie Fu
- School of Biological Sciences, Seoul National University, Seoul, South Korea
| | - Bruce Waldman
- School of Biological Sciences, Seoul National University, Seoul, South Korea
- Department of Integrative Biology, Oklahoma State University, Stillwater, Oklahoma, USA
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Cortazar-Chinarro M, Meurling S, Schroyens L, Siljestam M, Richter-Boix A, Laurila A, Höglund J. Major Histocompatibility Complex Variation and Haplotype Associated Survival in Response to Experimental Infection of Two Bd-GPL Strains Along a Latitudinal Gradient. Front Ecol Evol 2022. [DOI: 10.3389/fevo.2022.915271] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
While both innate and adaptive immune system mechanisms have been implicated in resistance against the chytrid fungus Batrachochytrium dendrobatidis (Bd), studies on the role of specific MHC haplotypes on Bd infection are rare. Here, we studied variation in MHC Class IIB loci in the common toad Bufo bufo along a latitudinal gradient across Sweden. In general, Swedish toad populations had few MHC Class IIB haplotypes and MHC diversity declined from south (13 haplotypes) to the north (four haplotypes). The low diversity may compromise the ability of northern populations to fight emerging disease, such as Bd. In a laboratory experiment, we infected newly metamorphosed toads with two strains of the Global Pandemic Lineage of the fungus (Bd-GPL) and compared survival with sham controls. Bd-infected toads had lower survival compared to controls. Moreover, survival was dependent on the Bd-strain and northern toads had lower Bd-mediated survival than southern individuals. MHC diversity was lower in northern toads. All northern experimental animals were monomorphic for a single MHC haplotype, whereas we found seven different haplotypes in southern experimental animals. In southern toads, survival was dependent on both Bd-strain and MHC haplotype suggesting differential infection dynamics depending on both Bd-strain and host immune system characteristics.
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12
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Cramp RL, Ohmer MEB, Franklin CE. UV exposure causes energy trade-offs leading to increased chytrid fungus susceptibility in green tree frog larvae. CONSERVATION PHYSIOLOGY 2022; 10:coac038. [PMID: 35795017 PMCID: PMC9252104 DOI: 10.1093/conphys/coac038] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Revised: 04/11/2022] [Accepted: 06/02/2022] [Indexed: 06/14/2023]
Abstract
Levels of ultraviolet (UV) radiation have increased in many parts of the world due to the anthropogenic destruction of the ozone layer. UV radiation is a potent immunosuppressant and can increase the susceptibility of animal hosts to pathogens. UV radiation can directly alter immune function via immunosuppression and photoimmunotolerance; however, UV may also influence pathogen defences by affecting the distribution of energy resources among competing physiological processes. Both defence against UV damage and repair of incurred damage, as well as the maintenance of immune defences and responding to an immune challenge, are energetically expensive. These competing demands for finite energy resources could trade off against one another, resulting in sub-optimal performance in one or both processes. We examined the potential for a disease-related energy trade-off in green tree frog (Litoria caerulea) larvae. Larvae were reared under high- or low-UV conditions for 12 weeks during which time we measured growth rates, metabolic rate and susceptibility to the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd). We found that larvae exposed to high levels of UV radiation had higher rates of energy expenditure than those exposed to low UV levels; however, UV exposure did not affect growth rates or developmental timings. Larvae exposed to high UV radiation also experienced greater Bd infection rates and carried a higher infection burden than those not exposed to elevated UV radiation. We propose that the increased energetic costs of responding to UV radiation were traded off against immune defences to protect larval growth rates. These findings have important implications for the aetiology of some Bd-associated amphibian declines, particularly in montane environments where Bd infections are most severe and where UV levels are highest.
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Affiliation(s)
- Rebecca L Cramp
- Corresponding author: School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia. Tel: +61 7 3365 8539.
| | - Michel E B Ohmer
- Department of Biology, University of Mississippi, MS, 38677, USA
| | - Craig E Franklin
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
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13
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Kásler A, Ujszegi J, Holly D, Üveges B, Móricz ÁM, Herczeg D, Hettyey A. Metamorphic common toads keep chytrid infection under control, but at a cost. J Zool (1987) 2022. [DOI: 10.1111/jzo.12974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- A. Kásler
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Doctoral School of Biology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
| | - J. Ujszegi
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Department of Systematic Zoology and Ecology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
| | - D. Holly
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Doctoral School of Biology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
| | - B. Üveges
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Molecular Ecology and Evolution at Bangor School of Natural Sciences Bangor University Bangor UK
| | - Á. M. Móricz
- Department of Pathophysiology Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
| | - D. Herczeg
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
| | - A. Hettyey
- Lendület Evolutionary Ecology Research Group Centre for Agricultural Research Plant Protection Institute Eötvös Loránd Research Network Budapest Hungary
- Department of Systematic Zoology and Ecology Institute of Biology ELTE Eötvös Loránd University Budapest Hungary
- Department of Ecology University of Veterinary Medicine Budapest Hungary
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14
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Daversa D, Bosch J, Manica A, Garner TWJ, Fenton A. Host identity matters – up to a point: the community context of Batrachochytrium dendrobatidis transmission. Am Nat 2022; 200:584-597. [DOI: 10.1086/720638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
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15
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Harjoe CC, Buck JC, Rohr JR, Roberts CE, Olson DH, Blaustein AR. Pathogenic fungus causes density‐ and trait‐mediated trophic cascades in an aquatic community. Ecosphere 2022. [DOI: 10.1002/ecs2.4043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Carmen C. Harjoe
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
| | - Julia C. Buck
- Department of Biology and Marine Biology University of North Carolina Wilmington Wilmington North Carolina USA
| | - Jason R. Rohr
- Department of Biological Sciences University of Notre Dame, Eck Institute for Global Health, and Environmental Change Initiative Notre Dame Indiana USA
| | - Claire E. Roberts
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
| | - Deanna H. Olson
- Pacific Northwest Research Station USDA Forest Service Corvallis Oregon USA
| | - Andrew R. Blaustein
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
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16
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Smith D, O'Brien D, Hall J, Sergeant C, Brookes LM, Harrison XA, Garner TWJ, Jehle R. Challenging a host-pathogen paradigm: Susceptibility to chytridiomycosis is decoupled from genetic erosion. J Evol Biol 2022; 35:589-598. [PMID: 35167143 PMCID: PMC9306973 DOI: 10.1111/jeb.13987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/07/2022] [Indexed: 11/26/2022]
Abstract
The putatively positive association between host genetic diversity and the ability to defend against pathogens has long attracted the attention of evolutionary biologists. Chytridiomycosis, a disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has emerged in recent decades as a cause of dramatic declines and extinctions across the amphibian clade. Bd susceptibility can vary widely across populations of the same species, but the relationship between standing genetic diversity and susceptibility has remained notably underexplored so far. Here, we focus on a putatively Bd-naive system of two mainland and two island populations of the common toad (Bufo bufo) at the edge of the species' range and use controlled infection experiments and dd-RAD sequencing of >10 000 SNPs across 95 individuals to characterize the role of host population identity, genetic variation and individual body mass in mediating host response to the pathogen. We found strong genetic differentiation between populations and marked variation in their susceptibility to Bd. This variation was not, however, governed by isolation-mediated genetic erosion, and individual heterozygosity was even found to be negatively correlated with survival. Individual survival during infection experiments was strongly positively related to body mass, which itself was unrelated to population of origin or heterozygosity. Our findings underscore the general importance of context-dependency when assessing the role of host genetic variation for the ability of defence against pathogens.
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Affiliation(s)
- Donal Smith
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
- Institute of ZoologyZoological Society of LondonLondonUK
| | | | | | - Chris Sergeant
- Institute of ZoologyZoological Society of LondonLondonUK
| | - Lola M. Brookes
- Institute of ZoologyZoological Society of LondonLondonUK
- Highland Amphibian and Reptile ProjectDingwallUK
- MRC Centre for Global Infectious Disease AnalysisImperial College School of Public HealthLondonUK
- Royal Veterinary CollegeHatfieldUK
| | - Xavier A. Harrison
- Institute of ZoologyZoological Society of LondonLondonUK
- Centre for Ecology and ConservationUniversity of ExeterExeterUK
| | | | - Robert Jehle
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
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17
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Bielby J, Sausor C, Monsalve-Carcaño C, Bosch J. Temperature and duration of exposure drive infection intensity with the amphibian pathogen Batrachochytrium dendrobatidis. PeerJ 2022; 10:e12889. [PMID: 35186480 PMCID: PMC8830297 DOI: 10.7717/peerj.12889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 01/14/2022] [Indexed: 01/11/2023] Open
Abstract
The intensity of a pathogen infection plays a key role in determining how the host responds to infection. Hosts with high infections are more likely to transmit infection to others, and are may be more likely to experience progression from infection to disease symptoms, to being physiologically compromised by disease. Understanding how and why hosts exhibit variation in infection intensity therefore plays a major part in developing and implementing measures aimed at controlling infection spread, its effects, and its chance of persisting and circulating within a population of hosts. To track the relative importance of a number of variables in determining the level of infection intensity, we ran field-surveys at two breeding sites over a 12 month period using marked larvae of the common midwife toad (Alyes obstetricans) and their levels of infection with the amphibian pathogen Batrachochytrium dendrobatidis (Bd). At each sampling occasion we measured the density of larvae, the temperature of the water in the 48 h prior to sampling, the period of time the sampled individual had been in the water body, the developmental (Gosner) stage and the intensity of Bd infection of the individual. Overall our data suggest that the temperature and the duration of time spent in the water play a major role in determining the intensity of Bd infection within an individual host. However, although the duration of time spent in the water was clearly associated with infection intensity, the relationship was negative: larvae that had spent less than 3-6 months in the water had significantly higher infection intensities than those that had spent over 12 months, although this infection intensity peaked between 9 and 12 months. This could be due to animals with heavier infections developing more quickly, suffering increased mortality or, more likely, losing their mouthparts (the only part of anuran larvae that can be infected with Bd). Overall, our results identify drivers of infection intensity, and potentially transmissibility and spread, and we attribute these differences to both host and pathogen biology.
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Affiliation(s)
- Jon Bielby
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | | | | | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain,Biodiversity Research Institute (University of Oviedo-CSIC-Principality of Asturias), Mieres, Spain
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18
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Adams AJ, Peralta-García A, Flores-López CA, Valdez-Villavicencio JH, Briggs CJ. High fungal pathogen loads and prevalence in Baja California amphibian communities: The importance of species, elevation, and historical context. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2021.e01968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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19
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Urbina J, Bredeweg EM, Blaustein AR, Garcia TS. Direct and Latent Effects of Pathogen Exposure Across Native and Invasive Amphibian Life Stages. Front Vet Sci 2021; 8:732993. [PMID: 34778428 PMCID: PMC8585985 DOI: 10.3389/fvets.2021.732993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Accepted: 09/28/2021] [Indexed: 11/13/2022] Open
Abstract
Emerging infectious diseases are one of the multiple factors contributing to the current "biodiversity crisis". As part of the worldwide biodiversity crisis, amphibian populations are declining globally. Chytridiomycosis, an emerging infectious disease, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is a major cause of amphibian population declines. This fungus primarily affects keratinized structures in larval, juvenile, and adult amphibians as well as heart function. However, we know little about how Bd can impact embryos as well as potential latent effects of Bd exposure over ontogeny. Using two different Bd strains and multiple exposure times, we examined the effects of Bd exposure in Pacific chorus frog (Pseudacris regilla), Western toad (Anaxyrus boreas) and American bullfrog (Lithobates catesbeianus) life stages. Using a factorial experimental design, embryos of these three species were exposed to Bd at early and late embryonic stages, with some individuals re-exposed after hatching. Embryonic Bd exposure resulted in differential survival as a function of host species, Bd strain and timing of exposure. P. regilla experienced embryonic mortality when exposed during later developmental stages to one Bd strain. There were no differences across the treatments in embryonic mortality of A. boreas and embryonic mortality of L. catesbeianus occurred in all Bd exposure treatments. We detected latent effects in A. boreas and L. catesbeianus larvae, as mortality increased when individuals had been exposed to any of the Bd strains during the embryonic stage. We also detected direct effects on larval mortality in all three anuran species as a function of Bd strain, and when individuals were double exposed (late in the embryonic stage and again as larvae). Our results suggest that exposure to Bd can directly affect embryo survival and has direct and latent effects on larvae survival of both native and invasive species. However, these impacts were highly context dependent, with timing of exposure and Bd strain influencing the severity of the effects.
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Affiliation(s)
- Jenny Urbina
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, OR, United States
| | - Evan M Bredeweg
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, OR, United States
| | - Andrew R Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States
| | - Tiffany S Garcia
- Department of Fisheries, Wildlife and Conservation Sciences, Oregon State University, Corvallis, OR, United States
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20
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Fisher MC, Pasmans F, Martel A. Virulence and Pathogenicity of Chytrid Fungi Causing Amphibian Extinctions. Annu Rev Microbiol 2021; 75:673-693. [PMID: 34351790 DOI: 10.1146/annurev-micro-052621-124212] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Ancient enzootic associations between wildlife and their infections allow evolution to innovate mechanisms of pathogenicity that are counterbalanced by host responses. However, erosion of barriers to pathogen dispersal by globalization leads to the infection of hosts that have not evolved effective resistance and the emergence of highly virulent infections. Global amphibian declines driven by the rise of chytrid fungi and chytridiomycosis are emblematic of emerging infections. Here, we review how modern biological methods have been used to understand the adaptations and counteradaptations that these fungi and their amphibian hosts have evolved. We explore the interplay of biotic and abiotic factors that modify the virulence of these infections and dissect the complexity of this disease system. We highlight progress that has led to insights into how we might in the future lessen the impact of these emerging infections. Expected final online publication date for the Annual Review of Microbiology, Volume 75 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Matthew C Fisher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial School of Public Health, Imperial College London, London W2 1PG, United Kingdom;
| | - Frank Pasmans
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - An Martel
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
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21
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Few Impacts of Introduced Cutthroat Trout (Oncorhynchus clarki) on Aquatic Stages of Boreal Toads (Anaxyrus boreas boreas). J HERPETOL 2021. [DOI: 10.1670/20-033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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22
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Ujszegi J, Ludányi K, Móricz ÁM, Krüzselyi D, Drahos L, Drexler T, Németh MZ, Vörös J, Garner TWJ, Hettyey A. Exposure to Batrachochytrium dendrobatidis affects chemical defences in two anuran amphibians, Rana dalmatina and Bufo bufo. BMC Ecol Evol 2021; 21:135. [PMID: 34217227 PMCID: PMC8254444 DOI: 10.1186/s12862-021-01867-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2020] [Accepted: 06/23/2021] [Indexed: 11/03/2022] Open
Abstract
Background Batrachochytrium dendrobatidis (Bd) is the causative agent of chytridiomycosis, one of the major causes of worldwide amphibian biodiversity loss. Many amphibians exhibit skin-based chemical defences, which may play an important role against invading pathogens, but whether the synthesis of these chemical compounds is enhanced or suppressed in the presence of pathogens is largely unknown. Here we investigated direct and indirect effects of larval exposure to the globally distributed and highly virulent Bd-GPL strain on skin secreted chemical defences and life history traits during early ontogeny of agile frogs (Rana dalmatina) and common toads (Bufo bufo). Results Exposure to Bd during the larval stage did not result in enhanced synthesis of the antimicrobial peptide Brevinin-1 Da in R. dalmatina tadpoles or in increased production of bufadienolides in B. bufo tadpoles. However, exposure to Bd during the larval stage had a carry-over effect reaching beyond metamorphosis: both R. dalmatina and B. bufo froglets contained smaller quantities of defensive chemicals than their Bd-naïve conspecifics in the control treatment. Prevalence of Bd and infection intensities were very low in both larvae and metamorphs of R. dalmatina, while in B. bufo we observed high Bd prevalence and infection intensities, especially in metamorphs. At the same time, we did not find a significant effect of Bd-exposure on body mass or development rate in larvae or metamorphs in either species. Conclusions The lack of detrimental effect of Bd-exposure on life history traits, even parallel with high infection intensities in the case of B. bufo individuals, is surprising and suggests high tolerance of local populations of these two species against Bd. However, the lowered quantity of defensive chemicals may compromise antimicrobial and antipredatory defences of froglets, which may ultimately contribute to population declines also in the absence of conspicuous mass-mortality events.
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Affiliation(s)
- János Ujszegi
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.
| | - Krisztina Ludányi
- Department of Pharmaceutics, Faculty of Pharmacy, Semmelweis University, Hőgyes Endre utca 7, Budapest, 1092, Hungary
| | - Ágnes M Móricz
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary
| | - Dániel Krüzselyi
- Department of Pathophysiology, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary
| | - László Drahos
- MS Proteomics Research Group, Institute of Organic Chemistry, Research Centre for Natural Sciences, Magyar tudósok körútja 2, Budapest, 1117, Hungary
| | - Tamás Drexler
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Ecology, Institute for Biology, University of Veterinary Medicine, Rottenbiller utca 50, Budapest, 1077, Hungary
| | - Márk Z Németh
- Department of Plant Pathology, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary
| | - Judit Vörös
- Department of Zoology, Hungarian Natural History Museum, Baross street 13, Budapest, 1088, Hungary
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK.,Unit for Environmental Sciences and Management, North-West University, Potchefstroom, 2520, South Africa
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Plant Protection Institute, Centre for Agricultural Research, Herman Ottó út 15, Budapest, 1022, Hungary.,Department of Ecology, Institute for Biology, University of Veterinary Medicine, Rottenbiller utca 50, Budapest, 1077, Hungary
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23
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Chytridiomycosis in Asian Amphibians, a Global Resource for Batrachochytrium dendrobatidis (Bd) Research. J Indian Inst Sci 2021; 101:227-241. [PMID: 34092943 PMCID: PMC8171229 DOI: 10.1007/s41745-021-00227-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 03/25/2021] [Indexed: 12/01/2022]
Abstract
Chytridiomycosis is an emerging infectious disease affecting amphibians globally and it is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). Chytridiomycosis has caused dramatic declines and even extinctions in wild amphibian populations in Europe, Australia, Central and North America. Spanning over two and a half decades, extensive research has led to discovery of epizootic and enzootic lineages of this pathogen. However, the Bd–amphibian system had garnered less attention in Asia until recently when an ancestral Bd lineage was identified in the Korean peninsula. Amphibians co-exist with the pathogen in Asia, only sub-lethal effects have been documented on hosts. Such regions are ‘coldspots’ of infection and are an important resource to understand the dynamics between the enzootic pathogen—Bd and its obligate host—amphibians. Insights into the biology of infection have provided new knowledge on the multi-faceted interaction of Bd in a hyperdiverse Asian amphibian community. We present the findings and highlight the knowledge gap that exists, and propose the ways to bridge them. We emphasize that chytridiomycosis in Asia is an important wildlife disease and it needs focussed research, as it is a dynamic front of pathogen diversity and virulence.
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24
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Farthing HN, Jiang J, Henwood AJ, Fenton A, Garner TWJ, Daversa DR, Fisher MC, Montagnes DJS. Microbial Grazers May Aid in Controlling Infections Caused by the Aquatic Zoosporic Fungus Batrachochytrium dendrobatidis. Front Microbiol 2021; 11:592286. [PMID: 33552011 PMCID: PMC7858660 DOI: 10.3389/fmicb.2020.592286] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/16/2020] [Indexed: 11/13/2022] Open
Abstract
Free-living eukaryotic microbes may reduce animal diseases. We evaluated the dynamics by which micrograzers (primarily protozoa) apply top-down control on the chytrid Batrachochytrium dendrobatidis (Bd) a devastating, panzootic pathogen of amphibians. Although micrograzers consumed zoospores (∼3 μm), the dispersal stage of chytrids, not all species grew monoxenically on zoospores. However, the ubiquitous ciliate Tetrahymena pyriformis, which likely co-occurs with Bd, grew at near its maximum rate (r = 1.7 d-1). A functional response (ingestion vs. prey abundance) for T. pyriformis, measured using spore-surrogates (microspheres) revealed maximum ingestion (I max ) of 1.63 × 103 zoospores d-1, with a half saturation constant (k) of 5.75 × 103 zoospores ml-1. Using these growth and grazing data we developed and assessed a population model that incorporated chytrid-host and micrograzer dynamics. Simulations using our data and realistic parameters obtained from the literature suggested that micrograzers could control Bd and potentially prevent chytridiomycosis (defined as 104 sporangia host-1). However, simulated inferior micrograzers (0.7 × I max and 1.5 × k) did not prevent chytridiomycosis, although they ultimately reduced pathogen abundance to below levels resulting in disease. These findings indicate how micrograzer responses can be applied when modeling disease dynamics for Bd and other zoosporic fungi.
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Affiliation(s)
- Hazel N. Farthing
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
- Department of Evolution, Ecology and Behaviour, Biosciences Building, University of Liverpool, Liverpool, United Kingdom
| | - Jiamei Jiang
- Shanghai Universities Key Laboratory of Marine Animal Taxonomy and Evolution, Key Laboratory of Exploration and Utilization of Aquatic Genetic Resources, National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai, China
| | - Alexandra J. Henwood
- Department of Evolution, Ecology and Behaviour, Biosciences Building, University of Liverpool, Liverpool, United Kingdom
| | - Andy Fenton
- Department of Evolution, Ecology and Behaviour, Biosciences Building, University of Liverpool, Liverpool, United Kingdom
| | - Trent W. J. Garner
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - David R. Daversa
- MRC Centre for Global Infectious Disease Analysis, Imperial College London, London, United Kingdom
| | - Matthew C. Fisher
- Department of Evolution, Ecology and Behaviour, Biosciences Building, University of Liverpool, Liverpool, United Kingdom
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - David J. S. Montagnes
- Department of Evolution, Ecology and Behaviour, Biosciences Building, University of Liverpool, Liverpool, United Kingdom
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25
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Oswald P, Rodríguez A, Bourke J, Wagner N, de Buhr N, Buschmann H, Köckritz-Blickwede MV, Pröhl H. Locality, time and heterozygosity affect chytrid infection in yellow-bellied toads. DISEASES OF AQUATIC ORGANISMS 2020; 142:225-237. [PMID: 33331290 DOI: 10.3354/dao03543] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) infects numerous amphibian species worldwide and is suggested to drive population declines and extinction events. We report a study of Bd infection at the northernmost distribution of the European yellow-bellied toad Bombina variegata. A total of 577 individuals from ponds in 16 study sites were sampled for DNA and Bd throughout the breeding season. Microsatellite genotyping revealed 3 genetic clusters for the host B. variegata with an overall low genetic diversity. One of the clusters displayed a low microsatellite heterozygosity, a high inbreeding coefficient as well as high Bd infection prevalence and intensities. Multi-model estimates identified site, time of sampling, and heterozygosity to be important predictors of an individual's Bd infection status, and identified a strong effect of site on individual Bd infection intensity. The study site effects are suggestive of localized infection peaks, and the increase of individual Bd infection probabilities towards the end of the sampling period suggests cumulative infection during the breeding season. This study highlights the need for regular monitoring of Bd infection variables at multiple localities and times to gain insights into Bd dynamics. Due to the detected relationship between individual Bd infection status and heterozygosity, conservation measures should focus on the maintenance of high genetic diversity and connectivity within and among amphibian populations.
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Affiliation(s)
- Pia Oswald
- Institute of Zoology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
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26
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Towards a food web based control strategy to mitigate an amphibian panzootic in agricultural landscapes. Glob Ecol Conserv 2020. [DOI: 10.1016/j.gecco.2020.e01314] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
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Bosch J, Carrascal LM, Manica A, Garner TWJ. Significant reductions of host abundance weakly impact infection intensity of Batrachochytrium dendrobatidis. PLoS One 2020; 15:e0242913. [PMID: 33253322 PMCID: PMC7703926 DOI: 10.1371/journal.pone.0242913] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2020] [Accepted: 11/10/2020] [Indexed: 11/19/2022] Open
Abstract
Infectious diseases are considered major threats to biodiversity, however strategies to mitigate their impacts in the natural world are scarce and largely unsuccessful. Chytridiomycosis is responsible for the decline of hundreds of amphibian species worldwide, but an effective disease management strategy that could be applied across natural habitats is still lacking. In general amphibian larvae can be easily captured, offering opportunities to ascertain the impact of altering the abundance of hosts, considered to be a key parameter affecting the severity of the disease. Here, we report the results of two experiments to investigate how altering host abundance affects infection intensity in amphibian populations of a montane area of Central Spain suffering from lethal amphibian chytridiomycosis. Our laboratory-based experiment supported the conclusion that varying density had a significant effect on infection intensity when salamander larvae were housed at low densities. Our field experiment showed that reducing the abundance of salamander larvae in the field also had a significant, but weak, impact on infection the following year, but only when removals were extreme. While this suggests adjusting host abundance as a mitigation strategy to reduce infection intensity could be useful, our evidence suggests only heavy culling efforts will succeed, which may run contrary to objectives for conservation.
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Affiliation(s)
- Jaime Bosch
- Research Unit of Biodiversity (CSIC, UO, PA), Gonzalo Gutiérrez Quirós s/n, Oviedo University - Campus Mieres, Edificio de Investigación, Mieres, Spain
- Centro de Investigación, Seguimiento y Evaluación, Rascafría, Spain
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
| | | | - Andrea Manica
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
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Meurling S, Kärvemo S, Chondrelli N, Cortazar Chinarro M, Åhlen D, Brookes L, Nyström P, Stenberg M, Garner TWJ, Höglund J, Laurila A. Occurrence of Batrachochytrium dendrobatidis in Sweden: higher infection prevalence in southern species. DISEASES OF AQUATIC ORGANISMS 2020; 140:209-218. [PMID: 32880378 DOI: 10.3354/dao03502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused worldwide declines in amphibian populations. While Bd is widespread in southern and central Europe, its occurrence and distribution in northernmost Europe is mostly unknown. We surveyed for Bd in breeding anurans in Sweden by sampling 1917 amphibians from 101 localities and 3 regions in Sweden (southern, northern and central). We found that Bd was widespread in southern and central Sweden, occurring in all 9 investigated species and in 45.5% of the 101 localities with an overall prevalence of 13.8%. No infected individuals were found in the 4 northern sites sampled. The records from central Sweden represent the northernmost records of Bd in Europe. While the proportion of sites positive for Bd was similar between the southern and central regions, prevalence was much higher in the southern region. This was because southern species with a distribution mainly restricted to southernmost Sweden had a higher prevalence than widespread generalist species. The nationally red-listed green toad Bufotes variabilis and the fire-bellied toad Bombina bombina had the highest prevalence (61.4 and 48.9%, respectively). Across species, Bd prevalence was strongly positively, correlated with water temperature at the start of egg laying. However, no individuals showing visual signs of chytridiomycosis were found in the field. These results indicate that Bd is widespread and common in southern and central Sweden with southern species, breeding in higher temperatures and with longer breeding periods, having higher prevalence. However, the impact of Bd on amphibian populations in northernmost Europe remains unknown.
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Affiliation(s)
- Sara Meurling
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
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Abstract
Discovering that chytrid fungi cause chytridiomycosis in amphibians represented a paradigm shift in our understanding of how emerging infectious diseases contribute to global patterns of biodiversity loss. In this Review we describe how the use of multidisciplinary biological approaches has been essential to pinpointing the origins of amphibian-parasitizing chytrid fungi, including Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, as well as to timing their emergence, tracking their cycles of expansion and identifying the core mechanisms that underpin their pathogenicity. We discuss the development of the experimental methods and bioinformatics toolkits that have provided a fuller understanding of batrachochytrid biology and informed policy and control measures.
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Crockett JG, Bailey LL, Muths E. Highly variable rates of survival to metamorphosis in wild boreal toads (
Anaxyrus boreas boreas
). POPUL ECOL 2020. [DOI: 10.1002/1438-390x.12044] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- John G. Crockett
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins Colorado
| | - Larissa L. Bailey
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins Colorado
| | - Erin Muths
- United States Geological Survey Fort Collins Science Center Fort Collins Colorado
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Barnhart KL, Bletz MC, LaBumbard BC, Tokash-Peters AG, Gabor CR, Woodhams DC. Batrachochytrium salamandrivorans ELICITS ACUTE STRESS RESPONSE IN SPOTTED SALAMANDERS BUT NOT INFECTION OR MORTALITY. Anim Conserv 2020; 23:533-546. [PMID: 33071596 DOI: 10.1111/acv.12565] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The emerging fungal pathogen Batrachochytrium salamandrivorans (Bsal) is a major threat to amphibian species worldwide with potential to infect many species if it invades salamander biodiversity hotspots in the Americas. Bsal can cause the disease chytridiomycosis, and it is important to assess the risk of Bsal-induced chytridiomycosis to species in North America. We evaluated the susceptibility to Bsal of the common and widespread spotted salamander, Ambystoma maculatum, across life history stages and monitored the effect of Bsal exposure on growth rate and response of the stress hormone, corticosterone. We conclude that spotted salamanders appear resistant to Bsal because they showed no indication of disease or infection, and experienced minor effects on growth upon exposure. While we focused on a single population for this study, results were consistent across conditions of exposure including high or repeated doses of Bsal, life-stage at exposure, environmental conditions including two temperatures and two substrates, and promoting pathogen infectivity by conditioning Bsal cultures with thyroid hormone. Exposure to high levels of Bsal elicited an acute but not chronic increase in corticosterone in spotted salamanders, and reduced growth. We hypothesize that the early acute increase in corticosterone facilitated mounting an immune response to the pathogen, perhaps through immunoredistribution to the skin, but further study is needed to determine immune responses to Bsal. These results will contribute to development of appropriate Bsal management plans to conserve species at risk of emerging disease.
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Affiliation(s)
- Kelly L Barnhart
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Molly C Bletz
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Brandon C LaBumbard
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Amanda G Tokash-Peters
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
| | - Caitlin R Gabor
- Texas State University, Department of Biology, 601 University Drive, San Marcos, TX 78666
| | - Douglas C Woodhams
- University of Massachusetts Boston, Department of Biology, 100 William T Morrissey Blvd, Boston, MA 02125
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32
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A subtle threat: behavioral and phenotypic consequences of invasive mosquitofish on a native paedomorphic newt. Biol Invasions 2019. [DOI: 10.1007/s10530-019-02181-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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LETHAL AND SUBLETHAL AMPHIBIAN HOST RESPONSES TO BATRACHOCHYTRIUM DENDROBATIDIS EXPOSURE ARE DETERMINED BY THE ADDITIVE INFLUENCE OF HOST RESOURCE AVAILABILITY. J Wildl Dis 2019. [PMID: 31769713 DOI: 10.7589/2019-01-021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Host species may differ in their responses to pathogen exposures based on host energy reserves, which could be important for long-term trends in host population growth. Batrachochytrium dendrobatidis (BD) is a pathogen associated with amphibian population declines but also occurs without causing mass mortalities. The impact of BD in populations without associated declines is not well understood, and food abundance could play a role in determining the magnitude of its effects. We exposed American toad (Anaxyrus americanus), northern leopard frog (Lithobates pipiens), and cricket frog (Acris blanchardi) metamorphs to BD under low or high food treatments. Overall, anuran species responded differently to BD exposure and the combined effect of BD exposure and food abundance was additive. American toad survival was lowered by BD exposure and low food availability. Based on these results, we developed a population model for American toads to estimate how reductions in survival could influence population growth. We found that BD could reduce population growth by 14% with high food availability and 21% with low food availability. In contrast, survival of northern leopard frogs was high across all treatments, but their growth was negatively impacted by the additive effects of BD exposure and low food availability. Cricket frog growth and survival were unaffected by BD exposure, suggesting that this species is not sensitive to the effects of this pathogen in terms of growth and survival across environments of different quality in the time period examined. Our results showed that low food availability additively increased the species-specific lethal and sublethal impacts of BD on hosts, which could have implications for long-term host population dynamics.
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Verbrugghe E, Van Rooij P, Favoreel H, Martel A, Pasmans F. In vitro modeling of Batrachochytrium dendrobatidis infection of the amphibian skin. PLoS One 2019; 14:e0225224. [PMID: 31725762 PMCID: PMC6855447 DOI: 10.1371/journal.pone.0225224] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Accepted: 10/30/2019] [Indexed: 11/19/2022] Open
Abstract
The largest current disease-induced loss of vertebrate biodiversity is due to chytridiomycosis and despite the increasing understanding of the pathogenesis, knowledge unravelling the early host-pathogen interactions remains limited. Batrachochytrium dendrobatidis (Bd) zoospores attach to and invade the amphibian epidermis, with subsequent invasive growth in the host skin. Availability of an in vitro assay would facilitate in depth study of this interaction while reducing the number of experimental animals needed. We describe a fluorescent cell-based in vitro infection model that reproduces host-Bd interactions. Using primary keratinocytes from Litoria caerulea and the epithelial cell line A6 from Xenopus laevis, we reproduced different stages of host cell infection and intracellular growth of Bd, resulting in host cell death, a key event in chytridiomycosis. The presented in vitro models may facilitate future mechanistic studies of host susceptibility and pathogen virulence.
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Affiliation(s)
- Elin Verbrugghe
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
- * E-mail:
| | - Pascale Van Rooij
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Herman Favoreel
- Department of Virology, Parasitology and Immunology, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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Bradley PW, Brawner MD, Raffel TR, Rohr JR, Olson DH, Blaustein AR. Shifts in temperature influence how Batrachochytrium dendrobatidis infects amphibian larvae. PLoS One 2019; 14:e0222237. [PMID: 31536533 PMCID: PMC6752834 DOI: 10.1371/journal.pone.0222237] [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: 05/02/2019] [Accepted: 08/23/2019] [Indexed: 11/18/2022] Open
Abstract
Many climate change models predict increases in frequency and magnitude of temperature fluctuations that might impact how ectotherms are affected by disease. Shifts in temperature might especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites might acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity. Support for components of this climate-variability based hypothesis have been provided by prior studies of the fungus Batrachochytrium dendrobatidis (Bd) that causes the disease chytridiomycosis in amphibians. We experimentally tested whether temperature shifts before exposure to Batrachochytrium dendrobatidis (Bd) alters susceptibility to the disease chytridiomycosis in the larval stage of two amphibian species–western toads (Anaxyrus boreas) and northern red legged frogs (Rana aurora). Both host species harbored elevated Bd infection intensities under constant cold (15° C) temperature in comparison to constant warm (20° C) temperature. Additionally, both species experienced an increase in Bd infection abundance after shifted from 15° C to 20° C, compared to a constant 20° C but they experienced a decrease in Bd after shifted from 20° C to 15° C, compared to a constant 15° C. These results are in contrast to prior studies of adult amphibians highlighting the potential for species and stage differences in the temperature-dependence of chytridiomycosis.
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Affiliation(s)
- Paul W. Bradley
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Michael D. Brawner
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States of America
| | - Thomas R. Raffel
- Department of Biology, Oakland University, Rochester, MI, United States of America
| | - Jason R. Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL, United States of America
| | - Deanna H. Olson
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States of America
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36
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McMahon TA, Laggan NA, Hill MN. Metabolites produced by Batrachochytrium dendrobatidis alter development in tadpoles, but not growth or mortality. DISEASES OF AQUATIC ORGANISMS 2019; 135:251-255. [PMID: 31535620 DOI: 10.3354/dao03401] [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
The mass decline of amphibian populations poses a serious threat to global biodiversity and ecosystem stability. The pathogenic fungus Batrachochytrium dendrobatidis (Bd) has contributed to the extirpation and extinction of hundreds of amphibian species worldwide. Bd produces potentially damaging metabolites during the host infection process that may affect amphibian growth and development, even in the absence of infection. In this experiment, Cuban tree frog Osteopilus septentrionalis tadpoles and adults were exposed once to either artificial spring water (ASW) or Bd metabolites (n = 31 tadpoles per treatment and n = 30 and 20 adults per treatment, respectively). Tadpoles exposed to Bd metabolites alone developed faster than those exposed to ASW; however, there was no difference in tadpole length, weight change, or mortality between treatments. Despite the faster developmental speed, metabolite exposure did not reduce tadpole weight or length (compared at Gosner stages 27, 29, and 31). There was no effect of treatment on adult size or mortality. These results indicate that both tadpole and adult O. septentrionalis do not appear to be negatively impacted by exposure to non-infectious Bd-contaminated water. In fact, tadpoles developed faster when exposed to metabolites and were of equal size as those in their stage cohort, implying a potential long-term benefit if faster development allows them to leave Bd-infected waters sooner.
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Affiliation(s)
- Taegan A McMahon
- University of Tampa, Department of Biology, 401 W. Kennedy Blvd., Tampa, FL 33606, USA
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37
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Bradley PW, Snyder PW, Blaustein AR. Host age alters amphibian susceptibility to Batrachochytrium dendrobatidis, an emerging infectious fungal pathogen. PLoS One 2019; 14:e0222181. [PMID: 31491016 PMCID: PMC6730893 DOI: 10.1371/journal.pone.0222181] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/23/2019] [Indexed: 11/18/2022] Open
Abstract
Parasites and pathogens are often aggregated in a minority of susceptible hosts within a population, with a majority of individuals harboring low infection intensities. However, determining the relative importance of host traits to explain this heterogeneity is a challenge. One ecologically important pathogen is Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis and has been associated with many amphibian population declines worldwide. For many hosts, post-metamorphic stages are generally more susceptible than the larval stage. Yet, examination of the effects of Bd infection at different ages within a life stage, has received little attention. This study investigated the hypothesis that recently-post-metamorphic frogs were more sensitive to chytridiomycosis than older frogs, and that sensitivity to Bd infection decreased as frogs aged. We examined this relationship with Pacific treefrogs (Pseudacris regilla) and red legged frogs (Rana aurora). Age had a strong effect on susceptibility to infection, infection intensity, and survival-but not in the directions we had predicted. In both host species, an increase in age was associated with frogs becoming more susceptible to Bd infection, harboring larger infection intensities, and greater risk of mortality. This suggests that the timing of Bd exposure may influence amphibian population dynamics.
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Affiliation(s)
- Paul W. Bradley
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Paul W. Snyder
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
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38
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Endemic Infection of Batrachochytrium dendrobatidis in Costa Rica: Implications for Amphibian Conservation at Regional and Species Level. DIVERSITY 2019. [DOI: 10.3390/d11080129] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Batrachochytrium dendrobatidis (Bd) has been associated with the severe declines and extinctions of amphibians in Costa Rica that primarily occurred during the 1980s and 1990s. However, the current impact of Bd infection on amphibian species in Costa Rica is unknown. We aimed to update the list of amphibian species in Costa Rica and evaluate the prevalence and infection intensity of Bd infection across the country to aid in the development of effective conservation strategies for amphibians. We reviewed taxonomic lists and included new species descriptions and records for a total of 215 amphibian species in Costa Rica. We also sampled for Bd at nine localities from 2015–2018 and combined these data with additional Bd occurrence data from multiple studies conducted in amphibian communities across Costa Rica from 2005–2018. With this combined dataset, we found that Bd was common (overall infection rate of 23%) across regions and elevations, but infection intensity was below theoretical thresholds associated with mortality. Bd was also more prevalent in Caribbean lowlands and in terrestrial amphibians with an aquatic larval stage; meanwhile, infection load was the highest in direct-developing species (forest and stream-dwellers). Our findings can be used to prioritize regions and taxonomic groups for conservation strategies.
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Hettyey A, Ujszegi J, Herczeg D, Holly D, Vörös J, Schmidt BR, Bosch J. Mitigating Disease Impacts in Amphibian Populations: Capitalizing on the Thermal Optimum Mismatch Between a Pathogen and Its Host. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00254] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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40
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Greenspan SE, Lyra ML, Migliorini GH, Kersch-Becker MF, Bletz MC, Lisboa CS, Pontes MR, Ribeiro LP, Neely WJ, Rezende F, Romero GQ, Woodhams DC, Haddad CFB, Toledo LF, Becker CG. Arthropod-bacteria interactions influence assembly of aquatic host microbiome and pathogen defense. Proc Biol Sci 2019; 286:20190924. [PMID: 31238845 DOI: 10.1098/rspb.2019.0924] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The host-associated microbiome is vital to host immunity and pathogen defense. In aquatic ecosystems, organisms may interact with environmental bacteria to influence the pool of potential symbionts, but the effects of these interactions on host microbiome assembly and pathogen resistance are unresolved. We used replicated bromeliad microecosystems to test for indirect effects of arthropod-bacteria interactions on host microbiome assembly and pathogen burden, using tadpoles and the fungal amphibian pathogen Batrachochytrium dendrobatidis as a model host-pathogen system. Arthropods influenced host microbiome assembly by altering the pool of environmental bacteria, with arthropod-bacteria interactions specifically reducing host colonization by transient bacteria and promoting antimicrobial components of aquatic bacterial communities. Arthropods also reduced fungal zoospores in the environment, but fungal infection burdens in tadpoles corresponded most closely with arthropod-mediated patterns in microbiome assembly. This result indicates that the cascading effects of arthropods on the maintenance of a protective host microbiome may be more strongly linked to host health than negative effects of arthropods on pools of pathogenic zoospores. Our work reveals tight links between healthy ecosystem dynamics and the functioning of host microbiomes, suggesting that ecosystem disturbances such as loss of arthropods may have downstream effects on host-associated microbial pathogen defenses and host fitness.
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Affiliation(s)
- Sasha E Greenspan
- 1 Department of Biological Sciences, The University of Alabama , Tuscaloosa, AL 35487 , USA
| | - Mariana L Lyra
- 2 Department of Zoology and Aquaculture Center (CAUNESP), Universidade Estadual Paulista , Rio Claro , SP 13506-900 , Brazil
| | - Gustavo H Migliorini
- 3 Programa de Pós-graduação em Biologia Animal, Universidade Estadual Paulista 'Júlio de Mesquita Filho' , São José do Rio Preto SP 15054-000 , Brazil
| | - Mônica F Kersch-Becker
- 1 Department of Biological Sciences, The University of Alabama , Tuscaloosa, AL 35487 , USA
| | - Molly C Bletz
- 4 Department of Biology, University of Massachusetts Boston , Boston, MA 02125 , USA
| | | | - Mariana R Pontes
- 6 Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas , Campinas, SP 13083-862 , Brazil.,8 Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Universidade Estadual de Campinas , Campinas, SP 13083-862 , Brazil
| | - Luisa P Ribeiro
- 6 Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas , Campinas, SP 13083-862 , Brazil.,8 Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Universidade Estadual de Campinas , Campinas, SP 13083-862 , Brazil
| | - Wesley J Neely
- 1 Department of Biological Sciences, The University of Alabama , Tuscaloosa, AL 35487 , USA
| | - Felipe Rezende
- 6 Programa de Pós-Graduação em Ecologia, Instituto de Biologia, Universidade Estadual de Campinas , Campinas, SP 13083-862 , Brazil
| | - Gustavo Q Romero
- 7 Departamento de Biologia Animal, Universidade Estadual de Campinas , Campinas SP 13083-862 , Brazil
| | - Douglas C Woodhams
- 4 Department of Biology, University of Massachusetts Boston , Boston, MA 02125 , USA
| | - Célio F B Haddad
- 2 Department of Zoology and Aquaculture Center (CAUNESP), Universidade Estadual Paulista , Rio Claro , SP 13506-900 , Brazil
| | - Luís Felipe Toledo
- 8 Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Universidade Estadual de Campinas , Campinas, SP 13083-862 , Brazil
| | - C Guilherme Becker
- 1 Department of Biological Sciences, The University of Alabama , Tuscaloosa, AL 35487 , USA
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Kohli AK, Lindauer AL, Brannelly LA, Ohmer MEB, Richards-Zawacki C, Rollins-Smith L, Voyles J. Disease and the Drying Pond: Examining Possible Links among Drought, Immune Function, and Disease Development in Amphibians. Physiol Biochem Zool 2019; 92:339-348. [PMID: 30990770 DOI: 10.1086/703137] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Drought can heavily impact aquatic ecosystems. For amphibian species that rely on water availability for larval development, drought can have direct and indirect effects on larval survival and postmetamorphic fitness. Some amphibian species can accelerate the timing of metamorphosis to escape drying habitats through developmental plasticity. However, trade-offs associated with premature metamorphosis, such as reduced body size and altered immune function in the recently metamorphosed individual, may have downstream effects on susceptibility to disease. Here, we review the physiological mechanisms driving patterns in larval amphibian development under low water conditions. Specifically, we discuss drought-induced accelerated metamorphosis and how it may alter immune function, predisposing juvenile amphibians to infectious disease. In addition, we consider how these physiological and immunological adjustments could play out in a lethal disease system, amphibian chytridiomycosis. Last, we propose avenues for future research that adopt an ecoimmunological approach to evaluate the combined threats of drought and disease for amphibian populations.
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The Costs of Living Together: Immune Responses to the Microbiota and Chronic Gut Inflammation. Appl Environ Microbiol 2019; 85:AEM.02147-18. [PMID: 30530709 DOI: 10.1128/aem.02147-18] [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] [Indexed: 02/06/2023] Open
Abstract
While the vertebrate microbiota is critical to the normal function of many host traits, hosts may expend a large amount of energy to constrain and interface with their microbiota via their immune system to avoid the high fitness costs associated with gut dysbiosis, pathobionts, and opportunistic pathogens. All jawed vertebrates share mucosal immunity dedicated to isolating the microbiota, and a breakdown of this system can result in chronic gut inflammation. In humans, chronic gut inflammation negatively affects growth and development. There is little information available on the prevalence of chronic gut inflammation in wild animals, but given that animals with different life histories emphasize different immune responses, it follows that wild animals may vary in their susceptibility to chronic gut inflammation, and most animals will experience signaling that can lead to this state. These can be top-down signals originating from sources like the central nervous system or bottom-up signals originating from changes in the gut microbiota. The sources of these signals might include stress, developmental transitions, food restriction, and dietary shifts. Here, we briefly discuss host-microbiota interactions from the perspective of life history theory and ecoimmunology, focusing on the mucosal immune system and chronic gut inflammation. We also include future directions for research and the tools necessary to investigate them.
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Kärvemo S, Laurila A, Höglund J. Urban environment and reservoir host species are associated with Batrachochytrium dendrobatidis infection prevalence in the common toad. DISEASES OF AQUATIC ORGANISMS 2019; 134:33-42. [PMID: 32132271 DOI: 10.3354/dao03359] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Human-induced changes of the environment, including landscape alteration and habitat loss, may affect wildlife disease dynamics and have important ramifications for wildlife conservation. Amphibians are among the vertebrate taxa most threatened by anthropogenic habitat change. The emerging fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused extinctions and population declines in hundreds of anuran species globally. We studied how the urban landscape is associated with the prevalence of Bd infections by sampling 655 anurans of 3 species (mainly the common toad Bufo bufo) in 42 ponds surrounded by different amounts of urban habitat (defined as towns, cities or villages). We also examined the association between Bd infections and a potential reservoir host species (the moor frog Rana arvalis). We found that 38% of the sites were positive for Bd with an infection prevalence of 4.4%. The extent of urban landscape was negatively correlated with Bd infection prevalence. However, the positive association of Bd with the presence of the possible reservoir species was substantially stronger than the urban effects. The body condition index of B. bufo was negatively associated with Bd infection. This Bd effect was stronger than the negative effect of urban landscape on body condition. Our results suggest that urban environments in Sweden have a negative impact on Bd infections, while the presence of the reservoir species has a positive impact on Bd prevalence. Our study also highlights the potential importance of Bd infection on host fitness, especially in rural landscapes.
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Affiliation(s)
- Simon Kärvemo
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, 75236 Uppsala, Sweden
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Verbrugghe E, Adriaensen C, Martel A, Vanhaecke L, Pasmans F. Growth Regulation in Amphibian Pathogenic Chytrid Fungi by the Quorum Sensing Metabolite Tryptophol. Front Microbiol 2019; 9:3277. [PMID: 30671052 PMCID: PMC6331427 DOI: 10.3389/fmicb.2018.03277] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 12/17/2018] [Indexed: 01/06/2023] Open
Abstract
Amphibians face many threats leading to declines and extinctions, but the chytrid fungal skin pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) have been identified as the causative factors leading to one of the greatest disease-driven losses of amphibian biodiversity worldwide. Infection may lead to different clinical outcomes, and lethal infections are commonly associated with unrestricted, exponential fungal growth in the amphibian epidermis. Mechanisms underpinning Bd and Bsal growth in the amphibian host are poorly understood. Here, we describe a quorum sensing mechanism that allows cell-to-cell communication by Bd and Bsal in order to regulate fungal densities and infection strategies. Addition of chytrid culture supernatant to chytrid cultures resulted in a concentration-dependent growth reduction and using dialysis, small metabolites were shown to be the causative factor. U-HPLC-MS/MS and in vitro growth tests identified the aromatic alcohol tryptophol as a key metabolite in regulating fungal growth. We determined tryptophol kinetics in both Bd and Bsal and confirmed the autostimulatory mode of action of this quorum sensing metabolite. Finally, we linked expression of genes that might be involved in tryptophol production, with in vitro and in vivo chytrid growth. Our results show that Bd and Bsal fungi use tryptophol to act as multicellular entities in order to regulate their growth.
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Affiliation(s)
- Elin Verbrugghe
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Connie Adriaensen
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Lynn Vanhaecke
- Laboratory of Chemical Analysis, Faculty of Veterinary Medicine, Department of Veterinary Public Health and Food Safety, Ghent University, Merelbeke, Belgium
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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45
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Campbell L, Bower DS, Clulow S, Stockwell M, Clulow J, Mahony M. Interaction between temperature and sublethal infection with the amphibian chytrid fungus impacts a susceptible frog species. Sci Rep 2019; 9:83. [PMID: 30643160 PMCID: PMC6331562 DOI: 10.1038/s41598-018-35874-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2017] [Accepted: 11/07/2018] [Indexed: 11/09/2022] Open
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis is an emerging infectious pathogen present on every continent except Antarctica. It causes the disease chytridiomycosis in a subset of species but does not always result in disease or death for every host. Ambient temperature influences both amphibian metabolism and chytrid pathogenicity, however the interactive effects on host physiology is not well understood. We investigated the sublethal effect of B. dendrobatidis infection on a susceptible host, Litoria aurea to test (1) whether the infection load, metabolic activity, body fat and gonad size differed in L. aurea at either 24 °C or 12 °C ambient temperatures and (2) whether previous Bd infection caused long-term changes to body fat and gonad size. Litoria aurea in 12 °C treatments had higher infection loads of B. dendrobatidis and lower survivorship. Metabolic rate was higher and fat mass was lower in infected individuals and in animals in 24 °C treatments. Male L. aurea previously infected with B. dendrobatidis had smaller testes 5 months-post clearance of infection, an effect likely to translate to fitness costs in wild populations. These experiments demonstrate a physiological cost to sublethal B. dendrobatidis infection, which suggests a reduction in host fitness mediated by temperature in the host's environment regardless of whether infection leads to mortality.
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Affiliation(s)
- Lachlan Campbell
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia.
| | - Deborah S Bower
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia.,James Cook University, Townsville, 4811, Qld, Australia
| | - Simon Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia.,Department of Biological Sciences, Macquarie University, Sydney, NSW, 2109, Australia
| | - Michelle Stockwell
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia
| | - John Clulow
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia
| | - Michael Mahony
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, Newcastle, 2300, NSW, Australia
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46
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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: 25] [Impact Index Per Article: 4.2] [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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47
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de Jong MS, van Dyk R, Weldon C. Antifungal efficacy of F10SC veterinary disinfectant against Batrachochytrium dendrobatidis. Med Mycol 2018; 56:60-68. [PMID: 28371902 DOI: 10.1093/mmy/myx023] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2016] [Accepted: 02/28/2017] [Indexed: 11/13/2022] Open
Abstract
The Infectious disease chytridiomycosis, which is caused by the fungal pathogen Batrachochytrium dendrobatidis, has been identified as one of the most important drivers of amphibian declines and extinction. In vitro B. dendrobatidis is susceptible to a range of disinfectants, but not all have been tested on animals and some that have been proven effective have harmful side effects on the surrounding environment or the animals being treated. We tested the efficacy of F10SC veterinary disinfectant to treat B. dendrobatidis in experimentally infected tadpole and juvenile Sclerophrys gutturalis and tadpoles of Sclerophrys poweri and Amietia hymenopus. The minimum inhibitory concentration for F10SC on in vitro B. dendrobatidis ranged between 1:7000 for 5-min contact time and 1:10000 for 10-min contact time. Based on the survival data of test animals the no observed effect concentration for 15-min contact time was estimated to be 1:2000 dilution for juveniles, and 1:10000 for tadpoles. In S. gutturalis juveniles an 86% infection clearance rate was achieved after five 15-min doses of 1:3000 dilution. A 100% clearance was achieved in A. hymenopus tadpoles after seven 15-min doses of 1:10000 dilution, and after nine doses of the same treatment in S. poweri tadpoles. F10SC has the benefit of being a concentrated compound that provides a treatment protocol which is nontoxic to tadpoles and post-metamorphic individuals, has a short half-life and is effective against B. dendrobatidis during short contact times, but further testing on different species of amphibians is advised.
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Affiliation(s)
- M S de Jong
- Unit for Environmental Research and Management, North-West University, Potchefstroom 2520, South Africa
| | - R van Dyk
- Unit for Environmental Research and Management, North-West University, Potchefstroom 2520, South Africa
| | - C Weldon
- Unit for Environmental Research and Management, North-West University, Potchefstroom 2520, South Africa
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48
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Christie MR, Searle CL. Evolutionary rescue in a host-pathogen system results in coexistence not clearance. Evol Appl 2018; 11:681-693. [PMID: 29875810 PMCID: PMC5979755 DOI: 10.1111/eva.12568] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Accepted: 10/17/2017] [Indexed: 01/14/2023] Open
Abstract
The evolutionary rescue of host populations may prevent extinction from novel pathogens. However, the conditions that facilitate rapid evolution of hosts, in particular the population variation in host susceptibility, and the effects of host evolution in response to pathogens on population outcomes remain largely unknown. We constructed an individual-based model to determine the relationships between genetic variation in host susceptibility and population persistence in an amphibian-fungal pathogen (Batrachochytrium dendrobatidis) system. We found that host populations can rapidly evolve reduced susceptibility to a novel pathogen and that this rapid evolution led to a 71-fold increase in the likelihood of host-pathogen coexistence. However, the increased rates of coexistence came at a cost to host populations; fewer populations cleared infection, population sizes were depressed, and neutral genetic diversity was lost. Larger adult host population sizes and greater adaptive genetic variation prior to the onset of pathogen introduction led to substantially reduced rates of extinction, suggesting that populations with these characteristics should be prioritized for conservation when species are threatened by novel infectious diseases.
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Affiliation(s)
- Mark Redpath Christie
- Department of Biological SciencesPurdue UniversityWest LafayetteINUSA
- Department of Forestry and Natural ResourcesPurdue UniversityWest LafayetteINUSA
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49
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Bosch J, Fernández-Beaskoetxea S, Garner TWJ, Carrascal LM. Long-term monitoring of an amphibian community after a climate change- and infectious disease-driven species extirpation. GLOBAL CHANGE BIOLOGY 2018; 24:2622-2632. [PMID: 29446515 DOI: 10.1111/gcb.14092] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/11/2018] [Accepted: 01/26/2018] [Indexed: 05/28/2023]
Abstract
Infectious disease and climate change are considered major threats to biodiversity and act as drivers behind the global amphibian decline. This is, to a large extent, based on short-term studies that are designed to detect the immediate and strongest biodiversity responses to a threatening process. What few long-term studies are available, although typically focused on single species, report outcomes that often diverge significantly from the short-term species responses. Here, we report the results of an 18-year survey of an amphibian community exposed to both climate warming and the emergence of lethal chytridiomycosis. Our study shows that the impacts of infectious disease are ongoing but restricted to two out of nine species that form the community, despite the fact all species can become infected with the fungus. Climate warming appears to be affecting four out of the nine species, but the response of three of these is an increase in abundance. Our study supports a decreasing role of infectious disease on the community, and an increasing and currently positive effect of climate warming. We caution that if the warming trends continue, the net positive effect will turn negative as amphibian breeding habitat becomes unavailable as water bodies dry, a pattern that already may be underway.
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Affiliation(s)
- Jaime Bosch
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
- Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Rascafría, Spain
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50
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Fisher MC, Ghosh P, Shelton JMG, Bates K, Brookes L, Wierzbicki C, Rosa GM, Farrer RA, Aanensen DM, Alvarado-Rybak M, Bataille A, Berger L, Böll S, Bosch J, Clare FC, A Courtois E, Crottini A, Cunningham AA, Doherty-Bone TM, Gebresenbet F, Gower DJ, Höglund J, James TY, Jenkinson TS, Kosch TA, Lambertini C, Laurila A, Lin CF, Loyau A, Martel A, Meurling S, Miaud C, Minting P, Ndriantsoa S, O'Hanlon SJ, Pasmans F, Rakotonanahary T, Rabemananjara FCE, Ribeiro LP, Schmeller DS, Schmidt BR, Skerratt L, Smith F, Soto-Azat C, Tessa G, Toledo LF, Valenzuela-Sánchez A, Verster R, Vörös J, Waldman B, Webb RJ, Weldon C, Wombwell E, Zamudio KR, Longcore JE, Garner TWJ. Development and worldwide use of non-lethal, and minimal population-level impact, protocols for the isolation of amphibian chytrid fungi. Sci Rep 2018; 8:7772. [PMID: 29773857 PMCID: PMC5958081 DOI: 10.1038/s41598-018-24472-2] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2018] [Accepted: 03/23/2018] [Indexed: 11/09/2022] Open
Abstract
Parasitic chytrid fungi have emerged as a significant threat to amphibian species worldwide, necessitating the development of techniques to isolate these pathogens into culture for research purposes. However, early methods of isolating chytrids from their hosts relied on killing amphibians. We modified a pre-existing protocol for isolating chytrids from infected animals to use toe clips and biopsies from toe webbing rather than euthanizing hosts, and distributed the protocol to researchers as part of the BiodivERsA project RACE; here called the RML protocol. In tandem, we developed a lethal procedure for isolating chytrids from tadpole mouthparts. Reviewing a database of use a decade after their inception, we find that these methods have been applied across 5 continents, 23 countries and in 62 amphibian species. Isolation of chytrids by the non-lethal RML protocol occured in 18% of attempts with 207 fungal isolates and three species of chytrid being recovered. Isolation of chytrids from tadpoles occured in 43% of attempts with 334 fungal isolates of one species (Batrachochytrium dendrobatidis) being recovered. Together, these methods have resulted in a significant reduction and refinement of our use of threatened amphibian species and have improved our ability to work with this group of emerging pathogens.
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Affiliation(s)
- Matthew C Fisher
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK.
| | - Pria Ghosh
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK.,Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom, 2520, South Africa
| | - Jennifer M G Shelton
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK
| | - Kieran Bates
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK
| | - Lola Brookes
- Institute of Zoology, Regent's Park, London, NW1 4RY, UK
| | - Claudia Wierzbicki
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK
| | - Gonçalo M Rosa
- Institute of Zoology, Regent's Park, London, NW1 4RY, UK.,Centre for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal
| | - Rhys A Farrer
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK
| | - David M Aanensen
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK.,Centre for Genomic Pathogen Surveillance, Wellcome Genome Campus, Cambridgeshire, UK
| | - Mario Alvarado-Rybak
- Centro de Investigación para la Sustentabilidad, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Republica 440, Santiago, Chile
| | - Arnaud Bataille
- Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 08826, South Korea.,CIRAD, UMR ASTRE, F-34398 Montpellier, France; ASTRE, Univ Montpellier, CIRAD, INRA, Montpellier, France
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, 4811, Australia
| | - Susanne Böll
- Agency for Population Ecology and Nature Conservancy, Gerbrunn, Germany
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC c/Jose Gutierrez Abascal 2, 28006, Madrid, Spain
| | - Frances C Clare
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK
| | - Elodie A Courtois
- Laboratoire Ecologie, évolution, interactions des systèmes amazoniens (LEEISA), Université de Guyane, CNRS, IFREMER, 97300, Cayenne, French Guiana
| | - Angelica Crottini
- CIBIO - Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO, Universidade do Porto, 4485-661, Vairão, Portugal
| | | | | | - Fikirte Gebresenbet
- Department of Integrative Biology, Oklahoma State University, 113 Life Sciences West, Stillwater, OK, 74078, USA
| | - David J Gower
- Life Sciences, The Natural History Museum, London, SW7 5BD, UK
| | - Jacob Höglund
- Department of Ecology and Genetics, EBC, Uppsala University, Norbyv. 18D, SE-75236, Uppsala, Sweden
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Thomas S Jenkinson
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Tiffany A Kosch
- Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 08826, South Korea.,One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, 4811, Australia
| | - Carolina Lambertini
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, 13083-862, Brazil
| | - Anssi Laurila
- Department of Ecology and Genetics, EBC, Uppsala University, Norbyv. 18D, SE-75236, Uppsala, Sweden
| | - Chun-Fu Lin
- Zoology Division, Endemic Species Research Institute, 1 Ming-shen East Road, Jiji, Nantou, 552, Taiwan
| | - Adeline Loyau
- Helmholtz Centre for Environmental Research - UFZ, Department of Conservation Biology, Permoserstrasse 15, 04318, Leipzig, Germany.,ECOLAB, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France
| | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | - Sara Meurling
- Department of Ecology and Genetics, EBC, Uppsala University, Norbyv. 18D, SE-75236, Uppsala, Sweden
| | - Claude Miaud
- PSL Research University, CEFE UMR 5175, CNRS, Université de Montpellier, Université Paul-Valéry Montpellier, EPHE, Biogéographie et Ecologie des vertébrés, Montpellier, France
| | - Pete Minting
- Amphibian and Reptile Conservation (ARC) Trust, 655A Christchurch Road, Boscombe, Bournemouth, Dorset, BH1 4AP, UK
| | - Serge Ndriantsoa
- Durrell Wildlife Conservation Trust, Madagascar Programme, Antananarivo, Madagascar
| | - Simon J O'Hanlon
- Department of Infectious Disease Epidemiology, School of Public Health, Faculty of Medicine (St Mary's campus), Imperial College London, London, W2 1PG, UK.,Institute of Zoology, Regent's Park, London, NW1 4RY, UK
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, B-9820, Merelbeke, Belgium
| | | | - Falitiana C E Rabemananjara
- Durrell Wildlife Conservation Trust, Madagascar Programme, Antananarivo, Madagascar.,IUCN SSC Amphibian Specialist Group-Madagascar, 101, Antananarivo, Madagascar
| | - Luisa P Ribeiro
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, 13083-862, Brazil
| | - Dirk S Schmeller
- Helmholtz Centre for Environmental Research - UFZ, Department of Conservation Biology, Permoserstrasse 15, 04318, Leipzig, Germany.,ECOLAB, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France
| | - Benedikt R Schmidt
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.,Info Fauna Karch, Université de Neuchâtel, Bellevaux 51, UniMail Bâtiment 6, 2000, Neuchâtel, Switzerland
| | - Lee Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, 4811, Australia
| | - Freya Smith
- National Wildlife Management Centre, APHA, Woodchester Park, Gloucestershire, GL10 3UJ, UK
| | - Claudio Soto-Azat
- Centro de Investigación para la Sustentabilidad, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Republica 440, Santiago, Chile
| | - Giulia Tessa
- Non-profit Association Zirichiltaggi - Sardinia Wildlife Conservation, Strada Vicinale Filigheddu 62/C, I-07100, Sassari, Italy
| | - Luís Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, 13083-862, Brazil
| | - Andrés Valenzuela-Sánchez
- Centro de Investigación para la Sustentabilidad, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Republica 440, Santiago, Chile.,ONG Ranita de Darwin, Nataniel Cox 152, Santiago, Chile
| | - Ruhan Verster
- Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom, 2520, South Africa
| | - Judit Vörös
- Collection of Amphibians and Reptiles, Department of Zoology, Hungarian Natural History Museum, Budapest, Baross u, 13., 1088, Hungary
| | - Bruce Waldman
- Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul, 08826, South Korea
| | - Rebecca J Webb
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland, 4811, Australia
| | - Che Weldon
- Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom, 2520, South Africa
| | - Emma Wombwell
- Institute of Zoology, Regent's Park, London, NW1 4RY, UK
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, New York, 14853, USA
| | - Joyce E Longcore
- School of Biology and Ecology, University of Maine, Orono, Maine, 04469, USA
| | - Trenton W J Garner
- Institute of Zoology, Regent's Park, London, NW1 4RY, UK.,Non-profit Association Zirichiltaggi - Sardinia Wildlife Conservation, Strada Vicinale Filigheddu 62/C, I-07100, Sassari, Italy.,Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom, 2520, South Africa
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