1
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Esmaeilbeigi M, P Duncan R, J Kefford B, Ezaz T, Clulow S. Evidence for a metal disease refuge: The amphibian-killing fungus (Batrachochytrium dendrobatidis) is inhibited by environmentally-relevant concentrations of metals tolerated by amphibians. ENVIRONMENTAL RESEARCH 2024; 261:119752. [PMID: 39117053 DOI: 10.1016/j.envres.2024.119752] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2024] [Revised: 07/27/2024] [Accepted: 08/05/2024] [Indexed: 08/10/2024]
Abstract
The amphibian-killing fungus Batrachochytrium dendrobatidis (Bd) has caused substantial declines in Bd-susceptible amphibian species worldwide. However, some populations of Bd-susceptible frogs have managed to survive at existing metal-polluted sites, giving rise to the hypothesis that frogs might persist in the presence of Bd if Bd is inhibited by metals at concentrations that frogs can tolerate. We tested this hypothesis by measuring the survival of Bd zoospores, the life stage that infects amphibians, and calculated the LC50 after exposure to environmentally-relevant elevated concentrations of copper (Cu), zinc (Zn), and their combination (Cu + Zn) in two repeated 4-day acute exposure runs. We also measured the chronic sensitivity of Bd to these metals over three generations by measuring the number of colonies and live zoospores and calculating EC50 concentrations after 42 days of exposure. We then compared acute and chronic sensitivity of Bd with amphibian sensitivities by constructing species sensitivity distributions (SSDs) using LC50 and EC50 data obtained from the literature. Acute sensitivity data showed that Bd zoospore survival decreased with increasing metal concentrations and exposure durations relative to the control, with the highest LC50 values for Cu and Zn being 2.5 μg/L and 250 μg/L, respectively. Chronic exposures to metals resulted in decreased numbers of Bd colonies and live zoospores after 42 days, with EC50 values of 0.75 μg/L and 1.19 μg/L for Cu and Zn, respectively. Bd zoospore survival was 10 and 8 times more sensitive to Cu and Zn, respectively in acute, and 2 and 5 times more sensitive to Cu and Zn in chronic exposure experiments than the most sensitive amphibian species recorded. Our findings are consistent with the hypothesis that metals in existing metal-polluted sites may have a greater impact on Bd relative to amphibians' performance, potentially enabling Bd-susceptible amphibians to persist with Bd at these sites.
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Affiliation(s)
- Milad Esmaeilbeigi
- Centre for Applied Water Science, Institute for Applied Ecology, Faculty of Science and Technology, University of Canberra, Canberra, Bruce ACT, 2617, Australia.
| | - Richard P Duncan
- Center for Conservation Ecology and Genomics, Institute for Applied Ecology, Faculty of Science and Technology, University of Canberra, Canberra, Bruce ACT, 2617, Australia.
| | - Ben J Kefford
- Centre for Applied Water Science, Institute for Applied Ecology, Faculty of Science and Technology, University of Canberra, Canberra, Bruce ACT, 2617, Australia.
| | - Tariq Ezaz
- Center for Conservation Ecology and Genomics, Institute for Applied Ecology, Faculty of Science and Technology, University of Canberra, Canberra, Bruce ACT, 2617, Australia.
| | - Simon Clulow
- Center for Conservation Ecology and Genomics, Institute for Applied Ecology, Faculty of Science and Technology, University of Canberra, Canberra, Bruce ACT, 2617, Australia.
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2
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Jakóbik J, Drohvalenko M, Fernandez Melendez E, Kępa E, Klynova O, Fedorova A, Korshunov O, Marushchak O, Nekrasova O, Suriadna N, Smirnov N, Tkachenko O, Tupikov A, Dufresnes C, Zinenko O, Pabijan M. Countrywide screening supports model-based predictions of the distribution of Batrachochytrium dendrobatidis in Ukraine. DISEASES OF AQUATIC ORGANISMS 2024; 159:15-27. [PMID: 39087616 DOI: 10.3354/dao03802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/02/2024]
Abstract
The chytrid Batrachochytrium dendrobatidis (Bd) is a widespread fungus causing amphibian declines across the globe. Although data on Bd occurrence in Eastern Europe are scarce, a recent species distribution model (SDM) for Bd reported that western and north-western parts of Ukraine are highly suitable to the pathogen. We verified the SDM-predicted range of Bd in Ukraine by sampling amphibians across the country and screening for Bd using qPCR. A total of 446 amphibian samples (tissue and skin swabs) from 11 species were collected from 36 localities. We obtained qPCR-positive results for 33 samples including waterfrogs (Pelophylax esculentus complex) and fire- and yellow-bellied toads (Bombina spp.) from 8 localities. We found that Bd-positive localities had significantly higher predicted Bd habitat suitability than sites that were pathogen-free. Amplification and sequencing of the internal transcribed spacer (ITS) region of samples with the highest Bd load revealed matches with ITS haplotypes of the globally distributed BdGPL strain, and a single case of the BdASIA-2/BdBRAZIL haplotype. We found that Bd was non-randomly distributed across Ukraine, with infections present in the western and north-central forested peripheries of the country with a relatively cool, moist climate. On the other hand, our results suggest that Bd is absent or present in low abundance in the more continental central, southern and eastern regions of Ukraine, corroborating the model-predicted distribution of chytrid fungus. These areas could potentially serve as climatic refugia for Bd-susceptible amphibian hosts.
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Affiliation(s)
- Joanna Jakóbik
- Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland
| | - Mykola Drohvalenko
- Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland
- Zoology and Animal Ecology Department, School of Biology, V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
| | - Eduardo Fernandez Melendez
- Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, 9820 Merelbeke, Belgium
| | - Emilia Kępa
- Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland
| | - Oleksandra Klynova
- Department of Mycology and Plant Resistance, School of Biology, V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
| | - Anna Fedorova
- Zoology and Animal Ecology Department, School of Biology, V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
- Laboratory of Fish Genetics, Institute of Animal Physiology and Genetics, Czech Academy of Sciences, 277 21 Liběchov, Czech Republic
| | - Oleksii Korshunov
- Zoology and Animal Ecology Department, School of Biology, V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
| | - Oleksii Marushchak
- I. I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 01054 Kyiv, Ukraine
- Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
| | - Oksana Nekrasova
- I. I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 01054 Kyiv, Ukraine
- Université de Strasbourg, CNRS, IPHC UMR 7178, 67000 Strasbourg, France
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, 5401 Daugavpils, Latvia
| | - Natalia Suriadna
- Melitopol Institute of Ecology and Social Technologies of the University Ukraine, 04071 Kyiv, Ukraine
| | - Nazar Smirnov
- Chernivtsi Regional Museum of Local Lore, 58002 Chernivtsi, Ukraine
| | - Oksana Tkachenko
- T.H. Shevchenko National University Chernihiv Colehium, 14013 Chernihiv, Ukraine
| | - Andrii Tupikov
- Society for Conservation GIS Ukraine, Svobody sq. 4, 61022 Kharkiv, Ukraine
| | - Christophe Dufresnes
- Institut de Systématique, Evolution, Biodiversité, Muséum national d'Histoire naturelle, CNRS, Sorbonne Université, EPHE-PSL, Université des Antilles, 75005 Paris, France
| | - Oleksandr Zinenko
- Department of Mycology and Plant Resistance, School of Biology, V. N. Karazin Kharkiv National University, 61022 Kharkiv, Ukraine
| | - Maciej Pabijan
- Institute of Zoology and Biomedical Research, Faculty of Biology, Jagiellonian University, 30-387 Kraków, Poland
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3
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Waddle AW, Clulow S, Aquilina A, Sauer EL, Kaiser SW, Miller C, Flegg JA, Campbell PT, Gallagher H, Dimovski I, Lambreghts Y, Berger L, Skerratt LF, Shine R. Hotspot shelters stimulate frog resistance to chytridiomycosis. Nature 2024; 631:344-349. [PMID: 38926575 DOI: 10.1038/s41586-024-07582-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2023] [Accepted: 05/17/2024] [Indexed: 06/28/2024]
Abstract
Many threats to biodiversity cannot be eliminated; for example, invasive pathogens may be ubiquitous. Chytridiomycosis is a fungal disease that has spread worldwide, driving at least 90 amphibian species to extinction, and severely affecting hundreds of others1-4. Once the disease spreads to a new environment, it is likely to become a permanent part of that ecosystem. To enable coexistence with chytridiomycosis in the field, we devised an intervention that exploits host defences and pathogen vulnerabilities. Here we show that sunlight-heated artificial refugia attract endangered frogs and enable body temperatures high enough to clear infections, and that having recovered in this way, frogs are subsequently resistant to chytridiomycosis even under cool conditions that are optimal for fungal growth. Our results provide a simple, inexpensive and widely applicable strategy to buffer frogs against chytridiomycosis in nature. The refugia are immediately useful for the endangered species we tested and will have broader utility for amphibian species with similar ecologies. Furthermore, our concept could be applied to other wildlife diseases in which differences in host and pathogen physiologies can be exploited. The refugia are made from cheap and readily available materials and therefore could be rapidly adopted by wildlife managers and the public. In summary, habitat protection alone cannot protect species that are affected by invasive diseases, but simple manipulations to microhabitat structure could spell the difference between the extinction and the persistence of endangered amphibians.
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Affiliation(s)
- Anthony W Waddle
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia.
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia.
- Applied BioSciences, Macquarie University, Sydney, New South Wales, Australia.
| | - Simon Clulow
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- Centre for Conservation Ecology and Genomics, Institute for Applied Ecology, University of Canberra, Bruce, Australian Capital Territory, Australia
| | - Amy Aquilina
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Erin L Sauer
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR, USA
| | - Shannon W Kaiser
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Claire Miller
- School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia
- Auckland Bioengineering Institute, University of Auckland, Auckland, New Zealand
| | - Jennifer A Flegg
- School of Mathematics and Statistics, University of Melbourne, Parkville, Victoria, Australia
| | - Patricia T Campbell
- Department of Infectious Diseases, University of Melbourne at the Peter Doherty Institute for Infection and Immunity, Melbourne, Victoria, Australia
- Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, University of Melbourne, Melbourne, Victoria, Australia
| | - Harrison Gallagher
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Ivana Dimovski
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Yorick Lambreghts
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
- School of Natural Sciences, University of Tasmania, Hobart, Tasmania, Australia
| | - Lee Berger
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
| | - Lee F Skerratt
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
| | - Richard Shine
- School of Natural Sciences, Macquarie University, Sydney, New South Wales, Australia
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4
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Webb RJ, Cuff C, Berger L. Glutathione-Mediated Metal Tolerance in an Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis). ENVIRONMENTAL TOXICOLOGY AND CHEMISTRY 2024; 43:1583-1591. [PMID: 38726969 DOI: 10.1002/etc.5885] [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: 01/02/2024] [Revised: 02/21/2024] [Accepted: 04/07/2024] [Indexed: 06/27/2024]
Abstract
The spread of the amphibian chytrid fungus Batrachochytrium dendrobatidis, which causes the disease chytridiomycosis, has resulted in amphibian declines and extinctions worldwide. Some susceptible amphibian species can persist in contaminated habitats, prompting the hypothesis that B. dendrobatidis might be sensitive to heavy metals. We tested a panel of 12 metals to rank their toxicity to B. dendrobatidis zoospores and zoosporangia during a 6-h exposure. To better understand the mechanism for metal detoxification, we also evaluated whether glutathione is required for metal tolerance by depleting cellular glutathione before metal exposure. In addition, we investigated whether prior exposure to low metal concentrations impacted tolerance of subsequent exposure, as well as identifying metal combinations that may act synergistically. Silver (Ag), cadmium (Cd), and copper (Cu) were particularly toxic to B. dendrobatidis, with zoospore minimum lethal concentration values of 0.01 mM (Ag), 0.025 mM (Cd), and 0.5 mM (Cu). These three metals along with zinc (Zn) were also inhibitory to zoosporangia, with minimum inhibitory concentration values of 0.005 mM (Ag), 0.04 mM (Cd), 0.075 mM (Cu), and 0.04 mM (Zn). The fungicidal effects of several metals was reduced when assays were conducted in nutrient medium compared with synthetic pond water, highlighting the need for careful in vitro assay design and interpretation. Glutathione depletion strongly influenced tolerance of Cd and Ag (85% and 75% less growth, respectively) and moderately influenced tolerance of Cu, Zn, and lead (37%, 18%, and 14% less growth, respectively), indicating the importance of glutathione for metal detoxification. In general, the minimum metal concentrations that inhibited growth of B. dendrobatidis far exceeded values detected in contaminated amphibian habitats in Australia, suggesting that metal contamination alone may not have a strong protective effect against chytridiomycosis. We discuss future research directions to futher understand the potential for dissolved metals to create chytrid refuges. Environ Toxicol Chem 2024;43:1583-1591. © 2024 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.
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Affiliation(s)
- Rebecca J Webb
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
| | | | - Lee Berger
- Melbourne Veterinary School, University of Melbourne, Werribee, Victoria, Australia
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5
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Holmes ML, Shine R, Waddle AW. Spontaneous reoccurrence of Batrachochytrium dendrobatidis infections in Australian green tree frogs (Litoria caerulea) following apparently successful heat therapy: Case report. Vet Res Commun 2024:10.1007/s11259-024-10449-2. [PMID: 38951465 DOI: 10.1007/s11259-024-10449-2] [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: 04/03/2024] [Accepted: 06/23/2024] [Indexed: 07/03/2024]
Abstract
Heat therapy has been reported as a safe, effective, and readily available treatment method for heat-tolerant frogs infected with Batrachochytrium dendrobatidis (Bd). We treated wild-caught Australian green tree frogs (Litoria caerulea) infected with Bd using two periods of elevated ambient room temperature (28.2-30.3 °C for 7 weeks followed by 28.9-34.1 °C for 4 weeks). Frogs exhibited persistent and even increasing infection loads in the first treatment period despite prolonged exposure to elevated temperatures, likely due to the presence of cooler microenvironments within their enclosure (25.5-27.0 °C). All frogs eventually returned negative qPCR tests for Bd at the end of the second treatment period, but detectable infections reoccurred one month after frogs were returned to standard housing temperatures (21.2-28.7 °C). Our findings suggest that elevated ambient temperature alone might not eliminate Bd in vivo but can reduce infections loads such that they are undetectable by qPCR analysis of skin swabs. Additional factors, such as cooler microenvironments within enclosures or relative humidity, may influence the success of heat therapy. We recommend further research into the combined effects of temperature and humidity during heat therapy and emphasize the importance of accurate temperature measurements as well as post-treatment monitoring at Bd-permissive temperatures to confirm successful clearance of infections.
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Affiliation(s)
- Madeleine L Holmes
- School of Natural Sciences, Macquarie University, Sydney, NSW, Australia.
| | - Richard Shine
- School of Natural Sciences, Macquarie University, Sydney, NSW, Australia
| | - Anthony W Waddle
- Applied Biosciences, Macquarie University, Sydney, NSW, Australia
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6
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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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7
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McGrath-Blaser SE, McGathey N, Pardon A, Hartmann AM, Longo AV. Invasibility of a North American soil ecosystem to amphibian-killing fungal pathogens. Proc Biol Sci 2024; 291:20232658. [PMID: 38628130 PMCID: PMC11021929 DOI: 10.1098/rspb.2023.2658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2023] [Accepted: 03/19/2024] [Indexed: 04/19/2024] Open
Abstract
North American salamanders are threatened by intercontinental spread of chytridiomycosis, a deadly disease caused by the fungal pathogen Batrachochytrium salamandrivorans (Bsal). To predict potential dispersal of Bsal spores to salamander habitats, we evaluated the capacity of soil microbial communities to resist invasion. We determined the degree of habitat invasibility using soils from five locations throughout the Great Smoky Mountains National Park, a region with a high abundance of susceptible hosts. Our experimental design consisted of replicate soil microcosms exposed to different propagule pressures of the non-native pathogen, Bsal, and an introduced but endemic pathogen, B. dendrobatidis (Bd). To compare growth and competitive interactions, we used quantitative PCR, live/dead cell viability assays, and full-length 16S rRNA sequencing. We found that soil microcosms with intact bacterial communities inhibited both Bsal and Bd growth, but inhibitory capacity diminished with increased propagule pressure. Bsal showed greater persistence than Bd. Linear discriminant analysis (LDA) identified the family Burkolderiaceae as increasing in relative abundance with the decline of both pathogens. Although our findings provide evidence of environmental filtering in soils, such barriers weakened in response to pathogen type and propagule pressure, showing that habitats vary their invasibility based on properties of their local microbial communities.
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Affiliation(s)
| | - Natalie McGathey
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Allison Pardon
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Arik M. Hartmann
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Ana V. Longo
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
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8
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Belasen AM, Peek RA, Adams AJ, Russell ID, De León ME, Adams MJ, Bettaso J, Breedveld KGH, Catenazzi A, Dillingham CP, Grear DA, Halstead BJ, Johnson PG, Kleeman PM, Koo MS, Koppl CW, Lauder JD, Padgett-Flohr G, Piovia-Scott J, Pope KL, Vredenburg V, Westphal M, Wiseman K, Kupferberg SJ. Chytrid infections exhibit historical spread and contemporary seasonality in a declining stream-breeding frog. ROYAL SOCIETY OPEN SCIENCE 2024; 11:231270. [PMID: 38298390 PMCID: PMC10827429 DOI: 10.1098/rsos.231270] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2023] [Accepted: 12/18/2023] [Indexed: 02/02/2024]
Abstract
Species with extensive geographical ranges pose special challenges to assessing drivers of wildlife disease, necessitating collaborative and large-scale analyses. The imperilled foothill yellow-legged frog (Rana boylii) inhabits a wide geographical range and variable conditions in rivers of California and Oregon (USA), and is considered threatened by the pathogen Batrachochytrium dendrobatidis (Bd). To assess drivers of Bd infections over time and space, we compiled over 2000 datapoints from R. boylii museum specimens (collected 1897-2005) and field samples (2005-2021) spanning 9° of latitude. We observed a south-to-north spread of Bd detections beginning in the 1940s and increase in prevalence from the 1940s to 1970s, coinciding with extirpation from southern latitudes. We detected eight high-prevalence geographical clusters through time that span the species' geographical range. Field-sampled male R. boylii exhibited the highest prevalence, and juveniles sampled in autumn exhibited the highest loads. Bd infection risk was highest in lower elevation rain-dominated watersheds, and with cool temperatures and low stream-flow conditions at the end of the dry season. Through a holistic assessment of relationships between infection risk, geographical context and time, we identify the locations and time periods where Bd mitigation and monitoring will be critical for conservation of this imperilled species.
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Affiliation(s)
- A. M. Belasen
- Department of Integrative Biology, University of Texas at Austin, Austin, TX, USA
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY, USA
| | - R. A. Peek
- California Department of Fish and Wildlife, West Sacramento, CA, USA
| | - A. J. Adams
- Earth Research Institute, University of California, Santa Barbara, CA, USA
| | - I. D. Russell
- Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
| | - M. E. De León
- Genome Center, University of California, Davis, CA, USA
| | - M. J. Adams
- U.S. Geological Survey, Forest and Rangeland Ecosystem Science Center, Corvallis, OR, USA
| | - J. Bettaso
- Six Rivers National Forest, Lower Trinity Ranger District, USDA Forest Service, P.O. Box 68, Willow Creek, CA, USA
| | | | - A. Catenazzi
- Department of Biological Sciences, Florida International University, Miami, FL, USA
| | | | - D. A. Grear
- U.S. Geological Survey, National Wildlife Health Center, Madison, WI, USA
| | - B. J. Halstead
- Point Reyes Field Station, U.S. Geological Survey, Western Ecological Research Center, Point Reyes Station, CA, USA
| | - P. G. Johnson
- Pinnacles National Park, National Park Service, Paicines, CA, USA
| | - P. M. Kleeman
- Point Reyes Field Station, U.S. Geological Survey, Western Ecological Research Center, Point Reyes Station, CA, USA
| | - M. S. Koo
- Museum of Vertebrate Zoology, University of California, Berkeley, CA
| | - C. W. Koppl
- Plumas National Forest, USDA Forest Service, Quincy, CA, USA
| | | | | | - J. Piovia-Scott
- School of Biological Sciences, Washington State University, Vancouver, WA, USA
| | - K. L. Pope
- Pacific Southwest Research Station, USDA Forest Service, Arcata, CA, USA
| | - V. Vredenburg
- Department of Biology, San Francisco State University, San Francisco, CA, USA
| | - M. Westphal
- Central Coast Field Office, United States Bureau of Land Management, Marina, CA, USA
| | - K. Wiseman
- Department of Herpetology, California Academy of Sciences, San Francisco, CA, USA
| | - S. J. Kupferberg
- Department of Integrative Biology, University of California, Berkeley, CA, USA
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9
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Webb RJ, Rush C, Berger L, Skerratt LF, Roberts AA. Glutathione is required for growth and cadmium tolerance in the amphibian chytrid fungus, Batrachochytrium dendrobatidis. Biochimie 2023; 220:22-30. [PMID: 38104714 DOI: 10.1016/j.biochi.2023.12.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 11/24/2023] [Accepted: 12/12/2023] [Indexed: 12/19/2023]
Abstract
Batrachochytrium dendrobatidis (Bd) is a lethal amphibian pathogen, partly due to its ability to evade the immune system of susceptible frog species. In many pathogenic fungi, the antioxidant glutathione is a virulence factor that helps neutralise oxidative stressors generated from host immune cells, as well as other environmental stressors such as heavy metals. The role of glutathione in stress tolerance in Bd has not been investigated. Here, we examine the changes in the glutathione pool after stress exposure and quantify the effect of glutathione depletion on cell growth and stress tolerance. Depletion of glutathione repressed growth and release of zoospores, suggesting that glutathione is essential for life cycle completion in Bd. Supplementation with <2 mM exogenous glutathione accelerated zoospore development, but concentrations >2 mM were strongly inhibitory to Bd cells. While hydrogen peroxide exposure lowered the total cellular glutathione levels by 42 %, glutathione depletion did not increase the sensitivity to hydrogen peroxide. Exposure to cadmium increased total cellular glutathione levels by 93 %. Glutathione-depleted cells were more sensitive to cadmium, and this effect was attenuated by glutathione supplementation, suggesting that glutathione plays an important role in cadmium tolerance. The effects of heat and salt were exacerbated by the addition of exogenous glutathione. The impact of glutathione levels on Bd stress sensitivity may help explain differences in host susceptibility to chytridiomycosis and may provide opportunities for synergistic therapeutics.
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Affiliation(s)
- Rebecca J Webb
- James Cook University, Townsville, QLD, 4811, Australia; Melbourne Veterinary School, University of Melbourne, Werribee, VIC, 3030, Australia.
| | | | - Lee Berger
- Melbourne Veterinary School, University of Melbourne, Werribee, VIC, 3030, Australia
| | - Lee F Skerratt
- Melbourne Veterinary School, University of Melbourne, Werribee, VIC, 3030, Australia
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10
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Ange-Stark M, Parise KL, Cheng TL, Hoyt JR, Langwig KE, Frick WF, Kilpatrick AM, Gillece J, MacManes MD, Foster JT. White-nose syndrome restructures bat skin microbiomes. Microbiol Spectr 2023; 11:e0271523. [PMID: 37888992 PMCID: PMC10714735 DOI: 10.1128/spectrum.02715-23] [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: 06/30/2023] [Accepted: 09/13/2023] [Indexed: 10/28/2023] Open
Abstract
IMPORTANCE Inherent complexities in the composition of microbiomes can often preclude investigations of microbe-associated diseases. Instead of single organisms being associated with disease, community characteristics may be more relevant. Longitudinal microbiome studies of the same individual bats as pathogens arrive and infect a population are the ideal experiment but remain logistically challenging; therefore, investigations like our approach that are able to correlate invasive pathogens to alterations within a microbiome may be the next best alternative. The results of this study potentially suggest that microbiome-host interactions may determine the likelihood of infection. However, the contrasting relationship between Pd and the bacterial microbiomes of Myotis lucifugus and Perimyotis subflavus indicate that we are just beginning to understand how the bat microbiome interacts with a fungal invader such as Pd.
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Affiliation(s)
- Meghan Ange-Stark
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
| | - Katy L. Parise
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Tina L. Cheng
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA
- Bat Conservation International, Austin, Texas, USA
| | - Joseph R. Hoyt
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Kate E. Langwig
- Department of Biological Sciences, Virginia Tech, Blacksburg, Virginia, USA
| | - Winifred F. Frick
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA
- Bat Conservation International, Austin, Texas, USA
| | - A. Marm Kilpatrick
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California, USA
| | - John Gillece
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Matthew D. MacManes
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
| | - Jeffrey T. Foster
- Department of Molecular, Cellular and Biomedical Sciences, University of New Hampshire, Durham, New Hampshire, USA
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
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11
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Neely WJ, Martins RA, Mendonça da Silva CM, Ferreira da Silva T, Fleck LE, Whetstone RD, Woodhams DC, Cook WH, Prist PR, Valiati VH, Greenspan SE, Tozetti AM, Earley RL, Becker CG. Linking microbiome and stress hormone responses in wild tropical treefrogs across continuous and fragmented forests. Commun Biol 2023; 6:1261. [PMID: 38087051 PMCID: PMC10716138 DOI: 10.1038/s42003-023-05600-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Accepted: 11/16/2023] [Indexed: 12/18/2023] Open
Abstract
The amphibian skin microbiome is an important component of anti-pathogen defense, but the impact of environmental change on the link between microbiome composition and host stress remains unclear. In this study, we used radiotelemetry and host translocation to track microbiome composition and function, pathogen infection, and host stress over time across natural movement paths for the forest-associated treefrog, Boana faber. We found a negative correlation between cortisol levels and putative microbiome function for frogs translocated to forest fragments, indicating strong integration of host stress response and anti-pathogen potential of the microbiome. Additionally, we observed a capacity for resilience (resistance to structural change and functional loss) in the amphibian skin microbiome, with maintenance of putative pathogen-inhibitory function despite major temporal shifts in microbiome composition. Although microbiome community composition did not return to baseline during the study period, the rate of microbiome change indicated that forest fragmentation had more pronounced effects on microbiome composition than translocation alone. Our findings reveal associations between stress hormones and host microbiome defenses, with implications for resilience of amphibians and their associated microbes facing accelerated tropical deforestation.
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Affiliation(s)
- Wesley J Neely
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA.
- Department of Biology, Texas State University, San Marcos, TX, 78666, USA.
| | - Renato A Martins
- Department of Biology, and Center for Infectious Disease Dynamics, One Health Microbiome Center, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA
| | - Camila M Mendonça da Silva
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Tainá Ferreira da Silva
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Lucas E Fleck
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Ross D Whetstone
- Department of Biology, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, MA, 02125, USA
| | - W Harrison Cook
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | - Paula R Prist
- EcoHealth Alliance, 520 Eight Avenue, Suite 1200, New York, NY, 10018, USA
| | - Victor H Valiati
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Sasha E Greenspan
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | - Alexandro M Tozetti
- Programa de Pos‑Graduacão em Biologia, Universidade do Vale do Rio dos Sinos, São Leopoldo, RS, 93022‑750, Brazil
| | - Ryan L Earley
- Department of Biology, The University of Alabama, Tuscaloosa, AL, 35487, USA
| | - C Guilherme Becker
- Department of Biology, and Center for Infectious Disease Dynamics, One Health Microbiome Center, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA, 16802, USA.
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12
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Roth SA, Griffis-Kyle KL, Barnes MA. Batrachochytrium dendrobatidis in the Arid and Thermally Extreme Sonoran Desert. ECOHEALTH 2023; 20:370-380. [PMID: 38243042 DOI: 10.1007/s10393-023-01668-1] [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: 02/07/2023] [Accepted: 12/08/2023] [Indexed: 01/21/2024]
Abstract
Batrachochytrium dendrobatidis (Bd), the causative agent of the devastating global amphibian disease chytridiomycosis, was not projected to threaten amphibians in hot and arid regions due to its sensitivity to heat and desiccation. However, Bd is being detected more frequently than ever in hot and arid regions of Australia and the USA, challenging our current understanding of the environmental tolerances of the pathogen under natural conditions. We surveyed for Bd in an extremely hot and arid portion of the Sonoran Desert, where the pathogen is not projected to occur, and related presence and prevalence of the pathogen to local environmental conditions. We collected eDNA samples from isolated desert water sites including six tinajas and 13 catchments in June and August of 2020 and swabbed a total of 281 anurans of three species (red-spotted toad Anaxyrus punctatus, Couch's spadefoot Scaphiopus couchii, and the Sonoran Desert toad Incillius alvarius) across five catchments and six tinajas from June to September of 2020. Overall, Bd occurred at 68.4% of sites, despite extreme heat and aridity routinely exceeding tolerances established in laboratory studies. Average summer maximum air and water temperatures were 40.7°C and 30.7°C, respectively, and sites received an average of just 16.9 mm of precipitation throughout the summer monsoon season. Prevalence was low (5.7%) across species and life stage. Our results demonstrate that Bd is capable of persisting and infecting amphibians beyond its projected range, indicating a need to account for higher thermal tolerances when quantifying risk of Bd presence and infection.
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Affiliation(s)
- Sadie A Roth
- Department of Natural Resources Management, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA.
| | - Kerry L Griffis-Kyle
- Department of Natural Resources Management, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA
| | - Matthew A Barnes
- Department of Natural Resources Management, Texas Tech University, 2500 Broadway, Lubbock, TX, 79409, USA
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13
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Reinhold JM, Halbert E, Roark M, Smith SN, Stroh KM, Siler CD, McLeod DS, Lahondère C. The role of Culex territans mosquitoes in the transmission of Batrachochytrium dendrobatidis to amphibian hosts. Parasit Vectors 2023; 16:424. [PMID: 37974288 PMCID: PMC10655354 DOI: 10.1186/s13071-023-05992-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2023] [Accepted: 09/29/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Mosquitoes are the deadliest organisms in the world, killing an estimated 750,000 people per year due to the pathogens they can transmit. Mosquitoes also pose a major threat to other vertebrate animals. Culex territans is a mosquito species found in temperate zones worldwide that feeds almost exclusively on amphibians and can transmit parasites; however, little is known about its ability to transmit other pathogens, including fungi. Batrachochytrium dendrobatidis (Bd) is a topical pathogenic fungus that spreads through contact. With amphibian populations around the world experiencing mass die-offs and extinctions due to this pathogen, it is critical to study all potential modes of transmission. Because Cx. territans mosquitoes are in contact with their hosts for long periods of time while blood-feeding, we hypothesize that they can transmit and pick up Bd. METHODS In this study, we first assessed Cx. territans ability to transfer the fungus from an infected surface to a clean one under laboratory conditions. We also conducted a surveillance study of Bd infections in frogs and mosquitoes in the field (Mountain Lake Biological station, VA, USA). In parallel, we determined Cx. territans host preference via blood meal analysis of field caught mosquitoes. RESULTS We found that this mosquito species can carry the fungus to an uninfected surface, implying that they may have the ability to transmit Bd to their amphibian hosts. We also found that Cx. territans feed primarily on green frogs (Rana clamitans) and bullfrogs (Rana catesbeiana) and that the prevalence of Bd within the frog population at our field site varied between years. CONCLUSIONS This study provides critical insights into understanding the role of amphibian-biting mosquitoes in transmitting pathogens, which can be applied to disease ecology of susceptible amphibian populations worldwide.
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Affiliation(s)
- Joanna M Reinhold
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA
- The Fralin Life Science, InstituteVirginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA
| | | | - Megan Roark
- University of Virginia's College at Wise, Wise, VA, 24293, USA
| | - Sierra N Smith
- Sam Noble Oklahoma Museum of Natural History and School of Biological Sciences, The University of Oklahoma, Norman, OK, 73072, USA
| | - Katherine M Stroh
- Sam Noble Oklahoma Museum of Natural History and School of Biological Sciences, The University of Oklahoma, Norman, OK, 73072, USA
| | - Cameron D Siler
- Sam Noble Oklahoma Museum of Natural History and School of Biological Sciences, The University of Oklahoma, Norman, OK, 73072, USA
| | - David S McLeod
- Murphy Deming College of Health Sciences, Mary Baldwin University, Staunton, VA, 24401, USA
| | - Chloé Lahondère
- Department of Biochemistry, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
- The Fralin Life Science, InstituteVirginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
- Center of Emerging, Zoonotic and Arthropod-Borne Pathogens, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
- The Global Change Center, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
- Department of Entomology, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA.
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14
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Robak MJ, Saenz V, de Cortie E, Richards-Zawacki CL. Effects of temperature on the interaction between amphibian skin bacteria and Batrachochytrium dendrobatidis. Front Microbiol 2023; 14:1253482. [PMID: 37942072 PMCID: PMC10628663 DOI: 10.3389/fmicb.2023.1253482] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2023] [Accepted: 10/06/2023] [Indexed: 11/10/2023] Open
Abstract
Symbiotic relationships between animals and microbes are important for a range of functions, from digestion to protection from pathogens. However, the impact of temperature variation on these animal-microbe interactions remains poorly understood. Amphibians have experienced population declines and even extinctions on a global scale due to chytridiomycosis, a disease caused by chytrid fungi in the genus Batrachochytrium. Variation in susceptibility to this disease exists within and among host species. While the mechanisms generating differences in host susceptibility remain elusive, differences in immune system components, as well as variation in host and environmental temperatures, have been associated with this variation. The symbiotic cutaneous bacteria of amphibians are another potential cause for variation in susceptibility to chytridiomycosis, with some bacterial species producing antifungal metabolites that prevent the growth of Bd. The growth of both Bd and bacteria are affected by temperature, and thus we hypothesized that amphibian skin bacteria may be more effective at preventing Bd growth at certain temperatures. To test this, we collected bacteria from the skins of frogs, harvested the metabolites they produced when grown at three different temperatures, and then grew Bd in the presence of those metabolites under those same three temperatures in a three-by-three fully crossed design. We found that both the temperature at which cutaneous bacteria were grown (and metabolites produced) as well as the temperature at which Bd is grown can impact the ability of cutaneous bacteria to inhibit the growth of Bd. While some bacterial isolates showed the ability to inhibit Bd growth across multiple temperature treatments, no isolate was found to be inhibitive across all combinations of bacterial incubation or Bd challenge temperatures, suggesting that temperature affects both the metabolites produced and the effectiveness of those metabolites against the Bd pathogen. These findings move us closer to a mechanistic understanding of why chytridiomycosis outbreaks and related amphibian declines are often limited to certain climates and seasons.
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Affiliation(s)
- Matthew J. Robak
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA, United States
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA, United States
- Department of Biology, The Pennsylvania State University, State College, PA, United States
| | - Esmee de Cortie
- Falk School of Sustainability and Environment, Chatham University, Pittsburgh, PA, United States
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15
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Siomko SA, Greenspan SE, Barnett KM, Neely WJ, Chtarbanova S, Woodhams DC, McMahon TA, Becker CG. Selection of an anti-pathogen skin microbiome following prophylaxis treatment in an amphibian model system. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220126. [PMID: 37305917 PMCID: PMC10258671 DOI: 10.1098/rstb.2022.0126] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2022] [Accepted: 11/03/2022] [Indexed: 06/13/2023] Open
Abstract
With emerging diseases on the rise, there is an urgent need to identify and understand novel mechanisms of prophylactic protection in vertebrate hosts. Inducing resistance against emerging pathogens through prophylaxis is an ideal management strategy that may impact pathogens and their host-associated microbiome. The host microbiome is recognized as a critical component of immunity, but the effects of prophylactic inoculation on the microbiome are unknown. In this study, we investigate the effects of prophylaxis on host microbiome composition, focusing on the selection of anti-pathogenic microbes contributing to host acquired immunity in a model host-fungal disease system, amphibian chytridiomycosis. We inoculated larval Pseudacris regilla against the fungal pathogen Batrachochytrium dendrobatidis (Bd) with a Bd metabolite-based prophylactic. Increased prophylactic concentration and exposure duration were associated with significant increases in proportions of putatively Bd-inhibitory host-associated bacterial taxa, indicating a protective prophylactic-induced shift towards microbiome members that are antagonistic to Bd. Our findings are in accordance with the adaptive microbiome hypothesis, where exposure to a pathogen alters the microbiome to better cope with subsequent pathogen encounters. Our study advances research on the temporal dynamics of microbiome memory and the role of prophylaxis-induced shifts in microbiomes contributing to prophylaxis effectiveness. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
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Affiliation(s)
- Samantha A. Siomko
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - Sasha E. Greenspan
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | - K. M. Barnett
- Department of Biology, Emory University, Atlanta, GA 30322, USA
| | - Wesley J. Neely
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL 35487, USA
| | | | - Douglas C. Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Taegan A. McMahon
- Department of Biology, Connecticut College, New London, CT 06320, USA
| | - C. Guilherme Becker
- Department of Biology, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
- Center for Infectious Disease Dynamics, One Health Microbiome Center, The Huck Institutes of the Life Sciences, The Pennsylvania State University, University Park, PA 16802, USA
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16
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Sun D, Ellepola G, Herath J, Meegaskumbura M. The two chytrid pathogens of amphibians in Eurasia-climatic niches and future expansion. BMC Ecol Evol 2023; 23:26. [PMID: 37370002 DOI: 10.1186/s12862-023-02132-y] [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: 06/17/2022] [Accepted: 06/12/2023] [Indexed: 06/29/2023] Open
Abstract
BACKGROUND Climate affects the thermal adaptation and distribution of hosts, and drives the spread of Chytridiomycosis-a keratin-associated infectious disease of amphibians caused by the sister pathogens Batrachochytrium dendrobatidi (Bd) and B. salamandrivorans (Bsal). We focus on their climate-pathogen relationships in Eurasia, the only region where their geographical distributions overlap. Eurasia harbours invaded and native areas of both pathogens and the natural habitats where they co-exist, making it an ideal region to examine their environmental niche correlations. Our understanding of how climate change will affect their distribution is broadened by the differences in climate correlates and niche characteristics between Bd and Bsal in Asia and Europe. This knowledge has potential conservation implications, informing future spread of the disease in different regions. RESULTS We quantified the environmental niche overlap between Bd and Bsal in Eurasia using niche analyses. Results revealed partial overlap in the niche with a unique 4% of non-overlapping values for Bsal, suggesting segregation along certain climate axes. Bd tolerates higher temperature fluctuations, while Bsal requires more stable, lower temperature and wetter conditions. Projections of their Realized Climatic Niches (RCNs) to future conditions show a larger expansion of suitable ranges (SRs) for Bd compared to Bsal in both Asia and Europe, with their centroids shifting in different directions. Notably, both pathogens' highly suitable areas in Asia are expected to shrink significantly, especially under the extreme climate scenarios. In Europe, they are expected to expand significantly. CONCLUSIONS Climate change will impact or increase disease risk to amphibian hosts, particularly in Europe. Given the shared niche space of the two pathogens across available climate gradients, as has already been witnessed in Eurasia with an increased range expansion and niche overlap due to climate change, we expect that regions where Bsal is currently absent but salamanders are present, and where Bd is already prevalent, may be conducive for the spread of Bsal.
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Affiliation(s)
- Dan Sun
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
| | - Gajaba Ellepola
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
- Department of Zoology, Faculty of Science, University of Peradeniya, Peradeniya, Kandy, 20400, Sri Lanka
| | - Jayampathi Herath
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China
| | - Madhava Meegaskumbura
- Guangxi Key Laboratory for Forest Ecology and Conservation, College of Forestry, Guangxi University, Nanning, Guangxi, 530000, People's Republic of China.
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17
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Tytar V, Nekrasova O, Pupins M, Skute A, Kirjušina M, Gravele E, Mezaraupe L, Marushchak O, Čeirāns A, Kozynenko I, Kulikova AA. Modeling the Distribution of the Chytrid Fungus Batrachochytrium dendrobatidis with Special Reference to Ukraine. J Fungi (Basel) 2023; 9:607. [PMID: 37367543 DOI: 10.3390/jof9060607] [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: 03/28/2023] [Revised: 05/21/2023] [Accepted: 05/22/2023] [Indexed: 06/28/2023] Open
Abstract
Amphibians are the most threatened group of vertebrates. While habitat loss poses the greatest threat to amphibians, a spreading fungal disease caused by Batrachochytrium dendrobatidis Longcore, Pessier & D.K. Nichols 1999 (Bd) is seriously affecting an increasing number of species. Although Bd is widely prevalent, there are identifiable heterogeneities in the pathogen's distribution that are linked to environmental parameters. Our objective was to identify conditions that affect the geographic distribution of this pathogen using species distribution models (SDMs) with a special focus on Eastern Europe. SDMs can help identify hotspots for future outbreaks of Bd but perhaps more importantly identify locations that may be environmental refuges ("coldspots") from infection. In general, climate is considered a major factor driving amphibian disease dynamics, but temperature in particular has received increased attention. Here, 42 environmental raster layers containing data on climate, soil, and human impact were used. The mean annual temperature range (or 'continentality') was found to have the strongest constraint on the geographic distribution of this pathogen. The modeling allowed to distinguish presumable locations that may be environmental refuges from infection and set up a framework to guide future search (sampling) of chytridiomycosis in Eastern Europe.
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Affiliation(s)
- Volodymyr Tytar
- I.I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 01030 Kyiv, Ukraine
| | - Oksana Nekrasova
- I.I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 01030 Kyiv, Ukraine
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Mihails Pupins
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Arturs Skute
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Muza Kirjušina
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Evita Gravele
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Ligita Mezaraupe
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Oleksii Marushchak
- I.I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 01030 Kyiv, Ukraine
| | - Andris Čeirāns
- Department of Ecology, Institute of Life Sciences and Technologies, Daugavpils University, LV5400 Daugavpils, Latvia
| | - Iryna Kozynenko
- I.I. Schmalhausen Institute of Zoology, National Academy of Sciences of Ukraine, 01030 Kyiv, Ukraine
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18
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Nolan N, Hayward MW, Klop-Toker K, Mahony M, Lemckert F, Callen A. Complex Organisms Must Deal with Complex Threats: How Does Amphibian Conservation Deal with Biphasic Life Cycles? Animals (Basel) 2023; 13:ani13101634. [PMID: 37238064 DOI: 10.3390/ani13101634] [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: 04/14/2023] [Revised: 05/08/2023] [Accepted: 05/11/2023] [Indexed: 05/28/2023] Open
Abstract
The unprecedented rate of global amphibian decline is attributed to The Anthropocene, with human actions triggering the Sixth Mass Extinction Event. Amphibians have suffered some of the most extreme declines, and their lack of response to conservation actions may reflect challenges faced by taxa that exhibit biphasic life histories. There is an urgent need to ensure that conservation measures are cost-effective and yield positive outcomes. Many conservation actions have failed to meet their intended goals of bolstering populations to ensure the persistence of species into the future. We suggest that past conservation efforts have not considered how different threats influence multiple life stages of amphibians, potentially leading to suboptimal outcomes for their conservation. Our review highlights the multitude of threats amphibians face at each life stage and the conservation actions used to mitigate these threats. We also draw attention to the paucity of studies that have employed multiple actions across more than one life stage. Conservation programs for biphasic amphibians, and the research that guides them, lack a multi-pronged approach to deal with multiple threats across the lifecycle. Conservation management programs must recognise the changing threat landscape for biphasic amphibians to reduce their notoriety as the most threatened vertebrate taxa globally.
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Affiliation(s)
- Nadine Nolan
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Matthew W Hayward
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Kaya Klop-Toker
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Michael Mahony
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
| | - Frank Lemckert
- Eco Logical Australia Pty Ltd., Perth, WA 6000, Australia
| | - Alex Callen
- Conservation Science Research Group, School of Environmental and Life Sciences, University of Newcastle, Callaghan, NSW 2308, Australia
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19
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Schilliger L, Paillusseau C, François C, Bonwitt J. Major Emerging Fungal Diseases of Reptiles and Amphibians. Pathogens 2023; 12:pathogens12030429. [PMID: 36986351 PMCID: PMC10053826 DOI: 10.3390/pathogens12030429] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/16/2023] [Accepted: 03/06/2023] [Indexed: 03/11/2023] Open
Abstract
Emerging infectious diseases (EIDs) are caused by pathogens that have undergone recent changes in terms of geographic spread, increasing incidence, or expanding host range. In this narrative review, we describe three important fungal EIDs with keratin trophism that are relevant to reptile and amphibian conservation and veterinary practice. Nannizziopsis spp. have been mainly described in saurians; infection results in thickened, discolored skin crusting, with eventual progression to deep tissues. Previously only reported in captive populations, it was first described in wild animals in Australia in 2020. Ophidiomyces ophidiicola (formely O. ophiodiicola) is only known to infect snakes; clinical signs include ulcerating lesions in the cranial, ventral, and pericloacal regions. It has been associated with mortality events in wild populations in North America. Batrachochytrium spp. cause ulceration, hyperkeratosis, and erythema in amphibians. They are a major cause of catastrophic amphibian declines worldwide. In general, infection and clinical course are determined by host-related characteristics (e.g., nutritional, metabolic, and immune status), pathogens (e.g., virulence and environmental survival), and environment (e.g., temperature, hygrometry, and water quality). The animal trade is thought to be an important cause of worldwide spread, with global modifications in temperature, hygrometry, and water quality further affecting fungal pathogenicity and host immune response.
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Affiliation(s)
- Lionel Schilliger
- Argos Veterinary Clinic of Paris Auteuil, 35 Rue Leconte de Lisle, 75016 Paris, France
- SpéNac Referral Center, 100 Boulevard de la Tour Maubourg, 75007 Paris, France
- Correspondence: ; Tel.: +33-188-616-831
| | - Clément Paillusseau
- Argos Veterinary Clinic of Paris Auteuil, 35 Rue Leconte de Lisle, 75016 Paris, France
- SpéNac Referral Center, 100 Boulevard de la Tour Maubourg, 75007 Paris, France
| | - Camille François
- Argos Veterinary Clinic of Paris Auteuil, 35 Rue Leconte de Lisle, 75016 Paris, France
- SpéNac Referral Center, 100 Boulevard de la Tour Maubourg, 75007 Paris, France
| | - Jesse Bonwitt
- Department of Anthropology, Durham University, South Rd., Durham DH1 3LE, UK
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20
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Kásler A, Holly D, Herczeg D, Ujszegi J, Hettyey A. Chytridiomycosis and climate change: exposure to
Batrachochytrium dendrobatidis
and mild winter conditions do not increase mortality in juvenile agile frogs during hibernation. Anim Conserv 2023. [DOI: 10.1111/acv.12851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- A. Kásler
- Department of Evolutionary Ecology Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network Budapest Hungary
- Doctoral School of Biology Institute of Biology, ELTE Eötvös Loránd University Budapest Hungary
| | - D. Holly
- Department of Evolutionary Ecology Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network Budapest Hungary
- Doctoral School of Biology Institute of Biology, ELTE Eötvös Loránd University Budapest Hungary
| | - D. Herczeg
- Department of Evolutionary Ecology Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network Budapest Hungary
- ELKH‐ELTE‐MTM Integrative Ecology Research Group Budapest Hungary
| | - J. Ujszegi
- Department of Evolutionary Ecology Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network Budapest Hungary
- Department of Systematic Zoology and Ecology ELTE Eötvös Loránd University Budapest Hungary
| | - A. Hettyey
- Department of Evolutionary Ecology Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network Budapest Hungary
- Department of Systematic Zoology and Ecology ELTE Eötvös Loránd University Budapest Hungary
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21
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Bolom‐Huet R, Pineda E, Andrade‐Torres A, Díaz‐Fleischer F, Muñoz AL, Galindo‐González J. Chytrid prevalence and infection intensity in treefrogs from three environments with different degrees of conservation in Mexico. Biotropica 2022. [DOI: 10.1111/btp.13186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- René Bolom‐Huet
- Centro de Investigaciones en Ciencias Biológicas Aplicadas Universidad Autónoma del Estado de México Toluca Estado de México Mexico
- Universidad Veracruzana – Instituto de Biotecnología y Ecología Aplicada (INBIOTECA) Xalapa, Veracruz Mexico
| | - Eduardo Pineda
- Instituto de Ecologia – Red de Biología y Conservación de Vertebrados Xalapa, Veracruz Mexico
| | - Antonio Andrade‐Torres
- Universidad Veracruzana – Instituto de Biotecnología y Ecología Aplicada (INBIOTECA) Xalapa, Veracruz Mexico
| | - Francisco Díaz‐Fleischer
- Universidad Veracruzana – Instituto de Biotecnología y Ecología Aplicada (INBIOTECA) Xalapa, Veracruz Mexico
| | - Antonio L. Muñoz
- ECOSUR – Conservación de la Biodiversidad San Cristobal de las Casas, Chiapas Mexico
| | - Jorge Galindo‐González
- Universidad Veracruzana – Instituto de Biotecnología y Ecología Aplicada (INBIOTECA) Xalapa, Veracruz Mexico
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22
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Hulting KA, Mason SD, Story CM, Keller GS. Wetland cohesion is associated with increased probability of infection by the amphibian chytrid fungus Batrachochytrium dendrobatidis. DISEASES OF AQUATIC ORGANISMS 2022; 151:97-109. [PMID: 36226838 DOI: 10.3354/dao03692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) poses a substantial threat to amphibian populations. Understanding the landscape conditions that facilitate Bd transmission and persistence is crucial for predicting Bd trends in amphibian populations. Here, we investigated the interactions between land use, wetland connectivity, and Bd occurrence and infection intensity. In northeastern Massachusetts, we sampled Pseudacris crucifer, Lithobates sylvaticus, L. clamitans, and L. pipiens from 24 sites. We found an overall 30.6% Bd prevalence at our sites, with prevalence differing among species. Bd occurrence increased with wetland-patch cohesion, potentially due to microclimate shifts from decreased forest or changes in host movement. Bd infection intensity was not mediated by landscape context. Overall, our results highlight the importance of landscape structure for Bd dynamics, suggesting that certain landscapes may facilitate transmission and harbor Bd more than others. To mitigate the impacts of Bd on amphibian populations, conservation efforts should account for interactions between Bd and landscape variables.
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Affiliation(s)
- Katherine A Hulting
- Landscape Ecology Lab, Department of Life, Health, and Physical Sciences, Gordon College, Wenham, MA 01984, USA
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23
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Osman OA, Andersson J, Martin-Sanchez PM, Eiler A. National eDNA-based monitoring of Batrachochytrium dendrobatidis and amphibian species in Norway. METABARCODING AND METAGENOMICS 2022. [DOI: 10.3897/mbmg.6.85199] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Freshwaters represent the most threatened environments with regard to biodiversity loss and, therefore, there is a need for national monitoring programs to effectively document species distribution and evaluate potential risks for vulnerable species. The monitoring of species for effective management practices is, however, challenged by insufficient data acquisition when using traditional methods. Here we present the application of environmental DNA (eDNA) metabarcoding of amphibians in combination with quantitative PCR (qPCR) assays for an invasive pathogenic chytrid species (Batrachochytrium dendrobatidis -Bd), a potential threat to endemic and endangered amphibian species. Statistical comparison of amphibian species detection using either traditional or eDNA-based approaches showed weak correspondence. By tracking the distribution of Bd over three years, we concluded that the risk for amphibian extinction is low since Bd was only detected at five sites where multiple amphibians were present over the sampled years. Our results show that eDNA-based detection can be used for simultaneous monitoring of amphibian diversity and the presence of amphibian pathogens at the national level in order to assess potential species extinction risks and establish effective management practices. As such our study represents suggestions for a national monitoring program based on eDNA.
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24
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Neely WJ, Greenspan SE, Stahl LM, Heraghty SD, Marshall VM, Atkinson CL, Becker CG. Habitat Disturbance Linked with Host Microbiome Dispersion and Bd Dynamics in Temperate Amphibians. MICROBIAL ECOLOGY 2022; 84:901-910. [PMID: 34671826 DOI: 10.1007/s00248-021-01897-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2021] [Accepted: 10/08/2021] [Indexed: 06/13/2023]
Abstract
Anthropogenic habitat disturbances can dramatically alter ecological community interactions, including host-pathogen dynamics. Recent work has highlighted the potential for habitat disturbances to alter host-associated microbial communities, but the associations between anthropogenic disturbance, host microbiomes, and pathogens are unresolved. Amphibian skin microbial communities are particularly responsive to factors like temperature, physiochemistry, pathogen infection, and environmental microbial reservoirs. Through a field survey on wild populations of Acris crepitans (Hylidae) and Lithobates catesbeianus (Ranidae), we assessed the effects of habitat disturbance and connectivity on environmental bacterial reservoirs, Batrachochytrium dendrobatidis (Bd) infection, and skin microbiome composition. We found higher measures of microbiome dispersion (a measure of community variability) in A. crepitans from more disturbed ponds, supporting the hypothesis that disturbance increases stochasticity in biological communities. We also found that habitat disturbance limited microbiome similarity between locations for both species, suggesting greater isolation of bacterial assemblages in more disturbed areas. Higher disturbance was associated with lower Bd prevalence for A. crepitans, which could signify suboptimal microclimates for Bd in disturbed habitats. Combined, our findings show that reduced microbiome stability stemming from habitat disturbance could compromise population health, even in the absence of pathogenic infection.
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Affiliation(s)
- Wesley J Neely
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA.
| | - Sasha E Greenspan
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Leigha M Stahl
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Sam D Heraghty
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Vanessa M Marshall
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - Carla L Atkinson
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
| | - C Guilherme Becker
- Department of Biology, The University of Alabama, 1301 Sciences and Engineering Complex, 300 Hackberry Ln, Tuscaloosa, AL, 35487, USA
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25
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Zumbado-Ulate H, Neam K, García-Rodríguez A, Ochoa-Ochoa L, Chaves G, Kolby JE, Granados-Martínez S, Hertz A, Bolaños F, Ariano-Sánchez D, Puschendorf R, Searle CL. Ecological correlates of extinction risk and persistence of direct-developing stream-dwelling frogs in Mesoamerica. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2022.e02197] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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26
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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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27
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Efficacy of Plant-Derived Fungicides at Inhibiting Batrachochytrium salamandrivorans Growth. J Fungi (Basel) 2022; 8:jof8101025. [PMID: 36294589 PMCID: PMC9605044 DOI: 10.3390/jof8101025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2022] [Revised: 09/23/2022] [Accepted: 09/27/2022] [Indexed: 11/21/2022] Open
Abstract
The emerging fungal amphibian pathogen, Batrachochytrium salamandrivorans (Bsal), is currently spreading across Europe and given its estimated invasion potential, has the capacity to decimate salamander populations worldwide. Fungicides are a promising in situ management strategy for Bsal due to their ability to treat the environment and infected individuals. However, antifungal drugs or pesticides could adversely affect the environment and non-target hosts, thus identifying safe, effective candidate fungicides for in situ treatment is needed. Here, we estimated the inhibitory fungicidal efficacy of five plant-derived fungicides (thymol, curcumin, allicin, 6-gingerol, and Pond Pimafix®) and one chemical fungicide (Virkon® Aquatic) against Bsal zoospores in vitro. We used a broth microdilution method in 48-well plates to test the efficacy of six concentrations per fungicide on Bsal zoospore viability. Following plate incubation, we performed cell viability assays and agar plate growth trials to estimate the minimum inhibitory concentration (MIC) and minimum fungicidal concentration (MFC) of each fungicide. All six fungicides exhibited inhibitory and fungicidal effects against Bsal growth, with estimated MIC concentrations ranging from 60 to 0.156 μg/mL for the different compounds. Allicin showed the greatest efficacy (i.e., lowest MIC and MFC) against Bsal zoospores followed by curcumin, Pond Pimafix®, thymol, 6-gingerol, and Virkon® Aquatic, respectively. Our results provide evidence that plant-derived fungicides are effective at inhibiting and killing Bsal zoospores in vitro and may be useful for in situ treatment. Additional studies are needed to estimate the efficacy of these fungicides at inactivating Bsal in the environment and treating Bsal-infected amphibians.
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28
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Cook K, Pope K, Cummings A, Piovia‐Scott J. In situ treatment of juvenile frogs for disease can reverse population declines. CONSERVATION SCIENCE AND PRACTICE 2022. [DOI: 10.1111/csp2.12762] [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] Open
Affiliation(s)
- Kimberly Cook
- School of Biological Sciences Washington State University Vancouver WA USA
| | - Karen Pope
- Pacific Southwest Research Station United States Forest Service California USA
| | - Adam Cummings
- Pacific Southwest Research Station United States Forest Service California USA
| | - Jonah Piovia‐Scott
- School of Biological Sciences Washington State University Vancouver WA USA
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29
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Rawien J, Jairam-Doerga S. Predicted Batrachochytrium dendrobatidis infection sites in Guyana, Suriname, and French Guiana using the species distribution model maxent. PLoS One 2022; 17:e0270134. [PMID: 35834475 PMCID: PMC9282542 DOI: 10.1371/journal.pone.0270134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Accepted: 06/03/2022] [Indexed: 11/19/2022] Open
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) which causes that amphibian disease chytridiomycosis is expanding its worldwide range from an Asian origin, infecting amphibians in a growing number of countries. Modelling the potential range of this amphibian pathogen using environmental variables and presence data could advance our understanding of at-risk areas and species in locations with limited surveillance to date. We used a species distribution model to assess Bd habitat suitability in the three Guiana's (Guyana, Suriname, and French Guiana) in South America. The model output showed that all three countries have substantial areas where Bd could grow and proliferate, and maximum temperature of the warmest month was the top predictor of suitable Bd habitat, inversely correlated with modeled Bd occurrence. Predicted Bd infection areas in Guyana and French Guiana were large and localized whereas possible sites in Suriname were more scattered throughout the country. The areas projected as potential suitable in Suriname were mostly high elevation regions. These results could help inform efficiencies for development of a proactive monitoring program that could alert managers of novel Bd outbreaks for focused mitigation actions to forestall the spread of this amphibian disease.
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Affiliation(s)
- Jairam Rawien
- Anton de Kom University of Suriname, National Zoological Collection Suriname, Paramaribo, Suriname
| | - Sabitrie Jairam-Doerga
- Anton de Kom University of Suriname, National Herbarium of Suriname, Paramaribo, Suriname
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30
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Kásler A, Ujszegi J, Holly D, Jaloveczki B, Gál Z, Hettyey A. In vitro thermal tolerance of a hypervirulent lineage of Batrachochytrium dendrobatidis: Growth arrestment by elevated temperature and recovery following thermal treatment. Mycologia 2022; 114:661-669. [PMID: 35666647 DOI: 10.1080/00275514.2022.2065443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Chytridiomycosis, an emerging infectious disease caused by Batrachochytrium dendrobatidis (Bd), poses a serious threat to amphibians. The thermal optimum of Bd is lower than that of most amphibians, providing an opportunity to cure infected individuals with elevated temperature. However, this approach presupposes detailed knowledge about the thermal tolerance of the fungus. To determine the temperature that may effectively reduce infection burdens in vivo, detailed in vitro studies are needed to characterize thermal tolerance of the fungus without complexities introduced by the species-specific characteristics of hosts' immune systems. The aim of our study was to evaluate the thermal tolerance of a hypervirulent isolate of Bd, considering the limits of its thermal tolerance and its capacity to rebound following heat treatment. We incubated Bd cell cultures at five different temperatures (21, 25.5, 27, 29, or 30.5 C) for one of six exposure durations (3, 4, 5, 6, 7, or 8 days) and subsequently counted the number of zoospores to assess the temperature dependence of Bd growth. We observed intensive Bd growth at 21 C. At 25.5 C, the number of zoospores also increased over time, but the curve plateaued at about half of the maximum values observed in the lower temperature treatment. At temperatures of 27 C and above, the fungus showed no measurable growth. However, when we moved the cultures back to 21 C after the elevated temperature treatments, we observed recovery of Bd growth in all cultures previously treated at 27 C. At 29 C, a treatment duration of 8 days was necessary to prevent recovery of Bd growth, and at 30.5 C a treatment duration of 5 days was needed to achieve the same result, revealing that these moderately elevated temperatures applied for only a few days have merely a fungistatic rather than a fungicidal effect under in vitro conditions.
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Affiliation(s)
- Andrea Kásler
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest 1117, Hungary
| | - János Ujszegi
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest 1117, Hungary
| | - Dóra Holly
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest 1117, Hungary
| | - Boglárka Jaloveczki
- Department of Zoology, Centre for Agricultural Research, Plant Protection Institute, Budapest 1029, Hungary
| | - Zoltán Gál
- Institute of Genetics and Biotechnology, Animal Biotechnology Department, Hungarian University of Agriculture and Life Sciences, Gödöllő 2100, Hungary
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Department of Ecology, University of Veterinary Medicine, Budapest 1078, Hungary
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31
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Turner A, Heard G, Hall A, Wassens S. Age structure of amphibian populations with endemic chytridiomycosis, across climatic regions with markedly different infection risk. Ecol Evol 2022; 12:e9123. [PMID: 35898428 PMCID: PMC9309026 DOI: 10.1002/ece3.9123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 06/05/2022] [Accepted: 06/28/2022] [Indexed: 11/30/2022] Open
Abstract
Threatening processes, such as disease, can drive major changes in population demographics of the host. Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has led to the decline of at least 500 amphibian species across the globe and has been shown to truncate host age structure by lowering adult survival rates. This results in heavy reliance on annual recruitment and the inability to recover in the event of periodic recruitment failure. We used skeletochronology to determine the age structure, growth, and survival rates of populations of an endangered amphibian, Litoria raniformis, with endemic chytridiomycosis, across two climatically disparate regions in south‐eastern Australia: semi‐arid and temperate. Contrary to predictions, populations in the semi‐arid region (in which chytrid prevalence is substantially lower due to high temperatures) displayed a more truncated age structure than populations in the temperate study regions. Maximum recorded age was only two years in the semi‐arid region compared with up to four years in the temperate region. Wetland hydroperiod and average seasonal air temperature were correlated with age, and males had a slightly higher survival rate than females (0.31 for males and 0.27 for females). Despite the previously documented differences in chytrid prevalence between the two climatic regions, water availability and wetland hydroperiods appear the over‐riding determinants of the age structure and survival rates of L. raniformis. Targeted management which ensures water availability and improves survival of 1‐year‐old frogs into their second and third breeding season would reduce the impact of stochastic events on L. raniformis, and this may be true for numerous frog species susceptible to chytridiomycosis.
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Affiliation(s)
- Anna Turner
- School of Agricultural, Environmental and Veterinary Science Charles Sturt University Albury New South Wales Australia
| | - Geoffrey Heard
- Terrestrial Ecosystem Research Network The University of Queensland Indooroopily Queensland Australia
| | - Andrew Hall
- School of Agricultural, Environmental and Veterinary Science Charles Sturt University Albury New South Wales Australia
| | - Skye Wassens
- School of Agricultural, Environmental and Veterinary Science Charles Sturt University Albury New South Wales Australia
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32
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Venesky MD, DeMarchi J, Hickerson C, Anthony CD. Does the thermal mismatch hypothesis predict disease outcomes in different morphs of a terrestrial salamander? JOURNAL OF EXPERIMENTAL ZOOLOGY. PART A, ECOLOGICAL AND INTEGRATIVE PHYSIOLOGY 2022; 337:467-476. [PMID: 35167180 DOI: 10.1002/jez.2581] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/22/2021] [Revised: 12/23/2021] [Accepted: 01/19/2022] [Indexed: 06/14/2023]
Abstract
Many aspects of ectotherm physiology are temperature-dependent. The immune system of temperate-dwelling ectothermic host species is no exception and their immune function is often downregulated in cold temperatures. Likewise, species of ectothermic pathogens experience temperature-mediated effects on rates of transmission and/or virulence. Although seemingly straightforward, predicting the outcomes of ectothermic host-pathogen interactions is quite challenging. A recent hypothesis termed the thermal mismatch hypothesis posits that cool-adapted host species should be most susceptible to pathogen infection during warm temperature periods whereas warm-adapted host species should be most susceptible to pathogens during periods of cool temperatures. We explore this hypothesis using two ecologically and physiologically differentiated color morphs of the Eastern Red-backed Salamander (Plethodon cinereus) and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis; hereafter "Bd") using a fully factorial laboratory experiment. At cool temperatures, unstriped salamanders (i.e., those that are tolerant of warm temperatures) had a significantly higher probability of Bd infection compared with cool-tolerant striped salamanders, consistent with the thermal mismatch hypothesis. However, we found no support for this hypothesis when salamanders were exposed to Bd at warm temperatures: the probability of Bd infection in the cool-tolerant striped salamanders was nearly identical in both cool and warm temperatures, opposite the predictions of the thermal mismatch hypothesis. Our results are most consistent with the fact that Bd grows poorly at warm temperatures. Alternatively, our data could indicate that the two color morphs do not differ in their tolerance to warm temperatures but that striped salamanders are more tolerant to cool temperatures than unstriped salamanders.
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Affiliation(s)
- Matthew D Venesky
- Department of Biology, Allegheny College, Meadville, Pennsylvania, USA
| | - Joseph DeMarchi
- Department of Biology, John Carroll University, University Heights, Ohio, USA
| | - Cari Hickerson
- Department of Biology, John Carroll University, University Heights, Ohio, USA
| | - Carl D Anthony
- Department of Biology, John Carroll University, University Heights, Ohio, USA
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33
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Deknock A, Pasmans F, van Leeuwenberg R, Van Praet S, De Troyer N, Goessens T, Lammens L, Bruneel S, Lens L, Martel A, Croubels S, Goethals P. Impact of heavy metal exposure on biological control of a deadly amphibian pathogen by zooplankton. THE SCIENCE OF THE TOTAL ENVIRONMENT 2022; 823:153800. [PMID: 35150694 DOI: 10.1016/j.scitotenv.2022.153800] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 02/07/2022] [Accepted: 02/07/2022] [Indexed: 06/14/2023]
Abstract
Despite devastating effects on global biodiversity, efficient mitigation strategies against amphibian chytridiomycosis are lacking. Since the free-living pathogenic zoospores of Batrachochytrium dendrobatidis (Bd), the infective stage of this disease, can serve as a nutritious food source for components of zooplankton communities, these groups may act as biological control agents by eliminating zoospores from the aquatic environment. Such pathogen-predator interaction is, however, embedded in the aquatic food web structure and is therefore affected by abiotic factors interfering with these networks. Heavy metals, released from both natural and anthropogenic sources, are widespread contaminants of aquatic ecosystems and may interfere with planktonic communities and thus pathogen elimination rates. We investigated the interaction between zooplankton communities and chytridiomycosis infections in a Flemish agricultural region. Moreover, we also investigated the impact of heavy metal contamination, that was previously investigated in the region and presented in recent work, on zooplankton assemblages and chytridiomycosis infections. Finally, we tested the effect of sublethal concentrations of copper and zinc on Bd removal rates by Daphnia magna in a laboratory assay. Although zinc, copper, nickel and chromium were widely abundant pollutants, heavy metals were no driving force for zooplankton assemblages at our study locations. Moreover, our field survey did not reveal indirect effects of zooplankton assemblages on chytridiomycosis infections. However, sampling occasions testing negative for Bd showed a higher degree of copper contamination compared to positive sampling occasions, indicating a potential inhibitory effect of copper on Bd prevalence. Finally, whereas D. magna significantly reduced zoospore densities in its environment, sublethal concentrations of copper and zinc showed no interference with pathogen removal in the laboratory assay. Our results provide perspectives for further research on such a biological control strategy against chytridiomycosis by optimizing environmental conditions for pathogen predation.
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Affiliation(s)
- Arne Deknock
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Building F, B-9000 Ghent, Belgium.
| | - Frank Pasmans
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Robby van Leeuwenberg
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Sarah Van Praet
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Niels De Troyer
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Building F, B-9000 Ghent, Belgium
| | - Tess Goessens
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Leni Lammens
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Stijn Bruneel
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Building F, B-9000 Ghent, Belgium
| | - Luc Lens
- Department of Biology, Faculty of Sciences, Ghent University, K.L. Ledeganckstraat 35, B-9000 Ghent, Belgium
| | - An Martel
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Siska Croubels
- Department of Pathobiology, Pharmacology and Zoological Medicine, Faculty of Veterinary Medicine, Ghent University, Salisburylaan 133, D9, B-9820 Merelbeke, Belgium
| | - Peter Goethals
- Department of Animal Sciences and Aquatic Ecology, Faculty of Bioscience Engineering, Ghent University, Coupure Links 653, Building F, B-9000 Ghent, Belgium
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34
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Wilber MQ, Ohmer MEB, Altman KA, Brannelly LA, LaBumbard BC, Le Sage EH, McDonnell NB, Muñiz Torres AY, Nordheim CL, Pfab F, Richards-Zawacki CL, Rollins-Smith LA, Saenz V, Voyles J, Wetzel DP, Woodhams DC, Briggs CJ. Once a reservoir, always a reservoir? Seasonality affects the pathogen maintenance potential of amphibian hosts. Ecology 2022; 103:e3759. [PMID: 35593515 DOI: 10.1002/ecy.3759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 03/18/2022] [Accepted: 03/31/2022] [Indexed: 11/10/2022]
Abstract
Host species that can independently maintain a pathogen in a host community and contribute to infection in other species are important targets for disease management. However, the potential of host species to maintain a pathogen is not fixed over time, and an important challenge is understanding how within- and across-season variability in host maintenance potential affects pathogen persistence over longer time scales relevant for disease management (e.g., years). Here, we sought to understand the causes and consequences of seasonal infection dynamics in leopard frogs (Rana sphenocephala and R. pipiens) infected with the fungal pathogen Batrachochytrium dendrobatidis (Bd). We addressed three questions broadly applicable to seasonal host-parasite systems. First, to what degree are observed seasonal patterns in infection driven by temperature-dependent infection processes compared to seasonal host demographic processes? Second, how does seasonal variation in maintenance potential affect long-term pathogen persistence in multihost communities? Third, does high deterministic maintenance potential relate to the long-term stochastic persistence of pathogens in host populations with seasonal infection dynamics? To answer these questions, we used field data collected over three years on >1400 amphibians across four geographic locations, laboratory and mesocosm experiments, and a novel mathematical model. We found that the mechanisms that drive seasonal prevalence were different than those driving seasonal infection intensity. Seasonal variation in Bd prevalence was driven primarily by changes in host contact rates associated with breeding migrations to and from aquatic habitat. In contrast, seasonal changes in infection intensity were driven by temperature-induced changes in Bd growth rate. Using our model, we found that the maintenance potential of leopard frogs varied significantly throughout the year and that seasonal troughs in infection prevalence made it unlikely that leopard frogs were responsible for long-term Bd persistence in these seasonal amphibian communities, highlighting the importance of alternative pathogen reservoirs for Bd persistence. Our results have broad implications for management in seasonal host-pathogen systems, showing that seasonal changes in host and pathogen vital rates, rather than the depletion of susceptible hosts, can lead to troughs in pathogen prevalence and stochastic pathogen extirpation.
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Affiliation(s)
- Mark Q Wilber
- Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Institute of Agriculture, Knoxville, TN.,Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Michel E B Ohmer
- Living Earth Collaborative, Washington University in St. Louis, St. Louis, MO.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, University of Mississippi, Oxford, MS
| | - Karie A Altman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, St. Bonaventure University, St Bonaventure, NY
| | - Laura A Brannelly
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Brandon C LaBumbard
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Emily H Le Sage
- Department of Pathology Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Nina B McDonnell
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Aura Y Muñiz Torres
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Caitlin L Nordheim
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Ferdinand Pfab
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
| | | | - Louise A Rollins-Smith
- Department of Pathology Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, Reno, NV
| | - Daniel P Wetzel
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
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35
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Microbial Diversity of the Chinese Tiger Frog (Hoplobatrachus rugulosus) on Healthy versus Ulcerated Skin. Animals (Basel) 2022; 12:ani12101241. [PMID: 35625087 PMCID: PMC9137582 DOI: 10.3390/ani12101241] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/21/2022] [Accepted: 05/05/2022] [Indexed: 02/01/2023] Open
Abstract
Simple Summary As amphibians’ skin is highly sensitive to the environment, skin defects such as ulceration may pose a particular threat to them. Our study has found a stark difference in the microbial communities between healthy and ulcerated Hoplobatrachus rugulosus skin. The proportion and type of bacteria differed between the two groups, and we suggest that ulceration on the skin may lead to changes in skin microbial communities. The functional pathways of skin microbes may be influenced by ulceration on the skin surface of H. rugulosus. We also found that Vogesella is more abundant in healthy H. rugulosus, which may be a potential probiotic candidate for the reduction or removal of pathogens. Abstract The Chinese tiger frog (Hoplobatrachus rugulosus) is extensively farmed in southern China. Due to cramped living conditions, skin diseases are prevalent among unhealthy tiger frogs which thereby affects their welfare. In this study, the differences in microbiota present on healthy versus ulcerated H. rugulosus skin were examined using 16S rRNA sequences. Proteobacteria were the dominant phylum on H. rugulosus skin, but their abundance was greater on the healthy skin than on the ulcerated skin. Rhodocyclaceae and Comamonadaceae were the most dominant families on the healthy skin, whereas Moraxellaceae was the most dominant family on the ulcerated skin. The abundance of these three families was different between the groups. Acidovorax was the most dominant genus on the healthy skin, whereas Acinetobacter was the most dominant genus on the ulcerated skin, and its abundance was greater on the ulcerated skin than on the healthy skin. Moreover, the genes related to the Kyoto Encyclopedia of Genes and Genomes pathways of levels 2–3, especially those genes that are involved in cell motility, flagellar assembly, and bacterial chemotaxis in the skin microbiota, were found to be greater on the healthy skin than on the ulcerated skin, indicating that the function of skin microbiota was affected by ulceration. Overall, the composition, abundance, and function of skin microbial communities differed between the healthy and ulcerated H. rugulosus skin. Our results may assist in developing measures to combat diseases in H. rugulosus.
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Crawshaw L, Buchanan T, Shirose L, Palahnuk A, Cai HY, Bennett AM, Jardine CM, Davy CM. Widespread occurrence of
Batrachochytrium dendrobatidis
in Ontario, Canada, and predicted habitat suitability for the emerging
Batrachochytrium salamandrivorans. Ecol Evol 2022; 12:e8798. [PMID: 35475183 PMCID: PMC9020443 DOI: 10.1002/ece3.8798] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 03/06/2022] [Accepted: 03/16/2022] [Indexed: 12/30/2022] Open
Abstract
Chytridiomycosis, caused by the fungi Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, is associated with massive amphibian mortality events worldwide and with some species’ extinctions. Previous ecological niche models suggest that B. dendrobatidis is not well‐suited to northern, temperate climates, but these predictions have often relied on datasets in which northern latitudes are underrepresented. Recent northern detections of B. dendrobatidis suggest that these models may have underestimated the suitability of higher latitudes for this fungus. We used qPCR to test for B. dendrobatidis in 1,041 non‐invasive epithelial swab samples from 18 species of amphibians collected across 735,345 km2 in Ontario and Akimiski Island (Nunavut), Canada. We detected the pathogen in 113 samples (10.9%) from 11 species. Only one specimen exhibited potential clinical signs of disease. We used these data to produce six Species Distribution Models of B. dendrobatidis, which classified half of the study area as potential habitat for the fungus. We also tested each sample for B. salamandrivorans, an emerging pathogen that is causing alarming declines in European salamanders, but is not yet detected in North America. We did not detect B. salamandrivorans in any of the samples, providing a baseline for future surveillance. We assessed the potential risk of future introduction by comparing salamander richness to temperature‐dependent mortality, predicted by a previous exposure study. Areas with the highest species diversity and predicted mortality risk extended 60,530 km2 across southern Ontario, highlighting the potential threat B. salamandrivorans poses to northern Nearctic amphibians. Preventing initial introduction will require coordinated, transboundary regulation of trade in amphibians (including frogs that can carry and disperse B. salamandrivorans), and surveillance of the pathways of introduction (e.g., water and wildlife). Our results can inform surveillance for both pathogens and efforts to mitigate the spread of chytridiomycosis through wild populations.
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Affiliation(s)
- Lauren Crawshaw
- Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry Wildlife Research and Monitoring Section Trent University Peterborough ON Canada
| | - Tore Buchanan
- Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry Wildlife Research and Monitoring Section Trent University Peterborough ON Canada
| | - Leonard Shirose
- Canadian Wildlife Health Cooperative Department of Pathobiology University of Guelph Guelph ON Canada
- Department of Pathobiology University of Guelph Guelph ON Canada
| | - Amanda Palahnuk
- Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry Wildlife Research and Monitoring Section Trent University Peterborough ON Canada
| | - Hugh Y. Cai
- Animal Health Laboratory University of Guelph Guelph ON Canada
| | | | - Claire M. Jardine
- Canadian Wildlife Health Cooperative Department of Pathobiology University of Guelph Guelph ON Canada
- Department of Pathobiology University of Guelph Guelph ON Canada
| | - Christina M. Davy
- Ontario Ministry of Northern Development, Mines, Natural Resources and Forestry Wildlife Research and Monitoring Section Trent University Peterborough ON Canada
- Department of Biology Trent University Peterborough ON Canada
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37
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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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38
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Robinson KA, Prostak SM, Campbell Grant EH, Fritz-Laylin LK. Amphibian mucus triggers a developmental transition in the frog-killing chytrid fungus. Curr Biol 2022; 32:2765-2771.e4. [DOI: 10.1016/j.cub.2022.04.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 03/25/2022] [Accepted: 04/04/2022] [Indexed: 12/20/2022]
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39
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Garnham JI, Bower DS, Stockwell MP, Pickett EJ, Pollard CJ, Clulow J, Mahony MJ. Seasonal variation in the prevalence of a fungal pathogen and unexpected clearance from infection in a susceptible frog species. DISEASES OF AQUATIC ORGANISMS 2022; 148:1-11. [PMID: 35142293 DOI: 10.3354/dao03628] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causes the disease chytridiomycosis, which is a primary driver for amphibian population declines and extinctions worldwide. For highly susceptible species, such as the green and golden bell frog Litoria aurea, large numbers of Bd-related mortalities are thought to occur during the colder season (winter), when low temperatures favour the growth of the pathogen. However, extant L. aurea populations are persisting with Bd. We measured Bd prevalence and infection levels of wild L. aurea using capture-mark-recapture and radio-tracking methods. Using this information, we sought to determine host and environmental correlates of Bd prevalence and infection load. Mean ± SE infection load was higher in frogs sampled in autumn (431.5 ± 310.4 genomic equivalents; GE) and winter (1147.5 ± 735.8 GE), compared to spring (21.8 ± 19.3 GE) and summer (0.9 ± 0.8 GE). Furthermore, prevalence of Bd infection in L. aurea was highest in winter (43.6%; 95% CI 33.1-54.7%) and lowest in summer (11.2%; 95% CI 6.8-17.9%). Both prevalence and infection load decreased with increasing temperature. Seven frogs cleared their fungal infection during the coolest months when Bd prevalence was highest; however, these clearances were not permanent, as 5 frogs became infected again. Understanding the factors that allow amphibians to clear their Bd infections when temperatures are optimal for Bd growth presents the potential for manipulating such factors and provides an important step in future research.
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Affiliation(s)
- James I Garnham
- School of Environmental and Life Sciences, University of Newcastle, Callaghan, New South Wales 2308, Australia
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40
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Bielby J, Sausor C, Monsalve-Carcaño C, Bosch J. Temperature and duration of exposure drive infection intensity with the amphibian pathogen Batrachochytrium dendrobatidis. PeerJ 2022; 10:e12889. [PMID: 35186480 PMCID: PMC8830297 DOI: 10.7717/peerj.12889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 01/14/2022] [Indexed: 01/11/2023] Open
Abstract
The intensity of a pathogen infection plays a key role in determining how the host responds to infection. Hosts with high infections are more likely to transmit infection to others, and are may be more likely to experience progression from infection to disease symptoms, to being physiologically compromised by disease. Understanding how and why hosts exhibit variation in infection intensity therefore plays a major part in developing and implementing measures aimed at controlling infection spread, its effects, and its chance of persisting and circulating within a population of hosts. To track the relative importance of a number of variables in determining the level of infection intensity, we ran field-surveys at two breeding sites over a 12 month period using marked larvae of the common midwife toad (Alyes obstetricans) and their levels of infection with the amphibian pathogen Batrachochytrium dendrobatidis (Bd). At each sampling occasion we measured the density of larvae, the temperature of the water in the 48 h prior to sampling, the period of time the sampled individual had been in the water body, the developmental (Gosner) stage and the intensity of Bd infection of the individual. Overall our data suggest that the temperature and the duration of time spent in the water play a major role in determining the intensity of Bd infection within an individual host. However, although the duration of time spent in the water was clearly associated with infection intensity, the relationship was negative: larvae that had spent less than 3-6 months in the water had significantly higher infection intensities than those that had spent over 12 months, although this infection intensity peaked between 9 and 12 months. This could be due to animals with heavier infections developing more quickly, suffering increased mortality or, more likely, losing their mouthparts (the only part of anuran larvae that can be infected with Bd). Overall, our results identify drivers of infection intensity, and potentially transmissibility and spread, and we attribute these differences to both host and pathogen biology.
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Affiliation(s)
- Jon Bielby
- School of Natural Sciences and Psychology, Liverpool John Moores University, Liverpool, United Kingdom
| | | | | | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, Madrid, Spain,Biodiversity Research Institute (University of Oviedo-CSIC-Principality of Asturias), Mieres, Spain
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41
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Adams AJ, Peralta-García A, Flores-López CA, Valdez-Villavicencio JH, Briggs CJ. High fungal pathogen loads and prevalence in Baja California amphibian communities: The importance of species, elevation, and historical context. Glob Ecol Conserv 2022. [DOI: 10.1016/j.gecco.2021.e01968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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42
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Basanta MD, Rebollar EA, García-Castillo MG, Rosenblum EB, Byrne AQ, Piovia-Scott J, Parra-Olea G. Genetic variation of Batrachochytrium dendrobatidis is linked to skin bacterial diversity in the Pacific treefrog Hyliola regilla (hypochondriaca). Environ Microbiol 2021; 24:494-506. [PMID: 34959256 DOI: 10.1111/1462-2920.15861] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 11/22/2021] [Accepted: 11/27/2021] [Indexed: 11/29/2022]
Abstract
Symbiotic bacterial communities are crucial to combating infections and contribute to host health. The amphibian skin microbiome plays an important role in protecting their hosts against pathogens such as Batrachochytrium dendrobatidis (Bd), one of the causative agents of chytridiomycosis, which is responsible for dramatic amphibian population declines worldwide. Although symbiotic skin bacteria are known to inhibit Bd growth, an understanding of the relationship between Bd genetic variability, environmental conditions, and skin bacterial communities is limited. Therefore, we examined the associations between Bd infection load, Bd genetic diversity and skin bacterial communities in five populations of Hyliola regilla (hypochondriaca) from environmentally contrasting sites in Baja California, Mexico. We observed differences in Bd genetics and infection load among sites and environments. Genetic analysis of Bd isolates revealed patterns of spatial structure corresponding to the five sites sampled. Amphibian skin bacterial diversity and community structure differed among environments and sites. Bacterial community composition was correlated with Bd genetic differences and infection load, with specific bacterial taxa enriched on infected and un-infected frogs. Our results indicate that skin-associated bacteria and Bd strains likely interact on the host skin, with consequences for microbial community structure and Bd infection intensity.
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Affiliation(s)
- María Delia Basanta
- Instituto de Biología, Universidad Nacional Autónoma de México, Mexico.,Posgrado en Ciencias Biológicas, Instituto de Biología, Universidad Nacional Autónoma de México, Ciudad de México, AP 70-153, C.P. 04510, Mexico.,Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Eria A Rebollar
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, Mexico
| | - Mirna G García-Castillo
- Universidad Politécnica de Huatusco, Huatusco, Veracruz, Mexico.,Universidad Veracruzana, Facultad de Ciencias Biológicas y Agropecuarias Región: Orizaba-Córdoba, Amatlán de los Reyes, Veracruz, Mexico
| | - Erica Bree Rosenblum
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA.,Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA
| | - Allison Q Byrne
- Museum of Vertebrate Zoology, University of California, Berkeley, CA, USA.,Department of Environmental Science, Policy, and Management, University of California, Berkeley, CA, USA
| | - Jonah Piovia-Scott
- School of Biological Sciences, Washington State University, Vancouver, WA, USA
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43
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Urgiles VL, Ramírez ER, Villalta CI, Siddons DC, Savage AE. Three Pathogens Impact Terrestrial Frogs from a High-Elevation Tropical Hotspot. ECOHEALTH 2021; 18:451-464. [PMID: 34894333 DOI: 10.1007/s10393-021-01570-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 11/05/2021] [Accepted: 11/08/2021] [Indexed: 06/14/2023]
Abstract
Three infectious pathogens Batrachochytrium dendrobatidis (Bd), Ranavirus (Rv) and Perkinsea (Pr) are associated with widespread and ongoing amphibian population declines. Although their geographic and host ranges vary widely, recent studies have suggested that the occurrence of these pathogens could be more common than previously thought, even in direct-developing terrestrial species traditionally considered less likely to harbor these largely aquatic pathogens. Here, we characterize Bd, Rv, and Pr infections in direct-developing terrestrial amphibians of the Pristimantis genus from the highland Ecuadorean Andes. We confirm the first detection of Pr in terrestrial-breeding amphibians and in the Andean region, present the first report of Rv in Ecuador, and we add to the handful of studies finding Bd infecting Pristimantis. Infection prevalence did not differ significantly among pathogens, but infection intensity was significantly higher for Bd compared to Pr. Neither prevalence nor intensity differed significantly across locality and elevation for Bd and Rv, although low prevalence in our dataset and lack of seasonal sampling could have prevented important epidemiological patterns from emerging. Our study highlights the importance of incorporating pathogen surveillance in biodiversity monitoring in the Andean region and serves as starting point to understand pathogen dynamics, transmission, and impacts in terrestrial-breeding frogs.
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Affiliation(s)
- Veronica L Urgiles
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL, 32816, USA.
- Instituto Nacional de Biodiversidad del Ecuador, Pasaje Rumipamba 341 y Avenida de los Shirys, Quito, Ecuador.
| | - Ervin R Ramírez
- Escuela de Biología, Ecología y Gestión, Universidad del Azuay, Ave 24 de Mayo 7-77, Cuenca, Ecuador
| | - Cristian I Villalta
- Escuela de Biología, Ecología y Gestión, Universidad del Azuay, Ave 24 de Mayo 7-77, Cuenca, Ecuador
| | - David C Siddons
- Escuela de Biología, Ecología y Gestión, Universidad del Azuay, Ave 24 de Mayo 7-77, Cuenca, Ecuador
| | - Anna E Savage
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL, 32816, USA
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44
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Gajewski Z, Stevenson LA, Pike DA, Roznik EA, Alford RA, Johnson LR. Predicting the growth of the amphibian chytrid fungus in varying temperature environments. Ecol Evol 2021; 11:17920-17931. [PMID: 35003647 PMCID: PMC8717292 DOI: 10.1002/ece3.8379] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2021] [Revised: 10/23/2021] [Accepted: 11/03/2021] [Indexed: 11/11/2022] Open
Abstract
Environmental temperature is a crucial abiotic factor that influences the success of ectothermic organisms, including hosts and pathogens in disease systems. One example is the amphibian chytrid fungus, Batrachochytrium dendrobatidis (Bd), which has led to widespread amphibian population declines. Understanding its thermal ecology is essential to effectively predict outbreaks. Studies that examine the impact of temperature on hosts and pathogens often do so in controlled constant temperatures. Although varying temperature experiments are becoming increasingly common, it is unrealistic to test every temperature scenario. Thus, reliable methods that use constant temperature data to predict performance in varying temperatures are needed. In this study, we tested whether we could accurately predict Bd growth in three varying temperature regimes, using a Bayesian hierarchical model fit with constant temperature Bd growth data. We fit the Bayesian hierarchical model five times, each time changing the thermal performance curve (TPC) used to constrain the logistic growth rate to determine how TPCs influence the predictions. We then validated the model predictions using Bd growth data collected from the three tested varying temperature regimes. Although all TPCs overpredicted Bd growth in the varying temperature regimes, some functional forms performed better than others. Varying temperature impacts on disease systems are still not well understood and improving our understanding and methodologies to predict these effects could provide insights into disease systems and help conservation efforts.
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Affiliation(s)
- Zachary Gajewski
- Department of Biological ScienceVirginia TechBlacksburgVirginiaUSA
- Department of StatisticsVirginia TechBlacksburgVirginiaUSA
| | - Lisa A. Stevenson
- College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
| | - David A. Pike
- College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
| | - Elizabeth A. Roznik
- College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
- North Carolina ZooAsheboroNorth CarolinaUSA
| | - Ross A. Alford
- College of Science and EngineeringJames Cook UniversityTownsvilleQldAustralia
| | - Leah R. Johnson
- Department of Biological ScienceVirginia TechBlacksburgVirginiaUSA
- Department of StatisticsVirginia TechBlacksburgVirginiaUSA
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45
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Palomar G, Jakóbik J, Bosch J, Kolenda K, Kaczmarski M, Jośko P, Roces-Díaz JV, Stachyra P, Thumsová B, Zieliński P, Pabijan M. Emerging infectious diseases of amphibians in Poland: distribution and environmental drivers. DISEASES OF AQUATIC ORGANISMS 2021; 147:1-12. [PMID: 34734569 DOI: 10.3354/dao03631] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Emerging infectious diseases are a threat to biodiversity and have taken a large toll on amphibian populations worldwide. The chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), and the iridovirus Ranavirus (Rv), are of concern as all have contributed to amphibian declines. In central and eastern Europe, their geographical and host distributions and main environmental drivers determining prevalence are poorly known. We screened over 1000 amphibians from natural and captive populations in Poland for the presence of Bd, Bsal and Rv. In wild amphibian populations, we found that Bd is widespread, present in 46 out of 115 sampled localities as well as 2 captive colonies, and relatively common with overall prevalence at 14.4% in 9 species. We found lower prevalence of Rv at 2.4%, present in 11 out of 92 sampling sites, with a taxonomic breadth of 8 different amphibian species. Bsal infection was not detected in any individuals. In natural populations, Pelophylax esculentus and Bombina variegata accounted for 75% of all Bd infections, suggesting a major role for these 2 species as pathogen reservoirs in Central European freshwater habitats. General linear models showed that climatic as well as landscape features are associated with Bd infection in Poland. We found that higher average annual temperature constrains Bd infection, while landscapes with numerous water bodies or artificial elements (a surrogate for urbanization) increase the chances of infection. Our results show that a combination of climatic and landscape variables may drive regional and local pathogen emergence.
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Affiliation(s)
- Gemma Palomar
- Institute of Environmental Sciences, Faculty of Biology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland
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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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Deknock A, Pasmans F, van Leeuwenberg R, Van Praet S, Bruneel S, Lens L, Croubels S, Martel A, Goethals P. Alternative food sources interfere with removal of a fungal amphibian pathogen by zooplankton. J Appl Ecol 2021. [DOI: 10.1111/1365-2664.14018] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Arne Deknock
- Department of Animal Sciences and Aquatic Ecology Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - Frank Pasmans
- Department of Pathology, Bacteriology and Poultry Diseases Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - Robby van Leeuwenberg
- Department of Pathology, Bacteriology and Poultry Diseases Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - Sarah Van Praet
- Department of Pathology, Bacteriology and Poultry Diseases Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - Stijn Bruneel
- Department of Animal Sciences and Aquatic Ecology Faculty of Bioscience Engineering Ghent University Ghent Belgium
| | - Luc Lens
- Department of Biology Faculty of Sciences Ghent University Ghent Belgium
| | - Siska Croubels
- Department of Pharmacology Toxicology and Biochemistry Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - An Martel
- Department of Pathology, Bacteriology and Poultry Diseases Faculty of Veterinary Medicine Ghent University Merelbeke Belgium
| | - Peter Goethals
- Department of Animal Sciences and Aquatic Ecology Faculty of Bioscience Engineering Ghent University Ghent Belgium
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Villamizar-Gomez A, Wang HH, Peterson MR, Grant WE, Forstner MRJ. Environmental determinants of Batrachochytrium dendrobatidis and the likelihood of further dispersion in the face of climate change in Texas, USA. DISEASES OF AQUATIC ORGANISMS 2021; 146:29-39. [PMID: 34498608 DOI: 10.3354/dao03613] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
One of the major drivers of amphibian population declines is Batrachochytrium dendrobatidis (Bd). We sought to identify the major environmental drivers of Bd prevalence in Texas, USA, by drawing results from museum specimens. We sampled one of the largest museum collections in Texas, the Biodiversity Research and Teaching Collections at Texas A&M University. Our sampling focused on the 9 amphibian species with the widest geographical distribution within the state, where we sub-sampled 30% of each species per decade from 1930 to present via skin swabs, totaling 1501 independent sampling events, and used quantitative real-time PCR (qPCR) to detect pathogen presence. We analyzed several geo-referenced variables describing climatic conditions to identify potential factors influencing the likelihood of presence of Bd using boosted regression trees. Our final model suggests the most influential variables are mean temperature of driest quarter, annual mean temperature, temperature annual range, and mean diurnal range. The most likely suitable range for Bd is currently found in the Blackland Prairie and Cross Timbers ecoregions. Results of our future (to the year 2040) projections suggest that Bd could expand its current distribution. Our model could play an important role when developing an integrated conservation plan through (1) focusing future field work on locations with a high likelihood of presence, (2) assisting in the choice of locations for restoration, and (3) developing future research plans including those necessary for projecting reactions to climate change. Our model also could integrate new presence data of Bd when they become available to enhance prediction precision.
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Bakewell L, Kelehear C, Graham S. Impacts of temperature on immune performance in a desert anuran (
Anaxyrus punctatus
). J Zool (1987) 2021. [DOI: 10.1111/jzo.12891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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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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