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Yarzábal Rodríguez LA, Álvarez Gutiérrez PE, Gunde-Cimerman N, Ciancas Jiménez JC, Gutiérrez-Cepeda A, Ocaña AMF, Batista-García RA. Exploring extremophilic fungi in soil mycobiome for sustainable agriculture amid global change. Nat Commun 2024; 15:6951. [PMID: 39138171 PMCID: PMC11322326 DOI: 10.1038/s41467-024-51223-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: 01/29/2024] [Accepted: 07/24/2024] [Indexed: 08/15/2024] Open
Abstract
As the Earth warms, alternatives to traditional farming are crucial. Exploring fungi, especially poly extremophilic and extremotolerant species, to be used as plant probiotics, represents a promising option. Extremophilic fungi offer avenues for developing and producing innovative biofertilizers, effective biocontrol agents against plant pathogens, and resilient enzymes active under extreme conditions, all of which are crucial to enhance agricultural efficiency and sustainability through improved soil fertility and decreased reliance on agrochemicals. Yet, extremophilic fungi's potential remains underexplored and, therefore, comprehensive research is needed to understand their roles as tools to foster sustainable agriculture practices amid climate change. Efforts should concentrate on unraveling the complex dynamics of plant-fungi interactions and harnessing extremophilic fungi's ecological functions to influence plant growth and development. Aspects such as plant's epigenome remodeling, fungal extracellular vesicle production, secondary metabolism regulation, and impact on native soil microbiota are among many deserving to be explored in depth. Caution is advised, however, as extremophilic and extremotolerant fungi can act as both mitigators of crop diseases and as opportunistic pathogens, underscoring the necessity for balanced research to optimize benefits while mitigating risks in agricultural settings.
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Grants
- This work was supported by Fondo Nacional de Innovación y Desarrollo Científico-Tecnológico (FONDOCYT), Ministerio de Educación Superior, Ciencia y Tecnología (MESCYT), Government of Dominican Republic: Project COD. 2022-2B2-078. This work was supported by Darwin Initiative Round 27: Partnership Project DARPP220, and Darwin Initiative Round 30: Project DIR30S2/1004. This study was also supported by funding from the Slovenian Research Agency to Infrastructural Centre Mycosmo (MRIC UL, I0-0022), programs P4-0432 and P1-0198. Authors appreciate the support received from the European Commission – Program H2020, Project GEN4OLIVE: 101000427, Topic SFS-28-2018-2019-2020 Genetic resources and pre-breeding communities. RAB-G received a Sabbatical fellowship (CVU: 389616) from the National Council of Humanities, Sciences and Technologies (CONAHCyT), Government of Mexico. This work was supported by RYC2022-037554-I project funded by MCIN/AEI/10.13039/501100011033 and FSE+.
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Affiliation(s)
- Luis Andrés Yarzábal Rodríguez
- Carrera de Bioquímica y Farmacia. Grupo de Microbiología Molecular y Biotecnología (GI-M2YB). Unidad de Salud y Bienestar, Universidad Católica de Cuenca, Cuenca, Ecuador
| | | | - Nina Gunde-Cimerman
- Departament of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia
| | | | - Adrián Gutiérrez-Cepeda
- Instituto de Investigación en Salud, Facultad de Ciencias de la Salud, Universidad Autónoma de Santo Domingo, Santo Domingo, Dominican Republic
- Instituto de Química, Facultad de Ciencias, Universidad Autónoma de Santo Domingo, Santo Domingo, Dominican Republic
| | - Ana María Fernández Ocaña
- Departamento de Biología Animal, Biología Vegetal y Ecología. Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain
| | - Ramón Alberto Batista-García
- Departamento de Biología Animal, Biología Vegetal y Ecología. Facultad de Ciencias Experimentales, Universidad de Jaén, Jaén, Spain.
- Centro de Investigación en Dinámica Celular, Instituto de Investigación en Ciencias Básicas y Aplicadas, Universidad Autónoma del Estado de Morelos, Cuernavaca, Morelos, Mexico.
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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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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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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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5
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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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6
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Auliya M, Altherr S, Nithart C, Hughes A, Bickford D. Numerous uncertainties in the multifaceted global trade in frogs’ legs with the EU as the major consumer. NATURE CONSERVATION 2023. [DOI: 10.3897/natureconservation.51.93868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/11/2023]
Abstract
The commercial trade in frogs and their body parts is global, dynamic and occurs in extremely large volumes (in the thousands of tonnes/yr or billions of frogs/yr). The European Union (EU) remains the single largest importer of frogs’ legs, with most frogs still caught from the wild. Amongst the many drivers of species extinction or population decline (e.g. due to habitat loss, climate change, disease etc.), overexploitation is becoming increasingly more prominent. Due to global declines and extinctions, new attention is being focused on these markets, in part to try to ensure sustainability. While the trade is plagued by daunting realities of data deficiency and uncertainty and the conflicts of commercial interests associated with these data, it is clear is that EU countries are most responsible for the largest portion of the international trade in frogs’ legs of wild species. Over decades of exploitation, the EU imports have contributed to a decline in wild frog populations in an increasing number of supplying countries, such as India and Bangladesh, as well as Indonesia, Turkey and Albania more recently. However, there have been no concerted attempts by the EU and present export countries to ensure sustainability of this trade. Further work is needed to validate species identities, secure data on wild frog populations, establish reasonable monitored harvest/export quotas and disease surveillance and ensure data integrity, quality and security standards for frog farms. Herein, we call upon those countries and their representative governments to assume responsibility for the sustainability of the trade. The EU should take immediate action to channel all imports through a single centralised database and list sensitive species in the Annexes of the EU Wildlife Trade Regulation. Further, listing in CITES (the Convention on International Trade in Endangered Species of Wild Fauna and Flora) can enforce international trade restrictions. More joint efforts are needed to improve regional monitoring schemes before the commercial trade causes irreversible extinctions of populations and species of frogs.
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7
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Nie P, Feng J. Global niche and range shifts of Batrachochytrium dendrobatidis, a highly virulent amphibian-killing fungus. Fungal Biol 2022; 126:809-816. [PMID: 36517148 DOI: 10.1016/j.funbio.2022.10.004] [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: 07/05/2022] [Revised: 10/05/2022] [Accepted: 10/18/2022] [Indexed: 01/07/2023]
Abstract
Batrachochytrium dendrobatidis (Bd) is one of the world's most invasive species, and is responsible for chytridiomycosis, an emerging infectious disease that has caused huge losses of global amphibian biodiversity. Few studies have investigated invasive Bd's niche and range relative to those of native Bd. In the present study, we applied niche and range dynamic models to investigate global niche and range dynamics between native and invasive Bd. Invasive Bd occupied wider and different niche positions than did native Bd. Additionally, invasive Bd was observed in hotter, colder, wetter, drier, and more labile climatic conditions. Contrast to most relevant studies presuming Bd's niche remaining stable, we found that invasive Bd rejected niche conservatism hypotheses, suggesting its high lability in niche, and huge invasion potential. Bd's niche non-conservatism may result in range lability, and small niche expansions could induce large increases in range. Niche shifts may therefore be a more sensitive indicator of invasion than are range shifts. Our findings indicate that Bd is a high-risk invasive fungus not only due to its high infection and mortality rates, but also due to its high niche and range lability, which enhance its ability to adapt to novel climatic conditions. Therefore, invasive Bd should be a high-priority focus species in strategizing against biological invasions.
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Affiliation(s)
- Peixiao Nie
- Department of Life Science and Agronomy, Dali University, Dali, 671003, China
| | - Jianmeng Feng
- Department of Life Science and Agronomy, Dali University, Dali, 671003, China.
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8
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Moubarak M, Fischhoff IR, Han BA, Castellanos AA. A spatially explicit risk assessment of salamander populations to
Batrachochytrium salamandrivorans
in the United States. DIVERS DISTRIB 2022. [DOI: 10.1111/ddi.13627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Affiliation(s)
| | | | - Barbara A. Han
- Cary Institute of Ecosystem Studies Millbrook New York USA
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9
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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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10
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Sopniewski J, Scheele BC, Cardillo M. Predicting the distribution of Australian frogs and their overlap with
Batrachochytrium dendrobatidis
under climate change. DIVERS DISTRIB 2022. [DOI: 10.1111/ddi.13533] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
Affiliation(s)
- Jarrod Sopniewski
- Macroevolution & Macroecology Research School of Biology The Australian National University Canberra Australian Capital Territory Australia
- School of Biological Sciences The University of Western Australia Crawley Western Australia Australia
| | - Benjamin C. Scheele
- Macroevolution & Macroecology Research School of Biology The Australian National University Canberra Australian Capital Territory Australia
- Fenner School of Environment and Society The Australian National University Canberra Australian Capital Territory Australia
| | - Marcel Cardillo
- Macroevolution & Macroecology Research School of Biology The Australian National University Canberra Australian Capital Territory Australia
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11
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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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12
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Harjoe CC, Buck JC, Rohr JR, Roberts CE, Olson DH, Blaustein AR. Pathogenic fungus causes density‐ and trait‐mediated trophic cascades in an aquatic community. Ecosphere 2022. [DOI: 10.1002/ecs2.4043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Carmen C. Harjoe
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
| | - Julia C. Buck
- Department of Biology and Marine Biology University of North Carolina Wilmington Wilmington North Carolina USA
| | - Jason R. Rohr
- Department of Biological Sciences University of Notre Dame, Eck Institute for Global Health, and Environmental Change Initiative Notre Dame Indiana USA
| | - Claire E. Roberts
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
| | - Deanna H. Olson
- Pacific Northwest Research Station USDA Forest Service Corvallis Oregon USA
| | - Andrew R. Blaustein
- Department of Integrative Biology Oregon State University Corvallis Oregon USA
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13
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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: 7] [Impact Index Per Article: 3.5] [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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14
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Smith D, O'Brien D, Hall J, Sergeant C, Brookes LM, Harrison XA, Garner TWJ, Jehle R. Challenging a host-pathogen paradigm: Susceptibility to chytridiomycosis is decoupled from genetic erosion. J Evol Biol 2022; 35:589-598. [PMID: 35167143 PMCID: PMC9306973 DOI: 10.1111/jeb.13987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2021] [Accepted: 02/07/2022] [Indexed: 11/26/2022]
Abstract
The putatively positive association between host genetic diversity and the ability to defend against pathogens has long attracted the attention of evolutionary biologists. Chytridiomycosis, a disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), has emerged in recent decades as a cause of dramatic declines and extinctions across the amphibian clade. Bd susceptibility can vary widely across populations of the same species, but the relationship between standing genetic diversity and susceptibility has remained notably underexplored so far. Here, we focus on a putatively Bd-naive system of two mainland and two island populations of the common toad (Bufo bufo) at the edge of the species' range and use controlled infection experiments and dd-RAD sequencing of >10 000 SNPs across 95 individuals to characterize the role of host population identity, genetic variation and individual body mass in mediating host response to the pathogen. We found strong genetic differentiation between populations and marked variation in their susceptibility to Bd. This variation was not, however, governed by isolation-mediated genetic erosion, and individual heterozygosity was even found to be negatively correlated with survival. Individual survival during infection experiments was strongly positively related to body mass, which itself was unrelated to population of origin or heterozygosity. Our findings underscore the general importance of context-dependency when assessing the role of host genetic variation for the ability of defence against pathogens.
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Affiliation(s)
- Donal Smith
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
- Institute of ZoologyZoological Society of LondonLondonUK
| | | | | | - Chris Sergeant
- Institute of ZoologyZoological Society of LondonLondonUK
| | - Lola M. Brookes
- Institute of ZoologyZoological Society of LondonLondonUK
- Highland Amphibian and Reptile ProjectDingwallUK
- MRC Centre for Global Infectious Disease AnalysisImperial College School of Public HealthLondonUK
- Royal Veterinary CollegeHatfieldUK
| | - Xavier A. Harrison
- Institute of ZoologyZoological Society of LondonLondonUK
- Centre for Ecology and ConservationUniversity of ExeterExeterUK
| | | | - Robert Jehle
- School of Science, Engineering and EnvironmentUniversity of SalfordSalfordUK
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15
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Prediction of the potential geographical distribution of Betula platyphylla Suk. in China under climate change scenarios. PLoS One 2022; 17:e0262540. [PMID: 35358194 PMCID: PMC8970525 DOI: 10.1371/journal.pone.0262540] [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: 09/09/2021] [Accepted: 12/28/2021] [Indexed: 11/19/2022] Open
Abstract
Climate is a dominant factor affecting the potential geographical distribution of species. Understanding the impact of climate change on the potential geographic distribution of species, which is of great significance to the exploitation, utilization, and protection of resources, as well as ecologically sustainable development. Betula platyphylla Suk. is one of the most widely distributed temperate deciduous tree species in East Asia and has important economic and ecological value. Based on 231 species distribution data points of Betula platyphylla Suk. in China and 37 bioclimatic, soil, and topography variables (with correlation coefficients < 0.75), the potential geographical distribution pattern of Betula platyphylla Suk. under Representative Concentration Pathway (RCP) climate change scenarios at present and in the 2050s and 2070s was predicted using the MaxEnt model. We analyzed the main environmental variables affecting the distribution and change of suitable areas and compared the scope and change of suitable areas under different climate scenarios. This study found: (1) At present, the main suitable area for Betula platyphylla Suk. extends from northeastern to southwestern China, with the periphery area showing fragmented distribution. (2) Annual precipitation, precipitation of the warmest quarter, mean temperature of the warmest quarter, annual mean temperature, and precipitation of the driest month are the dominant environmental variables that affect the potential geographical distribution of Betula platyphylla Suk. (3) The suitable area for Betula platyphylla Suk. is expected to expand under global warming scenarios. In recent years, due to the impact of diseases and insect infestation, and environmental damage, the natural Betula platyphylla Suk. forest in China has gradually narrowed. This study accurately predicted the potential geographical distribution of Betula platyphylla Suk. under current and future climate change scenarios, which can provide the scientific basis for the cultivation, management, and sustainable utilization of Betula platyphylla Suk. resources.
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16
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Bosch J, Thumsová B, López-Rojo N, Pérez J, Alonso A, Fisher MC, Boyero L. Microplastics increase susceptibility of amphibian larvae to the chytrid fungus Batrachochytrium dendrobatidis. Sci Rep 2021; 11:22438. [PMID: 34789869 PMCID: PMC8599647 DOI: 10.1038/s41598-021-01973-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2021] [Accepted: 11/08/2021] [Indexed: 11/09/2022] Open
Abstract
Microplastics (MPs), a new class of pollutants that pose a threat to aquatic biodiversity, are of increasing global concern. In tandem, the amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) causing the disease chytridiomycosis is emerging worldwide as a major stressor to amphibians. We here assess whether synergies exist between this infectious disease and MP pollution by mimicking natural contact of a highly susceptible species (midwife toads, Alytes obstetricans) with a Bd-infected reservoir species (fire salamanders, Salamandra salamandra) in the presence and absence of MPs. We found that MP ingestion increases the burden of infection by Bd in a dose-dependent manner. However, MPs accumulated to a greater extent in amphibians that were not exposed to Bd, likely due to Bd-damaged tadpole mouthparts interfering with MP ingestion. Our experimental approach showed compelling interactions between two emergent processes, chytridiomycosis and MP pollution, necessitating further research into potential synergies between these biotic and abiotic threats to amphibians.
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Affiliation(s)
- Jaime Bosch
- Biodiversity Research Institute, University of Oviedo-Principality of Asturias-CSIC, Mieres, Spain. .,Centro de Investigación, Seguimiento y Evaluación, Parque Nacional Sierra de Guadarrama, Rascafría, Spain. .,Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain.
| | - Barbora Thumsová
- Museo Nacional de Ciencias Naturales-CSIC, Madrid, Spain.,Asociación Herpetológica Española, Madrid, Spain
| | - Naiara López-Rojo
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain.,Laboratoire d'Ecologie Alpine (LECA), Université Grenoble Alpes, UMR CNRS-UGA-USMB, Grenoble, France
| | - Javier Pérez
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Alberto Alonso
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain
| | - Matthew C Fisher
- MRC Centre for Global Infectious Disease Analysis, Department of Infectious Disease Epidemiology, Imperial School of Public Health, London, UK
| | - Luz Boyero
- Department of Plant Biology and Ecology, University of the Basque Country (UPV/EHU), Leioa, Spain.,IKERBASQUE, Bilbao, Spain
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17
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Alvarado-Rybak M, Lepe-Lopez M, Peñafiel-Ricaurte A, Valenzuela-Sánchez A, Valdivia C, Mardones FO, Bacigalupe LD, Puschendorf R, Cunningham AA, Azat C. Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient. Sci Rep 2021; 11:17383. [PMID: 34462470 PMCID: PMC8405646 DOI: 10.1038/s41598-021-96535-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused the greatest known loss of biodiversity due to an infectious disease. We used Bd infection data from quantitative real-time PCR (qPCR) assays of amphibian skin swabs collected across Chile during 2008-2018 to model Bd occurrence with the aim to determine bioclimatic and anthropogenic variables associated with Bd infection. Also, we used Bd presence/absence records to identify geographical Bd high-risk areas and compare Bd prevalence and infection loads between amphibian families, ecoregions, and host ecology. Data comprised 4155 Bd-specific qPCR assays from 162 locations across a latitudinal gradient of 3700 km (18º to 51ºS). Results showed a significant clustering of Bd associated with urban centres and anthropogenically highly disturbed ecosystems in central-south Chile. Both Bd prevalence and Bd infection loads were higher in aquatic than terrestrial amphibian species. Our model indicated positive associations of Bd prevalence with altitude, temperature, precipitation and human-modified landscapes. Also, we found that macroscale drivers, such as land use change and climate, shape the occurrence of Bd at the landscape level. Our study provides with new evidence that can improve the effectiveness of strategies to mitigate biodiversity loss due to amphibian chytridiomycosis.
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Affiliation(s)
- Mario Alvarado-Rybak
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
- Núcleo de Ciencias Aplicadas en Ciencias Veterinarias y Agronómicas, Universidad de las Américas, Echaurren 140, Santiago, Chile
| | - Manuel Lepe-Lopez
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
| | - Alexandra Peñafiel-Ricaurte
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
| | - Andrés Valenzuela-Sánchez
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
- ONG Ranita de Darwin, Nataniel Cox 152, Santiago, Chile
- Instituto de Conservación, Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, 5110566, Valdivia, Chile
| | - Catalina Valdivia
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
| | - Fernando O Mardones
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Leonardo D Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Robert Puschendorf
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, PL4 8AA, UK
| | - Andrew A Cunningham
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
| | - Claudio Azat
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile.
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18
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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: 26] [Impact Index Per Article: 8.7] [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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19
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Retuci Pontes M, Bardier C, Medina D, Pereira G, Lambertini C, Toledo LF. Seasonal variation of Batrachochytrium dendrobatidis in a threatened anuran species from Uruguay. DISEASES OF AQUATIC ORGANISMS 2021; 145:79-88. [PMID: 34137378 DOI: 10.3354/dao03603] [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: 06/12/2023]
Abstract
Chytridiomycosis, an emergent infectious disease caused by the fungus Batrachochytrium dendrobatidis (Bd), is considered one of the drivers of the current amphibian biodiversity loss. To inform endangered species conservation efforts, it is essential to improve our knowledge about the abiotic and biotic factors that influence Bd infection dynamics in the wild. Here, we analyzed variation of Bd infection in the redbelly toad Melanophryniscus montevidensis, a threatened bufonid from Uruguay. We tested the influence of temperature, precipitation, season, and host population size on Bd prevalence and intensity. Additionally, considering the sub-lethal effects of Bd, we tested if these variables, potentially through their effect on Bd, also explain the variation in host body condition. We determined a high Bd prevalence of 41% (100/241), and that population size influenced both Bd prevalence and infection intensity. We identified an effect of precipitation and season on Bd infection intensity and an effect of season on toad body condition. In addition, we found a negative effect of infection intensity on body condition; moreover, while some toads cleared the infection, their body condition did not improve, suggesting a long-term cost. This is the first report on host population size as an important factor in Bd infection dynamics in a threatened anuran species, and seasonal demographic changes appear to play an important role in the dynamics. Finally, we highlight the need for monitoring Bd in this and other endangered amphibian populations, especially those within the genus Melanophryniscus, which includes several Endangered and Data Deficient species in South America.
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Affiliation(s)
- Mariana Retuci Pontes
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, SP 13083-862, Brazil
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20
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21
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Rahman MM, Jahan H, Rabbe MF, Chakraborty M, Salauddin M. First Detection of Batrachochytrium dendrobatidis in Wild Frogs from Bangladesh. ECOHEALTH 2021; 18:31-43. [PMID: 34028636 DOI: 10.1007/s10393-021-01522-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2020] [Revised: 02/25/2021] [Accepted: 03/17/2021] [Indexed: 06/12/2023]
Abstract
Global amphibian populations are facing a novel threat, chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), which is responsible for the severe decline of a number of species across several continents. Chytridiomycosis in Asia is a relatively recent discovery yet there have been no reports on Bd-presence in Bangladeshi amphibians. We conducted a preliminary study on 133 wild frogs from seven sites in Bangladesh between April and July 2018. Nested PCR analysis showed 20 samples (15.04%) and 50% of the tested taxa (9 species from 6 genera and 4 families) as Bd-positive. Eight of the nine species are discovered as newly infected hosts. Analysis of Bd-positive samples shows prevalence does not significantly vary among different land cover categories, although the occurrence is higher in forested areas. The prevalence rate is similar in high and low disturbed areas, but the range of occurrence is statistically higher in low disturbance areas. Maximum entropy distribution modeling indicates high probabilities of Bd occurrence in hilly and forested areas in southeast and central-north Bangladesh. The Bd-specific ITS1-5.8S-ITS2 ribosomal gene sequence from the Bd-positive samples tested is completely identical. A neighbor-joining phylogenetic tree reveals that the identified strain shares a common ancestry with strains previously discovered in different Asian regions. Our results provide the first evidence of Bd-presence in Bangladeshi amphibians, inferring that diversity is at risk. The effects of environmental and climatic factors along with quantitative PCR analysis are required to determine the infection intensity and susceptibility of amphibians in the country.
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Affiliation(s)
- Md Mokhlesur Rahman
- Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh.
- Department of Anthropology, Durham University, South Road, Durham, DH1 3LE, UK.
| | - Hawa Jahan
- Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh
- Division of Evolution and Genomic Sciences, FBMH, School of Biological Sciences, University of Manchester, Oxford Rd, Manchester, M13 9PT, UK
| | - Md Fazle Rabbe
- Department of Zoology, University of Dhaka, Dhaka, 1000, Bangladesh
| | | | - Md Salauddin
- Department of Geography and Environment, Jagannath University, Dhaka, 1100, Bangladesh
- Disaster Risk Management Department, Bangladesh Red Crescent Society, Red Crescent Sarak, Bara Moghbazar, Dhaka, 1217, Bangladesh
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22
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Zumbado‐Ulate H, García‐Rodríguez A, Searle CL. Species distribution models predict the geographic expansion of an enzootic amphibian pathogen. Biotropica 2020. [DOI: 10.1111/btp.12863] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
| | - Adrián García‐Rodríguez
- Departamento de Zoología Instituto de Biología Universidad Nacional Autónoma de MéxicoUNAM Ciudad de México México
- Museo de Zoología Escuela de Biología Universidad de Costa Rica San José Costa Rica
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23
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Meurling S, Kärvemo S, Chondrelli N, Cortazar Chinarro M, Åhlen D, Brookes L, Nyström P, Stenberg M, Garner TWJ, Höglund J, Laurila A. Occurrence of Batrachochytrium dendrobatidis in Sweden: higher infection prevalence in southern species. DISEASES OF AQUATIC ORGANISMS 2020; 140:209-218. [PMID: 32880378 DOI: 10.3354/dao03502] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) has caused worldwide declines in amphibian populations. While Bd is widespread in southern and central Europe, its occurrence and distribution in northernmost Europe is mostly unknown. We surveyed for Bd in breeding anurans in Sweden by sampling 1917 amphibians from 101 localities and 3 regions in Sweden (southern, northern and central). We found that Bd was widespread in southern and central Sweden, occurring in all 9 investigated species and in 45.5% of the 101 localities with an overall prevalence of 13.8%. No infected individuals were found in the 4 northern sites sampled. The records from central Sweden represent the northernmost records of Bd in Europe. While the proportion of sites positive for Bd was similar between the southern and central regions, prevalence was much higher in the southern region. This was because southern species with a distribution mainly restricted to southernmost Sweden had a higher prevalence than widespread generalist species. The nationally red-listed green toad Bufotes variabilis and the fire-bellied toad Bombina bombina had the highest prevalence (61.4 and 48.9%, respectively). Across species, Bd prevalence was strongly positively, correlated with water temperature at the start of egg laying. However, no individuals showing visual signs of chytridiomycosis were found in the field. These results indicate that Bd is widespread and common in southern and central Sweden with southern species, breeding in higher temperatures and with longer breeding periods, having higher prevalence. However, the impact of Bd on amphibian populations in northernmost Europe remains unknown.
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Affiliation(s)
- Sara Meurling
- Animal Ecology/ Department of Ecology and Genetics, Uppsala University, Norbyvägen 18D, 75236 Uppsala, Sweden
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24
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Effects of invasive larval bullfrogs (Rana catesbeiana) on disease transmission, growth and survival in the larvae of native amphibians. Biol Invasions 2020. [DOI: 10.1007/s10530-020-02218-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
AbstractThe mechanisms by which invasive species negatively affect native species include competition, predation, and the introduction of novel pathogens. Moreover, if an invasive species is a competent disease reservoir, it may facilitate the long-term maintenance and spread of pathogens in ecological assemblages and drive the extinction of less tolerant or less resistant species. Disease-driven loss of biodiversity is exemplified by the amphibian–chytrid fungus system. The disease chytridiomycosis is caused by the aquatic chytrid fungus Batrachochytrium dendrobatidis (Bd) in anurans and is associated with worldwide amphibian population declines and extinctions. For amphibian species that metamorphose and leave infected aquatic habitats, the mechanisms by which Bd persists over winter in these habitats remains a critical open question. A leading hypothesis is that American bullfrogs (Rana catesbeiana), a worldwide invasive species, are tolerant to Bd and serve as a reservoir host for Bd during winter months and subsequently infect native species that return to breed in spring. Using outdoor mesocosms, we experimentally examined if two strains of Bd could overwinter in aquatic systems, in the presence or absence of bullfrog tadpoles, and if overwintered Bd could be transmitted to tadpoles of two spring-breeding species: Pacific treefrogs (Pseudacris regilla) and Cascades frogs (Rana cascadae). We found that only 4 of 448 total animals (one bullfrog and three spring breeders) tested positive for Bd after overwintering. Moreover, two of the three infected spring breeders emerged from tanks that contained overwintered Bd but in the absence of infected bullfrogs. This suggests that Bd can persist over winter without bullfrogs as a reservoir host. We found no effect of Bd strain on bullfrog survival after overwintering. For Pacific treefrogs, Bd exposure did not significantly affect mass at or time to metamorphosis while exposure to bullfrogs reduced survival. For Cascades frogs, we found an interactive effect of Bd strain and bullfrog presence on time to metamorphosis, but no main or interactive effects on their survival or mass at metamorphosis. In short, bullfrog tadpoles rarely retained and transmitted Bd infection in our experiment and we found limited evidence that Bd successfully overwinters in the absence of bullfrog tadpoles and infects spring-breeding amphibians.
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McMillan KM, Lesbarrères D, Harrison XA, Garner TWJ. Spatiotemporal heterogeneity decouples infection parameters of amphibian chytridiomycosis. J Anim Ecol 2020; 89:1109-1121. [PMID: 31872434 DOI: 10.1111/1365-2656.13170] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2019] [Accepted: 11/01/2019] [Indexed: 11/27/2022]
Abstract
Emerging infectious diseases are responsible for declines in wildlife populations around the globe. Mass mortality events associated with emerging infectious diseases are often associated with high number of infected individuals (prevalence) and high pathogen loads within individuals (intensity). At the landscape scale, spatial and temporal variation in environmental conditions can alter the relationship between these infection parameters and blur the overall picture of disease dynamics. Quantitative estimates of how infection parameters covary with environmental heterogeneity at the landscape scale are scarce. If we are to identify wild populations at risk of disease epidemics, we must elucidate the factors that shape, and potentially decouple, the link between pathogen prevalence and intensity of infection over complex ecological landscapes. Using a network of 41 populations of the amphibian host Rana pipiens in Ontario, Canada, we present the spatial and temporal heterogeneity in pathogen prevalence and intensity of infection of the chytrid fungus Batrachochytrium dendrobatidis (Bd), across a 3-year period. We then quantify how covariation between both infection parameters measured during late summer is modified by previously experienced spatiotemporal environmental heterogeneity across 14 repeat sampled populations. Late summer Bd infection parameters are governed, at least in part, by different environmental factors operating during separate host life-history events. Our results provide evidence for a relationship between Bd prevalence and thermal regimes prior to host breeding at the site level, and a relationship between intensity of infection and aquatic conditions (precipitation, hydroshed size and river density) throughout host breeding period at the site level. This demonstrates that microclimatic variation within temporal windows can drive divergent patterns of pathogen dynamics within and across years, by effecting changes in host behaviour which interfere with the pathogen's ability to infect and re-infect hosts. A clearer understanding of the role that spatiotemporal heterogeneity has upon infection parameters will provide valuable insights into host-pathogen epidemiology, as well as more fundamental aspects of the ecology and evolution of interspecific interactions.
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Affiliation(s)
- Kirsten M McMillan
- Institute of Zoology, Zoological Society of London, London, UK.,Department of Biology, Laurentian University, Sudbury, ON, Canada
| | | | - Xavier A Harrison
- Institute of Zoology, Zoological Society of London, London, UK.,University of Exeter, Exeter, UK
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Hybridization Facilitates Adaptive Evolution in Two Major Fungal Pathogens. Genes (Basel) 2020; 11:genes11010101. [PMID: 31963231 PMCID: PMC7017293 DOI: 10.3390/genes11010101] [Citation(s) in RCA: 22] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 01/02/2020] [Accepted: 01/14/2020] [Indexed: 01/13/2023] Open
Abstract
Hybridization is increasingly recognized as an important force impacting adaptation and evolution in many lineages of fungi. During hybridization, divergent genomes and alleles are brought together into the same cell, potentiating adaptation by increasing genomic plasticity. Here, we review hybridization in fungi by focusing on two fungal pathogens of animals. Hybridization is common between the basidiomycete yeast species Cryptococcus neoformans × Cryptococcus deneoformans, and hybrid genotypes are frequently found in both environmental and clinical settings. The two species show 10-15% nucleotide divergence at the genome level, and their hybrids are highly heterozygous. Though largely sterile and unable to mate, these hybrids can propagate asexually and generate diverse genotypes by nondisjunction, aberrant meiosis, mitotic recombination, and gene conversion. Under stress conditions, the rate of such genetic changes can increase, leading to rapid adaptation. Conversely, in hybrids formed between lineages of the chytridiomycete frog pathogen Batrachochytrium dendrobatidis (Bd), the parental genotypes are considerably less diverged (0.2% divergent). Bd hybrids are formed from crosses between lineages that rarely undergo sex. A common theme in both species is that hybrids show genome plasticity via aneuploidy or loss of heterozygosity and leverage these mechanisms as a rapid way to generate genotypic/phenotypic diversity. Some hybrids show greater fitness and survival in both virulence and virulence-associated phenotypes than parental lineages under certain conditions. These studies showcase how experimentation in model species such as Cryptococcus can be a powerful tool in elucidating the genotypic and phenotypic consequences of hybridization.
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Bradley PW, Brawner MD, Raffel TR, Rohr JR, Olson DH, Blaustein AR. Shifts in temperature influence how Batrachochytrium dendrobatidis infects amphibian larvae. PLoS One 2019; 14:e0222237. [PMID: 31536533 PMCID: PMC6752834 DOI: 10.1371/journal.pone.0222237] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 08/23/2019] [Indexed: 11/18/2022] Open
Abstract
Many climate change models predict increases in frequency and magnitude of temperature fluctuations that might impact how ectotherms are affected by disease. Shifts in temperature might especially affect amphibians, a group with populations that have been challenged by several pathogens. Because amphibian hosts invest more in immunity at warmer than cooler temperatures and parasites might acclimate to temperature shifts faster than hosts (creating lags in optimal host immunity), researchers have hypothesized that a temperature shift from cold-to-warm might result in increased amphibian sensitivity to pathogens, whereas a shift from warm-to-cold might result in decreased sensitivity. Support for components of this climate-variability based hypothesis have been provided by prior studies of the fungus Batrachochytrium dendrobatidis (Bd) that causes the disease chytridiomycosis in amphibians. We experimentally tested whether temperature shifts before exposure to Batrachochytrium dendrobatidis (Bd) alters susceptibility to the disease chytridiomycosis in the larval stage of two amphibian species–western toads (Anaxyrus boreas) and northern red legged frogs (Rana aurora). Both host species harbored elevated Bd infection intensities under constant cold (15° C) temperature in comparison to constant warm (20° C) temperature. Additionally, both species experienced an increase in Bd infection abundance after shifted from 15° C to 20° C, compared to a constant 20° C but they experienced a decrease in Bd after shifted from 20° C to 15° C, compared to a constant 15° C. These results are in contrast to prior studies of adult amphibians highlighting the potential for species and stage differences in the temperature-dependence of chytridiomycosis.
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Affiliation(s)
- Paul W. Bradley
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Michael D. Brawner
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States of America
| | - Thomas R. Raffel
- Department of Biology, Oakland University, Rochester, MI, United States of America
| | - Jason R. Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL, United States of America
| | - Deanna H. Olson
- USDA Forest Service, Pacific Northwest Research Station, Corvallis, OR, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, OR, United States of America
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Bradley PW, Snyder PW, Blaustein AR. Host age alters amphibian susceptibility to Batrachochytrium dendrobatidis, an emerging infectious fungal pathogen. PLoS One 2019; 14:e0222181. [PMID: 31491016 PMCID: PMC6730893 DOI: 10.1371/journal.pone.0222181] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2018] [Accepted: 08/23/2019] [Indexed: 11/18/2022] Open
Abstract
Parasites and pathogens are often aggregated in a minority of susceptible hosts within a population, with a majority of individuals harboring low infection intensities. However, determining the relative importance of host traits to explain this heterogeneity is a challenge. One ecologically important pathogen is Batrachochytrium dendrobatidis (Bd), which causes the disease chytridiomycosis and has been associated with many amphibian population declines worldwide. For many hosts, post-metamorphic stages are generally more susceptible than the larval stage. Yet, examination of the effects of Bd infection at different ages within a life stage, has received little attention. This study investigated the hypothesis that recently-post-metamorphic frogs were more sensitive to chytridiomycosis than older frogs, and that sensitivity to Bd infection decreased as frogs aged. We examined this relationship with Pacific treefrogs (Pseudacris regilla) and red legged frogs (Rana aurora). Age had a strong effect on susceptibility to infection, infection intensity, and survival-but not in the directions we had predicted. In both host species, an increase in age was associated with frogs becoming more susceptible to Bd infection, harboring larger infection intensities, and greater risk of mortality. This suggests that the timing of Bd exposure may influence amphibian population dynamics.
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Affiliation(s)
- Paul W. Bradley
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
- * E-mail:
| | - Paul W. Snyder
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
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The invasive red swamp crayfish (Procambarus clarkii) increases infection of the amphibian chytrid fungus (Batrachochytrium dendrobatidis). Biol Invasions 2019. [DOI: 10.1007/s10530-019-02041-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Bacigalupe LD, Vásquez IA, Estay SA, Valenzuela‐Sánchez A, Alvarado‐Rybak M, Peñafiel‐Ricaurte A, Cunningham AA, Soto‐Azat C. The amphibian‐killing fungus in a biodiversity hotspot: identifying and validating high‐risk areas and refugia. Ecosphere 2019. [DOI: 10.1002/ecs2.2724] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Affiliation(s)
- Leonardo D. Bacigalupe
- Facultad de Ciencias Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
| | - Inao A. Vásquez
- Facultad de Ciencias Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
| | - Sergio A. Estay
- Facultad de Ciencias Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
- Center of Applied Ecology and Sustainability Pontificia Universidad Católica de Chile Santiago Chile
| | - Andrés Valenzuela‐Sánchez
- Facultad de Ciencias Instituto de Ciencias Ambientales y Evolutivas Universidad Austral de Chile Valdivia Chile
- ONG Ranita de Darwin Santiago Chile
| | - Mario Alvarado‐Rybak
- Centro de Investigación para la Sustentabilidad Facultad de Ciencias de la Vida & Doctorado en Medicina de la Conservación Universidad Andrés Bello Santiago Chile
- Institute of Zoology Zoological Society of London Regent's Park London NW1 4RY UK
| | - Alexandra Peñafiel‐Ricaurte
- Centro de Investigación para la Sustentabilidad Facultad de Ciencias de la Vida & Doctorado en Medicina de la Conservación Universidad Andrés Bello Santiago Chile
- Institute of Zoology Zoological Society of London Regent's Park London NW1 4RY UK
| | - Andrew A. Cunningham
- Institute of Zoology Zoological Society of London Regent's Park London NW1 4RY UK
| | - Claudio Soto‐Azat
- Centro de Investigación para la Sustentabilidad Facultad de Ciencias de la Vida & Doctorado en Medicina de la Conservación Universidad Andrés Bello Santiago Chile
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Forecasting herd-level porcine epidemic diarrhea (PED) frequency trends in Ontario (Canada). Prev Vet Med 2019; 164:15-22. [PMID: 30771890 PMCID: PMC7125872 DOI: 10.1016/j.prevetmed.2019.01.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2018] [Revised: 01/11/2019] [Accepted: 01/11/2019] [Indexed: 11/23/2022]
Abstract
Porcine Epidemic Diarrhea Virus (PEDV) emerged in North America in 2013. The first case of PEDV in Canada was identified on an Ontario farm in January 2014. Surveillance was instrumental in identifying the initial case and in minimizing the spread of the virus to other farms. With recent advances in predictive analytics showing promise for health and disease forecasting, the primary objective of this study was to apply machine learning predictive methods (random forest, artificial neural networks, and classification and regression trees) to provincial PEDV incidence data, and in so doing determine their accuracy for predicting future PEDV trends. Trend was defined as the cumulative number of new cases over a four-week interval, and consisted of four levels (zero, low, medium and high). Provincial PEDV incidence and prevalence estimates from an industry database, as well as temperature, humidity, and precipitation data, were combined to create the forecast dataset. With 10-fold cross validation performed on the entire dataset, the overall accuracy was 0.68 (95% CI: 0.60 - 0.75), 0.57 (95% CI: 0.49 - 0.64), and 0.55 (0.47 - 0.63) for the random forest, artificial neural network, and classification and regression tree models, respectively. Based on the cross-validation approach to evaluating predictive accuracy, the random forest model provided the best prediction.
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Kärvemo S, Meurling S, Berger D, Höglund J, Laurila A. Effects of host species and environmental factors on the prevalence of Batrachochytrium dendrobatidis in northern Europe. PLoS One 2018; 13:e0199852. [PMID: 30359384 PMCID: PMC6201871 DOI: 10.1371/journal.pone.0199852] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2018] [Accepted: 10/09/2018] [Indexed: 11/18/2022] Open
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) poses a major threat to amphibian populations. To assist efforts to address such threats, we examined differences in Bd host infection prevalence among amphibian species and its relations to both local environmental factors in breeding habitats and landscape variables measured at three scales (500, 2000 and 5000 m radii) around breeding sites in southernmost Sweden. We sampled 947 anurans of six species in 31 ponds and assessed their infection status. We then examined correlations of infection prevalence with canopy cover, pond perimeter and pH (treated as local-scale pond characteristics), and the number of ponds, area of arable land, area of mature forest, number of resident people and presence of sea within the three radii (treated as landscape variables). The Bd infection prevalence was very low, 0.5–1.0%, in two of the six anuran species (Bufo bufo and Rana temporaria), and substantially higher (13–64%) in the other four (Bombina bombina, Bufotes variabilis, Epidalea calamita, Rana arvalis). In the latter four species Bd infection prevalence was positively associated with ponds’ pH (site range: 5.3–8.1), and negatively associated with areas of mature forest and/or wetlands in the surroundings. Our results show that the infection dynamics of Bd are complex and associated with host species, local pond characteristics and several landscape variables at larger spatial scales. Knowledge of environmental factors associated with Bd infections and differences in species’ susceptibility may help to counter further spread of the disease and guide conservation action plans, especially for the most threatened species.
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Affiliation(s)
- Simon Kärvemo
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
- * E-mail:
| | - Sara Meurling
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - David Berger
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - Jacob Höglund
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
| | - Anssi Laurila
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, Uppsala, Sweden
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Effects of Emerging Infectious Diseases on Amphibians: A Review of Experimental Studies. DIVERSITY-BASEL 2018. [DOI: 10.3390/d10030081] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Numerous factors are contributing to the loss of biodiversity. These include complex effects of multiple abiotic and biotic stressors that may drive population losses. These losses are especially illustrated by amphibians, whose populations are declining worldwide. The causes of amphibian population declines are multifaceted and context-dependent. One major factor affecting amphibian populations is emerging infectious disease. Several pathogens and their associated diseases are especially significant contributors to amphibian population declines. These include the fungi Batrachochytrium dendrobatidis and B. salamandrivorans, and ranaviruses. In this review, we assess the effects of these three pathogens on amphibian hosts as found through experimental studies. Such studies offer valuable insights to the causal factors underpinning broad patterns reported through observational studies. We summarize key findings from experimental studies in the laboratory, in mesocosms, and from the field. We also summarize experiments that explore the interactive effects of these pathogens with other contributors of amphibian population declines. Though well-designed experimental studies are critical for understanding the impacts of disease, inconsistencies in experimental methodologies limit our ability to form comparisons and conclusions. Studies of the three pathogens we focus on show that host susceptibility varies with such factors as species, host age, life history stage, population and biotic (e.g., presence of competitors, predators) and abiotic conditions (e.g., temperature, presence of contaminants), as well as the strain and dose of the pathogen, to which hosts are exposed. Our findings suggest the importance of implementing standard protocols and reporting for experimental studies of amphibian disease.
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Yap TA, Koo MS, Ambrose RF, Vredenburg VT. Introduced bullfrog facilitates pathogen invasion in the western United States. PLoS One 2018; 13:e0188384. [PMID: 29659568 PMCID: PMC5901863 DOI: 10.1371/journal.pone.0188384] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 11/06/2017] [Indexed: 11/22/2022] Open
Abstract
Batrachochytrium dendrobatidis (Bd), a causal agent of the amphibian fungal skin disease chytridiomycosis, has been implicated in the decline and extinction of over 200 species worldwide since the 1970s. Despite almost two decades of research, the history of Bd and its global spread is not well understood. However, the spread of the Global Panzootic Lineage of Bd (Bd-GPL), the lineage associated with amphibian die-offs, has been linked with the American bullfrog (Rana [Aqurana] catesbeiana) and global trade. Interestingly, R. catesbeiana is native to the eastern U.S., where no Bd-related declines have been observed despite Bd’s presence since the late 1800s. In contrast Bd has been found to have emerged in California and Mexico in the 1960s and 1970s, after which epizootics (i.e., epidemics in wildlife) ensued. We hypothesize that Bd-GPL spread from the eastern U.S. with the introduction of R. catesbeiana into the western US, resulting in epizootics and declines of native host species. Using museum records, we investigated the historical relationship between R. catesbeiana and Bd invasion in the western US and found that R. catesbeiana arrived in the same year or prior to Bd in most western watersheds that had data for both species, suggesting that Bd-GPL may have originated in the eastern US and R. catesbeiana may have facilitated Bd invasion in the western US. To predict areas with greatest suitability for Bd, we created a suitability model by integrating habitat suitability and host availability. When we incorporated invasion history with high Bd suitability, we found that watersheds with non-native R. catesbeiana in the mountain ranges of the West Coast have the highest disease risk. These findings shed light on the invasion history and disease dynamics of Bd in North America. Targeted historical surveys using archived specimens in natural history collections and present-day field surveys along with more localized, community-level studies, monitoring, and surveillance are needed to further test this hypothesis and grow our understanding of the disease ecology and host-pathogen dynamics of Bd.
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Affiliation(s)
- Tiffany A. Yap
- Institute of the Environment and Sustainability, University of California, Los Angeles, California, United States of America
- Museum of Vertebrate Zoology, University of California, Berkeley, California, United States of America
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Michelle S. Koo
- Museum of Vertebrate Zoology, University of California, Berkeley, California, United States of America
| | - Richard F. Ambrose
- Institute of the Environment and Sustainability, University of California, Los Angeles, California, United States of America
- Department of Environmental Health Sciences, University of California, Los Angeles, California, United States of America
| | - Vance T. Vredenburg
- Museum of Vertebrate Zoology, University of California, Berkeley, California, United States of America
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
- * E-mail:
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Forti LR, Becker CG, Tacioli L, Pereira VR, Santos ACFA, Oliveira I, Haddad CFB, Toledo LF. Perspectives on invasive amphibians in Brazil. PLoS One 2017; 12:e0184703. [PMID: 28938024 PMCID: PMC5609743 DOI: 10.1371/journal.pone.0184703] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2016] [Accepted: 08/29/2017] [Indexed: 11/18/2022] Open
Abstract
Introduced species have the potential to become invasive and jeopardize entire ecosystems. The success of species establishing viable populations outside their original extent depends primarily on favorable climatic conditions in the invasive ranges. Species distribution modeling (SDM) can thus be used to estimate potential habitat suitability for populations of invasive species. Here we review the status of six amphibian species with invasive populations in Brazil (four domestic species and two imported species). We (i) modeled the current habitat suitability and future potential distribution of these six focal species, (ii) reported on the disease status of Eleutherodactylus johnstonei and Phyllodytes luteolus, and (iii) quantified the acoustic overlap of P. luteolus and Leptodactylus labyrinthicus with three co-occurring native species. Our models indicated that all six invasive species could potentially expand their ranges in Brazil within the next few decades. In addition, our SDMs predicted important expansions in available habitat for 2 out of 6 invasive species under future (2100) climatic conditions. We detected high acoustic niche overlap between invasive and native amphibian species, underscoring that acoustic interference might reduce mating success in local frogs. Despite the American bullfrog Lithobates catesbeianus being recognized as a potential reservoir for the frog-killing fungus Batrachochytrium dendrobatidis (Bd) in Brazil, we did not detect Bd in the recently introduced population of E. johnstonei and P. luteolus in the State of São Paulo. We emphasize that the number of invasive amphibian species in Brazil is increasing exponentially, highlighting the urgent need to monitor and control these populations and decrease potential impacts on the locally biodiverse wildlife.
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Affiliation(s)
- Lucas Rodriguez Forti
- Laboratório Multiusuário de Bioacústica (LMBio) and Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - C. Guilherme Becker
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, Alabama, United States of America
| | - Leandro Tacioli
- Laboratório Multiusuário de Bioacústica (LMBio) and Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Vânia Rosa Pereira
- Centro de Pesquisas Meteorológicas e Climáticas Aplicadas à Agricultura (CEPAGRI), Universidade Estadual de Campinas, Cidade Universitária Zeferino Vaz, Campinas, São Paulo, Brazil
| | - André Cid F. A. Santos
- Pontifícia Universidade Católica de São Paulo, Praça Dr. Ermírio de Morais, Sorocaba, São Paulo, Brazil
| | - Igor Oliveira
- Laboratório Multiusuário de Bioacústica (LMBio) and Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
| | - Célio F. B. Haddad
- Departamento de Zoologia, Instituto de Biociências, Universidade Estadual de Paulista, Rio Claro, São Paulo, Brazil
| | - Luís Felipe Toledo
- Laboratório Multiusuário de Bioacústica (LMBio) and Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo, Brazil
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Gervasi SS, Stephens PR, Hua J, Searle CL, Xie GY, Urbina J, Olson DH, Bancroft BA, Weis V, Hammond JI, Relyea RA, Blaustein AR. Linking Ecology and Epidemiology to Understand Predictors of Multi-Host Responses to an Emerging Pathogen, the Amphibian Chytrid Fungus. PLoS One 2017; 12:e0167882. [PMID: 28095428 PMCID: PMC5240985 DOI: 10.1371/journal.pone.0167882] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 11/22/2016] [Indexed: 12/12/2022] Open
Abstract
Variation in host responses to pathogens can have cascading effects on populations and communities when some individuals or groups of individuals display disproportionate vulnerability to infection or differ in their competence to transmit infection. The fungal pathogen, Batrachochytrium dendrobatidis (Bd) has been detected in almost 700 different amphibian species and is implicated in numerous global amphibian population declines. Identifying key hosts in the amphibian-Bd system–those who are at greatest risk or who pose the greatest risk for others–is challenging due in part to many extrinsic environmental factors driving spatiotemporal Bd distribution and context-dependent host responses to Bd in the wild. One way to improve predictive risk models and generate testable mechanistic hypotheses about vulnerability is to complement what we know about the spatial epidemiology of Bd with data collected through comparative experimental studies. We used standardized pathogen challenges to quantify amphibian survival and infection trajectories across 20 post-metamorphic North American species raised from eggs. We then incorporated trait-based models to investigate the predictive power of phylogenetic history, habitat use, and ecological and life history traits in explaining responses to Bd. True frogs (Ranidae) displayed the lowest infection intensities, whereas toads (Bufonidae) generally displayed the greatest levels of mortality after Bd exposure. Affiliation with ephemeral aquatic habitat and breadth of habitat use were strong predictors of vulnerability to and intensity of infection and several other traits including body size, lifespan, age at sexual maturity, and geographic range also appeared in top models explaining host responses to Bd. Several of the species examined are highly understudied with respect to Bd such that this study represents the first experimental susceptibility data. Combining insights gained from experimental studies with observations of landscape-level disease prevalence may help explain current and predict future pathogen dynamics in the Bd system.
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Affiliation(s)
- Stephanie S. Gervasi
- Monell Chemical Senses Center, Philadelphia, Pennsylvania, United States of America
- * E-mail:
| | - Patrick R. Stephens
- Odum School of Ecology, University of Georgia, Athens, Georgia, United States of America
| | - Jessica Hua
- Biological Sciences Department, Binghamton University, Binghamton, New York, United States of America
| | - Catherine L. Searle
- Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America
| | - Gisselle Yang Xie
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - Jenny Urbina
- Environmental Sciences Graduate Program, Oregon State University, Corvallis, Oregon, United States of America
| | - Deanna H. Olson
- United States Forest Service, Pacific Northwest Research Station, Corvallis, Oregon, United States of America
| | - Betsy A. Bancroft
- Biology Department, Gonzaga University, Spokane, Washington, United States of America
| | - Virginia Weis
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
| | - John I. Hammond
- Department of Biology, University of New Mexico, Albuquerque, New Mexico, United States of America
| | - Rick A. Relyea
- Department of Biological Sciences, Rensselaer Polytechnic Institute, Troy, New York, United States of America
| | - Andrew R. Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, Oregon, United States of America
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