1
|
Bosch J, Thumsová B, Puschendorf R, Bielby J. Drivers of Batrachochytrium dendrobatidis infection load, with evidence of infection tolerance in adult male toads (Bufo spinosus). Oecologia 2023; 202:165-174. [PMID: 37147397 DOI: 10.1007/s00442-023-05380-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2022] [Accepted: 04/25/2023] [Indexed: 05/07/2023]
Abstract
Chytridiomycosis is affecting hundreds of amphibian species worldwide, but while in tropical areas, adult individuals have been the focus of most investigations, the exact role played by infection intensity of breeding adults is not well understood in temperate areas. We conducted mark-recapture-capture surveys during spiny common toad breeding seasons from 2006 to 2018 at the site of the first recorded outbreak of chytridiomycosis in Europe, the Peñalara Massif (Sierra de Guadarrama National Park, central Spain), and collected infection samples and several variables related to the reproductive effort of male individuals. We used general linear mixed models to evaluate the contribution of study variables on the infection loads of adult male toads exhibited at their capturing date. We also analysed the differences on several male characteristics between the pond with the largest breeding population against the rest of the ponds. We found that the duration of time spent in the waterbody and the condition of the host predicted infection loads. Animals of good physical condition, that spent longer in water, have higher infection levels than individuals with the opposite set of traits. The pond supporting the largest breeding population housed smaller male toads and in poorer condition. Our results are consistent with a shift in reproductive strategy in response to infection and potentially a strategy of tolerance, rather than resistance to infection. These findings have applications for disease mitigation and theoretical implications related to the trade-offs made and the evolution of traits in response to the disease.
Collapse
Affiliation(s)
- Jaime Bosch
- Biodiversity Research Institute (IMIB), CSIC-University of Oviedo-Principality of Asturias, Mieres, Spain.
- Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Rascafría, Spain.
| | - Barbora Thumsová
- Asociación Herpetológica Española (AHE), Madrid, Spain
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
| | - Robert Puschendorf
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, UK
| | - Jon Bielby
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, UK
| |
Collapse
|
2
|
Pabijan M, Palomar G, Antunes B, Antoł W, Zieliński P, Babik W. Evolutionary principles guiding amphibian conservation. Evol Appl 2020; 13:857-878. [PMID: 32431739 PMCID: PMC7232768 DOI: 10.1111/eva.12940] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2019] [Revised: 02/05/2020] [Accepted: 02/18/2020] [Indexed: 12/18/2022] Open
Abstract
The Anthropocene has witnessed catastrophic amphibian declines across the globe. A multitude of new, primarily human-induced drivers of decline may lead to extinction, but can also push species onto novel evolutionary trajectories. If these are recognized by amphibian biologists, they can be engaged in conservation actions. Here, we summarize how principles stemming from evolutionary concepts have been applied for conservation purposes, and address emerging ideas at the vanguard of amphibian conservation science. In particular, we examine the consequences of increased drift and inbreeding in small populations and their implications for practical conservation. We then review studies of connectivity between populations at the landscape level, which have emphasized the limiting influence of anthropogenic structures and degraded habitat on genetic cohesion. The rapid pace of environmental changes leads to the central question of whether amphibian populations can cope either by adapting to new conditions or by shifting their ranges. We gloomily conclude that extinction seems far more likely than adaptation or range shifts for most species. That said, conservation strategies employing evolutionary principles, such as selective breeding, introduction of adaptive variants through translocations, ecosystem interventions aimed at decreasing phenotype-environment mismatch, or genetic engineering, may effectively counter amphibian decline in some areas or for some species. The spread of invasive species and infectious diseases has often had disastrous consequences, but has also provided some premier examples of rapid evolution with conservation implications. Much can be done in terms of setting aside valuable amphibian habitat that should encompass both natural and agricultural areas, as well as designing protected areas to maximize the phylogenetic and functional diversity of the amphibian community. We conclude that an explicit consideration and application of evolutionary principles, although certainly not a silver bullet, should increase effectiveness of amphibian conservation in both the short and long term.
Collapse
Affiliation(s)
- Maciej Pabijan
- Institute of Zoology and Biomedical ResearchFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Gemma Palomar
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Bernardo Antunes
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Weronika Antoł
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Piotr Zieliński
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| | - Wiesław Babik
- Institute of Environmental SciencesFaculty of BiologyJagiellonian UniversityKrakówPoland
| |
Collapse
|
3
|
Bosch J, Fernández-Beaskoetxea S, Garner TWJ, Carrascal LM. Long-term monitoring of an amphibian community after a climate change- and infectious disease-driven species extirpation. GLOBAL CHANGE BIOLOGY 2018; 24:2622-2632. [PMID: 29446515 DOI: 10.1111/gcb.14092] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 01/11/2018] [Accepted: 01/26/2018] [Indexed: 05/28/2023]
Abstract
Infectious disease and climate change are considered major threats to biodiversity and act as drivers behind the global amphibian decline. This is, to a large extent, based on short-term studies that are designed to detect the immediate and strongest biodiversity responses to a threatening process. What few long-term studies are available, although typically focused on single species, report outcomes that often diverge significantly from the short-term species responses. Here, we report the results of an 18-year survey of an amphibian community exposed to both climate warming and the emergence of lethal chytridiomycosis. Our study shows that the impacts of infectious disease are ongoing but restricted to two out of nine species that form the community, despite the fact all species can become infected with the fungus. Climate warming appears to be affecting four out of the nine species, but the response of three of these is an increase in abundance. Our study supports a decreasing role of infectious disease on the community, and an increasing and currently positive effect of climate warming. We caution that if the warming trends continue, the net positive effect will turn negative as amphibian breeding habitat becomes unavailable as water bodies dry, a pattern that already may be underway.
Collapse
Affiliation(s)
- Jaime Bosch
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain
- Centro de Investigación, Seguimiento y Evaluación, Parque Nacional de la Sierra de Guadarrama, Rascafría, Spain
| | | | | | | |
Collapse
|
4
|
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
|
5
|
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
|
6
|
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: 7] [Impact Index Per Article: 0.9] [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
|
7
|
Evidence of a salt refuge: chytrid infection loads are suppressed in hosts exposed to salt. Oecologia 2014; 177:901-910. [PMID: 25416999 DOI: 10.1007/s00442-014-3157-6] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
Abstract
With the incidence of emerging infectious diseases on the rise, it is becoming increasingly important to identify refuge areas that protect hosts from pathogens and therefore prevent population declines. For the chytrid fungus Batrachochytrium dendrobatidis, temperature and humidity refuge areas for amphibian hosts exist but are difficult to manipulate. Other environmental features that may affect the outcome of infection include water quality, drying regimes, abundance of alternate hosts and isolation from other hosts. We identified relationships between water bodies with these features and infection levels in the free-living hosts inhabiting them. Where significant relationships were identified, we used a series of controlled experiments to test for causation. Infection loads were negatively correlated with the salt concentration of the aquatic habitat and the degree of water level fluctuation and positively correlated with fish abundance. However, only the relationship with salt was confirmed experimentally. Free-living hosts inhabiting water bodies with mean salinities of up to 3.5 ppt had lower infection loads than those exposed to less salt. The experiment confirmed that exposure to sodium chloride concentrations >2 ppt significantly reduced host infection loads compared to no exposure (0 ppt). These results suggest that the exposure of amphibians to salt concentrations found naturally in lentic habitats may be responsible for the persistence of some susceptible species in the presence of B. dendrobatidis. By manipulating the salinity of water bodies, it may be possible to create refuges for declining amphibians, thus allowing them to be reintroduced to their former ranges.
Collapse
|
8
|
Balá V, Vojar J, Civi P, Andera M, Rozínek R. Chytridiomycosis risk among Central European amphibians based on surveillance data. DISEASES OF AQUATIC ORGANISMS 2014; 112:1-8. [PMID: 25392037 DOI: 10.3354/dao02799] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The Czech Republic hosts a surprisingly rich biodiversity of amphibians representing the majority of amphibian species present in all of Central and Eastern Europe. Surveillance data of Batrachochytrium dendrobatidis (Bd) collected during 2008 to 2012 were analysed for basic patterns of prevalence and infection intensity among species, age groups and localities. In addition, an investigation was made into possible data bias due to varying PCR inhibition. Infection prevalence in the genus Pelophylax was significantly higher than in other sampled taxa, while Bombina and Bufo were infected with intermediate prevalence. Individual mortalities putatively caused by chytridiomycosis were detected in Bombina and Bufo, but not in Pelophylax. Differences among localities were seen to modulate the pathogen's infection rate and influence overall individual infection intensities. PCR inhibition occurred significantly more often in samples from the genus Pelophylax than in other tested taxa (Bufo bufo, B. viridis, Bombina bombina, Pelobates fuscus and Rana dalmatina). Although we found no completely inhibited samples within the genus Bombina, the infection loads were lower in the sample set processed without bovine serum albumin, suggesting some level of PCR inhibition. The combination of high Bd prevalence with no apparent deleterious effect and the high dispersal abilities of water frogs predispose them to act as vectors for chytridiomycosis. It is possible that the role of Pelophylax frogs in the spread of Bd is overlooked due to a large proportion of unrecognized false negatives, but this issue needs further confirmation.
Collapse
Affiliation(s)
- Vojtech Balá
- Department of Biology and Wildlife Diseases, Faculty of Veterinary Hygiene and Ecology, University of Veterinary and Pharmaceutical Sciences Brno, Palackého trˇ. 1/3, Brno 612 42, Czech Republic
| | | | | | | | | |
Collapse
|
9
|
|
10
|
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
|
11
|
Bosch J, García-Alonso D, Fernández-Beaskoetxea S, Fisher MC, Garner TWJ. Evidence for the introduction of lethal Chytridiomycosis affecting wild betic midwife toads (Alytes dickhilleni). ECOHEALTH 2013; 10:82-89. [PMID: 23494771 DOI: 10.1007/s10393-013-0828-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Revised: 02/04/2013] [Accepted: 02/08/2013] [Indexed: 06/01/2023]
Abstract
Batrachochytrium dendrobatidis is an unpredictable pathogen for European amphibian species, and existing field surveillance studies likely underestimate the scope of its distribution and effects. Mass mortality episodes recorded in Europe indicate that investigations of unstudied species should focus on members of the frog family Alytidae. Here, we report the combined results of a field survey and laboratory observations of field collected Alytes dickhilleni. Our data support the hypothesis that B. dendrobatidis has recently emerged in at least two disjunct locations in the species range and populations across much of the species range lack evidence of infection pathogen. Tadpoles taken into the laboratory from sites with infection experienced 70% mortality, unlike those taken into the laboratory from uninfected sites, and both infection and strength of infection was associated with mortality in animals collected from infected locations. Several conservation interventions are underway in response to our study, including the establishment of a captive assurance colony, a public awareness campaign, and experimental tests of disease mitigation schemes.
Collapse
Affiliation(s)
- Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, José Gutiérrez Abascal 2, 28006, Madrid, Spain.
| | | | | | | | | |
Collapse
|
12
|
Terrestrial Movement Patterns of the Common Toad (Bufo bufo) in Central Spain Reveal Habitat of Conservation Importance. J HERPETOL 2012. [DOI: 10.1670/11-012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
|
13
|
Hamilton PT, Richardson JM, Govindarajulu P, Anholt BR. Higher temperature variability increases the impact of Batrachochytrium dendrobatidis and shifts interspecific interactions in tadpole mesocosms. Ecol Evol 2012; 2:2450-9. [PMID: 23145331 PMCID: PMC3492772 DOI: 10.1002/ece3.369] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/26/2012] [Accepted: 07/31/2012] [Indexed: 11/24/2022] Open
Abstract
The emergence of amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd) has led to the decline and extinction of numerous amphibian species. Multiple studies have observed links between climatic factors and amphibian declines apparently caused by Bd. Using outdoor experimental mesocosms, we tested the response of red-legged frog (Rana aurora) tadpoles to increased variation in temperature, a component of climate linked to amphibian declines, and Bd exposure. We included tadpoles of a sympatric competitor species, Pacific chorus frog (Pseudacris regilla), in a fully factorial design to test the effects of Bd and temperature on interspecific interactions. We found that higher variation in temperature had numerous effects in mesocosms, including interacting with Bd presence to decrease the condition of R. aurora, shifting the relative performance of competing P. regilla and R. aurora, and accelerating the development of P. regilla relative to R. aurora. Our results demonstrate that increased variation in temperature can affect amphibians in multiple ways that will be contingent on ecological context, including the presence of Bd and competing species.
Collapse
Affiliation(s)
- Phineas T Hamilton
- Department of Biology, University of Victoria PO Box 3020, STN CSC, Victoria, British Columbia, V8W 3N5, Canada
| | | | | | | |
Collapse
|
14
|
Woodhams DC, Geiger CC, Reinert LK, Rollins-Smith LA, Lam B, Harris RN, Briggs CJ, Vredenburg VT, Voyles J. Treatment of amphibians infected with chytrid fungus: learning from failed trials with itraconazole, antimicrobial peptides, bacteria, and heat therapy. DISEASES OF AQUATIC ORGANISMS 2012; 98:11-25. [PMID: 22422126 DOI: 10.3354/dao02429] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Amphibian conservation goals depend on effective disease-treatment protocols. Desirable protocols are species, life stage, and context specific, but currently few treatment options exist for amphibians infected with the chytrid fungus Batrachochytrium dendrobatidis (Bd). Treatment options, at present, include antifungal drugs and heat therapy, but risks of toxicity and side-effects make these options untenable in some cases. Here, we report on the comparison of several novel treatments with a more generally accepted antifungal treatment in experimental scientific trials to treat Bd-infected frogs including Alytes obstetricans tadpoles and metamorphs, Bufo bufo and Limnodynastes peronii metamorphs, and Lithobates pipiens and Rana muscosa adults. The experimental treatments included commercial antifungal products (itraconazole, mandipropamid, steriplantN, and PIP Pond Plus), antimicrobial skin peptides from the Bd-resistant Pelophylax esculentus, microbial treatments (Pedobacter cryoconitis), and heat therapy (35°C for 24 h). None of the new experimental treatments were considered successful in terms of improving survival; however, these results may advance future research by indicating the limits and potential of the various protocols. Caution in the use of itraconazole is warranted because of observed toxicity in metamorphic and adult frogs, even at low concentrations. Results suggest that rather than focusing on a single cure-all, diverse lines of research may provide multiple options for treating Bd infection in amphibians. Learning from 'failed treatments' is essential for the timely achievement of conservation goals and one of the primary aims for a publicly accessible treatment database under development.
Collapse
Affiliation(s)
- Douglas C Woodhams
- Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
| | | | | | | | | | | | | | | | | |
Collapse
|
15
|
Ortiz-Santaliestra ME, Fisher MC, Fernández-Beaskoetxea S, Fernández-Benéitez MJ, Bosch J. Ambient ultraviolet B radiation and prevalence of infection by Batrachochytrium dendrobatidis in two amphibian species. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2011; 25:975-82. [PMID: 21676032 DOI: 10.1111/j.1523-1739.2011.01700.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
Chytridiomycosis, the emerging disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd) is responsible for declines and extirpations of amphibian populations worldwide. Environmental covariates modify the host-Bd interaction and thus affect the ongoing spread of the pathogen. One such covariate may be the intensity of ultraviolet B (UV-B) radiation. In a field experiment conducted in Laguna Grande de Peñalara (central Spain), a mountainous region where the presence of Bd has been documented since 1997, we analyzed the potential effect of environmental UV-B (daily maximum 2.5-3.9 W/m(2) ) on the susceptibility of larvae of the common toad (Bufo bufo) to Bd. The proportion of infected individuals increased as tadpoles developed. The prevalence of Bd was significantly lower in tadpoles exposed to environmental UV-B intensities (2.94%) than in tadpoles not exposed to the radiation (9.72%). This finding mirrors that seen for a second amphibian species, the European midwife toad (Alytes obstetricans), for which conditional prevalence (i.e., prevalence of infection conditioned on the probability of a site being infected) across the Iberian Peninsula was inversely correlated with the intensity of UV-B.
Collapse
Affiliation(s)
- Manuel E Ortiz-Santaliestra
- Instituto de Investigación en Recursos Cinegéticos UCLM-CSIC-JCCM, Ronda de Toledo s/n, 13071 Ciudad Real, Spain
| | | | | | | | | |
Collapse
|
16
|
The contribution of skin antimicrobial peptides to the system of innate immunity in anurans. Cell Tissue Res 2010; 343:201-12. [PMID: 20640445 DOI: 10.1007/s00441-010-1014-4] [Citation(s) in RCA: 114] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2010] [Accepted: 06/08/2010] [Indexed: 10/19/2022]
Abstract
Cationic peptides with the propensity to adopt an amphipathic α-helical conformation in a membrane-mimetic environment are synthesized in the skins of many species of anurans (frogs and toads). These peptides frequently display cytolytic activities against a range of pathogenic bacteria and fungi consistent with the idea that they play a role in the host's system of innate immunity. However, the importance of the peptides in the survival strategy of the animal is not clearly understood. It is a common misconception that antimicrobial peptides are synthesized in the skins of all anurans. In fact, the species distribution is sporadic suggesting that their production may confer some evolutionary advantage to the organism but is not necessary for survival. Although growth inhibitory activity against the chytrid fungus Batrachochytrium dendrobatidis, responsible for anuran population declines worldwide, has been demonstrated in vitro, the ability of frog skin antimicrobial peptides to protect the animal in the wild appears to be limited and there is no clear correlation between their production by a species and its resistance to fatal chytridiomycosis. The low potency of many frog skin antimicrobial peptides is consistent with the hypothesis that cutaneous symbiotic bacteria may provide the major system of defense against pathogenic microorganisms in the environment with antimicrobial peptides assuming a supplementary role in some species.
Collapse
|
17
|
Conlon JM, Demandt A, Nielsen PF, Leprince J, Vaudry H, Woodhams DC. The alyteserins: two families of antimicrobial peptides from the skin secretions of the midwife toad Alytes obstetricans (Alytidae). Peptides 2009; 30:1069-73. [PMID: 19463738 DOI: 10.1016/j.peptides.2009.03.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 03/07/2009] [Accepted: 03/09/2009] [Indexed: 10/21/2022]
Abstract
Two families of structurally related C-terminally alpha-amidated antimicrobial peptides have been identified in norepinephrine-stimulated skin secretions of the midwife toad Alytes obstetricans (Alytidae). The alyteserin-1 peptides (Gly-Leu-Lys-(Asp/Glu)-Ile-Phe-Lys-Ala-Gly-Leu-Gly-Ser-Leu-Val-Lys-(Gly/Asn)-Ile-Ala-Ala-His-Val-Ala-(Asn/Ser).NH(2)) show limited structural similarity to the ascaphins from the skins of frogs of the family Leiopelmatidae. Alyteserin-2a (Ile-Leu-Gly-Lys-Leu-Leu-Ser-Thr-Ala-Ala-Gly-Leu-Leu-Ser-Asn-Leu.NH(2)) and alyteserin-2b and -2c (Ile-Leu-Gly-Ala-Ile-Leu-Pro-Leu-Val-Ser-Gly-Leu-Leu-Ser-(Asn/Ser)-Lys-Leu x NH(2)) show limited sequence identity with bombinin H6, present in the skins of frogs of the family Bombinatoridae. The alyteserin-1 peptides show selective growth inhibitory activity against the Gram-negative bacteria Escherichia coli (MIC=25 microM) whereas alyteserin-2a is more potent against the Gram-positive bacteria Staphylococcus aureus (MIC=50 microM). The hemolytic activity against human erythrocytes of all peptides tested is relatively weak (LC(50)>100 microM). The data demonstrate that the frogs belonging to the family Alytidae are among those producing dermal antimicrobial peptides that may represent a component of the animal's system of innate immunity.
Collapse
Affiliation(s)
- J Michael Conlon
- Department of Biochemistry, Faculty of Medicine and Health Sciences, United Arab Emirates University, 17666 Al-Ain, United Arab Emirates.
| | | | | | | | | | | |
Collapse
|
18
|
James TY, Litvintseva AP, Vilgalys R, Morgan JAT, Taylor JW, Fisher MC, Berger L, Weldon C, du Preez L, Longcore JE. Rapid global expansion of the fungal disease chytridiomycosis into declining and healthy amphibian populations. PLoS Pathog 2009; 5:e1000458. [PMID: 19478871 PMCID: PMC2680619 DOI: 10.1371/journal.ppat.1000458] [Citation(s) in RCA: 155] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2009] [Accepted: 04/29/2009] [Indexed: 01/27/2023] Open
Abstract
The fungal disease chytridiomycosis, caused by Batrachochytrium dendrobatidis, is enigmatic because it occurs globally in both declining and apparently healthy (non-declining) amphibian populations. This distribution has fueled debate concerning whether, in sites where it has recently been found, the pathogen was introduced or is endemic. In this study, we addressed the molecular population genetics of a global collection of fungal strains from both declining and healthy amphibian populations using DNA sequence variation from 17 nuclear loci and a large fragment from the mitochondrial genome. We found a low rate of DNA polymorphism, with only two sequence alleles detected at each locus, but a high diversity of diploid genotypes. Half of the loci displayed an excess of heterozygous genotypes, consistent with a primarily clonal mode of reproduction. Despite the absence of obvious sex, genotypic diversity was high (44 unique genotypes out of 59 strains). We provide evidence that the observed genotypic variation can be generated by loss of heterozygosity through mitotic recombination. One strain isolated from a bullfrog possessed as much allelic diversity as the entire global sample, suggesting the current epidemic can be traced back to the outbreak of a single clonal lineage. These data are consistent with the current chytridiomycosis epidemic resulting from a novel pathogen undergoing a rapid and recent range expansion. The widespread occurrence of the same lineage in both healthy and declining populations suggests that the outcome of the disease is contingent on environmental factors and host resistance.
Collapse
|
19
|
Conlon JM, Iwamuro S, King JD. Dermal Cytolytic Peptides and the System of Innate Immunity in Anurans. Ann N Y Acad Sci 2009; 1163:75-82. [DOI: 10.1111/j.1749-6632.2008.03618.x] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|
20
|
Bielby J, Bovero S, Sotgiu G, Tessa G, Favelli M, Angelini C, Doglio S, Clare FC, Gazzaniga E, Lapietra F, Garner TWJ. Fatal chytridiomycosis in the tyrrhenian painted frog. ECOHEALTH 2009; 6:27-32. [PMID: 19418096 DOI: 10.1007/s10393-009-0232-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/03/2008] [Revised: 10/07/2008] [Accepted: 10/09/2008] [Indexed: 05/27/2023]
Abstract
Batrachochytrium dendrobatidis (Bd), the causative agent of the amphibian disease chytridiomycosis, is an important factor in the global decline of amphibians. Within Europe, animals that exhibit clinical signs of the disease have only been reported in Spain despite the pathogen's wide, but patchy, distribution on the continent. Recently, another occurrence of chytridiomycosis was reported in Euproctus platycephalus, the Sardinian brook newt, on the Mediterranean island of Sardinia, but without any evidence of fatal disease. We report further evidence of the emergence of Bd on Sardinia and the first evidence of lethal chytridiomycosis outside of Spain. Unusual mortalities of the Tyrrhenian painted frog (Discoglossus sardus) were found at three sites in the Limbara mountains of northern Sardinia. Molecular and histological screens of corpses, frogs, and tadpoles from these sites revealed infection with Bd. Infection and mortality occurred at locations that are unusual in terms of the published habitat requirements of the pathogen. Given the endemicity, the IUCN Red List status of the amphibian species on Sardinia, and the occurrence of infection and mortality caused by chytridiomycosis, there is serious reason for concern for the impact that disease emergence may have on the conservation of the amphibians of the island.
Collapse
Affiliation(s)
- Jon Bielby
- Institute of Zoology, Zoological Society of London, Regent's Park, London, UK
| | | | | | | | | | | | | | | | | | | | | |
Collapse
|
21
|
MARTÍNEZ-SOLANO IÑIGO, GONZÁLEZ ELENAG. Patterns of gene flow and source-sink dynamics in high altitude populations of the common toad Bufo bufo (Anura: Bufonidae). Biol J Linn Soc Lond 2008. [DOI: 10.1111/j.1095-8312.2008.01098.x] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
|