51
|
O'Hanlon SJ, Rieux A, Farrer RA, Rosa GM, Waldman B, Bataille A, Kosch TA, Murray KA, Brankovics B, Fumagalli M, Martin MD, Wales N, Alvarado-Rybak M, Bates KA, Berger L, Böll S, Brookes L, Clare F, Courtois EA, Cunningham AA, Doherty-Bone TM, Ghosh P, Gower DJ, Hintz WE, Höglund J, Jenkinson TS, Lin CF, Laurila A, Loyau A, Martel A, Meurling S, Miaud C, Minting P, Pasmans F, Schmeller DS, Schmidt BR, Shelton JMG, Skerratt LF, Smith F, Soto-Azat C, Spagnoletti M, Tessa G, Toledo LF, Valenzuela-Sánchez A, Verster R, Vörös J, Webb RJ, Wierzbicki C, Wombwell E, Zamudio KR, Aanensen DM, James TY, Gilbert MTP, Weldon C, Bosch J, Balloux F, Garner TWJ, Fisher MC. Recent Asian origin of chytrid fungi causing global amphibian declines. Science 2018; 360:621-627. [PMID: 29748278 PMCID: PMC6311102 DOI: 10.1126/science.aar1965] [Citation(s) in RCA: 288] [Impact Index Per Article: 48.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 03/29/2018] [Indexed: 12/14/2022]
Abstract
Globalized infectious diseases are causing species declines worldwide, but their source often remains elusive. We used whole-genome sequencing to solve the spatiotemporal origins of the most devastating panzootic to date, caused by the fungus Batrachochytrium dendrobatidis, a proximate driver of global amphibian declines. We traced the source of B. dendrobatidis to the Korean peninsula, where one lineage, BdASIA-1, exhibits the genetic hallmarks of an ancestral population that seeded the panzootic. We date the emergence of this pathogen to the early 20th century, coinciding with the global expansion of commercial trade in amphibians, and we show that intercontinental transmission is ongoing. Our findings point to East Asia as a geographic hotspot for B. dendrobatidis biodiversity and the original source of these lineages that now parasitize amphibians worldwide.
Collapse
Affiliation(s)
- Simon J O'Hanlon
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK.
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
| | - Adrien Rieux
- CIRAD, UMR PVBMT, 97410 St. Pierre, Reunion, France
| | - Rhys A Farrer
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Gonçalo M Rosa
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
- Department of Biology, University of Nevada, Reno, NV 89557, USA
- Centre for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciências da Universidade de Lisboa, Lisboa, Portugal
| | - Bruce Waldman
- Laboratory of Behavioral and Population Ecology, School of Biological Sciences, Seoul National University, Seoul 08826, South Korea
| | - 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
| | - 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
| | - Kris A Murray
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Balázs Brankovics
- Westerdijk Fungal Biodiversity Institute, Uppsalalaan 8, 3584CT Utrecht, Netherlands
- Institute of Biodiversity and Ecosystem Dynamics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
| | - Matteo Fumagalli
- Department of Life Sciences, Silwood Park Campus, Imperial College London, Ascot, UK
- UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Michael D Martin
- Department of Natural History, NTNU University Museum, Norwegian University of Science and Technology (NTNU), Erling Skakkes gate 49, NO-7012 Trondheim, Norway
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
| | - Nathan Wales
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
| | - Mario Alvarado-Rybak
- Centro de Investigación para la Sustentabilidad, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, Republica 440, Santiago, Chile
| | - Kieran A Bates
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
| | - 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
| | - Lola Brookes
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
| | - Frances Clare
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
| | - Elodie A Courtois
- Laboratoire Ecologie, Évolution, Interactions des Systèmes Amazoniens (LEEISA), Université de Guyane, CNRS, IFREMER, 97300 Cayenne, French Guiana
| | | | | | - Pria Ghosh
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
- Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom 2520, South Africa
| | - David J Gower
- Life Sciences, Natural History Museum, London SW7 5BD, UK
| | - William E Hintz
- Biology Department, University of Victoria, Victoria, BC V8W 3N5, Canada
| | - Jacob Höglund
- Department of Ecology and Genetics, EBC, Uppsala University, Norbyv. 18D, SE-75236, Uppsala, Sweden
| | - Thomas S Jenkinson
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Chun-Fu Lin
- Zoology Division, Endemic Species Research Institute, 1 Ming-shen East Road, Jiji, Nantou 552, Taiwan
| | - Anssi Laurila
- Department of Ecology and Genetics, EBC, Uppsala University, Norbyv. 18D, SE-75236, Uppsala, Sweden
| | - Adeline Loyau
- Department of Conservation Biology, Helmholtz Centre for Environmental Research-UFZ, 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, 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, Montpellier, France
| | - Pete Minting
- Amphibian and Reptile Conservation (ARC) Trust, Boscombe, Bournemouth, Dorset BH1 4AP, UK
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Dirk S Schmeller
- Department of Conservation Biology, Helmholtz Centre for Environmental Research-UFZ, 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, 8057 Zurich, Switzerland, and Info Fauna Karch, UniMail-Bâtiment G, Bellevaux 51, 2000 Neuchâtel, Switzerland
| | - Jennifer M G Shelton
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Lee F Skerratt
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Freya Smith
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
- 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, Unicamp, Campinas, 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
| | - Rebecca J Webb
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Claudia Wierzbicki
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Emma Wombwell
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - David M Aanensen
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
- Centre for Genomic Pathogen Surveillance, Wellcome Genome Campus, Cambridgeshire, UK
| | - Timothy Y James
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, MI 48109, USA
| | - M Thomas P Gilbert
- Department of Natural History, NTNU University Museum, Norwegian University of Science and Technology (NTNU), Erling Skakkes gate 49, NO-7012 Trondheim, Norway
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Øster Voldgade 5-7, 1350 Copenhagen, Denmark
| | - Ché Weldon
- Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom 2520, South Africa
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC c/ Jose Gutierrez Abascal 2, 28006 Madrid, Spain
| | - François Balloux
- UCL Genetics Institute, University College London, London WC1E 6BT, UK
| | - Trenton W J Garner
- Institute of Zoology, Regent's Park, London NW1 4RY, UK
- Unit for Environmental Sciences and Management, Private Bag x6001, North-West University, Potchefstroom 2520, South Africa
- Non-profit Association Zirichiltaggi-Sardinia Wildlife Conservation, Strada Vicinale Filigheddu 62/C, I-07100 Sassari, Italy
| | - Matthew C Fisher
- Department of Infectious Disease Epidemiology and MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK.
| |
Collapse
|
52
|
Daversa DR, Monsalve-Carcaño C, Carrascal LM, Bosch J. Seasonal migrations, body temperature fluctuations, and infection dynamics in adult amphibians. PeerJ 2018; 6:e4698. [PMID: 29761041 PMCID: PMC5947160 DOI: 10.7717/peerj.4698] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Accepted: 04/12/2018] [Indexed: 12/22/2022] Open
Abstract
Risks of parasitism vary over time, with infection prevalence often fluctuating with seasonal changes in the annual cycle. Identifying the biological mechanisms underlying seasonality in infection can enable better prediction and prevention of future infection peaks. Obtaining longitudinal data on individual infections and traits across seasons throughout the annual cycle is perhaps the most effective means of achieving this aim, yet few studies have obtained such information for wildlife. Here, we tracked spiny common toads (Bufo spinosus) within and across annual cycles to assess seasonal variation in movement, body temperatures and infection from the fungal parasite, Batrachochytrium dendrobatidis (Bd). Across annual cycles, toads did not consistently sustain infections but instead gained and lost infections from year to year. Radio-tracking showed that infected toads lose infections during post-breeding migrations, and no toads contracted infection following migration, which may be one explanation for the inter-annual variability in Bd infections. We also found pronounced seasonal variation in toad body temperatures. Body temperatures approached 0 °C during winter hibernation but remained largely within the thermal tolerance range of Bd. These findings provide direct documentation of migratory recovery (i.e., loss of infection during migration) and escape in a wild population. The body temperature reductions that we observed during hibernation warrant further consideration into the role that this period plays in seasonal Bd dynamics.
Collapse
Affiliation(s)
- David R Daversa
- Institute for Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Camino Monsalve-Carcaño
- Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain
| | - Luis M Carrascal
- Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain
| | - Jaime Bosch
- Department of Biogeography and Global Change, Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain.,Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Rascafría, Madrid, Spain
| |
Collapse
|
53
|
Carvalho T, Becker CG, Toledo LF. Historical amphibian declines and extinctions in Brazil linked to chytridiomycosis. Proc Biol Sci 2018; 284:rspb.2016.2254. [PMID: 28179514 DOI: 10.1098/rspb.2016.2254] [Citation(s) in RCA: 58] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2016] [Accepted: 01/10/2017] [Indexed: 12/20/2022] Open
Abstract
The recent increase in emerging fungal diseases is causing unprecedented threats to biodiversity. The origin of spread of the frog-killing fungus Batrachochytrium dendrobatidis (Bd) is a matter of continued debate. To date, the historical amphibian declines in Brazil could not be attributed to chytridiomycosis; the high diversity of hosts coupled with the presence of several Bd lineages predating the reported declines raised the hypothesis that a hypervirulent Bd genotype spread from Brazil to other continents causing the recent global amphibian crisis. We tested for a spatio-temporal overlap between Bd and areas of historical amphibian population declines and extinctions in Brazil. A spatio-temporal convergence between Bd and declines would support the hypothesis that Brazilian amphibians were not adapted to Bd prior to the reported declines, thus weakening the hypothesis that Brazil was the global origin of Bd emergence. Alternatively, a lack of spatio-temporal association between Bd and frog declines would indicate an evolution of host resistance in Brazilian frogs predating Bd's global emergence, further supporting Brazil as the potential origin of the Bd panzootic. Here, we Bd-screened over 30 000 museum-preserved tadpoles collected in Brazil between 1930 and 2015 and overlaid spatio-temporal Bd data with areas of historical amphibian declines. We detected an increase in the proportion of Bd-infected tadpoles during the peak of amphibian declines (1979-1987). We also found that clusters of Bd-positive samples spatio-temporally overlapped with most records of amphibian declines in Brazil's Atlantic Forest. Our findings indicate that Brazil is post epizootic for chytridiomycosis and provide another piece to the puzzle to explain the origin of Bd globally.
Collapse
Affiliation(s)
- Tamilie Carvalho
- 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
| | - C Guilherme Becker
- Departamento de Zoologia, Universidade Estadual Paulista, Rio Claro, São Paulo 13506-900, Brazil
| | - 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
| |
Collapse
|
54
|
Daversa DR, Manica A, Bosch J, Jolles JW, Garner TWJ. Routine habitat switching alters the likelihood and persistence of infection with a pathogenic parasite. Funct Ecol 2018. [DOI: 10.1111/1365-2435.13038] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- David R. Daversa
- Institute of Integrative BiologyUniversity of Liverpool Liverpool UK
- Department of ZoologyUniversity of Cambridge Cambridge UK
- Institute of ZoologyZoological Society of London London UK
| | - Andrea Manica
- Department of ZoologyUniversity of Cambridge Cambridge UK
| | - Jaime Bosch
- Museo Nacional de Ciencias NaturalesCSIC Madrid Spain
- Centro de InvestigaciónSeguimiento y EvaluaciónParque Nacional de la Sierra de Guadarrama Rascafría Spain
| | - Jolle W. Jolles
- Department of ZoologyUniversity of Cambridge Cambridge UK
- Department of Collective BehaviourMax Planck Institute for Ornithology Konstanz Germany
| | | |
Collapse
|
55
|
Hite JL, Bosch J, Fernández-Beaskoetxea S, Medina D, Hall SR. Joint effects of habitat, zooplankton, host stage structure and diversity on amphibian chytrid. Proc Biol Sci 2017; 283:rspb.2016.0832. [PMID: 27466456 DOI: 10.1098/rspb.2016.0832] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 07/05/2016] [Indexed: 11/12/2022] Open
Abstract
Why does the severity of parasite infection differ dramatically across habitats? This question remains challenging to answer because multiple correlated pathways drive disease. Here, we examined habitat-disease links through direct effects on parasites and indirect effects on parasite predators (zooplankton), host diversity and key life stages of hosts. We used a case study of amphibian hosts and the chytrid fungus, Batrachochytrium dendrobatidis, in a set of permanent and ephemeral alpine ponds. A field experiment showed that ultraviolet radiation (UVR) killed the free-living infectious stage of the parasite. Yet, permanent ponds with more UVR exposure had higher infection prevalence. Two habitat-related indirect effects worked together to counteract parasite losses from UVR: (i) UVR reduced the density of parasite predators and (ii) permanent sites fostered multi-season host larvae that fuelled parasite production. Host diversity was unlinked to hydroperiod or UVR but counteracted parasite gains; sites with higher diversity of host species had lower prevalence of infection. Thus, while habitat structure explained considerable variation in infection prevalence through two indirect pathways, it could not account for everything. This study demonstrates the importance of creating mechanistic, food web-based links between multiple habitat dimensions and disease.
Collapse
Affiliation(s)
- Jessica L Hite
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Cta. M-604, Km. 27.6, 28740 Rascafría, Spain
| | | | - Daniel Medina
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA, USA
| | - Spencer R Hall
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| |
Collapse
|
56
|
Clare FC, Halder JB, Daniel O, Bielby J, Semenov MA, Jombart T, Loyau A, Schmeller DS, Cunningham AA, Rowcliffe M, Garner TWJ, Bosch J, Fisher MC. Climate forcing of an emerging pathogenic fungus across a montane multi-host community. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2015.0454. [PMID: 28080980 PMCID: PMC5095533 DOI: 10.1098/rstb.2015.0454] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2016] [Indexed: 01/23/2023] Open
Abstract
Changes in the timings of seasonality as a result of anthropogenic climate change are predicted to occur over the coming decades. While this is expected to have widespread impacts on the dynamics of infectious disease through environmental forcing, empirical data are lacking. Here, we investigated whether seasonality, specifically the timing of spring ice-thaw, affected susceptibility to infection by the emerging pathogenic fungus Batrachochytrium dendrobatidis (Bd) across a montane community of amphibians that are suffering declines and extirpations as a consequence of this infection. We found a robust temporal association between the timing of the spring thaw and Bd infection in two host species, where we show that an early onset of spring forced high prevalences of infection. A third highly susceptible species (the midwife toad, Alytes obstetricans) maintained a high prevalence of infection independent of time of spring thaw. Our data show that perennially overwintering midwife toad larvae may act as a year-round reservoir of infection with variation in time of spring thaw determining the extent to which infection spills over into sympatric species. We used future temperature projections based on global climate models to demonstrate that the timing of spring thaw in this region will advance markedly by the 2050s, indicating that climate change will further force the severity of infection. Our findings on the effect of annual variability on multi-host infection dynamics show that the community-level impact of fungal infectious disease on biodiversity will need to be re-evaluated in the face of climate change.This article is part of the themed issue 'Tackling emerging fungal threats to animal health, food security and ecosystem resilience'.
Collapse
Affiliation(s)
- Frances C Clare
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK .,Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| | - Julia B Halder
- Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| | - Olivia Daniel
- Department of Life Sciences, Imperial College London, Silwood Park Campus, SL5 9PU, UK
| | - Jon Bielby
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Mikhail A Semenov
- Computational and Systems Biology, Rothamsted Research, West Common, Harpenden, Hertfordshire AL5 2JQ, UK
| | - Thibaut Jombart
- Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| | - Adeline Loyau
- Université de Toulouse; UPS, INPT; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, 31062 Toulouse, France.,Department of Conservation Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany.,Department of System Ecotoxicology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Dirk S Schmeller
- Université de Toulouse; UPS, INPT; EcoLab (Laboratoire Ecologie Fonctionnelle et Environnement), 118 route de Narbonne, 31062 Toulouse, France.,Department of Conservation Biology, Helmholtz Centre for Environmental Research - UFZ, Permoserstrasse 15, 04318 Leipzig, Germany
| | - Andrew A Cunningham
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Marcus Rowcliffe
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, Jose Gutierrez Abascal, 2 28006, Madrid, Spain
| | - Matthew C Fisher
- Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| |
Collapse
|
57
|
Burrow AK, Rumschlag SL, Boone MD. Host size influences the effects of four isolates of an amphibian chytrid fungus. Ecol Evol 2017; 7:9196-9202. [PMID: 29187961 PMCID: PMC5696404 DOI: 10.1002/ece3.3255] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2016] [Revised: 06/14/2017] [Accepted: 06/28/2017] [Indexed: 11/11/2022] Open
Abstract
Understanding factors that influence host–pathogen interactions is key to predicting outbreaks in natural systems experiencing environmental change. Many amphibian population declines have been attributed to an amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd). While this fungus is widespread, not all Bd‐positive populations have been associated with declines, which could be attributed to differences in pathogen virulence or host susceptibility. In a laboratory experiment, we examined the effects of Bd isolate origin, two from areas with Bd‐associated amphibian population declines (El Copé, Panama, and California, USA) and two from areas without Bd‐related population declines (Ohio and Maine, USA), on the terrestrial growth and survival of American toad (Anaxyrus americanus) metamorphs reared in larval environments with low or high intraspecific density. We predicted that (1) Bd isolates from areas experiencing declines would have greater negative effects than Bd isolates from areas without declines, and (2) across all isolates, growth and survival of smaller toads from high‐density larval conditions would be reduced by Bd exposure compared to larger toads from low‐density larval conditions. Our results showed that terrestrial survival was reduced for smaller toads exposed to Bd with variation in the response to different isolates, suggesting that smaller size increased susceptibility to Bd. Toads exposed to Bd gained less mass, which varied by isolate. Bd isolates from areas with population declines, however, did not have more negative effects than isolates from areas without recorded declines. Most strikingly, our study supports that host condition, measured by size, can be indicative of the negative effects of Bd exposure. Further, Bd isolates’ impact may vary in ways not predictable from place of origin or occurrence of disease‐related population declines. This research suggests that amphibian populations outside of areas experiencing Bd‐associated declines could be impacted by this pathogen and that the size of individuals could influence the magnitude of Bd's impact.
Collapse
|
58
|
Antifungal treatment of wild amphibian populations caused a transient reduction in the prevalence of the fungal pathogen, Batrachochytrium dendrobatidis. Sci Rep 2017; 7:5956. [PMID: 28729557 PMCID: PMC5519715 DOI: 10.1038/s41598-017-05798-9] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/06/2017] [Indexed: 01/09/2023] Open
Abstract
Emerging infectious diseases can drive host populations to extinction and are a major driver of biodiversity loss. Controlling diseases and mitigating their impacts is therefore a priority for conservation science and practice. Chytridiomycosis is a devastating disease of amphibians that is caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), and for which there is an urgent need to develop mitigation methods. We treated tadpoles of the common midwife toad (Alytes obstetricans) with antifungal agents using a capture-treat-release approach in the field. Antifungal treatment during the spring reduced the prevalence of Bd in the cohort of tadpoles that had overwintered and reduced transmission of Bd from this cohort to the uninfected young-of-the-year cohort. Unfortunately, the mitigation was only transient, and the antifungal treatment was unable to prevent the rapid spread of Bd through the young-of-the year cohort. During the winter, Bd prevalence reached 100% in both the control and treated ponds. In the following spring, no effects of treatment were detectable anymore. We conclude that the sporadic application of antifungal agents in the present study was not sufficient for the long-term and large-scale control of Bd in this amphibian system.
Collapse
|
59
|
Scheele BC, Skerratt LF, Hunter DA, Banks SC, Pierson JC, Driscoll DA, Byrne PG, Berger L. Disease-associated change in an amphibian life-history trait. Oecologia 2017; 184:825-833. [DOI: 10.1007/s00442-017-3911-7] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 07/06/2017] [Indexed: 11/30/2022]
|
60
|
Major histocompatibility complex variation and the evolution of resistance to amphibian chytridiomycosis. Immunogenetics 2017; 69:529-536. [PMID: 28695290 DOI: 10.1007/s00251-017-1008-4] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2017] [Accepted: 05/29/2017] [Indexed: 01/06/2023]
Abstract
Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has been implicated in population declines and species extinctions of amphibians around the world. Susceptibility to the disease varies both within and among species, most likely attributable to heritable immunogenetic variation. Analyses of transcriptional expression in hosts following their infection by Bd reveal complex responses. Species resistant to Bd generally show evidence of stronger innate and adaptive immune system responses. Major histocompatibility complex (MHC) class I and class II genes of some susceptible species are up-regulated following host infection by Bd, but resistant species show no comparable changes in transcriptional expression. Bd-resistant species share similar pocket conformations within the MHC-II antigen-binding groove. Among susceptible species, survivors of epizootics bear alleles encoding these conformations. Individuals with homozygous resistance alleles appear to benefit by enhanced resistance, especially in environmental conditions that promote pathogen virulence. Subjects that are repeatedly infected and subsequently cleared of Bd can develop an acquired immune response to the pathogen. Strong directional selection for MHC alleles that encode resistance to Bd may deplete genetic variation necessary to respond to other pathogens. Resistance to chytridiomycosis incurs life-history costs that require further study.
Collapse
|
61
|
Sabino‐Pinto J, Galán P, Rodríguez S, Bletz MC, Bhuju S, Geffers R, Jarek M, Vences M. Temporal changes in cutaneous bacterial communities of terrestrial‐ and aquatic‐phase newts (Amphibia). Environ Microbiol 2017; 19:3025-3038. [DOI: 10.1111/1462-2920.13762] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Revised: 04/05/2017] [Accepted: 04/08/2017] [Indexed: 12/18/2022]
Affiliation(s)
- Joana Sabino‐Pinto
- Zoological InstituteBraunschweig University of TechnologyBraunschweig38106 Germany
| | - Pedro Galán
- Departamento de Bioloxía, Facultade de CienciasUniversidade da Coruña, Grupo de Investigación en Biología Evolutiva (GIBE)A Coruña15071 Spain
| | - Silvia Rodríguez
- Departamento de Bioloxía, Facultade de CienciasUniversidade da Coruña, Grupo de Investigación en Biología Evolutiva (GIBE)A Coruña15071 Spain
| | - Molly C. Bletz
- Zoological InstituteBraunschweig University of TechnologyBraunschweig38106 Germany
| | - Sabin Bhuju
- Department of Genome AnalyticsHelmholtz Centre for Infection ResearchBraunschweig38124 Germany
| | - Robert Geffers
- Department of Genome AnalyticsHelmholtz Centre for Infection ResearchBraunschweig38124 Germany
| | - Michael Jarek
- Department of Genome AnalyticsHelmholtz Centre for Infection ResearchBraunschweig38124 Germany
| | - Miguel Vences
- Zoological InstituteBraunschweig University of TechnologyBraunschweig38106 Germany
| |
Collapse
|
62
|
Dang TD, Searle CL, Blaustein AR. Virulence variation among strains of the emerging infectious fungus Batrachochytrium dendrobatidis (Bd) in multiple amphibian host species. DISEASES OF AQUATIC ORGANISMS 2017; 124:233-239. [PMID: 28492179 DOI: 10.3354/dao03125] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Emerging infectious diseases have been documented in numerous plant and animal populations. The infectious disease amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is associated with global amphibian population declines. While much Bd-amphibian research has centered on response variation in hosts, a paucity of information exists on how variation in the pathogen, such as strain differences, affects infection dynamics. To examine how different Bd strains may differentially impact multiple hosts, we conducted laboratory experiments to measure 2 infection outcomes, viz. host survival and pathogen load, in 3 amphibian host species (Pacific treefrog, western toad, and Cascades frog) after exposure to 3 different Bd strains (an additional fourth Bd strain was tested in toads only). Our results confirm that the infection response differs among host species. Western toads experienced significant mortality, but Pacific treefrogs and Cascades frogs did not. Interestingly, our experiment also captured strain-dependent virulence variation but only in 1 host species, the western toad. Increased mortality was observed in 2 of the 4 Bd strains tested in this host species. Toads were also the only host species found to have variable pathogen load dependent on strain type; individuals exposed to the Panama strain harbored significantly higher loads compared to all other strains. These findings underscore the dynamic nature of Bd infection, showing that virulence can vary contingent on host and strain type. We highlight the importance of both host- and pathogen-dependent factors in determining overall infection virulence and show the need for in vivo testing to fully assess pathogenicity.
Collapse
Affiliation(s)
- Trang D Dang
- Department of Integrative Biology, Cordley Hall, Oregon State University, Corvallis, OR 97331, USA
| | | | | |
Collapse
|
63
|
Adams AJ, Kupferberg SJ, Wilber MQ, Pessier AP, Grefsrud M, Bobzien S, Vredenburg VT, Briggs CJ. Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian. Ecosphere 2017. [DOI: 10.1002/ecs2.1740] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Andrea J. Adams
- Department of Ecology, Evolution, and Marine Biology; University of California; Santa Barbara California 93106 USA
| | - Sarah J. Kupferberg
- Department of Integrative Biology; University of California; Berkeley California 94720 USA
| | - Mark Q. Wilber
- Department of Ecology, Evolution, and Marine Biology; University of California; Santa Barbara California 93106 USA
| | - Allan P. Pessier
- Department of Veterinary Microbiology and Pathology; College of Veterinary Medicine; Washington State University; Pullman Washington 99164 USA
| | - Marcia Grefsrud
- California Department of Fish and Wildlife; Bay Delta Region Napa California 94558 USA
| | - Steve Bobzien
- East Bay Regional Park District; Oakland California 94605 USA
| | | | - Cheryl J. Briggs
- Department of Ecology, Evolution, and Marine Biology; University of California; Santa Barbara California 93106 USA
| |
Collapse
|
64
|
Rosa GM, Sabino-Pinto J, Laurentino TG, Martel A, Pasmans F, Rebelo R, Griffiths RA, Stöhr AC, Marschang RE, Price SJ, Garner TWJ, Bosch J. Impact of asynchronous emergence of two lethal pathogens on amphibian assemblages. Sci Rep 2017; 7:43260. [PMID: 28240267 PMCID: PMC5327436 DOI: 10.1038/srep43260] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 01/17/2017] [Indexed: 12/15/2022] Open
Abstract
Emerging diseases have been increasingly associated with population declines, with co-infections exhibiting many types of interactions. The chytrid fungus (Batrachochytrium dendrobatidis) and ranaviruses have extraordinarily broad host ranges, however co-infection dynamics have been largely overlooked. We investigated the pattern of co-occurrence of these two pathogens in an amphibian assemblage in Serra da Estrela (Portugal). The detection of chytridiomycosis in Portugal was linked to population declines of midwife-toads (Alytes obstetricans). The asynchronous and subsequent emergence of a second pathogen - ranavirus - caused episodes of lethal ranavirosis. Chytrid effects were limited to high altitudes and a single host, while ranavirus was highly pathogenic across multiple hosts, life-stages and altitudinal range. This new strain (Portuguese newt and toad ranavirus – member of the CMTV clade) caused annual mass die-offs, similar in host range and rapidity of declines to other locations in Iberia affected by CMTV-like ranaviruses. However, ranavirus was not always associated with disease, mortality and declines, contrasting with previous reports on Iberian CMTV-like ranavirosis. We found little evidence that pre-existing chytrid emergence was associated with ranavirus and the emergence of ranavirosis. Despite the lack of cumulative or amplified effects, ranavirus drove declines of host assemblages and changed host community composition and structure, posing a grave threat to all amphibian populations.
Collapse
Affiliation(s)
- Gonçalo M Rosa
- Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK.,Institute of Zoology, Zoological Society of London, Regent's Park, NW1 4RY, London, UK.,Centre for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.,Department of Biology, University of Nevada, Reno, NV 89557, USA
| | - Joana Sabino-Pinto
- Technische Universität Braunschweig, Division of Evolutionary Biology, Zoological Institute, Mendelssohnstr. 4, 38106 Braunschweig, Germany
| | - Telma G Laurentino
- Computational Biology and Population Genomics Group, Centre for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal.,Zoological Institute, University of Basel, Vesalgasse 1, Basel, Switzerland
| | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Ghent, Belgium
| | - Rui Rebelo
- Centre for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciências da Universidade de Lisboa, Campo Grande, 1749-016 Lisboa, Portugal
| | - Richard A Griffiths
- Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK
| | - Anke C Stöhr
- Fachgebiet für Umwelt- und Tierhygiene, Universität Hohenheim, Stuttgart, Germany
| | - Rachel E Marschang
- Fachgebiet für Umwelt- und Tierhygiene, Universität Hohenheim, Stuttgart, Germany.,Laboklin GmbH &Co. KG, Laboratory for Clinical Diagnostics, Bad Kissingen, Germany
| | - Stephen J Price
- Institute of Zoology, Zoological Society of London, Regent's Park, NW1 4RY, London, UK.,UCL Genetics Institute, Gower Street, London, WC1E 6BT, UK
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, Regent's Park, NW1 4RY, London, UK
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006 Madrid, Spain
| |
Collapse
|
65
|
Jones DK, Dang TD, Urbina J, Bendis RJ, Buck JC, Cothran RD, Blaustein AR, Relyea RA. Effect of Simultaneous Amphibian Exposure to Pesticides and an Emerging Fungal Pathogen, Batrachochytrium dendrobatidis. ENVIRONMENTAL SCIENCE & TECHNOLOGY 2017; 51:671-679. [PMID: 28001054 DOI: 10.1021/acs.est.6b06055] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Amphibian declines have been linked to numerous factors, including pesticide use and the fungal pathogen Batrachochytrium dendrobatidis (Bd). Moreover, research has suggested a link between amphibian sensitivity to Bd and pesticide exposure. We simultaneously exposed postmetamorphic American toads (Anaxyrus americanus), western toads (A. boreas), spring peepers (Pseudacris crucifer), Pacific treefrogs (P. regilla), leopard frogs (Lithobates pipiens), and Cascades frogs (Rana cascadae) to a factorial combination of two pathogen treatments (Bd+, Bd-) and four pesticide treatments (control, ethanol vehicle, herbicide mixture, and insecticide mixture) for 14 d to quantify survival and infection load. We found no interactive effects of pesticides and Bd on anuran survival and no effects of pesticides on infection load. Mortality following Bd exposure increased in spring peepers and American toads and was dependent upon snout-vent length in western toads, American toads, and Pacific treefrogs. Previous studies reported effects of early sublethal pesticide exposure on amphibian Bd sensitivity and infection load at later life stages, but we found simultaneous exposure to sublethal pesticide concentrations and Bd had no such effect on postmetamorphic juvenile anurans. Future research investigating complex interactions between pesticides and Bd should employ a variety of pesticide formulations and Bd strains and follow the effects of exposure throughout ontogeny.
Collapse
Affiliation(s)
- Devin K Jones
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| | | | | | - Randall J Bendis
- Department of Biological Sciences, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States
| | - Julia C Buck
- Marine Science Institute, University of California Santa Barbara , Santa Barbara, California 93106, United States
| | - Rickey D Cothran
- Department of Biological Sciences, Southwestern Oklahoma State University , Weatherford, Oklahoma 73096, United States
| | | | - Rick A Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Institute , Troy, New York 12180, United States
| |
Collapse
|
66
|
Rollins-Smith LA. Amphibian immunity-stress, disease, and climate change. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 66:111-119. [PMID: 27387153 DOI: 10.1016/j.dci.2016.07.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Revised: 06/25/2016] [Accepted: 07/01/2016] [Indexed: 05/22/2023]
Abstract
Like all other vertebrate groups, amphibian responses to the environment are mediated through the brain (hypothalamic)-pituitary-adrenal/interrenal (HPA/I) axis and the sympathetic nervous system. Amphibians are facing historically unprecedented environmental stress due to climate change that will involve unpredictable temperature and rainfall regimes and possible nutritional deficits due to extremes of temperature and drought. At the same time, amphibians in all parts of the world are experiencing unprecedented declines due to the emerging diseases, chytridiomycosis (caused by Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans) and ranavirus diseases due to viruses of the genus Ranavirus in the family Iridoviridae. Other pathogens and parasites also afflict amphibians, but here I will limit myself to a review of recent literature linking stress and these emerging diseases (chytridiomycosis and ranavirus disease) in order to better predict how environmental stressors and disease will affect global amphibian populations.
Collapse
Affiliation(s)
- Louise A Rollins-Smith
- Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN 37232, USA; Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA; Department of Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
| |
Collapse
|
67
|
Gabor C, Forsburg Z, Vörös J, Serrano-Laguna C, Bosch J. Differences in chytridiomycosis infection costs between two amphibian species from Central Europe. AMPHIBIA-REPTILIA 2017. [DOI: 10.1163/15685381-00003099] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis associated with amphibian declines. Response and costs of infection varies greatly between species. Bd can induce a stress response in amphibians resulting in elevated corticosterone (CORT). We exposed Bombina variegata and Hyla arborea tadpoles to Bd+ or Bd- Salamandra salamandra larvae and measured CORT release rates, Bd infection loads, and survival through metamorphosis. Tadpoles of both species exposed to Bd+ larvae had elevated CORT release rates compared to tadpoles exposed to Bd- larvae. Bombina variegata appear less resistant to infection than H. arborea, showing higher Bd loads and more infected individuals. Within species, we did not find differences in cost of infection on survival, however more B. variegata tadpoles reached metamorphosis than H. arborea. The differences in resistance may be species specific, owing to higher immunity defenses with H. arborea having higher overall CORT release rates, and differences in antimicrobial peptides, or to differences in Bd strain or other unexplored mechanisms.
Collapse
Affiliation(s)
- Caitlin Gabor
- Texas State University, 601 University Drive, San Marcos, Texas, 78666, USA
| | - Zachery Forsburg
- Texas State University, 601 University Drive, San Marcos, Texas, 78666, USA
| | - Judit Vörös
- Department of Zoology, Hungarian Natural History Museum, 1088 Budapest, Baross u. 13., Hungary
| | - Celia Serrano-Laguna
- Museo Nacional de Ciencias Naturales, CSIC, c/ José Gutiérrez Abascal 2, 28006 Madrid, Spain
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, c/ José Gutiérrez Abascal 2, 28006 Madrid, Spain
- Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Cta. M-604, km 27.6, 28740 Rascafría, Spain
| |
Collapse
|
68
|
DiRenzo GV, Che-Castaldo C, Rugenski A, Brenes R, Whiles MR, Pringle CM, Kilham SS, Lips KR. Disassembly of a tadpole community by a multi-host fungal pathogen with limited evidence of recovery. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2017; 27:309-320. [PMID: 28052493 DOI: 10.1002/eap.1443] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2016] [Revised: 07/28/2016] [Accepted: 08/24/2016] [Indexed: 06/06/2023]
Abstract
Emerging infectious diseases can cause host community disassembly, but the mechanisms driving the order of species declines and extirpations following a disease outbreak are unclear. We documented the community disassembly of a Neotropical tadpole community during a chytridiomycosis outbreak, triggered by the generalist fungal pathogen, Batrachochytrium dendrobatidis (Bd). Within the first 11 months of Bd arrival, tadpole density and occupancy rapidly declined. Species rarity, in terms of tadpole occupancy and adult relative abundance, did not predict the odds of tadpole occupancy declines. But species losses were taxonomically selective, with glassfrogs (Family: Centrolenidae) disappearing the fastest and tree frogs (Family: Hylidae) and dart-poison frogs (Family: Dendrobatidae) remaining the longest. We detected biotic homogenization of tadpole communities, with post-decline communities resembling one another more strongly than pre-decline communities. The entire tadpole community was extirpated within 22 months following Bd arrival, and we found limited signs of recovery within 10 years post-outbreak. Because of imperfect species detection inherent to sampling species-rich tropical communities and the difficulty of devising a single study design protocol to sample physically complex tropical habitats, we used simulations to provide recommendations for future surveys to adequately sample diverse Neotropical communities. Our unique data set on tadpole community composition before and after Bd arrival is a valuable baseline for assessing amphibian recovery. Our results are of direct relevance to conservation managers and community ecologists interested in understanding the timing, magnitude, and consequences of disease outbreaks as emerging infectious diseases spread globally.
Collapse
Affiliation(s)
- Graziella V DiRenzo
- Department of Biology, University of Maryland, College Park, Maryland, 20744, USA
| | | | - Amanda Rugenski
- School of Life Sciences, Arizona State University, Tempe, Arizona, 85281, USA
| | - Roberto Brenes
- Department of Biology, Carroll University, Waukesha, Wisconsin, 53186, USA
| | - Matt R Whiles
- Department of Zoology and Center for Ecology, Southern Illinois University, Carbondale, Illinois, 62901, USA
| | | | - Susan S Kilham
- Department of Biodiversity, Earth and Environmental Science, Drexel University, Philadelphia, Pennsylvania, 19104, USA
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, Maryland, 20744, USA
| |
Collapse
|
69
|
Exposure to Corticosterone Affects Host Resistance, but Not Tolerance, to an Emerging Fungal Pathogen. PLoS One 2016; 11:e0163736. [PMID: 27690360 PMCID: PMC5045185 DOI: 10.1371/journal.pone.0163736] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Accepted: 09/13/2016] [Indexed: 11/19/2022] Open
Abstract
Host responses to pathogens include defenses that reduce infection burden (i.e., resistance) and traits that reduce the fitness consequences of an infection (i.e., tolerance). Resistance and tolerance are affected by an organism's physiological status. Corticosterone (“CORT”) is a hormone that is associated with the regulation of many physiological processes, including metabolism and reproduction. Because of its role in the stress response, CORT is also considered the primary vertebrate stress hormone. When secreted at high levels, CORT is generally thought to be immunosuppressive. Despite the known association between stress and disease resistance in domesticated organisms, it is unclear whether these associations are ecologically and evolutionary relevant in wildlife species. We conducted a 3x3 fully crossed experiment in which we exposed American toads (Anaxyrus [Bufo] americanus) to one of three levels of exogenous CORT (no CORT, low CORT, or high CORT) and then to either low or high doses of the pathogenic chytrid fungus Batrachochytrium dendrobatidis (“Bd”) or a sham exposure treatment. We assessed Bd infection levels and tested how CORT and Bd affected toad resistance, tolerance, and mortality. Exposure to the high CORT treatment significantly elevated CORT release in toads; however, there was no difference between toads given no CORT or low CORT. Exposure to CORT and Bd each increased toad mortality, but they did not interact to affect mortality. Toads that were exposed to CORT had higher Bd resistance than toads exposed to ethanol controls/low CORT, a pattern opposite that of most studies on domesticated animals. Exposure to CORT did not affect toad tolerance to Bd. Collectively, these results show that physiological stressors can alter a host’s response to a pathogen, but that the outcome might not be straightforward. Future studies that inhibit CORT secretion are needed to better our understanding of the relationship between stress physiology and disease resistance and tolerance in wild vertebrates.
Collapse
|
70
|
Ceccato E, Cramp RL, Seebacher F, Franklin CE. Early exposure to ultraviolet-B radiation decreases immune function later in life. CONSERVATION PHYSIOLOGY 2016; 4:cow037. [PMID: 27668081 PMCID: PMC5033135 DOI: 10.1093/conphys/cow037] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Revised: 08/12/2016] [Accepted: 08/18/2016] [Indexed: 05/23/2023]
Abstract
Amphibians have declined dramatically worldwide. Many of these declines are occurring in areas where no obvious anthropogenic stressors are present. It is proposed that in these areas, environmental factors such as elevated solar ultraviolet-B (UV-B) radiation could be responsible. Ultraviolet-B levels have increased in many parts of the world as a consequence of the anthropogenic destruction of the ozone layer. Amphibian tadpoles are particularly sensitive to the damaging effects of UV-B radiation, with exposure disrupting growth and fitness in many species. Given that UV-B can disrupt immune function in other animals, we tested the hypothesis that early UV-B exposure suppresses the immune responses of amphibian tadpoles and subsequent juvenile frogs. We exposed Limnodynastes peronii tadpoles to sublethal levels of UV-B radiation for 6 weeks after hatching, then examined indices of immune function in both the tadpoles and the subsequent metamorphs. There was no significant effect of UV-B on tadpole leucocyte counts or on their response to an acute antigen (phytohaemagglutinin) challenge. However, early UV-B exposure resulted in a significant reduction in both metamorph leucocyte abundance and their response to an acute phytohaemagglutinin challenge. These data demonstrate that early UV-B exposure can have carry-over effects on later life-history traits even if the applied stressor has no immediately discernible effect. These findings have important implications for our understanding of the effects of UV-B exposure on amphibian health and susceptibility to diseases such as chytridiomycosis.
Collapse
Affiliation(s)
- Emma Ceccato
- School of Biological Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Rebecca L. Cramp
- School of Biological Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Frank Seebacher
- School of Life and Environmental Sciences, University of Sydney, Sydney, NSW 2006, Australia
| | - Craig E. Franklin
- School of Biological Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| |
Collapse
|
71
|
Terrestrial Growth in Northern Leopard Frogs Reared in the Presence or Absence of Predators and Exposed to the Amphibian Chytrid Fungus at Metamorphosis. J HERPETOL 2016. [DOI: 10.1670/15-102] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
72
|
Palomar G, Bosch J, Cano JM. Heritability of Batrachochytrium dendrobatidis burden and its genetic correlation with development time in a population of Common toad (Bufo spinosus). Evolution 2016; 70:2346-2356. [PMID: 27480345 DOI: 10.1111/evo.13029] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2015] [Revised: 07/15/2016] [Accepted: 07/20/2016] [Indexed: 11/26/2022]
Abstract
Despite the important threat that emerging pathogens pose for the conservation of biodiversity as well as human health, very little is known about the adaptive potential of host species to withstand infections. We studied the quantitative genetic architecture responsible for the burden of the fungal pathogen Batrachochytrium dendrobatidis in a population of common toads in conjunction with other life-history traits (i.e., body size and development rate) that may be affected by common selective pressures. We found a significant heritable component that is associated with fungal burden, which may allow for local adaptation to this pathogen to proceed. In addition, the high genetic correlation found between fungal burden and development time suggests that both traits have to be taken into account in order to assess the adaptive response of host populations to this emerging pathogen.
Collapse
Affiliation(s)
- Gemma Palomar
- Research Unit of Biodiversity (UO-CSIC-PA), Edificio de Investigación, Gonzalo Gutiérrez Quirós s/n, 33600, Mieres, Spain. .,Department of Biology of Organisms and Systems, University of Oviedo, Catedrático Rodrigo Uría s/n, 33006, Oviedo, Spain.
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal, 2, 28006, Madrid, Spain.,Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Cta. M-604, Km. 27.6, 28740, Rascafría, Spain
| | - José Manuel Cano
- Research Unit of Biodiversity (UO-CSIC-PA), Edificio de Investigación, Gonzalo Gutiérrez Quirós s/n, 33600, Mieres, Spain.,Department of Biology of Organisms and Systems, University of Oviedo, Catedrático Rodrigo Uría s/n, 33006, Oviedo, Spain
| |
Collapse
|
73
|
Invasive North American bullfrogs transmit lethal fungus Batrachochytrium dendrobatidis infections to native amphibian host species. Biol Invasions 2016. [DOI: 10.1007/s10530-016-1161-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
74
|
Hirschfeld M, Blackburn DC, Doherty-Bone TM, Gonwouo LN, Ghose S, Rödel MO. Dramatic Declines of Montane Frogs in a Central African Biodiversity Hotspot. PLoS One 2016; 11:e0155129. [PMID: 27149624 PMCID: PMC4858272 DOI: 10.1371/journal.pone.0155129] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2015] [Accepted: 04/25/2016] [Indexed: 11/18/2022] Open
Abstract
Amphibian populations are vanishing worldwide. Declines and extinctions of many populations have been attributed to chytridiomycosis, a disease induced by the pathogenic fungus Batrachochytrium dendrobatidis (Bd). In Africa, however, changes in amphibian assemblages were typically attributed to habitat change. We conducted a retrospective study utilizing field surveys from 2004–2012 of the anuran faunas on two mountains in western Cameroon, a hotspot of African amphibian diversity. The number of species detected was negatively influenced by year, habitat degradation, and elevation, and we detected a decline of certain species. Because another study in this region revealed an emergence of Bd in 2008, we screened additional recent field-collected samples and also pre-decline preserved museum specimens for the presence of Bd supporting emergence before 2008. When comparing the years before and after Bd detection, we found significantly diminished frog species richness and abundance on both mountains after Bd emergence. Our analyses suggest that this may be the first disease-driven community-level decline in anuran biodiversity in Central Africa. The disappearance of several species known to tolerate habitat degradation, and a trend of stronger declines at higher elevations, are consistent with Bd-induced declines in other regions. Not all species decreased; populations of some species remained constant, and others increased after the emergence of Bd. This variation might be explained by species-specific differences in infection probability. Increased habitat protection and Bd-mitigation strategies are needed for sustaining diverse amphibian communities such as those on Mt. Manengouba, which contains nearly half of Cameroon’s frog diversity.
Collapse
Affiliation(s)
- Mareike Hirschfeld
- Museum für Naturkunde Berlin, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
- * E-mail:
| | - David C. Blackburn
- Department of Herpetology, California Academy of Sciences, San Francisco, California 94118, United States of America
| | - Thomas M. Doherty-Bone
- Conservation Research & Action for Amphibians of Cameroon, Royal Zoological Society of Scotland, Edinburgh Zoo, Edinburgh, United Kingdom
| | - LeGrand Nono Gonwouo
- Cameroon Herpetology-Conservation Biology Foundation (CAMHERP-CBF), PO Box 8218, Yaoundé, Cameroon
| | - Sonia Ghose
- Department of Herpetology, California Academy of Sciences, San Francisco, California 94118, United States of America
| | - Mark-Oliver Rödel
- Museum für Naturkunde Berlin, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstraße 43, 10115 Berlin, Germany
| |
Collapse
|
75
|
Prevalence of Batrachochytrium dendrobatidis in Eastern Hellbender (Cryptobranchus alleganiensis) Populations in West Virginia, USA. J Wildl Dis 2016; 52:391-4. [PMID: 27124331 DOI: 10.7589/2015-02-052] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The eastern hellbender (Cryptobranchus alleganiensis alleganiensis) is a North American salamander species in decline throughout its range. Efforts to identify the causes of decline have included surveillance for the chytrid fungus Batrachochytrium dendrobatidis (Bd), which has been associated with global amphibian population losses. We evaluated the prevalence of Bd in 42 hellbenders at four sites in West Virginia, US, from June to September 2013, using standard swab protocols and real-time PCR. Overall prevalence of Bd was 52% (22/42; 37.7-66.6%; 95% confidence interval). Prevalence was highest in individuals with body weight ≥695 g (χ(2)=7.2487, df=1, P=0.007), and was higher in montane sampling sites than lowland sites (t=-2.4599, df=44, P=0.02). While increased prevalence in montane sampling sites was expected, increased prevalence in larger hellbenders was unexpected and hypothesized to be associated with greater surface area for infection or prolonged periods of exposure in older, larger hellbenders. Wild hellbenders have not been reported to display clinical disease associated with Bd; however, prevalence in the population is important information for evaluating reservoir status and risk to other species, and as a baseline for investigation in the face of an outbreak of clinical disease.
Collapse
|
76
|
Susceptibility to disease varies with ontogeny and immunocompetence in a threatened amphibian. Oecologia 2016; 181:997-1009. [DOI: 10.1007/s00442-016-3607-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Accepted: 03/09/2016] [Indexed: 10/22/2022]
|
77
|
Fernández-Beaskoetxea S, Bosch J, Bielby J. Infection and transmission heterogeneity of a multi-host pathogen (Batrachochytrium dendrobatidis) within an amphibian community. DISEASES OF AQUATIC ORGANISMS 2016; 118:11-20. [PMID: 26865231 DOI: 10.3354/dao02963] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
The majority of parasites infect multiple hosts. As the outcome of the infection is different in each of them, most studies of wildlife disease focus on the few species that suffer the most severe consequences. However, the role that each host plays in the persistence and transmission of infection can be crucial to understanding the spread of a parasite and the risk it poses to the community. Current theory predicts that certain host species can modulate the infection in other species by amplifying or diluting both infection prevalence and infection intensity, both of which have implications for disease risk within those communities. The fungus Batrachochytrium dendrobatidis (Bd), the causal agent of the disease chytridiomycosis, has caused global amphibian population declines and extinctions. However, not all infected species are affected equally, and thus Bd is a good example of a multi-host pathogen that must ultimately be studied with a community approach. To test whether the common midwife toad Alytes obstetricans is a reservoir and possible amplifier of infection of other species, we used experimental approaches in captive and wild populations to determine the effect of common midwife toad larvae on infection of other amphibian species found in the Peñalara Massif, Spain. We observed that the most widely and heavily infected species, the common midwife toad, may be amplifying the infection loads in other species, all of which have different degrees of susceptibility to Bd infection. Our results have important implications for performing mitigation actions focused on potential 'amplifier' hosts and for better understanding the mechanisms of Bd transmission.
Collapse
|
78
|
Stockwell MP, Bower DS, Clulow J, Mahony MJ. The role of non-declining amphibian species as alternative hosts for Batrachochytrium dendrobatidis in an amphibian community. WILDLIFE RESEARCH 2016. [DOI: 10.1071/wr15223] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Context Pathogens with reservoir hosts have been responsible for most disease-induced wildlife extinctions because the decline of susceptible hosts does not cause the decline of the pathogen. The existence of reservoirs for Batrachochytrium dendrobatidis limits population recovery and conservation actions for threatened amphibians. As such, the effect of reservoirs on disease risk within host community assemblages needs to be considered, but rarely is. Aims In this study we aimed to determine if amphibian species co-occurring with the green and golden bell frog Litoria aurea, a declining species susceptible to B. dendrobatidis, act as alternate hosts. Methods We quantified B. dendrobatidis infection levels, sub-lethal effects on body condition and terminal signs of disease in amphibian communities on Kooragang Island and Sydney Olympic Park in New South Wales, Australia, where two of the largest remaining L. aurea populations persist. Key results We found L. aurea carried infections at a similar prevalence (6–38%) to alternate species. Infection loads ranged widely (0.01–11 107.3 zoospore equivalents) and L. aurea differed from only one alternate host species (higher median load in Litoria fallax) at one site. There were no terminal or sub-lethal signs of disease in any species co-occurring with L. aurea. Conclusion Our results suggest that co-occurring species are acting as alternate hosts to L. aurea and whether their presence dilutes or amplifies B. dendrobatidis in the community is a priority for future research. Implications For L. aurea and many other susceptible species, confirming the existence of reservoir hosts and understanding their role in community disease dynamics will be important for optimising the outcomes of threat mitigation and habitat creation initiatives for their long-term conservation.
Collapse
|
79
|
Polasik JS, Murphy MA, Abbott T, Vincent K. Factors limiting early life stage survival and growth during endangered Wyoming toad reintroductions. J Wildl Manage 2015. [DOI: 10.1002/jwmg.1031] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Affiliation(s)
- Julia S. Polasik
- Department of Ecosystem Science and Management; University of Wyoming; 1000 E. University Avenue Laramie WY 82071 USA
| | - Melanie A. Murphy
- Department of Ecosystem Science and Management, Program in Ecology; University of Wyoming; 1000 E. University Avenue Laramie WY 82071 USA
| | - Tyler Abbott
- U.S. Fish and Wildlife Service; Ecological Services Wyoming Field Office; 5353 Yellowstone Road, Suite 308A Cheyenne WY 82009 USA
| | - Kim Vincent
- Department of Ecology and Evolutionary Biology; University of Colorado; Ramaley N122 Boulder CO 80309 USA
| |
Collapse
|
80
|
Rumschlag SL, Boone MD. How Time of Exposure to the Amphibian Chytrid Fungus AffectsHyla chrysoscelisin the Presence of an Insecticide1. HERPETOLOGICA 2015. [DOI: 10.1655/herpetologica-d-13-00070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
81
|
Hagman M, Alford RA. Patterns of Batrachochytrium dendrobatidis transmission between tadpoles in a high-elevation rainforest stream in tropical Australia. DISEASES OF AQUATIC ORGANISMS 2015; 115:213-221. [PMID: 26290506 DOI: 10.3354/dao02898] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The highly virulent fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a global threat to amphibian biodiversity. Streams and other water bodies are central habitats in the ecology of the disease, particularly in rainforests where they may transport and transmit the pathogen and harbor infected tadpoles that serve as reservoir hosts. We conducted an experiment using larval green-eyed tree frogs Litoria serrata in semi-natural streamside channels to test the hypotheses that (1) the fungus can be transmitted downstream in stream habitats and (2) infection affects tadpole growth and mouthpart loss. Our results showed that transmission can occur downstream in flowing water with no contact between individuals, that newly infected tadpoles suffered increased mouthpart loss in comparison with controls that were never infected and that infected tadpoles grew at reduced rates. Although recently infected tadpoles showed substantial loss of mouthparts, individuals with longstanding infections did not, suggesting that mouthparts may re-grow following initial loss. Our study suggests that any management efforts that can reduce the prevalence of infections in tadpoles may be particularly effective if applied in headwater areas, as their effects are likely to be felt downstream.
Collapse
Affiliation(s)
- Mattias Hagman
- College of Marine and Environmental Science, James Cook University, Townsville, QLD 4811, Australia
| | | |
Collapse
|
82
|
Buck JC, Hua J, Brogan WR, Dang TD, Urbina J, Bendis RJ, Stoler AB, Blaustein AR, Relyea RA. Effects of Pesticide Mixtures on Host-Pathogen Dynamics of the Amphibian Chytrid Fungus. PLoS One 2015; 10:e0132832. [PMID: 26181492 PMCID: PMC4504700 DOI: 10.1371/journal.pone.0132832] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 06/19/2015] [Indexed: 01/22/2023] Open
Abstract
Anthropogenic and natural stressors often interact to affect organisms. Amphibian populations are undergoing unprecedented declines and extinctions with pesticides and emerging infectious diseases implicated as causal factors. Although these factors often co-occur, their effects on amphibians are usually examined in isolation. We hypothesized that exposure of larval and metamorphic amphibians to ecologically relevant concentrations of pesticide mixtures would increase their post-metamorphic susceptibility to the fungus Batrachochytrium dendrobatidis (Bd), a pathogen that has contributed to amphibian population declines worldwide. We exposed five anuran species (Pacific treefrog, Pseudacris regilla; spring peeper, Pseudacris crucifer; Cascades frog, Rana cascadae; northern leopard frog, Lithobates pipiens; and western toad, Anaxyrus boreas) from three families to mixtures of four common insecticides (chlorpyrifos, carbaryl, permethrin, and endosulfan) or herbicides (glyphosate, acetochlor, atrazine, and 2,4-D) or a control treatment, either as tadpoles or as newly metamorphic individuals (metamorphs). Subsequently, we exposed animals to Bd or a control inoculate after metamorphosis and compared survival and Bd load. Bd exposure significantly increased mortality in Pacific treefrogs, spring peepers, and western toads, but not in Cascades frogs or northern leopard frogs. However, the effects of pesticide exposure on mortality were negligible, regardless of the timing of exposure. Bd load varied considerably across species; Pacific treefrogs, spring peepers, and western toads had the highest loads, whereas Cascades frogs and northern leopard frogs had the lowest loads. The influence of pesticide exposure on Bd load depended on the amphibian species, timing of pesticide exposure, and the particular pesticide treatment. Our results suggest that exposure to realistic pesticide concentrations has minimal effects on Bd-induced mortality, but can alter Bd load. This result could have broad implications for risk assessment of amphibians; the outcome of exposure to multiple stressors may be unpredictable and can differ between species and life stages.
Collapse
Affiliation(s)
- Julia C. Buck
- Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, Texas, United States of America
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jessica Hua
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - William R. Brogan
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Trang D. Dang
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jenny Urbina
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
| | - Randall J. Bendis
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Aaron B. Stoler
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
| | - Rick A. Relyea
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| |
Collapse
|
83
|
Bielby J, Fisher MC, Clare FC, Rosa GM, Garner TWJ. Host species vary in infection probability, sub-lethal effects, and costs of immune response when exposed to an amphibian parasite. Sci Rep 2015; 5:10828. [PMID: 26022346 PMCID: PMC4448222 DOI: 10.1038/srep10828] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2014] [Accepted: 04/20/2015] [Indexed: 11/11/2022] Open
Abstract
The amphibian parasite Batrachochytrium dendrobatidis (Bd) is regarded as an extreme generalist, infecting over 500 species, but amongst these hosts there exists a great deal of variation in the susceptibility to and the costs of parasite exposure. We use two infection experiments to determine whether inter-specific variation in the sublethal and lethal effects of parasite exposure exist in two host species. We then tested the relative roles of host density and diversity on infection probability of a focal susceptible host. Our results show significant heterogeneity in host species response to parasite exposure, and that both lethal and sub-lethal costs exist in individuals that are able to resist infection, indicating that successful immune response to infection comes at a cost. Further, we show that increasing host density significantly increased the likelihood of susceptible individuals becoming infected with Bd irrespective of host diversity and variation in host susceptibility. These results suggest that populations of resistant species are likely to suffer ill-effects of exposure to Bd regardless of their infection status, and that at the stage of initial infection there was no support for the dilution of transmission events, in contrast to other studies that focus on subsequent transmission of infection.
Collapse
Affiliation(s)
- Jon Bielby
- 1] The Institute of Zoology, The Zoological Society of London, Regent's Park, London, NW1 4RY, UK [2] Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| | - Matthew C Fisher
- Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| | - Frances C Clare
- 1] The Institute of Zoology, The Zoological Society of London, Regent's Park, London, NW1 4RY, UK [2] Department of Infectious Disease Epidemiology, Imperial College London W2 1PG, UK
| | - Gonçalo M Rosa
- 1] The Institute of Zoology, The Zoological Society of London, Regent's Park, London, NW1 4RY, UK [2] Durrell Institute of Conservation and Ecology, School of Anthropology and Conservation, University of Kent, Canterbury, Kent, CT2 7NR, UK [3] Centre for Ecology, Evolution and Environmental Changes (CE3C), Faculdade de Ciências da Universidade de Lisboa, Bloco C2, Campo Grande, 1749-016 Lisboa, Portugal
| | - Trenton W J Garner
- The Institute of Zoology, The Zoological Society of London, Regent's Park, London, NW1 4RY, UK
| |
Collapse
|
84
|
Gabor CR, Fisher MC, Bosch J. Elevated Corticosterone Levels and Changes in Amphibian Behavior Are Associated with Batrachochytrium dendrobatidis (Bd) Infection and Bd Lineage. PLoS One 2015; 10:e0122685. [PMID: 25893675 PMCID: PMC4404099 DOI: 10.1371/journal.pone.0122685] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 02/06/2015] [Indexed: 11/24/2022] Open
Abstract
Few studies have examined the role hormones play in mediating clinical changes associated with infection by the parasite Batrachochytrium dendrobatidis (Bd). Glucocorticoid (GC) hormones such as corticosteroids (CORT) regulate homeostasis and likely play a key role in response to infection in amphibians. We explore the relationship between CORT release rates and Bd infection in tadpoles of the common midwife toad, Alytes obstetricians, using a non-invasive water-borne hormone collection method across seven populations. We further examined whether tadpoles of A. muletensis infected with a hypervirulent lineage of Bd, BdGPL, had greater CORT release rates than those infected with a hypovirulent lineage, BdCAPE. Finally, we examined the relationship between righting reflex and CORT release rates in infected metamorphic toads of A. obstetricans. We found an interaction between elevation and Bd infection status confirming that altitude is associated with the overall severity of infection. In tandem, increasing elevation was associated with increasing CORT release rates. Tadpoles infected with the hypervirulent BdGPL had significantly higher CORT release rates than tadpoles infected with BdCAPE showing that more aggressive infections lead to increased CORT release rates. Infected metamorphs with higher CORT levels had an impaired righting reflex, our defined experimental endpoint. These results provide evidence that CORT is associated with an amphibian’s vulnerability to Bd infection, and that CORT is also affected by the aggressiveness of infection by Bd. Together these results indicate that CORT is a viable biomarker of amphibian stress.
Collapse
Affiliation(s)
- Caitlin R. Gabor
- Department of Biology, Texas State University, San Marcos, Texas, United States of America
| | - Matthew C. Fisher
- Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, United Kingdom
- * E-mail:
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, c/ José Gutiérrez Abascal 2, Madrid, Spain
| |
Collapse
|
85
|
Presence and prevalence of Batrachochytrium dendrobatidis in commercial amphibians in Mexico City. J Zoo Wildl Med 2015; 45:830-5. [PMID: 25632670 DOI: 10.1638/2014-0023.1] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
In Mexico City, native and exotic amphibians are commonly sold through the pet trade. This study investigates the presence of Batrachochytrium dendrobatidis (Bd) in native amphibians being sold at two commercial markets and at a herpetarium in Mexico City. A total of 238 individuals (6 genera and 12 species) were tested for Bd using real-time polymerase chain reaction (PCR) analysis. There were 197 Bd-positive individuals (prevalence 82%) from five species of amphibians. Hyla eximia from the markets had very high Bd prevalence (100%; 76/76 and 99%; 88/89) but those from the herpetarium were Bd negative (0/12). Ambystoma mexicanum from the herpetarium also had a high Bd-positive prevalence (80%; 28/35). Though A. mexicanum is nearly extinct in the wild, a commercial market continues to flourish through the pet trade. Now that captive colonies of A. mexicanum are currently used for reintroduction programs, the authors recommend quarantine to reduce spread of Bd via movement of infected animals in the trade and between colonies and via disposal of wastewater from captive collections.
Collapse
|
86
|
McMahon TA, Rohr JR. Transition of chytrid fungus infection from mouthparts to hind limbs during amphibian metamorphosis. ECOHEALTH 2015; 12:188-193. [PMID: 25384612 DOI: 10.1007/s10393-014-0989-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 09/04/2014] [Accepted: 10/12/2014] [Indexed: 06/04/2023]
Abstract
The chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in worldwide amphibian declines. Bd has been shown to qualitatively transition from the mouthparts of tadpoles to the hindlimbs during metamorphosis, but we lack evidence of consistency in the timing of this transition across amphibian species. We also do not have predictive functions for the abundance of Bd in mouthparts and limbs as tadpoles develop or for the relationship between keratin and Bd abundance. Hence, researchers presently have little guidance on where to sample developing amphibians to maximize Bd detection, which could affect the accuracy of prevalence and abundance estimates for this deadly pathogen. Here, we show consistency in the timing of the transition of Bd from mouthparts to hind limbs across two frog species (Osteopilus septentrionalis and Mixophyes fasciolatus). Keratin and Bd simultaneously declined from the mouthparts starting at approximately Gosner stage 40. However, keratin on the hindlimbs began to appear at approximately stage 38 but, on average, Bd was not detectable on the hindlimbs until approximately stage 40, suggesting a lag between keratin and Bd arrival. Predictive functions for the relationships between developmental stage and keratin and developmental stage and Bd for mouthparts and hind limbs are provided so that researchers can optimize sampling designs and minimize erroneous conclusions associated with missing Bd infections or misestimating Bd abundance.
Collapse
Affiliation(s)
- Taegan A McMahon
- Department of Biology, University of Tampa, 401 W. Kennedy Ave, Tampa, FL, 33606, USA,
| | | |
Collapse
|
87
|
Young S, Whitehorn P, Berger L, Skerratt LF, Speare R, Garland S, Webb R. Defects in host immune function in tree frogs with chronic chytridiomycosis. PLoS One 2014; 9:e107284. [PMID: 25211333 PMCID: PMC4161418 DOI: 10.1371/journal.pone.0107284] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2014] [Accepted: 08/12/2014] [Indexed: 02/07/2023] Open
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused mass mortality leading to population declines and extinctions in many frog species worldwide. The lack of host resistance may be due to fungal immunosuppressive effects that have been observed when Bd is incubated with cultured lymphocytes, but whether in vivo host immunosuppression occurs is unknown. We used a broad range of hematologic and protein electrophoresis biomarkers, along with various functional tests, to assess immune competence in common green (Litoria caerulea) and white-lipped (L. infrafrenata) tree frogs experimentally infected with Bd. Compared with uninfected frogs, Bd infection in L. caerulea caused a reduction in immunoglobulin and splenic lymphocyte responses to antigenic stimulation with sheep red blood cells, along with decreased white blood cell and serum protein concentrations, indicating possible impaired immune response capability of Bd-infected frogs. This is the first in vivo study suggesting that infection with Bd causes multiple defects in systemic host immune function, and this may contribute to disease development in susceptible host species. Although L. infrafrenata failed to maintain Bd infection after exposure, white blood cell and serum globulin concentrations were lower in recovered frogs compared with unexposed frogs, but antigen-specific serum and splenic antibody, and splenic cellular, responses were similar in both recovered and unexposed frogs. This may indicate potential systemic costs associated with infection clearance and/or redirection of host resources towards more effective mechanisms to overcome infection. No clear mechanism for resistance was identified in L. infrafrenata, suggesting that localized and/or innate immune defense mechanisms may be important factors involved in disease resistance in this species.
Collapse
Affiliation(s)
- Sam Young
- James Cook University, One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia
- Mogo Zoo, Mogo, New South Wales, Australia
| | | | - Lee Berger
- James Cook University, One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia
| | - Lee F. Skerratt
- James Cook University, One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia
| | - Rick Speare
- James Cook University, One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia
| | - Stephen Garland
- James Cook University, One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia
| | - Rebecca Webb
- James Cook University, One Health Research Group, School of Public Health, Tropical Medicine and Rehabilitation Sciences, James Cook University, Townsville, Queensland, Australia
| |
Collapse
|
88
|
Lenker MA, Savage AE, Becker CG, Rodriguez D, Zamudio KR. Batrachochytrium dendrobatidis infection dynamics vary seasonally in upstate New York, USA. DISEASES OF AQUATIC ORGANISMS 2014; 111:51-60. [PMID: 25144117 DOI: 10.3354/dao02760] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The amphibian disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a major cause of worldwide amphibian declines and extinctions. Although several studies indicate that Bd prevalence and infection intensity vary seasonally, temporal variation of Bd at high-latitude sites, such as the northeastern USA, is still poorly characterized. We screened amphibians for Bd monthly at 2 study sites in New York State from April to October 2011 and used quantitative polymerase chain reaction (qPCR) to detect and quantify temporal variability in Bd infection prevalence and intensity. We found pronounced seasonal variation in both Bd infection prevalence and intensity at the community level, and our data indicate that this pattern is due to a few species (Lithobates catesbeianus, L. clamitans, and Notophthalmus viridescens) that drive temporal variability in disease dynamics. Amphibian body mass and sex were significant predictors of infection intensity but not infection prevalence. Understanding the temporal dynamics of Bd host-pathogen interactions provides important insight into regional, seasonal, and host-specific determinants of disease outbreaks. Further, our study elucidates the most relevant and informative timing for Bd surveys in temperate amphibian assemblages. Seasonal variation of infection dynamics suggests that Bd surveys from different sampling time points are not comparable, and summer surveys to evaluate chytridiomycosis may significantly underestimate Bd prevalence and intensity, leading to false conclusions about the severity of chytridiomycosis-induced amphibian mortality and population decline.
Collapse
Affiliation(s)
- Melissa A Lenker
- Cornell University, Department of Ecology and Evolutionary Biology, Ithaca, NY 14853, USA
| | | | | | | | | |
Collapse
|
89
|
Reshetnikov AN, Chestnut T, Brunner JL, Charles K, Nebergall EE, Olson DH. Detection of the emerging amphibian pathogens Batrachochytrium dendrobatidis and ranavirus in Russia. DISEASES OF AQUATIC ORGANISMS 2014; 110:235-240. [PMID: 25114047 DOI: 10.3354/dao02757] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In a population of the European common toad Bufo bufo from a rural pond in the region of Lake Glubokoe Regional Reserve in Moscow province, Russia, unexplained mass mortality events involving larvae and metamorphs have been observed over a monitoring period of >20 yr. We tested toads from this and a nearby site for the emerging amphibian pathogens Batrachochytrium dendrobatidis (Bd) and ranavirus (Rv). Both pathogens were detected, and at the rural pond site, with the above-noted losses and decline in toad breeding success, 40% of B. bufo metamorphs were Bd positive, 46% were Rv positive and 20% were co-infected with both pathogens. Toad metamorphs from a neighbouring water body were also Bd and Rv positive (25 and 55%, respectively). This is the first confirmation of these pathogens in Russia. Questions remain as to the origins of these pathogens in Russia and their roles in documented mass mortality events.
Collapse
|
90
|
Rohr JR, Raffel TR, Halstead NT, McMahon TA, Johnson SA, Boughton RK, Martin LB. Early-life exposure to a herbicide has enduring effects on pathogen-induced mortality. Proc Biol Sci 2014; 280:20131502. [PMID: 24266041 DOI: 10.1098/rspb.2013.1502] [Citation(s) in RCA: 64] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Exposure to stressors at formative stages in the development of wildlife and humans can have enduring effects on health. Understanding which, when and how stressors cause enduring health effects is crucial because these stressors might then be avoided or mitigated during formative stages to prevent lasting increases in disease susceptibility. Nevertheless, the impact of early-life exposure to stressors on the ability of hosts to resist and tolerate infections has yet to be thoroughly investigated. Here, we show that early-life, 6-day exposure to the herbicide atrazine (mean ± s.e.: 65.9±3.48 µg l(-1)) increased frog mortality 46 days after atrazine exposure (post-metamorphosis), but only when frogs were challenged with a chytrid fungus implicated in global amphibian declines. Previous atrazine exposure did not affect resistance of infection (fungal load). Rather, early-life exposure to atrazine altered growth and development, which resulted in exposure to chytrid at more susceptible developmental stages and sizes, and reduced tolerance of infection, elevating mortality risk at an equivalent fungal burden to frogs unexposed to atrazine. Moreover, there was no evidence of recovery from atrazine exposure. Hence, reducing early-life exposure of amphibians to atrazine could reduce lasting increases in the risk of mortality from a disease associated with worldwide amphibian declines. More generally, these findings highlight that a better understanding of how stressors cause enduring effects on disease susceptibility could facilitate disease prevention in wildlife and humans, an approach that is often more cost-effective and efficient than reactive medicine.
Collapse
|
91
|
Susceptibility to the amphibian chytrid fungus varies with ontogeny in the direct-developing frog, Eleutherodactylus coqui. J Wildl Dis 2014; 50:438-46. [PMID: 24807186 DOI: 10.7589/2013-10-268] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Age-related differences in susceptibility to infectious disease are known from a wide variety of plant and animal taxonomic groups. For example, the immature immune systems of young vertebrates, along with limited prior exposure to pathogens and behavioral factors, can place juveniles at greater risk of acquiring and succumbing to a pathogen. We studied the ontogenetic susceptibility of terrestrial direct-developing frogs (Eleutherodactylus coqui) to the fungal pathogen, Batrachochytrium dendrobatidis (Bd), which is responsible for the decline of amphibian species worldwide. By exposing juvenile and adult frogs to the same dose and strain of Bd, we uncovered ontogenetic differences in susceptibility. Froglets exposed to the pathogen had significantly lower survival rates compared with control froglets, while adult frogs largely cleared infection and had survival rates indistinguishable from control frogs, even when exposed to a much higher dose of Bd. The high disease-induced mortality rate of juveniles may explain ongoing population declines in eastern Puerto Rico, where Bd is endemic and juveniles experience higher prevalence and infection intensity compared to adults. Our results have important implications for understanding and modeling the decline, possibly to extinction, of amphibian populations and species.
Collapse
|
92
|
Louca S, Lampo M, Doebeli M. Assessing host extinction risk following exposure to Batrachochytrium dendrobatidis. Proc Biol Sci 2014; 281:20132783. [PMID: 24807247 DOI: 10.1098/rspb.2013.2783] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Wildlife diseases are increasingly recognized as a major threat to biodiversity. Chytridiomycosis is an emerging infectious disease of amphibians caused by the fungus Batrachochytrium dendrobatidis (Bd). Using a mathematical model and simulations, we study its effects on a generic riparian host population with a tadpole and adult life stage. An analytical expression for the basic reproduction quotient, Qo, of the pathogen is derived. By sampling the entire relevant parameter space, we perform a statistical assessment of the importance of all considered parameters in determining the risk of host extinction, upon exposure to Bd. We find that Qo not only gives a condition for the initial invasion of the fungus, but is in fact the best predictor for host extinction. We also show that the role of tadpoles, which in some species tolerate infections, is ambivalent. While tolerant tadpoles may provide a reservoir for the fungus, thus facilitating its persistence or even amplifying its outbreaks, they can also act as a rescue buffer for a stressed host population. Our results have important implications for amphibian conservation efforts.
Collapse
Affiliation(s)
- Stilianos Louca
- Institute of Applied Mathematics, University of British Columbia, , 121-1984 Mathematics Road, Vancouver, British Columbia, Canada , V6T 1Z2, Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, , Apartado 21827, Caracas 1020-A, Venezuela, Department of Zoology, University of British Columbia, , 6270 University Boulevard, Vancouver, British Columbia, Canada , V6T 1Z4, Department of Mathematics, University of British Columbia, , 6270 University Boulevard, Vancouver, British Columbia, Canada , V6T 1Z4
| | | | | |
Collapse
|
93
|
Narayan EJ, Graham C, McCallum H, Hero JM. Over-wintering tadpoles of Mixophyes fasciolatus act as reservoir host for Batrachochytrium dendrobatidis. PLoS One 2014; 9:e92499. [PMID: 24647532 PMCID: PMC3960252 DOI: 10.1371/journal.pone.0092499] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2013] [Accepted: 02/23/2014] [Indexed: 11/19/2022] Open
Abstract
Batrachochytrium dendrobatidis (Bd), a cutaneous amphibian fungus that causes the lethal disease chytridiomycosis, has been implicated as a cause of many amphibian declines. Bd can tolerate low temperatures with an optimum thermal range from 17-24°C. It has been shown that Bd infection may result in species extinction, avoiding the transmission threshold presented by density dependent transmission theory. Prevalence of Bd during autumn and winter has been shown to be as low as 0% in some species. It is currently unclear how Bd persists in field conditions and what processes result in carry-over between seasons. It has been hypothesised that overwintering tadpoles may host Bd between breeding seasons. The Great Barred Frog (Mixophyes fasciolatus) is a common, stable and widespread species in Queensland, Australia, and is known to carry Bd. Investigation into Bd infection of different life stages of M. fasciolatus during seasonally low prevalence may potentially reveal persistence and carry-over methods between seasons. Metamorphs, juveniles, and adults were swabbed for Bd infection over three months (between March and May, 2011) at 5 sites of varying altitude (66 m-790 m). A total of 93 swabs were analysed using Polymerase Chain Reaction (PCR) real-time analysis. PCR analysis showed 6 positive (1 excluded), 4 equivocal and 83 negative results for infection with Bd. Equivocal results were assumed to be negative using the precautionary principle. The 5 positive results consisted of 4 emerging (Gosner stage 43-45) metamorphs and 1 adult M. fasciolatus. Fisher's exact test on prevalence showed that the prevalence was significantly different between life stages. All positive results were sampled at high altitudes (790 m); however prevalence was not significantly different between altitudes. Infection of emerging metamorphs suggests that individuals were infected as tadpoles. We hypothesise that M. fasciolatus tadpoles carry Bd through seasons. Thus, Mixophyes fasciolatus may act as disease reservoirs at multiple life stages.
Collapse
Affiliation(s)
- Edward J. Narayan
- Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast Campus, Queensland, Australia
- * E-mail:
| | - Clara Graham
- Environmental Futures Research Institute, School of Environment, Griffith University, Nathan Campus, Queensland, Australia
| | - Hamish McCallum
- Environmental Futures Research Institute, School of Environment, Griffith University, Nathan Campus, Queensland, Australia
| | - Jean-Marc Hero
- Environmental Futures Research Institute, School of Environment, Griffith University, Gold Coast Campus, Queensland, Australia
| |
Collapse
|
94
|
|
95
|
Baláž V, Vörös J, Civiš P, Vojar J, Hettyey A, Sós E, Dankovics R, Jehle R, Christiansen DG, Clare F, Fisher MC, Garner TWJ, Bielby J. Assessing risk and guidance on monitoring of Batrachochytrium dendrobatidis in Europe through identification of taxonomic selectivity of infection. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2014; 28:213-223. [PMID: 24033675 DOI: 10.1111/cobi.12128] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2012] [Accepted: 04/04/2013] [Indexed: 06/02/2023]
Abstract
Amphibians are globally threatened, but not all species are affected equally by different threatening processes. This is true for the threat posed by the chytridiomycete fungus (Batrachochytrium dendrobatidis). We compiled a European data set for B. dendrobatidis to analyze the trends of infection in European amphibians. The risk of infection was not randomly distributed geographically or taxonomically across Europe. Within countries with different prevalence, infection was nonrandom in certain amphibian taxa. Brown frogs of the genus Rana were unlikely to be infected, whereas frogs in the families Alytidae and Bombinatoridae were significantly more likely to be infected than predicted by chance. Frogs in the 2 families susceptible to B. dendrobatidis should form the core of attempts to develop spatial surveillance studies of chytridiomycosis in Europe. Ideally, surveys for B. dendrobatidis should be augmented by sampling the widespread genus Pelophylax because this taxon exhibits geographically inconsistent overinfection with B. dendrobatidis and surveillance of it may facilitate recognition of factors causing spatial variability of infection intensity. Several European amphibian taxa were not represented in our data set; however, surveillance of unsampled species should also occur when warranted.
Collapse
Affiliation(s)
- Vojtech Baláž
- Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences Brno, Palackého tř. 1/3, 612 42, Brno Czech Republic
| | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
96
|
Hanlon SM, Parris MJ. The interactive effects of chytrid fungus, pesticides, and exposure timing on gray treefrog (Hyla versicolor) larvae. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2014; 33:216-22. [PMID: 24259231 DOI: 10.1002/etc.2419] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/12/2013] [Revised: 07/04/2013] [Accepted: 10/01/2013] [Indexed: 06/02/2023]
Abstract
Aquatic organisms are often exposed to a wide variety of perturbations in nature, including pathogens and chemical contaminants. Despite the co-occurrence of these 2 stressors, few studies have examined the effects of chemical contaminants on host-pathogen dynamics. The authors tested the individual and combined effects on gray treefrog (Hyla versicolor) tadpoles of 2 commonly used pesticides (Roundup® and Sevin®) and the pathogenic fungus Batrachochytrium dendrobatidis (Bd). A fully factorial design was used, and tadpoles were exposed to Bd, Roundup, or Sevin alone, or a combination of Bd and either pesticide at 3 points during larval development (early, mid, late). It was predicted that pesticides would mediate the effect of Bd on tadpoles and reduce the likelihood of negative consequences of infection and that timing of exposure would influence these effects. Tadpoles exposed to Bd at the mid point experienced higher survival through metamorphosis than those exposed to Bd at the early or late points, while tadpoles exposed to Sevin at the early point experienced reduced survival compared with those exposed to Roundup or no-pesticide control at the same exposure point. Roundup ameliorated the effects of Bd on survival compared with tadpoles exposed to Bd alone, while there was no interactive effect of Sevin on survival. In addition, Sevin reduced mass of new metamorphs compared with Roundup and reduced snout-vent length compared with all other treatments. The present study supports the hypothesis that pesticides can mitigate the effects of Bd on amphibian hosts and that such effects may depend on the timing of exposure.
Collapse
Affiliation(s)
- Shane M Hanlon
- Department of Biological Sciences, University of Memphis, Memphis, Tennessee, USA
| | | |
Collapse
|
97
|
Groner ML, Rollins-Smith LA, Reinert LK, Hempel J, Bier ME, Relyea RA. Interactive effects of competition and predator cues on immune responses of leopard frogs at metamorphosis. ACTA ACUST UNITED AC 2013; 217:351-8. [PMID: 24115058 DOI: 10.1242/jeb.091611] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
Recent hypotheses suggest that immunosuppression, resulting from altered environmental conditions, may contribute to the increased incidence of amphibian disease around the world. Antimicrobial peptides (AMPs) in amphibian skin are an important innate immune defense against fungal, viral and bacterial pathogens. Their release is tightly coupled with release of the stress hormone noradrenaline (norepinephrine). During metamorphosis, AMPs may constitute the primary immune response in the skin of some species because acquired immune functions are temporarily suppressed in order to prevent autoimmunity against new adult antigens. Suppression of AMPs during this transitional stage may impact disease rates. We exposed leopard frog tadpoles (Lithobates pipiens) to a factorial combination of competitor and caged-predator environments and measured their development, growth and production of hydrophobic skin peptides after metamorphosis. In the absence of predator cues, or if the exposure to predator cues was late in ontogeny, competition caused more than a 250% increase in mass-standardized hydrophobic skin peptides. Predator cues caused a decrease in mass-standardized hydrophobic skin peptides when the exposure was late in ontogeny under low competition, but otherwise had no effect. Liquid chromatography tandem mass spectrometry of the skin peptides showed that they include six AMPs in the brevinin and temporin families and at least three of these peptides are previously uncharacterized. Both of these peptide families have previously been shown to inhibit harmful microbes including Batrachochytrium dendrobatidis, the fungal pathogen associated with global amphibian declines. Our study shows that amphibians may be able to adjust their skin peptide defenses in response to stressors that are experienced early in ontogeny and that these effects extend through an important life-history transition.
Collapse
Affiliation(s)
- Maya L Groner
- Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE, Canada, C1A 4P3
| | | | | | | | | | | |
Collapse
|
98
|
Groner ML, Buck JC, Gervasi S, Blaustein AR, Reinert LK, Rollins-Smith LA, Bier ME, Hempel J, Relyea RA. Larval exposure to predator cues alters immune function and response to a fungal pathogen in post-metamorphic wood frogs. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2013; 23:1443-1454. [PMID: 24147415 DOI: 10.1890/12-1572.1] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
For the past several decades, amphibian populations have been decreasing around the globe at an unprecedented rate. Batrachochytrium dendrobatidis (Bd), the fungal pathogen that causes chytridiomycosis in amphibians, is contributing to amphibian declines. Natural and anthropogenic environmental factors are hypothesized to contribute to these declines by reducing the immunocompetence of amphibian hosts, making them more susceptible to infection. Antimicrobial peptides (AMPs) produced in the granular glands of a frog's skin are thought to be a key defense against Bd infection. These peptides may be a critical immune defense during metamorphosis because many acquired immune functions are suppressed during this time. To test if stressors alter AMP production and survival of frogs exposed to Bd, we exposed wood frog (Lithobates sylvaticus) tadpoles to the presence or absence of dragonfly predator cues crossed with a single exposure to three nominal concentrations of the insecticide malathion (0, 10, or 100 parts per billion [ppb]). We then exposed a subset of post-metamorphic frogs to the presence or absence of Bd zoospores and measured frog survival. Although predator cues and malathion had no effect on survival or size at metamorphosis, predator cues increased the time to metamorphosis by 1.5 days and caused a trend of a 20% decrease in hydrophobic skin peptides. Despite this decrease in peptides determined shortly after metamorphosis, previous exposure to predator cues increased survival in both Bd-exposed and unexposed frogs several weeks after metamorphosis. These results suggest that exposing tadpoles to predator cues confers fitness benefits later in life.
Collapse
Affiliation(s)
- Maya L Groner
- Center for Veterinary Epidemiological Research, Department of Health Management, Atlantic Veterinary College, University of Prince Edward Island, Prince Edward Island C1A 4P3, Canada.
| | | | | | | | | | | | | | | | | |
Collapse
|
99
|
Doddington BJ, Bosch J, Oliver JA, Grassly NC, Garcia G, Schmidt BR, Garner TWJ, Fisher MC. Context-dependent amphibian host population response to an invading pathogen. Ecology 2013; 94:1795-804. [DOI: 10.1890/12-1270.1] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
100
|
Cheatsazan H, de Almedia APLG, Russell AF, Bonneaud C. Experimental evidence for a cost of resistance to the fungal pathogen, Batrachochytrium dendrobatidis, for the palmate newt, Lissotriton helveticus. BMC Ecol 2013; 13:27. [PMID: 23866033 PMCID: PMC3722082 DOI: 10.1186/1472-6785-13-27] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2012] [Accepted: 06/20/2013] [Indexed: 11/13/2022] Open
Abstract
Background Batrachochytrium dendrobatidis (Bd), the causative agent of chytridiomycosis, is decimating amphibians worldwide. Unsurprisingly, the majority of studies have therefore concentrated on documenting morbidity and mortality of susceptible species and projecting population consequences as a consequence of this emerging infectious disease. Currently, there is a paucity of studies investigating the sub-lethal costs of Bd in apparently asymptomatic species, particularly in controlled experimental conditions. Here we report the consequences of a single dose of B. dendrobatidis zoospores on captive adult palmate newts (Lissotriton helveticus) for morphological and behavioural traits that associate with reproductive success. Results A single exposure to ~2000 zoospores induced a subclinical Bd infection. One week after inoculation 84% of newts tested positive for Bd, and of those, 98% had apparently lost the infection by the day 30. However, exposed newts suffered significant mass loss compared with control newts, and those experimental newts removing higher levels of Bd lost most mass. We found no evidence to suggest that three secondary sexual characteristics (areas of dorsal crest and rear foot webbing, and length of tail filament) were reduced between experimental versus control newts; in fact, rear foot webbing was 26% more expansive at the end of the experiment in exposed newts. Finally, compared with unexposed controls, exposure to Bd was associated with a 50% earlier initiation of the non-reproductive terrestrial phase. Conclusions Our results suggest that Bd has measureable, but sub-lethal effects, on adult palmate newts, at least under the laboratory conditions presented. We conclude that the effects reported are most likely to be mediated through the initiation of costly immune responses and/or tissue repair mechanisms. Although we found no evidence of hastened secondary sexual trait regression, through reducing individual body condition and potentially, breeding season duration, we predict that Bd exposure might have negative impacts on populations of palmate newts through reducing individual reproductive success and adult recruitment.
Collapse
|