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Chew A, West M, Berger L, Brannelly LA. The impacts of water quality on the amphibian chytrid fungal pathogen: A systematic review. ENVIRONMENTAL MICROBIOLOGY REPORTS 2024; 16:e13274. [PMID: 38775382 PMCID: PMC11110485 DOI: 10.1111/1758-2229.13274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 04/06/2024] [Indexed: 05/25/2024]
Abstract
The pathogenic fungus Batrachochytrium dendrobatidis has caused declines of amphibians worldwide. Yet our understanding of how water quality influences fungal pathogenicity is limited. Here, we reviewed experimental studies on the effect of water quality on this pathogen to determine which parameters impacted disease dynamics consistently. The strongest evidence for protective effects is salinity which shows strong antifungal properties in hosts at natural levels. Although many fungicides had detrimental effects on the fungal pathogen in vitro, their impact on the host is variable and they can worsen infection outcomes. However, one fungicide, epoxiconazole, reduced disease effects experimentally and likely in the field. While heavy metals are frequently studied, there is weak evidence that they influence infection outcomes. Nitrogen and phosphorous do not appear to impact pathogen growth or infection in the amphibian host. The effects of other chemicals, like pesticides and disinfectants on infection were mostly unclear with mixed results or lacking an in vivo component. Our study shows that water chemistry does impact disease dynamics, but the effects of specific parameters require more investigation. Improving our understanding of how water chemistry influences disease dynamics will help predict the impact of chytridiomycosis, especially in amphibian populations affected by land use changes.
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Affiliation(s)
- Adeline Chew
- School of BiosciencesThe University of MelbourneParkvilleVictoriaAustralia
| | - Matt West
- School of BiosciencesThe University of MelbourneParkvilleVictoriaAustralia
| | - Lee Berger
- Melbourne Veterinary SchoolThe University of MelbourneWerribeeVictoriaAustralia
| | - Laura A. Brannelly
- Melbourne Veterinary SchoolThe University of MelbourneWerribeeVictoriaAustralia
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2
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Porco D, Purnomo CA, Glesener L, Proess R, Lippert S, Jans K, Colling G, Schneider S, Stassen R, Frantz AC. eDNA-based monitoring of Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans with ddPCR in Luxembourg ponds: taking signals below the Limit of Detection (LOD) into account. BMC Ecol Evol 2024; 24:4. [PMID: 38178008 PMCID: PMC10768104 DOI: 10.1186/s12862-023-02189-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 12/09/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal) are two pathogenic fungi that are a significant threat to amphibian communities worldwide. European populations are strongly impacted and the monitoring of the presence and spread of these pathogens is crucial for efficient decision-making in conservation management. RESULTS Here we proposed an environmental DNA (eDNA) monitoring of these two pathogenic agents through droplet digital PCR (ddPCR) based on water samples from 24 ponds in Luxembourg. In addition, amphibians were swabbed in eight of the targeted ponds in order to compare the two approaches at site-level detection. This study allowed the development of a new method taking below-Limit of Detection (LOD) results into account thanks to the statistical comparison of the frequencies of false positives in no template controls (NTC) and below-LOD results in technical replicates. In the eDNA-based approach, the use of this method led to an increase in Bd and Bsal detection of 28 and 50% respectively. In swabbing, this resulted in 8% more positive results for Bd. In some samples, the use of technical replicates allowed to recover above-LOD signals and increase Bd detection by 35 and 33% respectively for eDNA and swabbing, and Bsal detection by 25% for eDNA. CONCLUSIONS These results confirmed the usefulness of technical replicates to overcome high levels of stochasticity in very low concentration samples even for a highly sensitive technique such as ddPCR. In addition, it showed that below-LOD signals could be consistently recovered and the corresponding amplification events assigned either to positive or negative detection via the method developed here. This methodology might be particularly worth pursuing in pathogenic agents' detection as false negatives could have important adverse consequences. In total, 15 ponds were found positive for Bd and four for Bsal. This study reports the first record of Bsal in Luxembourg.
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Affiliation(s)
- David Porco
- Musée national d'histoire naturelle du Luxembourg, 25, rue Münster, Luxembourg, L-2160, Luxembourg.
- Fondation Faune Flore, 24, rue Münster, Luxembourg, L-2160, Luxembourg.
| | - Chanistya Ayu Purnomo
- Musée national d'histoire naturelle du Luxembourg, 25, rue Münster, Luxembourg, L-2160, Luxembourg
| | - Liza Glesener
- Naturschutzsyndikat SICONA, 12, rue de Capellen, L-8393 Olm, Luxembourg, Luxembourg
| | - Roland Proess
- Umweltplanungsbüro Ecotop, 45, Schlassuecht, L-7435 Hollenfels, Luxembourg, Luxembourg
| | - Stéphanie Lippert
- Musée national d'histoire naturelle du Luxembourg, 25, rue Münster, Luxembourg, L-2160, Luxembourg
| | - Kevin Jans
- Natur&ëmwelt Fondation Hëllef fir d'Natur, 5, Route de Luxembourg, L-1899, Kockelscheuer, Luxembourg
| | - Guy Colling
- Musée national d'histoire naturelle du Luxembourg, 25, rue Münster, Luxembourg, L-2160, Luxembourg
- Fondation Faune Flore, 24, rue Münster, Luxembourg, L-2160, Luxembourg
| | - Simone Schneider
- Musée national d'histoire naturelle du Luxembourg, 25, rue Münster, Luxembourg, L-2160, Luxembourg
- Naturschutzsyndikat SICONA, 12, rue de Capellen, L-8393 Olm, Luxembourg, Luxembourg
| | - Raf Stassen
- Biota.lu, 9a, Rue Principale, L-6990, Hostert, Luxembourg
| | - Alain C Frantz
- Musée national d'histoire naturelle du Luxembourg, 25, rue Münster, Luxembourg, L-2160, Luxembourg
- Fondation Faune Flore, 24, rue Münster, Luxembourg, L-2160, Luxembourg
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3
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Setta SP, Lerch S, Jenkins BD, Dyhrman ST, Rynearson TA. Oligotrophic waters of the Northwest Atlantic support taxonomically diverse diatom communities that are distinct from coastal waters. JOURNAL OF PHYCOLOGY 2023; 59:1202-1216. [PMID: 37737069 DOI: 10.1111/jpy.13388] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2023] [Revised: 07/23/2023] [Accepted: 08/09/2023] [Indexed: 09/23/2023]
Abstract
Diatoms are important components of the marine food web and one of the most species-rich groups of phytoplankton. The diversity and composition of diatoms in eutrophic nearshore habitats have been well documented due to the outsized influence of diatoms on coastal ecosystem functioning. In contrast, patterns of both diatom diversity and community composition in offshore oligotrophic regions where diatom biomass is low have been poorly resolved. To compare the diatom diversity and community composition in oligotrophic and eutrophic waters, diatom communities were sampled along a 1,250 km transect from the oligotrophic Sargasso Sea to the coastal waters of the northeast US shelf. Diatom community composition was determined by amplifying and sequencing the 18S rDNA V4 region. Of the 301 amplicon sequence variants (ASVs) identified along the transect, the majority (70%) were sampled exclusively from oligotrophic waters of the Gulf Stream and Sargasso Sea and included the genera Bacteriastrum, Haslea, Hemiaulus, Pseudo-nitzschia, and Nitzschia. Diatom ASV richness did not vary along the transect, indicating that the oligotrophic Sargasso Sea and Gulf Stream are occupied by a diverse diatom community. Although ASV richness was similar between oligotrophic and coastal waters, diatom community composition in these regions differed significantly and was correlated with temperature and phosphate, two environmental variables known to influence diatom metabolism and geographic distribution. In sum, oligotrophic waters of the western North Atlantic harbor diverse diatom assemblages that are distinct from coastal regions, and these open ocean diatoms warrant additional study, as they may play critical roles in oligotrophic ecosystems.
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Affiliation(s)
- Samantha P Setta
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
| | - Sarah Lerch
- College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Bethany D Jenkins
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
- College of the Environment and Life Sciences, University of Rhode Island, Kingston, Rhode Island, USA
| | - Sonya T Dyhrman
- Department of Earth and Environmental Sciences, Columbia University, Palisades, New York, USA
- Lamont-Doherty Earth Observatory, Columbia University, Palisades, New York, USA
| | - Tatiana A Rynearson
- Graduate School of Oceanography, University of Rhode Island, Narragansett, Rhode Island, USA
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4
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Kamoroff C, Goldberg CS, Grasso RL. Rapid detection of amphibian chytrid fungus Batrachochytrium dendrobatidis using in situ DNA extraction and a handheld mobile thermocycler. DISEASES OF AQUATIC ORGANISMS 2022; 152:99-108. [PMID: 36519681 DOI: 10.3354/dao03708] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
The amphibian chytrid fungus (Bd) has caused declines and some extinctions of amphibian populations worldwide. Early and accurate Bd detection is essential for management of susceptible anurans. We analyzed the effectiveness of in situ DNA extraction with a handheld mobile quantitative PCR (qPCR) thermocycler to detect Bd on frog skin swabs and in water samples using environmental DNA (eDNA). We collected duplicate eDNA samples and skin swabs from 3 Bd-positive Rana sierrae populations. We processed one set of samples using a field protocol (a handheld thermocycler) and the other half using a standard lab protocol. We detected Bd DNA in all R. sierrae swabbed using both the field and lab protocols. We also detected Bd DNA in eDNA samples at all sites, although the field and lab protocols failed to detect Bd eDNA at separate singular sites; results from the field and lab eDNA protocol did not match. The probability of detecting Bd DNA in the technical replicates was lower for the field protocol than the lab protocol, suggesting the field protocol has lower sensitivity and may not detect low quantities of DNA. Our results suggest that the field extraction protocol using a handheld qPCR platform is a promising tool for rapid detection of Bd in susceptible amphibian populations, yielding accurate results in less than 60 min. However, the applied field protocol may be prone to false negatives when analyzing low-quantity DNA samples such as eDNA water samples or frog swabs with low pathogen loads.
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Affiliation(s)
- Colleen Kamoroff
- Resources Management and Science, Yosemite National Park, CA 95318, USA
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5
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Basanta MD, Anaya‐Morales SL, Martínez‐Ugalde E, González Martínez TM, Ávila‐Akerberg VD, Trejo MV, Rebollar EA. Metamorphosis and seasonality are major determinants of chytrid infection in a paedomorphic salamander. Anim Conserv 2022. [DOI: 10.1111/acv.12824] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. D. Basanta
- Centro de Ciencias Genómicas Universidad Nacional Autónoma de México Cuernavaca Morelos Mexico
- Department of Biology University of Nevada Reno Reno NV USA
| | - S. L. Anaya‐Morales
- Centro de Ciencias Genómicas Universidad Nacional Autónoma de México Cuernavaca Morelos Mexico
| | - E. Martínez‐Ugalde
- Centro de Ciencias Genómicas Universidad Nacional Autónoma de México Cuernavaca Morelos Mexico
| | - T. M. González Martínez
- Facultad de Ciencias Universidad Nacional Autónoma de México, Ciudad Universitaria Ciudad de México Mexico
| | - V. D. Ávila‐Akerberg
- Instituto de Ciencias Agropecuarias y Rurales Universidad Autónoma del Estado de México Toluca Estado de México Mexico
| | - M. V. Trejo
- Facultad de Ciencias Universidad Nacional Autónoma de México, Ciudad Universitaria Ciudad de México Mexico
| | - E. A. Rebollar
- Centro de Ciencias Genómicas Universidad Nacional Autónoma de México Cuernavaca Morelos Mexico
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6
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Harjoe CC, Buck JC, Rohr JR, Roberts CE, Olson DH, Blaustein AR. Pathogenic fungus causes density‐ and trait‐mediated trophic cascades in an aquatic community. Ecosphere 2022. [DOI: 10.1002/ecs2.4043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Carmen C. Harjoe
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
| | - Julia C. Buck
- Department of Biology and Marine Biology University of North Carolina Wilmington Wilmington North Carolina USA
| | - Jason R. Rohr
- Department of Biological Sciences University of Notre Dame, Eck Institute for Global Health, and Environmental Change Initiative Notre Dame Indiana USA
| | - Claire E. Roberts
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
| | - Deanna H. Olson
- Pacific Northwest Research Station USDA Forest Service Corvallis Oregon USA
| | - Andrew R. Blaustein
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
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7
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Haver M, Le Roux G, Friesen J, Loyau A, Vredenburg VT, Schmeller DS. The role of abiotic variables in an emerging global amphibian fungal disease in mountains. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 815:152735. [PMID: 34974000 DOI: 10.1016/j.scitotenv.2021.152735] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2021] [Revised: 12/23/2021] [Accepted: 12/23/2021] [Indexed: 06/14/2023]
Abstract
The emergence of the chytridiomycete fungal pathogen Batrachochytrium dendrobatidis (Bd), causing the disease chytridiomycosis, has caused collapse of amphibian communities in numerous mountain systems. The health of amphibians and of mountain freshwater habitats they inhabit is also threatened by ongoing changes in environmental and anthropogenic factors such as climate, hydrology, and pollution. Climate change is causing more extreme climatic events, shifts in ice occurrence, and changes in the timing of snowmelt and pollutant deposition cycles. All of these factors impact both pathogen and host, and disease dynamics. Here we review abiotic variables, known to control Bd occurrence and chytridiomycosis severity, and discuss how climate change may modify them. We propose two main categories of abiotic variables that may alter Bd distribution, persistence, and physiology: 1) climate and hydrology (temperature, precipitation, hydrology, ultraviolet radiation (UVR); and, 2) water chemistry (pH, salinity, pollution). For both categories, we identify topics for further research. More studies on the relationship between global change, pollution and pathogens in complex landscapes, such as mountains, are needed to allow for accurate risk assessments for freshwater ecosystems and resulting impacts on wildlife and human health. Our review emphasizes the importance of using data of higher spatiotemporal resolution and uniform abiotic metrics in order to better compare study outcomes. Fine-scale temperature variability, especially of water temperature, variability of moisture conditions and water levels, snow, ice and runoff dynamics should be assessed as abiotic variables shaping the mountain habitat of pathogen and host. A better understanding of hydroclimate and water chemistry variables, as co-factors in disease, will increase our understanding of chytridiomycosis dynamics.
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Affiliation(s)
- Marilen Haver
- Laboratoire Écologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France.
| | - Gaël Le Roux
- Laboratoire Écologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
| | - Jan Friesen
- Environmental and Biotechnology Centre, Helmholtz Centre for Environmental Research - UFZ, Leipzig, Germany
| | - Adeline Loyau
- Laboratoire Écologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France; Department of Experimental Limnology, Leibniz-Institute of Freshwater Ecology and Inland Fisheries (IGB), Alte Fischerhütte 2, Stechlin D-16775, Germany
| | - Vance T Vredenburg
- Department of Biology, San Francisco State University, 1600 Holloway Ave., San Francisco, CA 94132, USA
| | - Dirk S Schmeller
- Laboratoire Écologie Fonctionnelle et Environnement, Université de Toulouse, CNRS, Toulouse INP, Université Toulouse 3 - Paul Sabatier (UPS), Toulouse, France
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8
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Smalling KL, Mosher BA, Iwanowicz LR, Loftin KA, Boehlke A, Hladik ML, Muletz-Wolz CR, Córtes-Rodríguez N, Femmer R, Campbell Grant EH. Site- and Individual-Level Contaminations Affect Infection Prevalence of an Emerging Infectious Disease of Amphibians. ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2022; 41:781-791. [PMID: 35040181 DOI: 10.1002/etc.5291] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 11/29/2021] [Accepted: 01/09/2022] [Indexed: 06/14/2023]
Abstract
Emerging infectious disease outbreaks are one of multiple stressors responsible for amphibian declines globally. In the northeastern United States, ranaviral diseases are prevalent in amphibians and other ectothermic species, but there is still uncertainty as to whether their presence is leading to population-level effects. Further, there is also uncertainty surrounding the potential interactions among disease infection prevalence in free-ranging animals and habitat degradation (co-occurrence of chemical stressors). The present study was designed to provide field-based estimates of the relationship between amphibian disease and chemical stressors. We visited 40 wetlands across three protected areas, estimated the prevalence of ranavirus among populations of larval wood frogs and spotted salamanders, and assessed chemical and biological stressors in wetland habitats and larval amphibians using a suite of selected bioassays, screening tools, and chemical analyses. Ranavirus was detected on larval amphibians from each protected area with an estimated occupancy ranging from 0.27 to 0.55. Considerable variation in ranavirus occupancy was also observed within and among each protected area. Of the stressors evaluated, ranavirus prevalence was strongly and positively related to concentrations of metalloestrogens (metals with the potential to bind to estrogen receptors) and total metals in wetland sediments and weakly and negatively related to total pesticide concentrations in larval amphibians. These results can be used by land managers to refine habitat assessments to include such environmental factors with the potential to influence disease susceptibility. Environ Toxicol Chem 2022;41:781-791. © 2022 SETAC. This article has been contributed to by US Government employees and their work is in the public domain in the USA.
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Affiliation(s)
- Kelly L Smalling
- New Jersey Water Science Center, US Geological Survey, Lawrenceville, New Jersey, USA
| | - Brittany A Mosher
- Rubenstein School of Environment and Natural Resources, University of Vermont, Burlington, Vermont, USA
| | - Luke R Iwanowicz
- Eastern Ecological Science Center at Leetown, US Geological Survey, Kearneysville, West Virginia, USA
| | - Keith A Loftin
- Kansas Water Science Center, US Geological Survey, Lawrence, Kansas, USA
| | - Adam Boehlke
- Geology, Geochemistry and Geophysics Science Center, US Geological Survey, Denver, Colorado, USA
| | - Michelle L Hladik
- California Water Science Center, US Geological Survey, Sacramento, California, USA
| | - Carly R Muletz-Wolz
- Center for Conservation Genomics, Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA
| | - Nandadevi Córtes-Rodríguez
- Center for Conservation Genomics, Smithsonian National Zoo and Conservation Biology Institute, Washington, DC, USA
- Department of Biological Sciences, Ithaca College, Ithaca, New York, USA
| | - Robin Femmer
- Kansas Water Science Center, US Geological Survey, Lawrence, Kansas, USA
| | - Evan H Campbell Grant
- Eastern Ecological Science Center, S.O. Conte Anadromous Fish Research Laboratory, US Geological Survey, Turner Falls, Massachusetts, USA
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9
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Li Z, Wang Q, Sun K, Feng J. Prevalence of Batrachochytrium dendrobatidis in Amphibians From 2000 to 2021: A Global Systematic Review and Meta-Analysis. Front Vet Sci 2022; 8:791237. [PMID: 34977222 PMCID: PMC8718539 DOI: 10.3389/fvets.2021.791237] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2021] [Accepted: 11/26/2021] [Indexed: 11/16/2022] Open
Abstract
Chytridiomycosis is an amphibian fungal disease caused by Batrachochytrium dendrobatidis (Bd), which has caused large-scale death and population declines on several continents around the world. To determine the current status of Bd infection in amphibians, we conducted a global meta-analysis. Using PubMed, ScienceDirect, SpringerLink, China National Knowledge Infrastructure (CNKI) and Wanfang database searches, we retrieved a total of 111 articles from 2000 to 2021. Based on these, we estimated the Bd prevalence to be 18.54% (95% CI: 13.76–20.52) in current extent amphibians. Among these populations, the prevalence of Bd in Asia was the lowest at 7.88% (95% CI: 1.92–8.71). Further, no Bd infection was found in Vietnam. However, the prevalence of Bd in Oceania was the highest at 36.34% (95% CI: 11.31–46.52). The Bd prevalence in Venezuela was as high as 49.77% (95% CI: 45.92–53.62). After 2009, the global Bd prevalence decreased to 18.91% (95% CI: 13.23–21.56). The prevalence of Bd in epizootic populations was significantly higher than enzootic populations. The highest prevalence of Bd was detected with real-time PCR at 20.11% (95% CI: 13.12–21.38). The prevalence of Bd in frogs was the highest at 20.04% (95% CI: 13.52–21.71), and this different host was statistically significant (P < 0.05). At the same time, we analyzed the geographic factors (longitude, latitude, elevation, rainfall and temperature) that impacted the fungal prevalence in amphibians. Our meta-analysis revealed that factors including region, disease dynamic, detection method, host and climate may be sources of the observed heterogeneity. These results indicate that chytridiomycosis was a consistent threat to amphibians from 2000 to 2021. Based on different habitat types and geographical conditions, we recommend formulating corresponding control plans and adopting reasonable and efficient biological or chemical methods to reduce the severity of such diseases.
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Affiliation(s)
- Zhongle Li
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
| | - Qi Wang
- College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
| | - Keping Sun
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,Key Laboratory of Vegetation Ecology, Ministry of Education, Changchun, China
| | - Jiang Feng
- Jilin Provincial Key Laboratory of Animal Resource Conservation and Utilization, Northeast Normal University, Changchun, China.,College of Animal Science and Technology, Jilin Agricultural University, Changchun, China
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10
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Koo MS, Vredenburg VT, Deck JB, Olson DH, Ronnenberg KL, Wake DB. Tracking, Synthesizing, and Sharing Global Batrachochytrium Data at AmphibianDisease.org. Front Vet Sci 2021; 8:728232. [PMID: 34692807 PMCID: PMC8527349 DOI: 10.3389/fvets.2021.728232] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2021] [Accepted: 09/02/2021] [Indexed: 11/13/2022] Open
Abstract
Emerging infectious diseases have been especially devastating to amphibians, the most endangered class of vertebrates. For amphibians, the greatest disease threat is chytridiomycosis, caused by one of two chytridiomycete fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). Research over the last two decades has shown that susceptibility to this disease varies greatly with respect to a suite of host and pathogen factors such as phylogeny, geography (including abiotic factors), host community composition, and historical exposure to pathogens; yet, despite a growing body of research, a comprehensive understanding of global chytridiomycosis incidence remains elusive. In a large collaborative effort, Bd-Maps was launched in 2007 to increase multidisciplinary investigations and understanding using compiled global Bd occurrence data (Bsal was not discovered until 2013). As its database functions aged and became unsustainable, we sought to address critical needs utilizing new technologies to meet the challenges of aggregating data to facilitate research on both Bd and Bsal. Here, we introduce an advanced central online repository to archive, aggregate, and share Bd and Bsal data collected from around the world. The Amphibian Disease Portal (https://amphibiandisease.org) addresses several critical community needs while also helping to build basic biological knowledge of chytridiomycosis. This portal could be useful for other amphibian diseases and could also be replicated for uses with other wildlife diseases. We show how the Amphibian Disease Portal provides: (1) a new repository for the legacy Bd-Maps data; (2) a repository for sample-level data to archive datasets and host published data with permanent DOIs; (3) a flexible framework to adapt to advances in field, laboratory, and informatics technologies; and (4) a global aggregation of Bd and Bsal infection data to enable and accelerate research and conservation. The new framework for this project is built using biodiversity informatics best practices and metadata standards to ensure scientific reproducibility and linkages across other biological and biodiversity repositories.
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Affiliation(s)
- Michelle S Koo
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States
| | - Vance T Vredenburg
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States.,Department of Biology, San Francisco State University, San Francisco, CA, United States
| | - John B Deck
- Berkeley Natural History Museums, University of California, Berkeley, Berkeley, CA, United States
| | - Deanna H Olson
- US Department of Agriculture, Forest Service, Pacific Northwest Research Station, Corvallis, OR, United States
| | - Kathryn L Ronnenberg
- US Department of Agriculture, Forest Service, Pacific Northwest Research Station, Corvallis, OR, United States
| | - David B Wake
- Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States
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11
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Rumschlag SL, Roth SA, McMahon TA, Rohr JR, Civitello DJ. Variability in environmental persistence but not per capita transmission rates of the amphibian chytrid fungus leads to differences in host infection prevalence. J Anim Ecol 2021; 91:170-181. [PMID: 34668575 DOI: 10.1111/1365-2656.13612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/27/2021] [Indexed: 11/28/2022]
Abstract
Heterogeneities in infections among host populations may arise through differences in environmental conditions through two mechanisms. First, environmental conditions may alter host exposure to pathogens via effects on survival. Second, environmental conditions may alter host susceptibility, making infection more or less likely if contact between a host and pathogen occurs. Further, host susceptibility might be altered through acquired resistance, which hosts can develop, in some systems, through exposure to dead or decaying pathogens and their metabolites. Environmental conditions may alter the rates of pathogen decomposition, influencing the likelihood of hosts developing acquired resistance. The present study primarily tests how environmental context influences the relative contributions of pathogen survival and per capita transmission on host infection prevalence using the amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd) as a model system. Secondarily, we evaluate how environmental context influences the decomposition of Bd because previous studies have shown that dead Bd and its metabolites can illicit acquired resistance in hosts. We conducted Bd survival and infection experiments and then fit models to discern how Bd mortality, decomposition and per capita transmission rates vary among water sources [e.g. artificial spring water (ASW) or water from three ponds]. We found that infection prevalence differed among water sources, which was driven by differences in mortality rates of Bd, rather than differences in per capita transmission rates. Bd mortality rates varied among pond water treatments and were lower in ASW compared to pond water. These results suggest that variation in Bd infection dynamics could be a function of environmental factors in waterbodies that result in differences in exposure of hosts to live Bd. In contrast to the persistence of live Bd, we found that the rates of decomposition of dead Bd did not vary among water sources, which may suggest that exposure of hosts to dead Bd or its metabolites might not commonly vary among nearby sites. Ultimately, a mechanistic understanding of the environmental dependence of free-living pathogens could lead to a deeper understanding of the patterns of outbreak heterogeneity, which could inform surveillance and management strategies.
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Affiliation(s)
- Samantha L Rumschlag
- Department of Biological Sciences, Environmental Change Initiative, and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.,Department of Integrative Biology, University of South Florida, Tampa, FL, USA
| | - Sadie A Roth
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA.,Department of Natural Resources Management, Texas Tech University, Lubbock, TX, USA
| | - Taegan A McMahon
- Department of Biology, University of Tampa, Tampa, FL, USA.,Department of Biology, Connecticut College, New London, CT, USA
| | - Jason R Rohr
- Department of Biological Sciences, Environmental Change Initiative, and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.,Department of Integrative Biology, University of South Florida, Tampa, FL, USA
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12
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Olson DH, Ronnenberg KL, Glidden CK, Christiansen KR, Blaustein AR. Global Patterns of the Fungal Pathogen Batrachochytrium dendrobatidis Support Conservation Urgency. Front Vet Sci 2021; 8:685877. [PMID: 34336978 PMCID: PMC8322974 DOI: 10.3389/fvets.2021.685877] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 06/15/2021] [Indexed: 12/21/2022] Open
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is a skin pathogen that can cause the emerging infectious disease chytridiomycosis in susceptible species. It has been considered one of the most severe threats to amphibian biodiversity. We aimed to provide an updated compilation of global Bd occurrences by host taxon and geography, and with the larger global Bd dataset we reanalyzed Bd associations with environmental metrics at the world and regional scales. We also compared our Bd data compilation with a recent independent assessment to provide a more comprehensive count of species and countries with Bd occurrences. Bd has been detected in 1,375 of 2,525 (55%) species sampled, more than doubling known species infections since 2013. Bd occurrence is known from 93 of 134 (69%) countries at this writing; this compares to known occurrences in 56 of 82 (68%) countries in 2013. Climate-niche space is highly associated with Bd detection, with different climate metrics emerging as key predictors of Bd occurrence at regional scales; this warrants further assessment relative to climate-change projections. The accretion of Bd occurrence reports points to the common aims of worldwide investigators to understand the conservation concerns for amphibian biodiversity in the face of potential disease threat. Renewed calls for better mitigation of amphibian disease threats resonate across continents with amphibians, especially outside Asia. As Bd appears to be able to infect about half of amphibian taxa and sites, there is considerable room for biosecurity actions to forestall its spread using both bottom-up community-run efforts and top-down national-to-international policies. Conservation safeguards for sensitive species and biodiversity refugia are continuing priorities.
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Affiliation(s)
- Deanna H Olson
- Pacific Northwest Research Station, United States Department of Agriculture (USDA) Forest Service, Corvallis, OR, United States
| | - Kathryn L Ronnenberg
- Pacific Northwest Research Station, United States Department of Agriculture (USDA) Forest Service, Corvallis, OR, United States
| | | | - Kelly R Christiansen
- Pacific Northwest Research Station, United States Department of Agriculture (USDA) Forest Service, Corvallis, OR, United States
| | - Andrew R Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States
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13
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Ballestas O, Lampo M, Rodríguez D. Living with the pathogenic chytrid fungus: Exploring mechanisms of coexistence in the harlequin toad Atelopus cruciger. PLoS One 2021; 16:e0254439. [PMID: 34264969 PMCID: PMC8281998 DOI: 10.1371/journal.pone.0254439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Accepted: 06/28/2021] [Indexed: 11/19/2022] Open
Abstract
Chytridiomycosis, a disease caused by the fungus Batrachochytrium dendrobatidis (Bd), has been linked with the disappearance of amphibian populations worldwide. Harlequin toads (Atelopus) are among the most severely impacted genera. Two species are already considered extinct and most of the others are at high risk of extinction. The recent rediscovery of harlequin toad populations coexisting with Bd suggest that the pathogen can maintain enzootic cycles at some locations. The mechanisms promoting coexistence, however, are not well understood. We explore the dynamics of Bd infection in harlequin toads by modeling a two-stage host population with transmission through environmental reservoirs. Simulations showed that variations in the recruitment of adults and the persistence of zoospores in the environment were more likely to drive shifts between extinction and coexistence than changes in the vulnerability of toads to infection with Bd. These findings highlight the need to identify mechanisms for assuring adult recruitment or minimizing transmission from potential reservoirs, biotic or abiotic, in recovering populations.
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Affiliation(s)
- Onil Ballestas
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Margarita Lampo
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Caracas, Venezuela
| | - Diego Rodríguez
- Laboratorio de Ecología y Evolución, Instituto de Zoología y Ecología Tropical, Universidad Central de Venezuela, Caracas, Venezuela
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14
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Dual Detection of the Chytrid Fungi Batrachochytrium spp. with an Enhanced Environmental DNA Approach. J Fungi (Basel) 2021; 7:jof7040258. [PMID: 33808405 PMCID: PMC8065926 DOI: 10.3390/jof7040258] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2021] [Revised: 03/23/2021] [Accepted: 03/26/2021] [Indexed: 01/24/2023] Open
Abstract
Environmental DNA (eDNA) is becoming an indispensable tool in biodiversity monitoring, including the monitoring of invasive species and pathogens. Aquatic chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are major threats to amphibians. However, the use of eDNA for detecting these pathogens has not yet become widespread, due to technological and economic obstacles. Using the enhanced eDNA approach (a simple and cheap sampling protocol) and the universally accepted qPCR assay, we confirmed the presence of Bsal and Bd in previously identified sites in Spain, including four sites that were new for Bsal. The new approach was successfully tested in laboratory conditions using manufactured gene fragments (gBlocks) of the targeted DNA sequence. A comparison of storage methods showed that samples kept in ethanol had the best DNA yield. Our results showed that the number of DNA copies in the Internal Transcribed Spacer region was 120 copies per Bsal cell. Eradication of emerging diseases requires quick and cost-effective solutions. We therefore performed cost-efficiency analyses of standard animal swabbing, a previous eDNA approach, and our own approach. The procedure presented here was evaluated as the most cost-efficient. Our findings will help to disseminate information about efforts to prevent the spread of chytrid fungi.
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15
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Rahman MM, Jahan H, Rabbe MF, Chakraborty M, Salauddin M. First Detection of Batrachochytrium dendrobatidis in Wild Frogs from Bangladesh. ECOHEALTH 2021; 18:31-43. [PMID: 34028636 DOI: 10.1007/s10393-021-01522-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 02/25/2021] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
Global amphibian populations are facing a novel threat, chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), which is responsible for the severe decline of a number of species across several continents. Chytridiomycosis in Asia is a relatively recent discovery yet there have been no reports on Bd-presence in Bangladeshi amphibians. We conducted a preliminary study on 133 wild frogs from seven sites in Bangladesh between April and July 2018. Nested PCR analysis showed 20 samples (15.04%) and 50% of the tested taxa (9 species from 6 genera and 4 families) as Bd-positive. Eight of the nine species are discovered as newly infected hosts. Analysis of Bd-positive samples shows prevalence does not significantly vary among different land cover categories, although the occurrence is higher in forested areas. The prevalence rate is similar in high and low disturbed areas, but the range of occurrence is statistically higher in low disturbance areas. Maximum entropy distribution modeling indicates high probabilities of Bd occurrence in hilly and forested areas in southeast and central-north Bangladesh. The Bd-specific ITS1-5.8S-ITS2 ribosomal gene sequence from the Bd-positive samples tested is completely identical. A neighbor-joining phylogenetic tree reveals that the identified strain shares a common ancestry with strains previously discovered in different Asian regions. Our results provide the first evidence of Bd-presence in Bangladeshi amphibians, inferring that diversity is at risk. The effects of environmental and climatic factors along with quantitative PCR analysis are required to determine the infection intensity and susceptibility of amphibians in the country.
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Affiliation(s)
- Md Mokhlesur Rahman
- Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh.
- Department of Anthropology, Durham University, South Road, Durham, DH1 3LE, UK.
| | - Hawa Jahan
- Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh
- Division of Evolution and Genomic Sciences, FBMH, School of Biological Sciences, University of Manchester, Oxford Rd, Manchester, M13 9PT, UK
| | - Md Fazle Rabbe
- Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh
| | | | - Md Salauddin
- Department of Geography and Environment, Jagannath University, Dhaka, 1100, Bangladesh
- Disaster Risk Management Department, Bangladesh Red Crescent Society, Red Crescent Sarak, Bara Moghbazar, Dhaka, 1217, Bangladesh
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16
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Romero-Zambrano GL, Bermúdez-Puga SA, Sánchez-Yumbo AF, Yánez-Galarza JK, Ortega-Andrade HM, Naranjo-Briceño L. Amphibian chytridiomycosis, a lethal pandemic disease caused by the killer fungus Batrachochytrium dendrobatidis: New approaches to host defense mechanisms and techniques for detection and monitoring. BIONATURA 2021. [DOI: 10.21931/rb/2021.06.01.28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Chytridiomycosis is a catastrophic disease currently decimating worldwide amphibian populations, caused by the panzootic chytrid fungus Batrachochytrium dendrobatidis. Massive species decline to extinction catalyzes radical changes in ecosystems globally, including the largest continuous rainforest ecosystem on Earth, the Amazon rainforest. Innovative research that aims to propose feasible mechanisms of mitigation and the origins of the disease is vital, including studies addressing climatic effects on the expansion of chytridiomycosis. Thus, this publication aims to provide a comprehensive review of: i) the current technologies used for B. dendrobatidis detection and monitoring, and ii) the known Neotropical amphibian's skin microbiota with anti-fungal properties against B. dendrobatidis. Several immunologic and DNA-based methods are discussed to understand the emerging fungal pathogens and their effects on the biosphere, which can help to mitigate the devastating ecological impacts of mass amphibian morbidity. The establishment of rapid and highly accurate B. dendrobatidis detection techniques and methods for monitoring amphibian's cutaneous microbiome is crucial in the fight against chytridiomycosis.
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Affiliation(s)
- Génesis L. Romero-Zambrano
- Biotechnology Engineering Career. Faculty of Life Sciences. Universidad Regional Amazónica Ikiam, Tena, Ecuador 150150
| | - Stalin A. Bermúdez-Puga
- Biotechnology Engineering Career. Faculty of Life Sciences. Universidad Regional Amazónica Ikiam, Tena, Ecuador 150150
| | - Alex F. Sánchez-Yumbo
- Biotechnology Engineering Career. Faculty of Life Sciences. Universidad Regional Amazónica Ikiam, Tena, Ecuador 150150
| | - Jomira K. Yánez-Galarza
- Biotechnology Engineering Career. Faculty of Life Sciences. Universidad Regional Amazónica Ikiam, Tena, Ecuador 150150
| | - H. Mauricio Ortega-Andrade
- 2Biogeography and Spatial Ecology Research Group, Universidad Regional Amazónica Ikiam, Tena, Ecuador 150150 3Herpetology Division, Instituto Nacional de Biodiversidad (INABIO), calle Rumipamba 341 y Av. de los Shyris, Quito, Ecuador
| | - Leopoldo Naranjo-Briceño
- Biotechnology Engineering Career. Faculty of Life Sciences. Universidad Regional Amazónica Ikiam, Tena, Ecuador 150150
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17
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Zumbado‐Ulate H, García‐Rodríguez A, Searle CL. Species distribution models predict the geographic expansion of an enzootic amphibian pathogen. Biotropica 2020. [DOI: 10.1111/btp.12863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
| | - Adrián García‐Rodríguez
- Departamento de Zoología Instituto de Biología Universidad Nacional Autónoma de MéxicoUNAM Ciudad de México México
- Museo de Zoología Escuela de Biología Universidad de Costa Rica San José Costa Rica
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18
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Brannelly LA, Wetzel DP, Ohmer MEB, Zimmerman L, Saenz V, Richards-Zawacki CL. Evaluating environmental DNA as a tool for detecting an amphibian pathogen using an optimized extraction method. Oecologia 2020; 194:267-281. [PMID: 32880026 DOI: 10.1007/s00442-020-04743-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 08/26/2020] [Indexed: 12/29/2022]
Abstract
Environmental DNA (eDNA) detection is a valuable conservation tool that can be used to identify and monitor imperiled or invasive species and wildlife pathogens. Batrachochytrium pathogens are of global conservation concern because they are a leading cause of amphibian decline. While eDNA techniques have been used to detect Batrachochytrium DNA in the environment, a systematic comparison of extraction methods across environmental samples is lacking. In this study, we first compared eDNA extraction methods and found that a soil extraction kit (Qiagen PowerSoil) was the most effective for detecting Batrachochytrium dendrobatidis in water samples. The PowerSoil extraction had a minimum detection level of 100 zoospores and had a two- to four-fold higher detection probability than other commonly used extraction methods (e.g., QIAamp extraction, DNeasy+Qiashredder extraction method, respectively). Next, we used this extraction method on field-collected water and sediment samples and were able to detect pathogen DNA in both. While field-collected water filters were equivalent to amphibian skin swab samples in detecting the presence of pathogen DNA, the seasonal patterns in pathogen quantity were different between skin swabs and water samples. Detection rate was lowest in sediment samples. We also found that detection probability increases with the volume of water filtered. Our results indicate that water filter eDNA samples can be accurate in detecting pathogen presence at the habitat scale but their utility for quantifying pathogen loads in the environment appears limited. We suggest that eDNA techniques be used for early warning detection to guide animal sampling efforts.
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Affiliation(s)
- Laura A Brannelly
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA.
- Melbourne Veterinary School, Faculty of Agricultural and Veterinary Sciences, University of Melbourne, Werribee, VIC, Australia.
| | - Daniel P Wetzel
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Michel E B Ohmer
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Lydia Zimmerman
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Veronica Saenz
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
| | - Corinne L Richards-Zawacki
- Department of Biological Science, Dietrich School of Arts and Sciences, University of Pittsburgh, Pittsburgh, PA, USA
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19
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Sette CM, Vredenburg VT, Zink AG. Differences in Fungal Disease Dynamics in Co-occurring Terrestrial and Aquatic Amphibians. ECOHEALTH 2020; 17:302-314. [PMID: 33237500 DOI: 10.1007/s10393-020-01501-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2019] [Revised: 09/14/2020] [Accepted: 10/04/2020] [Indexed: 06/11/2023]
Abstract
The fungal pathogen, Batrachochytrium dendrobatidis (Bd), has devastated biodiversity and ecosystem health and is implicated as a driver of mass amphibian extinctions. This 100-year study investigates which environmental factors contribute to Bd prevalence in a fully terrestrial species, and determines whether infection patterns differ between a fully terrestrial amphibian and more aquatic host species. We performed a historical survey to quantify Bd prevalence in 1127 Batrachoseps gregarius museum specimens collected from 1920 to 2000, and recent data from 16 contemporary (live-caught) B. gregarius populations from the southwestern slopes of the Sierra Nevada mountains in California, USA. We compared these results to Bd detection rates in 1395 historical and 1033 contemporary specimens from 10 species of anurans and 427 historical Taricha salamander specimens collected throughout the Sierra Nevada mountains. Our results indicate that Bd dynamics in the entirely terrestrial species, B. gregarius, differ from aquatic species in the same region in terms of both seasonal patterns of Bd abundance and in the possible timing of Bd epizootics.
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Affiliation(s)
- Carla M Sette
- University of California, Santa Cruz, EEB/CBB mailstop, UCSC/Coastal Biology Building, 130 McAllister Way, Santa Cruz, CA, 95060, USA.
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20
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Batrachochytrium salamandrivorans (Bsal) not detected in an intensive survey of wild North American amphibians. Sci Rep 2020; 10:13012. [PMID: 32747670 PMCID: PMC7400573 DOI: 10.1038/s41598-020-69486-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2019] [Accepted: 05/22/2020] [Indexed: 11/22/2022] Open
Abstract
The salamander chytrid fungus (Batrachochytrium salamandrivorans [Bsal]) is causing massive mortality of salamanders in Europe. The potential for spread via international trade into North America and the high diversity of salamanders has catalyzed concern about Bsal in the U.S. Surveillance programs for invading pathogens must initially meet challenges that include low rates of occurrence on the landscape, low prevalence at a site, and imperfect detection of the diagnostic tests. We implemented a large-scale survey to determine if Bsal was present in North America designed to target taxa and localities where Bsal was determined highest risk to be present based on species susceptibility and geography. Our analysis included a Bayesian model to estimate the probability of occurrence of Bsal given our prior knowledge of the occurrence and prevalence of the pathogen. We failed to detect Bsal in any of 11,189 samples from 594 sites in 223 counties within 35 U.S. states and one site in Mexico. Our modeling indicates that Bsal is highly unlikely to occur within wild amphibians in the U.S. and suggests that the best proactive response is to continue mitigation efforts against the introduction and establishment of the disease and to develop plans to reduce impacts should Bsal establish.
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21
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The effects of atrazine on the microbiome of the eastern oyster: Crassostrea virginica. Sci Rep 2020; 10:11088. [PMID: 32632188 PMCID: PMC7338443 DOI: 10.1038/s41598-020-67851-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 05/26/2020] [Indexed: 12/11/2022] Open
Abstract
Long-standing evidence supports the importance of maintaining healthy populations of microbiota for the survival, homeostasis, and complete development of marine mollusks. However, the long-term ecological effects of agricultural runoff on these populations remains largely unknown. Atrazine (6-Chloro-n-ethyl-n'-(1-methylethyl)-triazine-2,4-diamine), a prevalent herbicide in the United States, is often used along tributaries of the Chesapeake Bay where oyster breeding programs are concentrated. To investigate any potential effects atrazine maybe having on mollusk-prokaryote interactions, we used 16S rRNA gene amplicons to evaluate how microbial compositions shift in response to exposure of environmentally relevant concentrations of atrazine previously found within the Chesapeake Bay. The dominant bacterial genera found within all groups included those belonging to Pseudoalteromonas, Burkholderia, Bacteroides, Lactobacillis, Acetobacter, Allobaculum, Ruminococcus, and Nocardia. Our results support previously published findings of a possible core microbial community in Crassostrea virginica. We also report a novel finding: oysters exposed to atrazine concentrations as low as 3 µg/L saw a significant loss of a key mutualistic microbial species and a subsequent colonization of a pathogenic bacteria Nocardia. We conclude that exposure to atrazine in the Chesapeake Bay may be contributing to a significant shift in the microbiomes of juvenile oysters that reduces fitness and impedes natural and artificial repopulation of the oyster species within the Bay.
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22
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Bienentreu JF, Lesbarrères D. Amphibian Disease Ecology: Are We Just Scratching the Surface? HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - David Lesbarrères
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
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23
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Hao T, Guillera-Arroita G, May TW, Lahoz-Monfort JJ, Elith J. Using Species Distribution Models For Fungi. FUNGAL BIOL REV 2020. [DOI: 10.1016/j.fbr.2020.01.002] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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24
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Effects of invasive larval bullfrogs (Rana catesbeiana) on disease transmission, growth and survival in the larvae of native amphibians. Biol Invasions 2020. [DOI: 10.1007/s10530-020-02218-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AbstractThe mechanisms by which invasive species negatively affect native species include competition, predation, and the introduction of novel pathogens. Moreover, if an invasive species is a competent disease reservoir, it may facilitate the long-term maintenance and spread of pathogens in ecological assemblages and drive the extinction of less tolerant or less resistant species. Disease-driven loss of biodiversity is exemplified by the amphibian–chytrid fungus system. The disease chytridiomycosis is caused by the aquatic chytrid fungus Batrachochytrium dendrobatidis (Bd) in anurans and is associated with worldwide amphibian population declines and extinctions. For amphibian species that metamorphose and leave infected aquatic habitats, the mechanisms by which Bd persists over winter in these habitats remains a critical open question. A leading hypothesis is that American bullfrogs (Rana catesbeiana), a worldwide invasive species, are tolerant to Bd and serve as a reservoir host for Bd during winter months and subsequently infect native species that return to breed in spring. Using outdoor mesocosms, we experimentally examined if two strains of Bd could overwinter in aquatic systems, in the presence or absence of bullfrog tadpoles, and if overwintered Bd could be transmitted to tadpoles of two spring-breeding species: Pacific treefrogs (Pseudacris regilla) and Cascades frogs (Rana cascadae). We found that only 4 of 448 total animals (one bullfrog and three spring breeders) tested positive for Bd after overwintering. Moreover, two of the three infected spring breeders emerged from tanks that contained overwintered Bd but in the absence of infected bullfrogs. This suggests that Bd can persist over winter without bullfrogs as a reservoir host. We found no effect of Bd strain on bullfrog survival after overwintering. For Pacific treefrogs, Bd exposure did not significantly affect mass at or time to metamorphosis while exposure to bullfrogs reduced survival. For Cascades frogs, we found an interactive effect of Bd strain and bullfrog presence on time to metamorphosis, but no main or interactive effects on their survival or mass at metamorphosis. In short, bullfrog tadpoles rarely retained and transmitted Bd infection in our experiment and we found limited evidence that Bd successfully overwinters in the absence of bullfrog tadpoles and infects spring-breeding amphibians.
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25
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Ribeiro JW, Siqueira T, DiRenzo GV, Lambertini C, Lyra ML, Toledo LF, Haddad CFB, Becker CG. Assessing amphibian disease risk across tropical streams while accounting for imperfect pathogen detection. Oecologia 2020; 193:237-248. [DOI: 10.1007/s00442-020-04646-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 04/07/2020] [Indexed: 12/23/2022]
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26
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Silva S, Matz L, Elmassry MM, San Francisco MJ. Characteristics of monolayer formation in vitro by the chytrid Batrachochytrium dendrobatidis. Biofilm 2019; 1:100009. [PMID: 33447796 PMCID: PMC7798445 DOI: 10.1016/j.bioflm.2019.100009] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 09/26/2019] [Accepted: 10/24/2019] [Indexed: 12/01/2022] Open
Abstract
Batrachochytrium dendrobatidis is a globally distributed generalist pathogen that has driven many amphibian populations to extinction. The life cycle of B. dendrobatidis has two main cell types, motile zoospores, and sessile reproductive sporangia. When grown in a nutrient-rich liquid medium, B. dendrobatidis forms aggregates of sporangia that transition into monolayers on surfaces and at the air-liquid interface. Pathogenic microorganisms use biofilms as mechanisms of group interactions to survive under harsh conditions in the absence of a suitable host. We used fluorescent and electron microscopy, crystal violet, transcriptomic, and gas chromatographic analyses to understand the characteristics of B. dendrobatidis monolayers. The cell-free monolayer fraction showed the presence of extracellular ribose, mannose, xylose, galactose, and glucose. Transcriptome analysis showed that 27%, 26%, and 4% of the genes were differentially expressed between sporangia/zoospores, monolayer/zoospores, and sporangia/monolayer pairs respectively. In pond water studies, zoospores developed into sporangia and formed floating aggregates at the air-water interface and attached film on the bottom of growth flasks. We propose that B. dendrobatidis can form surface-attached monolayers in nutrient-rich environments and aggregates of sporangia in nutrient-poor aquatic systems. These monolayers and aggregates may facilitate dispersal and survival of the fungus in the absence of a host. We provide evidence for using a combination of plant-based chemicals, allicin, gingerol, and curcumin as potential anti-chytrid drugs to mitigate chytridiomycosis.
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Affiliation(s)
- Shalika Silva
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Lisa Matz
- Baylor College of Medicine, Houston, TX, USA
| | - Moamen M Elmassry
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
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27
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Miaud C, Arnal V, Poulain M, Valentini A, Dejean T. eDNA Increases the Detectability of Ranavirus Infection in an Alpine Amphibian Population. Viruses 2019; 11:E526. [PMID: 31174349 PMCID: PMC6631829 DOI: 10.3390/v11060526] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2019] [Revised: 05/23/2019] [Accepted: 06/04/2019] [Indexed: 01/12/2023] Open
Abstract
The early detection and identification of pathogenic microorganisms is essential in order to deploy appropriate mitigation measures. Viruses in the Iridoviridae family, such as those in the Ranavirus genus, can infect amphibian species without resulting in mortality or clinical signs, and they can also infect other hosts than amphibian species. Diagnostic techniques allowing the detection of the pathogen outside the period of host die-off would thus be of particular use. In this study, we tested a method using environmental DNA (eDNA) on a population of common frogs (Rana temporaria) known to be affected by a Ranavirus in the southern Alps in France. In six sampling sessions between June and September (the species' activity period), we collected tissue samples from dead and live frogs (adults and tadpoles), as well as insects (aquatic and terrestrial), sediment, and water. At the beginning of the breeding season in June, one adult was found dead; at the end of July, a mass mortality of tadpoles was observed. The viral DNA was detected in both adults and tadpoles (dead or alive) and in water samples, but it was not detected in insects or sediment. In live frog specimens, the virus was detected from June to September and in water samples from August to September. Dead tadpoles that tested positive for Ranavirus were observed only on one date (at the end of July). Our results indicate that eDNA can be an effective alternative to tissue/specimen sampling and can detect Ranavirus presence outside die-offs. Another advantage is that the collection of water samples can be performed by most field technicians. This study confirms that the use of eDNA can increase the performance and accuracy of wildlife health status monitoring and thus contribute to more effective surveillance programs.
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Affiliation(s)
- Claude Miaud
- CEFE, EPHE-PSL, CNRS, Univ. Montpellier, Univ Paul Valéry Montpellier 3, IRD, Biogeography and Vertebrate Ecology, 1919 route de Mende, 34293 Montpellier, France.
| | - Véronique Arnal
- CEFE, EPHE-PSL, CNRS, Univ. Montpellier, Univ Paul Valéry Montpellier 3, IRD, Biogeography and Vertebrate Ecology, 1919 route de Mende, 34293 Montpellier, France.
| | - Marie Poulain
- CEFE, EPHE-PSL, CNRS, Univ. Montpellier, Univ Paul Valéry Montpellier 3, IRD, Biogeography and Vertebrate Ecology, 1919 route de Mende, 34293 Montpellier, France.
| | - Alice Valentini
- SPYGEN, 17 Rue du Lac Saint-André, 73370 Le Bourget-du-Lac, France.
| | - Tony Dejean
- SPYGEN, 17 Rue du Lac Saint-André, 73370 Le Bourget-du-Lac, France.
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Ribeiro H, Martins A, Gonçalves M, Guedes M, Tomasino MP, Dias N, Dias A, Mucha AP, Carvalho MF, Almeida CMR, Ramos S, Almeida JM, Silva E, Magalhães C. Development of an autonomous biosampler to capture in situ aquatic microbiomes. PLoS One 2019; 14:e0216882. [PMID: 31091277 PMCID: PMC6519839 DOI: 10.1371/journal.pone.0216882] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2018] [Accepted: 04/30/2019] [Indexed: 11/18/2022] Open
Abstract
The importance of planktonic microbial communities is well acknowledged, since they are fundamental for several natural processes of aquatic ecosystems. Microorganisms naturally control the flux of nutrients, and also degrade and recycle anthropogenic organic and inorganic contaminants. Nevertheless, climate change effects and/or the runoff of nutrients/pollutants can affect the equilibrium of natural microbial communities influencing the occurrence of microbial pathogens and/or microbial toxin producers, which can compromise ecosystem environmental status. Therefore, improved microbial plankton monitoring is essential to better understand how these communities respond to environmental shifts. The study of marine microbial communities typically involves highly cost and time-consuming sampling procedures, which can limit the frequency of sampling and data availability. In this context, we developed and validated an in situ autonomous biosampler (IS-ABS) able to collect/concentrate in situ planktonic communities of different size fractions (targeting prokaryotes and unicellular eukaryotes) for posterior genomic, metagenomic, and/or transcriptomic analysis at a home laboratory. The IS-ABS field prototype is a small size and compact system able to operate up to 150 m depth. Water is pumped by a micropump (TCS MG2000) through a hydraulic circuit that allows in situ filtration of environmental water in one or more Sterivex filters placed in a filter cartridge. The IS-ABS also includes an application to program sampling definitions, allowing pre-setting configuration of the sampling. The efficiency of the IS-ABS was tested against traditional laboratory filtration standardized protocols. Results showed a good performance in terms of DNA recovery, as well as prokaryotic (16S rDNA) and eukaryotic (18S rDNA) community diversity analysis, using either methodologies. The IS-ABS automates the process of collecting environmental DNA, and is suitable for integration in water observation systems, what will contribute to substantially increase biological surveillances. Also, the use of highly sensitive genomic approaches allows a further study of the diversity and functions of whole or specific microbial communities.
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Affiliation(s)
- Hugo Ribeiro
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
- Institute of Biomedical Sciences Abel Salazar (ICBAS-UP), University of Porto, Porto, Portugal
- * E-mail:
| | - Alfredo Martins
- INESC TEC–INESC Technology and Science, Porto, Portugal
- ISEP–School of Engineering, Polytechnic Institute of Porto, Porto, Portugal
| | | | | | - Maria Paola Tomasino
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
| | - Nuno Dias
- INESC TEC–INESC Technology and Science, Porto, Portugal
- ISEP–School of Engineering, Polytechnic Institute of Porto, Porto, Portugal
| | - André Dias
- INESC TEC–INESC Technology and Science, Porto, Portugal
- ISEP–School of Engineering, Polytechnic Institute of Porto, Porto, Portugal
| | - Ana Paula Mucha
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
| | - Maria F. Carvalho
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
| | - C. Marisa R. Almeida
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
| | - Sandra Ramos
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
- Institute of Estuarine and Coastal Studies, University of Hull, Hull, United Kingdom
| | - José Miguel Almeida
- INESC TEC–INESC Technology and Science, Porto, Portugal
- ISEP–School of Engineering, Polytechnic Institute of Porto, Porto, Portugal
| | - Eduardo Silva
- INESC TEC–INESC Technology and Science, Porto, Portugal
- ISEP–School of Engineering, Polytechnic Institute of Porto, Porto, Portugal
| | - Catarina Magalhães
- CIIMAR–Interdisciplinary Center of Marine and Environmental Research, University of Porto, Av. General Norton de Matos s/n, Matosinhos, Portugal
- FCUP–Faculty of Sciences of University of Porto, Porto, Portugal
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Determining Presence of Rare Amphibian Species: Testing and Combining Novel Survey Methods. J HERPETOL 2019. [DOI: 10.1670/18-122] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Metabolites Involved in Immune Evasion by Batrachochytrium dendrobatidis Include the Polyamine Spermidine. Infect Immun 2019; 87:IAI.00035-19. [PMID: 30833338 DOI: 10.1128/iai.00035-19] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2019] [Accepted: 03/01/2019] [Indexed: 12/24/2022] Open
Abstract
Amphibians have been declining around the world for more than four decades. One recognized driver of these declines is the chytrid fungus Batrachochytrium dendrobatidis, which causes the disease chytridiomycosis. Amphibians have complex and varied immune defenses against B. dendrobatidis, but the fungus also has a number of counterdefenses. Previously, we identified two small molecules produced by the fungus that inhibit frog lymphocyte proliferation, methylthioadenosine (MTA) and kynurenine (KYN). Here, we report on the isolation and identification of the polyamine spermidine (SPD) as another significant immunomodulatory molecule produced by B. dendrobatidis SPD and its precursor, putrescine (PUT), are the major polyamines detected, and SPD is required for growth. The major pathway of biosynthesis is from ornithine through putrescine to spermidine. An alternative pathway from arginine to agmatine to putrescine appears to be absent. SPD is inhibitory at concentrations of ≥10 μM and is found at concentrations between 1 and 10 μM in active fungal supernatants. Although PUT is detected in the fungal supernatants, it is not inhibitory to lymphocytes even at concentrations as high as 100 μM. Two other related polyamines, norspermidine (NSP) and spermine (SPM), also inhibit amphibian lymphocyte proliferation, but a third polyamine, cadaverine (CAD), does not. A suboptimal (noninhibitory) concentration of MTA (10 μM), a by-product of spermidine synthesis, enhances the inhibition of SPD at 1 and 10 μM. We interpret these results to suggest that B. dendrobatidis produces an "armamentarium" of small molecules that, alone or in concert, may help it to evade clearance by the amphibian immune system.
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Kärvemo S, Laurila A, Höglund J. Urban environment and reservoir host species are associated with Batrachochytrium dendrobatidis infection prevalence in the common toad. DISEASES OF AQUATIC ORGANISMS 2019; 134:33-42. [PMID: 32132271 DOI: 10.3354/dao03359] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Human-induced changes of the environment, including landscape alteration and habitat loss, may affect wildlife disease dynamics and have important ramifications for wildlife conservation. Amphibians are among the vertebrate taxa most threatened by anthropogenic habitat change. The emerging fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused extinctions and population declines in hundreds of anuran species globally. We studied how the urban landscape is associated with the prevalence of Bd infections by sampling 655 anurans of 3 species (mainly the common toad Bufo bufo) in 42 ponds surrounded by different amounts of urban habitat (defined as towns, cities or villages). We also examined the association between Bd infections and a potential reservoir host species (the moor frog Rana arvalis). We found that 38% of the sites were positive for Bd with an infection prevalence of 4.4%. The extent of urban landscape was negatively correlated with Bd infection prevalence. However, the positive association of Bd with the presence of the possible reservoir species was substantially stronger than the urban effects. The body condition index of B. bufo was negatively associated with Bd infection. This Bd effect was stronger than the negative effect of urban landscape on body condition. Our results suggest that urban environments in Sweden have a negative impact on Bd infections, while the presence of the reservoir species has a positive impact on Bd prevalence. Our study also highlights the potential importance of Bd infection on host fitness, especially in rural landscapes.
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Affiliation(s)
- Simon Kärvemo
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, 75236 Uppsala, Sweden
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Julian JT, Glenney GW, Rees C. Evaluating observer bias and seasonal detection rates in amphibian pathogen eDNA collections by citizen scientists. DISEASES OF AQUATIC ORGANISMS 2019; 134:15-24. [PMID: 32132269 DOI: 10.3354/dao03357] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
We trained volunteers from conservation organizations to collect environmental DNA (eDNA) from 21 ponds with amphibian communities that had a history of Batrachochytrium dendrobatidis (Bd) and ranavirus (Rv) infections. Volunteers were given sampling kits to filter pond water and preserve eDNA on filter paper, as were the principal investigators (PIs), who made independent collections within 48 h of volunteer collections. Using multi-scale occupancy modeling, we found no evidence to suggest the observer who collected the water sample (volunteer or PI) influenced either the probability of capturing eDNA on a filter or the probability of detecting extracted eDNA in a quantitative PCR (qPCR) reaction. The cumulative detection probability of Bd eDNA at a pond decreased from May through July 2017 because there was a decrease in the probability of detecting eDNA in qPCR reactions. In contrast, cumulative detection probability increased from May to July for Rv due to a higher probability of capturing eDNA on filters later in the year. Our models estimate that both pathogens could be detected with 95% confidence in as few as 5 water samples taken in June or July tested with either 4 or 3 qPCR reactions, respectively. Our eDNA protocols appeared to detect pathogens with 95% confidence using considerably fewer samples than protocols which typically recommend sampling ≥30 individual animals. In addition, eDNA sampling could reduce some biosecurity concerns, jurisdictional and institutional permitting, and stress to biota at ponds.
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Affiliation(s)
- James T Julian
- Division of Mathematics and Natural Science, Pennsylvania State University-Altoona College, Altoona, PA 16601, USA
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Orzechowski SCM, Frederick PC, Dorazio RM, Hunter ME. Environmental DNA sampling reveals high occupancy rates of invasive Burmese pythons at wading bird breeding aggregations in the central Everglades. PLoS One 2019; 14:e0213943. [PMID: 30970028 PMCID: PMC6457569 DOI: 10.1371/journal.pone.0213943] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Accepted: 03/04/2019] [Indexed: 11/18/2022] Open
Abstract
The Burmese python (Python bivittatus) is now established as a breeding population throughout south Florida, USA. However, the extent of the invasion, and the ecological impacts of this novel apex predator on animal communities are incompletely known, in large part because Burmese pythons (hereafter “pythons”) are extremely cryptic and there has been no efficient way to detect them. Pythons are recently confirmed nest predators of long-legged wading bird breeding colonies (orders Ciconiiformes and Pelecaniformes). Pythons can consume large quantities of prey and may not be recognized as predators by wading birds, therefore they could be a particular threat to colonies. To quantify python occupancy rates at tree islands where wading birds breed, we utilized environmental DNA (eDNA) analysis—a genetic tool which detects shed DNA in water samples and provides high detection probabilities. We fitted multi-scale Bayesian occupancy models to test the prediction that pythons occupy islands with wading bird colonies at higher rates compared to representative control islands containing no breeding birds. Our results suggest that pythons are widely distributed across the central Everglades in proximity to active wading bird colonies. In support of our prediction that pythons are attracted to colonies, site-level python eDNA occupancy rates were higher at wading bird colonies (ψ = 0.88, 95% credible interval [0.59–1.00]) than at the control islands (ψ = 0.42 [0.16–0.80]) in April through June (n = 15 colony-control pairs). We found our water temperature proxy (time of day) to be informative of detection probability, in accordance with other studies demonstrating an effect of temperature on eDNA degradation in occupied samples. Individual sample concentrations ranged from 0.26 to 38.29 copies/μL and we generally detected higher concentrations of python eDNA in colony sites. Continued monitoring of wading bird colonies is warranted to determine the effect pythons are having on populations and investigate putative management activities.
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Affiliation(s)
- Sophia C. M. Orzechowski
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida, United States of America
- * E-mail:
| | - Peter C. Frederick
- Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida, United States of America
| | - Robert M. Dorazio
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, Florida, United States of America
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Margaret E. Hunter
- U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, Florida, United States of America
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Cádiz A, Reytor ML, Díaz LM, Chestnut T, Burns JA, Amato G. The Chytrid Fungus, Batrachochytrium dendrobatidis, is Widespread Among Cuban Amphibians. ECOHEALTH 2019; 16:128-140. [PMID: 30377876 DOI: 10.1007/s10393-018-1383-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 10/04/2018] [Accepted: 10/09/2018] [Indexed: 06/08/2023]
Abstract
The fungus Batrachochytrium dendrobatidis (Bd) is a generalist amphibian pathogen responsible for chytridiomycosis. It was documented for the first time in Cuba in 2007, the apparent cause of the decline in one species of toad. In a recent survey, Bd was reported only for the highlands of Central Cuba. In the present study, we reexamined the geographic distribution and level of impact of Bd in Cuba by conducting an island-wide sampling in 10 localities and collecting skin swabs from 18 species and 28 environmental samples. We report detection of Bd in 60% of sampled sites and in 58% of sampled taxa. We show that Bd is associated with riparian, arboreal and terrestrial species, and it was estimated to occur in approximately 30% of the aquatic habitats we sampled. In addition, we confirmed that a dying individual of the species Eleutherodactylus casparii was severely infected with Bd. We also rise concern about the endanger toad Peltophryne longinasus and about three species of endemic riparian frogs that were not detected during our surveys. This study demonstrates that this pathogen is widespread throughout Cuba and provides relevant evidence to advance our understanding of its detection in amphibians and the aquatic environment in Cuba and about the occurrence of Bd in species with different ecologies. We provide valuable baseline information for Bd risk assessment and decision-making processes to mitigate its negative impact on Cuban amphibians.
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Affiliation(s)
- Antonio Cádiz
- Faculty of Biology, Havana University, La Havana, Cuba.
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, USA.
- , Weehawken, USA.
| | | | - Luis M Díaz
- National Museum of Natural History of Cuba, La Havana, Cuba
| | | | - John A Burns
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, USA
| | - George Amato
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, USA
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Kärvemo S, Meurling S, Berger D, Höglund J, Laurila A. Effects of host species and environmental factors on the prevalence of Batrachochytrium dendrobatidis in northern Europe. PLoS One 2018; 13:e0199852. [PMID: 30359384 PMCID: PMC6201871 DOI: 10.1371/journal.pone.0199852] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/09/2018] [Indexed: 11/18/2022] Open
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a major threat to amphibian populations. To assist efforts to address such threats, we examined differences in Bd host infection prevalence among amphibian species and its relations to both local environmental factors in breeding habitats and landscape variables measured at three scales (500, 2000 and 5000 m radii) around breeding sites in southernmost Sweden. We sampled 947 anurans of six species in 31 ponds and assessed their infection status. We then examined correlations of infection prevalence with canopy cover, pond perimeter and pH (treated as local-scale pond characteristics), and the number of ponds, area of arable land, area of mature forest, number of resident people and presence of sea within the three radii (treated as landscape variables). The Bd infection prevalence was very low, 0.5–1.0%, in two of the six anuran species (Bufo bufo and Rana temporaria), and substantially higher (13–64%) in the other four (Bombina bombina, Bufotes variabilis, Epidalea calamita, Rana arvalis). In the latter four species Bd infection prevalence was positively associated with ponds’ pH (site range: 5.3–8.1), and negatively associated with areas of mature forest and/or wetlands in the surroundings. Our results show that the infection dynamics of Bd are complex and associated with host species, local pond characteristics and several landscape variables at larger spatial scales. Knowledge of environmental factors associated with Bd infections and differences in species’ susceptibility may help to counter further spread of the disease and guide conservation action plans, especially for the most threatened species.
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Affiliation(s)
- Simon Kärvemo
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Sara Meurling
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - David Berger
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - Jacob Höglund
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - Anssi Laurila
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
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Mosher BA, Huyvaert KP, Bailey LL. Beyond the swab: ecosystem sampling to understand the persistence of an amphibian pathogen. Oecologia 2018; 188:319-330. [PMID: 29860635 DOI: 10.1007/s00442-018-4167-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2017] [Accepted: 05/12/2018] [Indexed: 10/14/2022]
Abstract
Understanding the ecosystem-level persistence of pathogens is essential for predicting and measuring host-pathogen dynamics. However, this process is often masked, in part due to a reliance on host-based pathogen detection methods. The amphibian pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal) are pathogens of global conservation concern. Despite having free-living life stages, little is known about the distribution and persistence of these pathogens outside of their amphibian hosts. We combine historic amphibian monitoring data with contemporary host- and environment-based pathogen detection data to obtain estimates of Bd occurrence independent of amphibian host distributions. We also evaluate differences in filter- and swab-based detection probability and assess inferential differences arising from using different decision criteria used to classify samples as positive or negative. Water filtration-based detection probabilities were lower than those from swabs but were > 10%, and swab-based detection probabilities varied seasonally, declining in the early fall. The decision criterion used to classify samples as positive or negative was important; using a more liberal criterion yielded higher estimates of Bd occurrence than when a conservative criterion was used. Different covariates were important when using the liberal or conservative criterion in modeling Bd detection. We found evidence of long-term Bd persistence for several years after an amphibian host species of conservation concern, the boreal toad (Anaxyrus boreas boreas), was last detected. Our work provides evidence of long-term Bd persistence in the ecosystem, and underscores the importance of environmental samples for understanding and mitigating disease-related threats to amphibian biodiversity.
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Affiliation(s)
- Brittany A Mosher
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA.
| | - Kathryn P Huyvaert
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA
| | - Larissa L Bailey
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, CO, 80523, USA
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Mosher BA, Bailey LL, Muths E, Huyvaert KP. Host-pathogen metapopulation dynamics suggest high elevation refugia for boreal toads. ECOLOGICAL APPLICATIONS : A PUBLICATION OF THE ECOLOGICAL SOCIETY OF AMERICA 2018; 28:926-937. [PMID: 29430754 DOI: 10.1002/eap.1699] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 12/18/2017] [Accepted: 01/02/2018] [Indexed: 06/08/2023]
Abstract
Emerging infectious diseases are an increasingly common threat to wildlife. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), is an emerging infectious disease that has been linked to amphibian declines around the world. Few studies exist that explore amphibian-Bd dynamics at the landscape scale, limiting our ability to identify which factors are associated with variation in population susceptibility and to develop effective in situ disease management. Declines of boreal toads (Anaxyrus boreas boreas) in the southern Rocky Mountains are largely attributed to chytridiomycosis but variation exists in local extinction of boreal toads across this metapopulation. Using a large-scale historic data set, we explored several potential factors influencing disease dynamics in the boreal toad-Bd system: geographic isolation of populations, amphibian community richness, elevational differences, and habitat permanence. We found evidence that boreal toad extinction risk was lowest at high elevations where temperatures may be suboptimal for Bd growth and where small boreal toad populations may be below the threshold needed for efficient pathogen transmission. In addition, boreal toads were more likely to recolonize high elevation sites after local extinction, again suggesting that high elevations may provide refuge from disease for boreal toads. We illustrate a modeling framework that will be useful to natural resource managers striving to make decisions in amphibian-Bd systems. Our data suggest that in the southern Rocky Mountains high elevation sites should be prioritized for conservation initiatives like reintroductions.
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Affiliation(s)
- Brittany A Mosher
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Larissa L Bailey
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, 80523, USA
| | - Erin Muths
- U.S. Geological Survey, Fort Collins Science Center, 2150 Centre Avenue, Building C, Fort Collins, Colorado, 80526, USA
| | - Kathryn P Huyvaert
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, 80523, USA
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Kamoroff C, Goldberg CS. Using environmental DNA for early detection of amphibian chytrid fungus Batrachochytrium dendrobatidis prior to a ranid die-off. DISEASES OF AQUATIC ORGANISMS 2017; 127:75-79. [PMID: 29256431 DOI: 10.3354/dao03183] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Amphibian chytridiomycosis caused by the fungus Batrachochytrium dendrobatidis (Bd) is an emerging infectious disease that has been associated with mass mortality and extinctions of amphibians worldwide. Environmental DNA (eDNA) techniques have been used to detect the presence of Bd in the environment, but not to detect Bd prior to an amphibian die-off. We collected eDNA using filtered water samples from 13 lakes across Sequoia Kings Canyon National Park. Seven of those sites had populations of mountain yellow-legged frogs, an amphibian highly susceptible to chytridiomycosis, and 3 of those populations experienced a Bd related die-off 1 mo post-eDNA sampling. We detected Bd in eDNA samples that were collected 1 mo prior to the observed Bd-caused die-off at all 3 sites affected by Bd, and we did not detect Bd at the other sites where no die-off was observed. Our study indicates the potential to use eDNA techniques for early detection of Bd in the environment.
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Affiliation(s)
- Colleen Kamoroff
- School of the Environment, Washington State University, Pullman, WA 99164, USA
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Mosher BA, Huyvaert KP, Chestnut T, Kerby JL, Madison JD, Bailey LL. Design- and model-based recommendations for detecting and quantifying an amphibian pathogen in environmental samples. Ecol Evol 2017; 7:10952-10962. [PMID: 29299272 PMCID: PMC5743658 DOI: 10.1002/ece3.3616] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2017] [Revised: 10/12/2017] [Accepted: 10/16/2017] [Indexed: 12/25/2022] Open
Abstract
Accurate pathogen detection is essential for developing management strategies to address emerging infectious diseases, an increasingly prominent threat to wildlife. Sampling for free‐living pathogens outside of their hosts has benefits for inference and study efficiency, but is still uncommon. We used a laboratory experiment to evaluate the influences of pathogen concentration, water type, and qPCR inhibitors on the detection and quantification of Batrachochytrium dendrobatidis (Bd) using water filtration. We compared results pre‐ and post‐inhibitor removal, and assessed inferential differences when single versus multiple samples were collected across space or time. We found that qPCR inhibition influenced both Bd detection and quantification in natural water samples, resulting in biased inferences about Bd occurrence and abundance. Biases in occurrence could be mitigated by collecting multiple samples in space or time, but biases in Bd quantification were persistent. Differences in Bd concentration resulted in variation in detection probability, indicating that occupancy modeling could be used to explore factors influencing heterogeneity in Bd abundance among samples, sites, or over time. Our work will influence the design of studies involving amphibian disease dynamics and studies utilizing environmental DNA (eDNA) to understand species distributions.
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Affiliation(s)
- Brittany A Mosher
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA
| | - Kathryn P Huyvaert
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA
| | - Tara Chestnut
- US Geological Survey Oregon Water Science Center Portland OR USA
| | - Jacob L Kerby
- Department of Biology University of South Dakota Vermillion SD USA
| | - Joseph D Madison
- Department of Biology University of South Dakota Vermillion SD USA
| | - Larissa L Bailey
- Department of Fish, Wildlife, and Conservation Biology Colorado State University Fort Collins CO USA
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Hanlon SM, Henson JR, Kerby JL. Detection of amphibian chytrid fungus on waterfowl integument in natural settings. DISEASES OF AQUATIC ORGANISMS 2017; 126:71-74. [PMID: 28930087 DOI: 10.3354/dao03160] [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] [Indexed: 06/07/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd), the causal agent of the amphibian disease chytridiomycosis, has spread at an alarming rate since its discovery. Bd was initially thought to only infect keratinizing epithelial cells in amphibians, a core component of amphibian skin. However, recent studies have detected Bd on the integument of non-amphibian hosts. We conducted a survey of 3 duck species (gadwalls, green-winged teals, and mallards) to determine whether Bd DNA could be found on their feet. Bd was found on the feet, by quantitative PCR, of individuals from all 3 species (5/11 gadwalls, 4/8 green-winged teals, and 13/21 mallards), though there were no significant differences in zoospore presence or load between species. We conclude that these waterfowl species may act as vector hosts for Bd, adding to the growing list of potential waterfowl vectors. Future studies are needed to determine whether Bd on waterfowl feet is viable and infectious to amphibian hosts.
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Affiliation(s)
- Shane M Hanlon
- Department of Biological Sciences, University of Memphis, Memphis, Tennessee 38152, USA
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Blooi M, Laking AE, Martel A, Haesebrouck F, Jocque M, Brown T, Green S, Vences M, Bletz MC, Pasmans F. Host niche may determine disease-driven extinction risk. PLoS One 2017; 12:e0181051. [PMID: 28704480 PMCID: PMC5509289 DOI: 10.1371/journal.pone.0181051] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 06/26/2017] [Indexed: 12/31/2022] Open
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) drives declines and extinctions in amphibian communities. However, not all regions and species are equally affected. Here, we show that association with amphibian aquatic habitat types (bromeliad phytotelmata versus stream) across Central America results in the odds of being threatened by Bd being five times higher in stream microhabitats. This differential threat of Bd was supported in our study by a significantly lower prevalence of Bd in bromeliad-associated amphibian species compared to riparian species in Honduran cloud forests. Evidence that the bromeliad environment is less favorable for Bd transmission is exemplified by significantly less suitable physicochemical conditions and higher abundance of Bd-ingesting micro-eukaryotes present in bromeliad water. These factors may inhibit aquatic Bd zoospore survival and the development of an environmental reservoir of the pathogen. Bromeliad phytotelmata thus may act as environmental refuges from Bd, which contribute to protecting associated amphibian communities against chytridiomycosis-driven amphibian declines that threaten the nearby riparian communities.
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Affiliation(s)
- Mark Blooi
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Alexandra E. Laking
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
- Operation Wallacea, Hope House, Old Bolingbroke, Lincolnshire, United Kingdom
| | - An Martel
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Freddy Haesebrouck
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
| | - Merlijn Jocque
- Operation Wallacea, Hope House, Old Bolingbroke, Lincolnshire, United Kingdom
- Hopkins Marine Station, Stanford University, Pacific Grove, California, United States of America
| | - Tom Brown
- Operation Wallacea, Hope House, Old Bolingbroke, Lincolnshire, United Kingdom
| | - Stephen Green
- Operation Wallacea, Hope House, Old Bolingbroke, Lincolnshire, United Kingdom
- Centre for Applied Zoology, Cornwall College Newquay, Cornwall, United Kingdom
| | - Miguel Vences
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Molly C. Bletz
- Zoological Institute, Technische Universität Braunschweig, Braunschweig, Germany
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, Merelbeke, Belgium
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The Emerging Amphibian Fungal Disease, Chytridiomycosis: A Key Example of the Global Phenomenon of Wildlife Emerging Infectious Diseases. Microbiol Spectr 2017; 4. [PMID: 27337484 DOI: 10.1128/microbiolspec.ei10-0004-2015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The spread of amphibian chytrid fungus, Batrachochytrium dendrobatidis, is associated with the emerging infectious wildlife disease chytridiomycosis. This fungus poses an overwhelming threat to global amphibian biodiversity and is contributing toward population declines and extinctions worldwide. Extremely low host-species specificity potentially threatens thousands of the 7,000+ amphibian species with infection, and hosts in additional classes of organisms have now also been identified, including crayfish and nematode worms.Soon after the discovery of B. dendrobatidis in 1999, it became apparent that this pathogen was already pandemic; dozens of countries and hundreds of amphibian species had already been exposed. The timeline of B. dendrobatidis's global emergence still remains a mystery, as does its point of origin. The reason why B. dendrobatidis seems to have only recently increased in virulence to catalyze this global disease event remains unknown, and despite 15 years of investigation, this wildlife pandemic continues primarily uncontrolled. Some disease treatments are effective on animals held in captivity, but there is currently no proven method to eradicate B. dendrobatidis from an affected habitat, nor have we been able to protect new regions from exposure despite knowledge of an approaching "wave" of B. dendrobatidis and ensuing disease.International spread of B. dendrobatidis is largely facilitated by the commercial trade in live amphibians. Chytridiomycosis was recently listed as a globally notifiable disease by the World Organization for Animal Health, but few countries, if any, have formally adopted recommended measures to control its spread. Wildlife diseases continue to emerge as a consequence of globalization, and greater effort is urgently needed to protect global health.
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Lampo M, Señaris C, García CZ. Population dynamics of the critically endangered toad Atelopus cruciger and the fungal disease chytridiomycosis. PLoS One 2017; 12:e0179007. [PMID: 28570689 PMCID: PMC5453621 DOI: 10.1371/journal.pone.0179007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 05/22/2017] [Indexed: 11/29/2022] Open
Abstract
Harlequin toads (Atelopus) are among the most severely impacted amphibians by the emergence of chytridiomycosis, a fungal disease caused by the pathogen Batrachochytrium dendrobatidis (Bd). Many species disappeared while others suffered drastic contractions of their geographic distribution to lower altitudes. A diminished virulence of Bd in warm habitats was proposed to explain the survival of lowland populations of harlequin toads (i.e. thermal refuge hypothesis). To understand the mechanisms that allow some populations to reach an endemic equilibrium with this pathogen, we estimated demographic and epidemiological parameters at one remnant population of Atelopus cruciger in Venezuela using mark-recapture data from 2007–2013. We demonstrated that Bd is highly virulent for A. cruciger, increasing the odds of dying of infected adults four times in relation to uninfected ones and reducing the life expectancy of reproductive toads to a few weeks. Despite an estimated annual loss of 18% of the reproductive population due to Bd-induced mortality, this population has persisted in an endemic equilibrium for the last decade through the large recruitment of healthy adults every year. Given the high vulnerability of harlequin toads to Bd in lowland populations, thermal refuges need to be redefined as habitats of reduced transmission rather than attenuated virulence.
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Affiliation(s)
- Margarita Lampo
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Kilómetro 11 Carretera Panamericana, Caracas, Venezuela
- * E-mail:
| | - Celsa Señaris
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Kilómetro 11 Carretera Panamericana, Caracas, Venezuela
| | - Carmen Zulay García
- Centro de Ecología, Instituto Venezolano de Investigaciones Científicas, Kilómetro 11 Carretera Panamericana, Caracas, Venezuela
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Gervasi SS, Stephens PR, Hua J, Searle CL, Xie GY, Urbina J, Olson DH, Bancroft BA, Weis V, Hammond JI, Relyea RA, Blaustein AR. Linking Ecology and Epidemiology to Understand Predictors of Multi-Host Responses to an Emerging Pathogen, the Amphibian Chytrid Fungus. PLoS One 2017; 12:e0167882. [PMID: 28095428 PMCID: PMC5240985 DOI: 10.1371/journal.pone.0167882] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 11/22/2016] [Indexed: 12/12/2022] Open
Abstract
Variation in host responses to pathogens can have cascading effects on populations and communities when some individuals or groups of individuals display disproportionate vulnerability to infection or differ in their competence to transmit infection. The fungal pathogen, Batrachochytrium dendrobatidis (Bd) has been detected in almost 700 different amphibian species and is implicated in numerous global amphibian population declines. Identifying key hosts in the amphibian-Bd system–those who are at greatest risk or who pose the greatest risk for others–is challenging due in part to many extrinsic environmental factors driving spatiotemporal Bd distribution and context-dependent host responses to Bd in the wild. One way to improve predictive risk models and generate testable mechanistic hypotheses about vulnerability is to complement what we know about the spatial epidemiology of Bd with data collected through comparative experimental studies. We used standardized pathogen challenges to quantify amphibian survival and infection trajectories across 20 post-metamorphic North American species raised from eggs. We then incorporated trait-based models to investigate the predictive power of phylogenetic history, habitat use, and ecological and life history traits in explaining responses to Bd. True frogs (Ranidae) displayed the lowest infection intensities, whereas toads (Bufonidae) generally displayed the greatest levels of mortality after Bd exposure. Affiliation with ephemeral aquatic habitat and breadth of habitat use were strong predictors of vulnerability to and intensity of infection and several other traits including body size, lifespan, age at sexual maturity, and geographic range also appeared in top models explaining host responses to Bd. Several of the species examined are highly understudied with respect to Bd such that this study represents the first experimental susceptibility data. Combining insights gained from experimental studies with observations of landscape-level disease prevalence may help explain current and predict future pathogen dynamics in the Bd system.
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Affiliation(s)
- Stephanie S. Gervasi
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| | - Patrick R. Stephens
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
| | - Jessica Hua
- Biological Sciences Department, Binghamton University, Binghamton, New York, United States of America
| | - Catherine L. Searle
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Gisselle Yang Xie
- 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
| | - Deanna H. Olson
- United States Forest Service, Pacific Northwest Research Station, Corvallis, Oregon, United States of America
| | - Betsy A. Bancroft
- Biology Department, Gonzaga University, Spokane, Washington, United States of America
| | - Virginia Weis
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - John I. Hammond
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Rick A. Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
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Courtois EA, Loyau A, Bourgoin M, Schmeller DS. Initiation of Batrachochytrium dendrobatidis
infection in the absence of physical contact with infected hosts - a field study in a high altitude lake. OIKOS 2016. [DOI: 10.1111/oik.03462] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- Elodie A. Courtois
- Laboratoire Ecologie, Evolution, Interactions des Systèmes Amazoniens (LEEISA); Univ. de Guyane; CNRS, IFREMER FR-97300 Cayenne France
- Dept of Biology; Univ. of Antwerp; Wilrijk Belgium
| | - Adeline Loyau
- Helmholtz Centre for Environmental Research - UFZ; Dept of Conservation Biology; Leipzig Germany
- EcoLab; Univ. de Toulouse; CNRS, INPT, UPS Toulouse France
| | - Mégane Bourgoin
- Station d'écologie expérimentale du CNRS à Moulis; Moulis France
| | - Dirk S. Schmeller
- Helmholtz Centre for Environmental Research - UFZ; Dept of Conservation Biology; Leipzig Germany
- EcoLab; Univ. de Toulouse; CNRS, INPT, UPS Toulouse France
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Spens J, Evans AR, Halfmaerten D, Knudsen SW, Sengupta ME, Mak SST, Sigsgaard EE, Hellström M. Comparison of capture and storage methods for aqueous macrobial
eDNA
using an optimized extraction protocol: advantage of enclosed filter. Methods Ecol Evol 2016. [DOI: 10.1111/2041-210x.12683] [Citation(s) in RCA: 177] [Impact Index Per Article: 22.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Affiliation(s)
- Johan Spens
- Centre for GeoGenetics Natural History Museum of Denmark Øster Voldgade 5‐7 1350 Copenhagen K Denmark
- Wildlife, Fish and Environmental Studies Swedish University of Agricultural Sciences Skogsmarksgränd 90183 Umeå Sweden
| | - Alice R. Evans
- Centre for GeoGenetics Natural History Museum of Denmark Øster Voldgade 5‐7 1350 Copenhagen K Denmark
| | - David Halfmaerten
- Research Institute for Nature and Forest Gaverstraat 4 9500 Geraardsbergen Belgium
| | - Steen W. Knudsen
- Centre for GeoGenetics Natural History Museum of Denmark Øster Voldgade 5‐7 1350 Copenhagen K Denmark
| | - Mita E. Sengupta
- Department of Veterinary Disease Biology Parasitology and Aquatic Diseases Dyrlægevej 100 1870 Frederiksberg C Copenhagen Denmark
| | - Sarah S. T. Mak
- Centre for GeoGenetics Natural History Museum of Denmark Øster Voldgade 5‐7 1350 Copenhagen K Denmark
| | - Eva E. Sigsgaard
- Centre for GeoGenetics Natural History Museum of Denmark Øster Voldgade 5‐7 1350 Copenhagen K Denmark
| | - Micaela Hellström
- Centre for GeoGenetics Natural History Museum of Denmark Øster Voldgade 5‐7 1350 Copenhagen K Denmark
- Department of Ecology, Environment and Plant Sciences Stockholm University 10691 Stockholm Sweden
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Battaglin WA, Smalling KL, Anderson C, Calhoun D, Chestnut T, Muths E. Potential interactions among disease, pesticides, water quality and adjacent land cover in amphibian habitats in the United States. THE SCIENCE OF THE TOTAL ENVIRONMENT 2016; 566-567:320-332. [PMID: 27232962 DOI: 10.1016/j.scitotenv.2016.05.062] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2016] [Revised: 05/06/2016] [Accepted: 05/06/2016] [Indexed: 05/21/2023]
Abstract
To investigate interactions among disease, pesticides, water quality, and adjacent land cover, we collected samples of water, sediment, and frog tissue from 21 sites in 7 States in the United States (US) representing a variety of amphibian habitats. All samples were analyzed for >90 pesticides and pesticide degradates, and water and frogs were screened for the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) using molecular methods. Pesticides and pesticide degradates were detected frequently in frog breeding habitats (water and sediment) as well as in frog tissue. Fungicides occurred more frequently in water, sediment, and tissue than was expected based upon their limited use relative to herbicides or insecticides. Pesticide occurrence in water or sediment was not a strong predictor of occurrence in tissue, but pesticide concentrations in tissue were correlated positively to agricultural and urban land, and negatively to forested land in 2-km buffers around the sites. Bd was detected in water at 45% of sites, and on 34% of swabbed frogs. Bd detections in water were not associated with differences in land use around sites, but sites with detections had colder water. Frogs that tested positive for Bd were associated with sites that had higher total fungicide concentrations in water and sediment, but lower insecticide concentrations in sediments relative to frogs that were Bd negative. Bd concentrations on frog swabs were positively correlated to dissolved organic carbon, and total nitrogen and phosphorus, and negatively correlated to pH and water temperature. Data were collected from a range of locations and amphibian habitats and represent some of the first field-collected information aimed at understanding the interactions between pesticides, land use, and amphibian disease. These interactions are of particular interest to conservation efforts as many amphibians live in altered habitats and may depend on wetlands embedded in these landscapes to survive.
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Affiliation(s)
- W A Battaglin
- U.S. Geological Survey, Colorado Water Science Center, Lakewood, CO, United States
| | - K L Smalling
- U.S. Geological Survey, New Jersey Water Science Center, Lawrenceville, NJ, United States
| | - C Anderson
- U.S. Geological Survey, Oregon Water Science Center, Portland, OR, United States
| | - D Calhoun
- U.S. Geological Survey South Atlantic Water Science Center, Atlanta, GA, United States
| | - T Chestnut
- National Park Service, Mount Rainer National Park, Ashford, WA, United States
| | - E Muths
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO, United States
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Rethinking the role of invertebrate hosts in the life cycle of the amphibian chytridiomycosis pathogen. Parasitology 2016; 143:1723-1729. [PMID: 27573338 DOI: 10.1017/s0031182016001360] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The amphibian pathogen Batrachochytrium dendrobatidis (Bd) has recently emerged as a primary factor behind declining global amphibian populations. Much about the basic biology of the pathogen is unknown, however, such as its true ecological niche and life cycle. Here we evaluated invertebrates as infection models by inoculating host species that had previously been suggested to be parasitized in laboratory settings: crayfish (Procambarus alleni) and nematodes (Caenorhabditis elegans). We found neither negative effects on either host nor evidence of persistent infection despite using higher inoculum loads and more pathogen genotypes than tested in previous studies. In contrast, addition of Bd to C. elegans cultures had a slight positive effect on host growth. Bd DNA was detected on the carapace of 2/34 crayfish 7 weeks post-inoculation, suggesting some means of persistence in the mesocosm. These results question the role of invertebrates as alternative hosts of Bd and their ability to modulate disease dynamics.
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Projecting the Global Distribution of the Emerging Amphibian Fungal Pathogen, Batrachochytrium dendrobatidis, Based on IPCC Climate Futures. PLoS One 2016; 11:e0160746. [PMID: 27513565 PMCID: PMC4981458 DOI: 10.1371/journal.pone.0160746] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2015] [Accepted: 07/25/2016] [Indexed: 11/19/2022] Open
Abstract
Projected changes in climate conditions are emerging as significant risk factors to numerous species, affecting habitat conditions and community interactions. Projections suggest species range shifts in response to climate change modifying environmental suitability and is supported by observational evidence. Both pathogens and their hosts can shift ranges with climate change. We consider how climate change may influence the distribution of the emerging infectious amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), a pathogen associated with worldwide amphibian population losses. Using an expanded global Bd database and a novel modeling approach, we examined a broad set of climate metrics to model the Bd-climate niche globally and regionally, then project how climate change may influence Bd distributions. Previous research showed that Bd distribution is dependent on climatic variables, in particular temperature. We trained a machine-learning model (random forest) with the most comprehensive global compilation of Bd sampling records (~5,000 site-level records, mid-2014 summary), including 13 climatic variables. We projected future Bd environmental suitability under IPCC scenarios. The learning model was trained with combined worldwide data (non-region specific) and also separately per region (region-specific). One goal of our study was to estimate of how Bd spatial risks may change under climate change based on the best available data. Our models supported differences in Bd-climate relationships among geographic regions. We projected that Bd ranges will shift into higher latitudes and altitudes due to increased environmental suitability in those regions under predicted climate change. Specifically, our model showed a broad expansion of areas environmentally suitable for establishment of Bd on amphibian hosts in the temperate zones of the Northern Hemisphere. Our projections are useful for the development of monitoring designs in these areas, especially for sensitive species and those vulnerable to multiple threats.
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Insights From Genomics Into Spatial and Temporal Variation in Batrachochytrium dendrobatidis. PROGRESS IN MOLECULAR BIOLOGY AND TRANSLATIONAL SCIENCE 2016. [PMID: 27571698 DOI: 10.1016/bs.pmbts.2016.05.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/20/2023]
Abstract
Advances in genetics and genomics have provided new tools for the study of emerging infectious diseases. Researchers can now move quickly from simple hypotheses to complex explanations for pathogen origin, spread, and mechanisms of virulence. Here we focus on the application of genomics to understanding the biology of the fungal pathogen Batrachochytrium dendrobatidis (Bd), a novel and deadly pathogen of amphibians. We provide a brief history of the system, then focus on key insights into Bd variation garnered from genomics approaches, and finally, highlight new frontiers for future discoveries. Genomic tools have revealed unexpected complexity and variation in the Bd system suggesting that the history and biology of emerging pathogens may not be as simple as they initially seem.
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