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Rothstein AP, Byrne AQ, Knapp RA, Briggs CJ, Voyles J, Richards-Zawacki CL, Rosenblum EB. Divergent regional evolutionary histories of a devastating global amphibian pathogen. Proc Biol Sci 2021; 288:20210782. [PMID: 34157877 PMCID: PMC8220259 DOI: 10.1098/rspb.2021.0782] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
Emerging infectious diseases are a pressing threat to global biological diversity. Increased incidence and severity of novel pathogens underscores the need for methodological advances to understand pathogen emergence and spread. Here, we use genetic epidemiology to test, and challenge, key hypotheses about a devastating zoonotic disease impacting amphibians globally. Using an amplicon-based sequencing method and non-invasive samples we retrospectively explore the history of the fungal pathogen Batrachochytrium dendrobatidis (Bd) in two emblematic amphibian systems: the Sierra Nevada of California and Central Panama. The hypothesis in both regions is the hypervirulent Global Panzootic Lineage of Bd (BdGPL) was recently introduced and spread rapidly in a wave-like pattern. Our data challenge this hypothesis by demonstrating similar epizootic signatures can have radically different underlying evolutionary histories. In Central Panama, our genetic data confirm a recent and rapid pathogen spread. However, BdGPL in the Sierra Nevada has remarkable spatial structuring, high genetic diversity and a relatively older history inferred from time-dated phylogenies. Thus, this deadly pathogen lineage may have a longer history in some regions than assumed, providing insights into its origin and spread. Overall, our results highlight the importance of integrating observed wildlife die-offs with genetic data to more accurately reconstruct pathogen outbreaks.
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Affiliation(s)
- Andrew P Rothstein
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA.,Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
| | - Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA.,Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA.,Center for Conservation Genomics, Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA
| | - Roland A Knapp
- Sierra Nevada Aquatic Research Laboratory, University of California, Mammoth Lakes, CA, USA.,Earth Research Institute, University of California, Santa Barbara, CA, USA
| | - Cheryl J Briggs
- Earth Research Institute, University of California, Santa Barbara, CA, USA.,Department of Ecology, Evolution, and Marine Biology, University of California, Santa Barbara, CA, USA
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV, USA
| | | | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California Berkeley, Berkeley, CA, USA.,Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, CA, USA
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52
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Sheets CN, Schmidt DR, Hurtado PJ, Byrne AQ, Rosenblum EB, Richards-Zawacki CL, Voyles J. Thermal Performance Curves of Multiple Isolates of Batrachochytrium dendrobatidis, a Lethal Pathogen of Amphibians. Front Vet Sci 2021; 8:687084. [PMID: 34239916 PMCID: PMC8258153 DOI: 10.3389/fvets.2021.687084] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2021] [Accepted: 05/20/2021] [Indexed: 11/13/2022] Open
Abstract
Emerging infectious disease is a key factor in the loss of amphibian diversity. In particular, the disease chytridiomycosis has caused severe declines around the world. The lethal fungal pathogen that causes chytridiomycosis, Batrachochytrium dendrobatidis (Bd), has affected amphibians in many different environments. One primary question for researchers grappling with disease-induced losses of amphibian biodiversity is what abiotic factors drive Bd pathogenicity in different environments. To study environmental influences on Bd pathogenicity, we quantified responses of Bd phenotypic traits (e.g., viability, zoospore densities, growth rates, and carrying capacities) over a range of environmental temperatures to generate thermal performance curves. We selected multiple Bd isolates that belong to a single genetic lineage but that were collected across a latitudinal gradient. For the population viability, we found that the isolates had similar thermal optima at 21°C, but there was considerable variation among the isolates in maximum viability at that temperature. Additionally, we found the densities of infectious zoospores varied among isolates across all temperatures. Our results suggest that temperatures across geographic point of origin (latitude) may explain some of the variation in Bd viability through vertical shifts in maximal performance. However, the same pattern was not evident for other reproductive parameters (zoospore densities, growth rates, fecundity), underscoring the importance of measuring multiple traits to understand variation in pathogen responses to environmental conditions. We suggest that variation among Bd genetic variants due to environmental factors may be an important determinant of disease dynamics for amphibians across a range of diverse environments.
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Affiliation(s)
- Ciara N Sheets
- Department of Biology, University of Nevada, Reno, NV, United States
| | - Deena R Schmidt
- Department of Mathematics and Statistics, University of Nevada, Reno, NV, United States
| | - Paul J Hurtado
- Department of Mathematics and Statistics, University of Nevada, Reno, NV, United States
| | - Allison Q Byrne
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, United States.,Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy, and Management, University of California, Berkeley, Berkeley, CA, United States.,Museum of Vertebrate Zoology, University of California, Berkeley, Berkeley, CA, United States
| | | | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV, United States
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53
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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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54
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Bie J, Zheng K, Gao X, Liu B, Ma J, Hayat MA, Xiao J, Wang H. Spatial Risk Analysis of Batrachochytrium dendrobatidis, A Global Emerging Fungal Pathogen. ECOHEALTH 2021; 18:3-12. [PMID: 34212260 DOI: 10.1007/s10393-021-01519-x] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Revised: 01/21/2021] [Accepted: 03/02/2021] [Indexed: 06/13/2023]
Abstract
Chytridiomycosis, a leading cause for the global decline in the number of amphibians, is caused by the fungal pathogen Batrachochytrium dendrobatidis. In this study, global distribution data of B. dendrobatidis were collected from January 2009 to May 2019. Space-time scan statistics and the maximum entropy (MaxEnt) model were used to analyze the epidemic trends and aggregation of the pathogen, and predict B. dendrobatidis distribution through its relationships with climate factors, wind speed, and solar radiation. The results of space-time scan statistics show seven clusters of data for the distribution of B. dendrobatidis. The time was mainly concentrated in 2009, 2013, 2015, and 2016, and the regions were primarily concentrated in southeastern Canada, southwestern France, Nigeria, Cameroon, eastern Brazil, southeastern Brazil, central Madagascar, and central and eastern Australia. MaxEnt showed that annual precipitation had the largest contribution percentage in the model, and annual mean temperature highly influenced the distribution of B. dendrobatidis. The global high-risk areas of B. dendrobatidis distribution were mainly observed in western Canada, southern Brazil, Chile, the United Kingdom, Japan, the Republic of Korea, eastern South Africa, eastern Madagascar, southeastern Australia, and southern China.
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Affiliation(s)
- Jia Bie
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Keren Zheng
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Xiang Gao
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Boyang Liu
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Jun Ma
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Muhammad Abid Hayat
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Jianhua Xiao
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China
| | - Hongbin Wang
- Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, College of Veterinary Medicine, Northeast Agricultural University, 600 Changjiang Road, Harbin, 150030, People's Republic of China.
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55
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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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56
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Neal KM, Fisher RN, Mitrovich MJ, Shaffer HB. Conservation Genomics of the Threatened Western Spadefoot, Spea hammondii, in Urbanized Southern California. J Hered 2021; 111:613-627. [PMID: 33245338 DOI: 10.1093/jhered/esaa049] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Revised: 02/17/2020] [Accepted: 11/19/2020] [Indexed: 11/14/2022] Open
Abstract
Populations of the western spadefoot (Spea hammondii) in southern California occur in one of the most urbanized and fragmented landscapes on the planet and have lost up to 80% of their native habitat. Orange County is one of the last strongholds for this pond-breeding amphibian in the region, and ongoing restoration efforts targeting S. hammondii have involved habitat protection and the construction of artificial breeding ponds. These efforts have successfully increased breeding activity, but genetic characterization of the populations, including estimates of effective population size and admixture between the gene pools of constructed artificial and natural ponds, has never been undertaken. Using thousands of genome-wide single-nucleotide polymorphisms, we characterized the population structure, genetic diversity, and genetic connectivity of spadefoots in Orange County to guide ongoing and future management efforts. We identified at least 2, and possibly 3 major genetic clusters, with additional substructure within clusters indicating that individual ponds are often genetically distinct. Estimates of landscape resistance suggest that ponds on either side of the Los Angeles Basin were likely interconnected historically, but intense urban development has rendered them essentially isolated, and the resulting risk of interruption to natural metapopulation dynamics appears to be high. Resistance surfaces show that the existing artificial ponds were well-placed and connected to natural populations by low-resistance corridors. Toad samples from all ponds (natural and artificial) returned extremely low estimates of effective population size, possibly due to a bottleneck caused by a recent multi-year drought. Management efforts should focus on maintaining gene flow among natural and artificial ponds by both assisted migration and construction of new ponds to bolster the existing pond network in the region.
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Affiliation(s)
- Kevin M Neal
- Department of Ecology and Evolutionary Biology, and La Kretz Center for California Conservation Science, University of California Los Angeles, Los Angeles, CA
| | - Robert N Fisher
- Western Ecological Research Center, U.S. Geological Survey, San Diego, CA
| | | | - H Bradley Shaffer
- Department of Ecology and Evolutionary Biology, and La Kretz Center for California Conservation Science, University of California Los Angeles, Los Angeles, CA
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57
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Ladin ZS, Ferrell B, Dums JT, Moore RM, Levia DF, Shriver WG, D'Amico V, Trammell TLE, Setubal JC, Wommack KE. Assessing the efficacy of eDNA metabarcoding for measuring microbial biodiversity within forest ecosystems. Sci Rep 2021; 11:1629. [PMID: 33452291 PMCID: PMC7811025 DOI: 10.1038/s41598-020-80602-9] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2020] [Accepted: 12/11/2020] [Indexed: 01/29/2023] Open
Abstract
We investigated the nascent application and efficacy of sampling and sequencing environmental DNA (eDNA) in terrestrial environments using rainwater that filters through the forest canopy and understory vegetation (i.e., throughfall). We demonstrate the utility and potential of this method for measuring microbial communities and forest biodiversity. We collected pure rainwater (open sky) and throughfall, successfully extracted DNA, and generated over 5000 unique amplicon sequence variants. We found that several taxa including Mycoplasma sp., Spirosoma sp., Roseomonas sp., and Lactococcus sp. were present only in throughfall samples. Spiroplasma sp., Methylobacterium sp., Massilia sp., Pantoea sp., and Sphingomonas sp. were found in both types of samples, but more abundantly in throughfall than in rainwater. Throughfall samples contained Gammaproteobacteria that have been previously found to be plant-associated, and may contribute to important functional roles. We illustrate how this novel method can be used for measuring microbial biodiversity in forest ecosystems, foreshadowing the utility for quantifying both prokaryotic and eukaryotic lifeforms. Leveraging these methods will enhance our ability to detect extant species, describe new species, and improve our overall understanding of ecological community dynamics in forest ecosystems.
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Affiliation(s)
- Zachary S Ladin
- Department of Plant and Soil Sciences, University of Delaware, 264 Townsend Hall, Newark, DE, 19716, USA.
| | - Barbra Ferrell
- Department of Plant and Soil Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE, 19716, USA
| | - Jacob T Dums
- Biotechnology Program, North Carolina State University, Raleigh, NC, 27695, USA
| | - Ryan M Moore
- Department of Plant and Soil Sciences, Delaware Biotechnology Institute, University of Delaware, Newark, DE, 19716, USA
| | - Delphis F Levia
- Department of Entomology and Wildlife Ecology, University of Delaware, 250 Townsend Hall, Newark, DE, 19716, USA
| | - W Gregory Shriver
- Departments of Geography and Spatial Sciences and Plant and Soil Sciences, University of Delaware, 216C Pearson Hall, Newark, DE, 19716, USA
| | - Vincent D'Amico
- US Forest Service, Northern Research Station, Newark, DE, USA
| | - Tara L E Trammell
- Department of Plant and Soil Sciences, University of Delaware, 264 Townsend Hall, Newark, DE, 19716, USA
| | - João Carlos Setubal
- Instituto de Química, University of Sao Paulo, São Paulo, SP, 05508-000, Brazil
| | - K Eric Wommack
- Department of Plant and Soil Sciences, University of Delaware, 264 Townsend Hall, Newark, DE, 19716, USA
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58
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Matthews E, Ellison A, Cable J. Saprolegnia parasitica zoospore activity and host survival indicates isolate variation in host preference. Fungal Biol 2020; 125:260-268. [PMID: 33766304 DOI: 10.1016/j.funbio.2020.11.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 11/09/2020] [Accepted: 11/12/2020] [Indexed: 11/18/2022]
Abstract
The ubiquitous freshwater pathogen Saprolegnia parasitica has long been considered a true generalist, capable of infecting a wide range of fish species. It remains unclear, however, whether different isolates of this pathogen, obtained from distinct geographic locations and host species, display differences in host preference. To assess this, the current study examined the induced zoospore encystment responses of four S. parasitica isolates towards the skin of four fish species. While three of the isolates displayed 'specialist' responses, one appeared to be more of a 'generalist'. In vivo challenge infections involving salmon and sea trout with the 'generalist' (salmon isolate EA001) and a 'specialist' (sea trout isolate EA016) pathogen, however, did not support the in vitro findings, with no apparent host preference reflected in infection outcomes. Survival of sea trout and salmon though was significantly different following a challenge infection with the sea trout (EA016) isolate. These results indicate that while S. parasitica isolates can be considered true generalists, they may target hosts to which they have been more frequently exposed (potential local adaptation). Understanding host preference of this pathogen could aid our understanding of infection epidemics and help with the development of fish management procedures.
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Affiliation(s)
- Emily Matthews
- School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK
| | - Amy Ellison
- School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK; School of Natural Sciences, Bangor University, Environment Centre Wales, Bangor, Gwynedd, LL57 2UW, UK
| | - Joanne Cable
- School of Biosciences, Cardiff University, Cardiff, CF10 3AX, UK.
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59
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Amphibian Infection Risk Changes with Host Life Stage and across a Landscape Gradient. J HERPETOL 2020. [DOI: 10.1670/19-107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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60
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Robinson KA, Dunn M, Hussey SP, Fritz-Laylin LK. Identification of antibiotics for use in selection of the chytrid fungi Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans. PLoS One 2020; 15:e0240480. [PMID: 33079945 PMCID: PMC7575076 DOI: 10.1371/journal.pone.0240480] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Accepted: 09/25/2020] [Indexed: 11/21/2022] Open
Abstract
Global amphibian populations are being decimated by chytridiomycosis, a deadly skin infection caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal). Although ongoing efforts are attempting to limit the spread of these infections, targeted treatments are necessary to manage the disease. Currently, no tools for genetic manipulation are available to identify and test specific drug targets in these fungi. To facilitate the development of genetic tools in Bd and Bsal, we have tested five commonly used antibiotics with available resistance genes: Hygromycin, Blasticidin, Puromycin, Zeocin, and Neomycin. We have identified effective concentrations of each for selection in both liquid culture and on solid media. These concentrations are within the range of concentrations used for selecting genetically modified cells from a variety of other eukaryotic species.
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Affiliation(s)
- Kristyn A. Robinson
- Department of Biology, The University of Massachusetts Amherst, Amherst, MA, United States of America
| | - Mallory Dunn
- Department of Biology, The University of Massachusetts Amherst, Amherst, MA, United States of America
| | - Shane P. Hussey
- Department of Biology, The University of Massachusetts Amherst, Amherst, MA, United States of America
| | - Lillian K. Fritz-Laylin
- Department of Biology, The University of Massachusetts Amherst, Amherst, MA, United States of America
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61
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Grogan LF, Humphries JE, Robert J, Lanctôt CM, Nock CJ, Newell DA, McCallum HI. Immunological Aspects of Chytridiomycosis. J Fungi (Basel) 2020; 6:jof6040234. [PMID: 33086692 PMCID: PMC7712659 DOI: 10.3390/jof6040234] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2020] [Revised: 10/14/2020] [Accepted: 10/15/2020] [Indexed: 12/27/2022] Open
Abstract
Amphibians are currently the most threatened vertebrate class, with the disease chytridiomycosis being a major contributor to their global declines. Chytridiomycosis is a frequently fatal skin disease caused by the fungal pathogens Batrachochytrium dendrobatidis (Bd) and Batrachochytrium salamandrivorans (Bsal). The severity and extent of the impact of the infection caused by these pathogens across modern Amphibia are unprecedented in the history of vertebrate infectious diseases. The immune system of amphibians is thought to be largely similar to that of other jawed vertebrates, such as mammals. However, amphibian hosts are both ectothermic and water-dependent, which are characteristics favouring fungal proliferation. Although amphibians possess robust constitutive host defences, Bd/Bsal replicate within host cells once these defences have been breached. Intracellular fungal localisation may contribute to evasion of the induced innate immune response. Increasing evidence suggests that once the innate defences are surpassed, fungal virulence factors suppress the targeted adaptive immune responses whilst promoting an ineffectual inflammatory cascade, resulting in immunopathology and systemic metabolic disruption. Thus, although infections are contained within the integument, crucial homeostatic processes become compromised, leading to mortality. In this paper, we present an integrated synthesis of amphibian post-metamorphic immunological responses and the corresponding outcomes of infection with Bd, focusing on recent developments within the field and highlighting future directions.
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Affiliation(s)
- Laura F. Grogan
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Southport, QLD 4222, Australia;
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia; (J.E.H.); (D.A.N.)
- Correspondence:
| | - Josephine E. Humphries
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia; (J.E.H.); (D.A.N.)
| | - Jacques Robert
- University of Rochester Medical Center, Rochester, NY 14642, USA;
| | - Chantal M. Lanctôt
- Australian Rivers Institute, Griffith University, Southport, QLD 4222, Australia;
| | - Catherine J. Nock
- Southern Cross Plant Science, Southern Cross University, Lismore, NSW 2480, Australia;
| | - David A. Newell
- Forest Research Centre, School of Environment, Science and Engineering, Southern Cross University, Lismore, NSW 2480, Australia; (J.E.H.); (D.A.N.)
| | - Hamish I. McCallum
- Environmental Futures Research Institute and School of Environment and Science, Griffith University, Southport, QLD 4222, Australia;
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62
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Rodriguez KM, Voyles J. The amphibian complement system and chytridiomycosis. JOURNAL OF EXPERIMENTAL ZOOLOGY PART 2020; 333:706-719. [PMID: 33052039 PMCID: PMC7821119 DOI: 10.1002/jez.2419] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/31/2020] [Revised: 08/26/2020] [Accepted: 09/24/2020] [Indexed: 12/26/2022]
Abstract
Understanding host immune function and ecoimmunology is increasingly important at a time when emerging infectious diseases (EIDs) threaten wildlife. One EID that has emerged and spread widely in recent years is chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which is implicated unprecedented amphibian declines around the world. The impacts of Bd have been severe for many amphibian species, but some populations have exhibited signs of persistence, and even recovery, in some regions. Many mechanisms may underpin this pattern and amphibian immune responses are likely one key component. Although we have made great strides in understanding amphibian immunity, the complement system remains poorly understood. The complement system is a nonspecific, innate immune defense that is known to enhance other immune responses. Complement activation can occur by three different biochemical pathways and result in protective mechanisms, such as inflammation, opsonization, and pathogen lysis, thereby providing protection to the host. We currently lack an understanding of complement pathway activation for chytridiomycosis, but several studies have suggested that it may be a key part of an early and robust immune response that confers host resistance. Here, we review the available research on the complement system in general as well as amphibian complement responses to Bd infection. Additionally, we propose future research directions that will increase our understanding of the amphibian complement system and other immune responses to Bd. Finally, we suggest how a deeper understanding of amphibian immunity could enhance the conservation and management of amphibian species that are threatened by chytridiomycosis.
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Affiliation(s)
| | - Jamie Voyles
- Department of Biology, University of Nevada-Reno, Reno, Nevada, USA
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63
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A historical overview of Batrachochytrium dendrobatidis infection from specimens at the National Zoological Collection Suriname. PLoS One 2020; 15:e0239220. [PMID: 33006994 PMCID: PMC7531862 DOI: 10.1371/journal.pone.0239220] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 09/01/2020] [Indexed: 11/19/2022] Open
Abstract
The amphibian skin disease chytridiomycosis, caused by the pathogenetic fungus Batrachochytrium dendrobatidis (Bd) has become one of the major contributors to global amphibian population declines and extinctions. This fungus has spread globally and has caused mortalities in nearly every continent. In South America, Suriname, Guyana and Paraguay are among the remaining three countries where Bd has not been detected to date. To complete the assessment of the possible presence of Bd in Suriname, 205 specimens from the Zoological Collection of Suriname, compromising 6 frog families and 15 genera were sampled for chytrid fungus. No specimens were found to be infected by this fungus and as such the outcome strengthens the previous result of field sampling that there is no support that Bd has spread to Suriname.
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Abstract
This article updates the understanding of two extirpation-driving infectious diseases, Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, and Ranavirus. Experimental studies and dynamic, multifactorial population modeling have outlined the epidemiology and future population impacts of B dendrobatidis, B salamandrivorans, and Ranavirus. New genomic findings on divergent fungal and viral pathogens can help optimize control and disease management strategies. Although there have been major advances in knowledge of amphibian pathogens, controlled studies are needed to guide population recovery to elucidate and evaluate transmission routes for several pathogens, examine environmental control, and validate new diagnostic tools to confirm the presence of disease.
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65
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Martinson VG. Rediscovering a Forgotten System of Symbiosis: Historical Perspective and Future Potential. Genes (Basel) 2020; 11:E1063. [PMID: 32916942 PMCID: PMC7563122 DOI: 10.3390/genes11091063] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2020] [Revised: 08/31/2020] [Accepted: 09/07/2020] [Indexed: 12/27/2022] Open
Abstract
While the majority of symbiosis research is focused on bacteria, microbial eukaryotes play important roles in the microbiota and as pathogens, especially the incredibly diverse Fungi kingdom. The recent emergence of widespread pathogens in wildlife (bats, amphibians, snakes) and multidrug-resistant opportunists in human populations (Candida auris) has highlighted the importance of better understanding animal-fungus interactions. Regardless of their prominence there are few animal-fungus symbiosis models, but modern technological advances are allowing researchers to utilize novel organisms and systems. Here, I review a forgotten system of animal-fungus interactions: the beetle-fungus symbioses of Drugstore and Cigarette beetles with their symbiont Symbiotaphrina. As pioneering systems for the study of mutualistic symbioses, they were heavily researched between 1920 and 1970, but have received only sporadic attention in the past 40 years. Several features make them unique research organisms, including (1) the symbiont is both extracellular and intracellular during the life cycle of the host, and (2) both beetle and fungus can be cultured in isolation. Specifically, fungal symbionts intracellularly infect cells in the larval and adult beetle gut, while accessory glands in adult females harbor extracellular fungi. In this way, research on the microbiota, pathogenesis/infection, and mutualism can be performed. Furthermore, these beetles are economically important stored-product pests found worldwide. In addition to providing a historical perspective of the research undertaken and an overview of beetle biology and their symbiosis with Symbiotaphrina, I performed two analyses on publicly available genomic data. First, in a preliminary comparative genomic analysis of the fungal symbionts, I found striking differences in the pathways for the biosynthesis of two B vitamins important for the host beetle, thiamine and biotin. Second, I estimated the most recent common ancestor for Drugstore and Cigarette beetles at 8.8-13.5 Mya using sequence divergence (CO1 gene). Together, these analyses demonstrate that modern methods and data (genomics, transcriptomes, etc.) have great potential to transform these beetle-fungus systems into model systems again.
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Affiliation(s)
- Vincent G Martinson
- Department of Biology, MSC03 2020, 1 University of New Mexico, Albuquerque, NM 87131-0001, USA
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66
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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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Castro Monzon F, Rödel MO, Jeschke JM. Tracking Batrachochytrium dendrobatidis Infection Across the Globe. ECOHEALTH 2020; 17:270-279. [PMID: 33201333 PMCID: PMC7719156 DOI: 10.1007/s10393-020-01504-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2019] [Revised: 09/21/2020] [Accepted: 09/21/2020] [Indexed: 05/17/2023]
Abstract
Infection records of Batrachochytrium dendrobatidis (Bd), a pathogen that has devastated amphibian populations worldwide, have rapidly increased since the pathogen's discovery. Dealing with so many records makes it difficult to (a) know where, when and in which species infections have been detected, (b) understand how widespread and pervasive Bd is and (c) prioritize study and management areas. We conducted a systematic review of papers and compiled a database with Bd infection records. Our dataset covers 71 amphibian families and 119 countries. The data revealed how widespread and adaptable Bd is, being able to infect over 50% of all tested amphibian species, with over 1000 confirmed host species and being present in 86 countries. The distribution of infected species is uneven among and within countries. Areas where the distributions of many infected species overlap are readily visible; these are regions where Bd likely develops well. Conversely, areas where the distributions of species that tested negative overlap, such as the Atlantic Coast in the USA, suggest the presence of Bd refuges. Finally, we report how the number of tested and infected species has changed through time, and provide a list of oldest detection records per country.
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Affiliation(s)
- Federico Castro Monzon
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, 14195, Berlin, Germany.
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany.
- Berlin-Brandenburg Institute of Advanced Biodiversity Research, Königin-Luise-Str. 2-4, 14195, Berlin, Germany.
| | - Mark-Oliver Rödel
- Berlin-Brandenburg Institute of Advanced Biodiversity Research, Königin-Luise-Str. 2-4, 14195, Berlin, Germany
- Museum für Naturkunde - Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, 10115, Berlin, Germany
| | - Jonathan M Jeschke
- Institute of Biology, Freie Universität Berlin, Königin-Luise-Str. 1-3, 14195, Berlin, Germany
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Müggelseedamm 310, 12587, Berlin, Germany
- Berlin-Brandenburg Institute of Advanced Biodiversity Research, Königin-Luise-Str. 2-4, 14195, Berlin, Germany
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Rollins-Smith LA. Global Amphibian Declines, Disease, and the Ongoing Battle between Batrachochytrium Fungi and the Immune System. HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.178] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Louise A. Rollins-Smith
- Departments of Pathology, Microbiology and Immunology and Pediatrics, Vanderbilt University School of Medicine, Nashville, TN 37232, USA Department of Biological Sciences, Vanderbilt University, Nashville, TN 37235, USA
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Bienentreu JF, Lesbarrères D. Amphibian Disease Ecology: Are We Just Scratching the Surface? HERPETOLOGICA 2020. [DOI: 10.1655/0018-0831-76.2.153] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
| | - David Lesbarrères
- Department of Biology, Laurentian University, Sudbury, ON P3E 2C6, Canada
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70
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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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71
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Ribeiro JW, Siqueira T, DiRenzo GV, Lambertini C, Lyra ML, Toledo LF, Haddad CFB, Becker CG. Assessing amphibian disease risk across tropical streams while accounting for imperfect pathogen detection. Oecologia 2020; 193:237-248. [DOI: 10.1007/s00442-020-04646-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Accepted: 04/07/2020] [Indexed: 12/23/2022]
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DiRenzo GV, Chen R, Ibsen K, Toothman M, Miller AJ, Gershman A, Mitragotri S, Briggs CJ. Investigating the potential use of an ionic liquid (1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide) as an anti-fungal treatment against the amphibian chytrid fungus, Batrachochytrium dendrobatidis. PLoS One 2020; 15:e0231811. [PMID: 32302369 PMCID: PMC7164615 DOI: 10.1371/journal.pone.0231811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Accepted: 04/01/2020] [Indexed: 11/19/2022] Open
Abstract
The disease chytridiomycosis, caused by the pathogenic chytrid fungus, Batrachochytrium dendrobatidis (Bd), has contributed to global amphibian declines. Bd infects the keratinized epidermal tissue in amphibians and causes hyperkeratosis and excessive skin shedding. In individuals of susceptible species, the regulatory function of the amphibian’s skin is disrupted resulting in an electrolyte depletion, osmotic imbalance, and eventually death. Safe and effective treatments for chytridiomycosis are urgently needed to control chytrid fungal infections and stabilize populations of endangered amphibian species in captivity and in the wild. Currently, the most widely used anti-Bd treatment is itraconazole. Preparations of itraconazole formulated for amphibian use has proved effective, but treatment involves short baths over seven to ten days, a process which is logistically challenging, stressful, and causes long-term health effects. Here, we explore a novel anti-fungal therapeutic using a single application of the ionic liquid, 1-Butyl-1-methylpyrrolidinium bis(trifluoromethylsulfonyl)imide (BMP-NTf2), for the treatment of chytridiomycosis. BMP-NTf2 was found be effective at killing Bd in vitro at low concentrations (1:1000 dilution). We tested BMP-NTf2 in vivo on two amphibian species, one that is relatively tolerant of chytridiomycosis (Pseudacris regilla) and one that is highly susceptible (Dendrobates tinctorius). A toxicity trial revealed a surprising interaction between Bd infection status and the impact of BMP-NTf2 on D. tinctorius survival. Uninfected D. tinctorius tolerated BMP-NTf2 (mean ± SE; 96.01 ± 9.00 μl/g), such that only 1 out of 30 frogs died following treatment (at a dose of 156.95 μL/g), whereas, a lower dose (mean ± SE; 97.45 ± 3.52 μL/g) was not tolerated by Bd-infected D. tinctorius, where 15 of 23 frogs died shortly upon BMP-NTf2 application. Those that tolerated the BMP-NTf2 application did not exhibit Bd clearance. Thus, BMP-NTf2 application, under the conditions tested here, is not a suitable option for clearing Bd infection in D. tinctorius. However, different results were obtained for P. regilla. Two topical applications of BMP-NTf2 on Bd-infected P. regilla (using a lower BMP-NTf2 dose than on D. tinctorius, mean ± SE; 9.42 ± 1.43 μL/g) reduced Bd growth, although the effect was lower than that obtained by daily doses of itracanozole (50% frogs exhibited complete clearance on day 16 vs. 100% for itracanozole). Our findings suggest that BMP-NTf2 has the potential to treat Bd infection, however the effect depends on several parameters. Further optimization of dose and schedule are needed before BMP-NTf2 can be considered as a safe and effective alternative to more conventional antifungal agents, such as itraconazole.
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Affiliation(s)
- Graziella V. DiRenzo
- Department of Ecology, Evolution, & Marine Biology, University of California, Santa Barbara, CA, United States of America
- * E-mail:
| | - Renwei Chen
- Center for Bioengineering, University of California, Santa Barbara, CA, United States of America
| | - Kelly Ibsen
- Center for Bioengineering, University of California, Santa Barbara, CA, United States of America
- Department of Chemical Engineering, University of California, Santa Barbara, CA, United States of America
- School of Engineering and Applied Sciences, Harvard University Cambridge, Cambridge, MA, United States of America
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States of America
| | - Mary Toothman
- Department of Ecology, Evolution, & Marine Biology, University of California, Santa Barbara, CA, United States of America
| | - Abigail J. Miller
- Department of Ecology, Evolution, & Marine Biology, University of California, Santa Barbara, CA, United States of America
| | - Ariel Gershman
- Department of Ecology, Evolution, & Marine Biology, University of California, Santa Barbara, CA, United States of America
| | - Samir Mitragotri
- Center for Bioengineering, University of California, Santa Barbara, CA, United States of America
- Department of Chemical Engineering, University of California, Santa Barbara, CA, United States of America
- School of Engineering and Applied Sciences, Harvard University Cambridge, Cambridge, MA, United States of America
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Boston, MA, United States of America
| | - Cheryl J. Briggs
- Department of Ecology, Evolution, & Marine Biology, University of California, Santa Barbara, CA, United States of America
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73
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Biobanking in amphibian and reptilian conservation and management: opportunities and challenges. CONSERV GENET RESOUR 2020. [DOI: 10.1007/s12686-020-01142-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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74
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Abstract
Discovering that chytrid fungi cause chytridiomycosis in amphibians represented a paradigm shift in our understanding of how emerging infectious diseases contribute to global patterns of biodiversity loss. In this Review we describe how the use of multidisciplinary biological approaches has been essential to pinpointing the origins of amphibian-parasitizing chytrid fungi, including Batrachochytrium dendrobatidis and Batrachochytrium salamandrivorans, as well as to timing their emergence, tracking their cycles of expansion and identifying the core mechanisms that underpin their pathogenicity. We discuss the development of the experimental methods and bioinformatics toolkits that have provided a fuller understanding of batrachochytrid biology and informed policy and control measures.
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75
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Ohmer MEB, Cramp RL, White CR, Harlow PS, McFadden MS, Merino-Viteri A, Pessier AP, Wu NC, Bishop PJ, Franklin CE. Phylogenetic investigation of skin sloughing rates in frogs: relationships with skin characteristics and disease-driven declines. Proc Biol Sci 2020; 286:20182378. [PMID: 30963925 DOI: 10.1098/rspb.2018.2378] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Amphibian skin is highly variable in structure and function across anurans, and plays an important role in physiological homeostasis and immune defence. For example, skin sloughing has been shown to reduce pathogen loads on the skin, such as the lethal fungus Batrachochytrium dendrobatidis ( Bd), but interspecific variation in sloughing frequency is largely unknown. Using phylogenetic linear mixed models, we assessed the relationship between skin turnover rate, skin morphology, ecological traits and overall evidence of Bd-driven declines. We examined skin sloughing rates in 21 frog species from three continents, as well as structural skin characteristics measured from preserved specimens. We found that sloughing rate varies significantly with phylogenetic group, but was not associated with evidence of Bd-driven declines, or other skin characteristics examined. This is the first comparison of sloughing rate across a wide range of amphibian species, and creates the first database of amphibian sloughing behaviour. Given the strong phylogenetic signal observed in sloughing rate, approximate sloughing rates of related species may be predicted based on phylogenetic position. While not related to available evidence of declines, understanding variation in sloughing rate may help explain differences in the severity of infection in genera with relatively slow skin turnover rates (e.g. Atelopus).
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Affiliation(s)
- Michel E B Ohmer
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia.,2 Department of Biological Sciences, University of Pittsburgh , Pittsburgh, PA 15260 , USA
| | - Rebecca L Cramp
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia
| | - Craig R White
- 3 School of Biological Sciences, Monash University, Centre for Geometric Biology , Victoria 3800 , Australia
| | - Peter S Harlow
- 4 Taronga Conservation Society Australia, Herpetofauna Division , Mosman, New South Wales , Australia
| | - Michael S McFadden
- 4 Taronga Conservation Society Australia, Herpetofauna Division , Mosman, New South Wales , Australia
| | - Andrés Merino-Viteri
- 5 Laboratorio de Ecofisiología/Museo de Zoología (QCAZ), Escuela de Ciencias Biológicas, Pontificia Universidad Católica del Ecuador , Quito , Ecuador
| | - Allan P Pessier
- 6 Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University , Pullman, WA 99164 , USA
| | - Nicholas C Wu
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia
| | - Phillip J Bishop
- 7 Department of Zoology, University of Otago , Dunedin , New Zealand
| | - Craig E Franklin
- 1 School of Biological Sciences, The University of Queensland , St Lucia, Queensland 4072 , Australia
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76
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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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77
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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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78
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De León ME, Zumbado-Ulate H, García-Rodríguez A, Alvarado G, Sulaeman H, Bolaños F, Vredenburg VT. Batrachochytrium dendrobatidis infection in amphibians predates first known epizootic in Costa Rica. PLoS One 2019; 14:e0208969. [PMID: 31821326 PMCID: PMC6903748 DOI: 10.1371/journal.pone.0208969] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Accepted: 10/18/2019] [Indexed: 11/19/2022] Open
Abstract
Emerging infectious diseases are a growing threat to biodiversity worldwide. Outbreaks of the infectious disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), are implicated in the decline and extinction of numerous amphibian species. In Costa Rica, a major decline event occurred in 1987, more than two decades before this pathogen was discovered. The loss of many species in Costa Rica is assumed to be due to Bd-epizootics, but there are few studies that provide data from amphibians in the time leading up to the proposed epizootics. In this study, we provide new data on Bd infection rates of amphibians collected throughout Costa Rica, in the decades prior to the epizootics. We used a quantitative PCR assay to test for Bd presence in 1016 anuran museum specimens collected throughout Costa Rica. The earliest specimen that tested positive for Bd was collected in 1964. Across all time periods, we found an overall infection rate (defined as the proportion of Bd-positive individuals) of 4%. The number of infected individuals remained relatively low across all species tested and the range of Bd-positive specimens was shown to be geographically constrained up until the 1980s; when epizootics are hypothesized to have occurred. After that time, infection rate increased three-fold, and the range of specimens tested positive for Bd increased, with Bd-positive specimens collected across the entire country. Our results suggest that Bd dynamics in Costa Rica are more complicated than previously thought. The discovery of Bd's presence in the country preceding massive declines leads to a number of different hypotheses: 1) Bd invaded Costa Rica earlier than previously known, and spread more slowly than previously reported; 2) Bd invaded multiple times and faded out; 3) an endemic Bd lineage existed; 4) an earlier Bd lineage evolved into the current Bd lineage or hybridized with an invasive lineage; or 5) an earlier Bd lineage went extinct and a new invasion event occurred causing epizootics. To help visualize areas where future studies should take place, we provide a Bd habitat suitability model trained with local data. Studies that provide information on genetic lineages of Bd are needed to determine the most plausible spatial-temporal, host-pathogen dynamics that could best explain the epizootics resulting in amphibian declines in Costa Rica and throughout Central America.
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Affiliation(s)
- Marina E. De León
- Department of Microbiology and Molecular genetics, University of California, Davis, United States of America
| | - Héctor Zumbado-Ulate
- Department of Biological Sciences, Purdue University, West Lafayette, IN, United States of America
| | - Adrián García-Rodríguez
- Escuela de Biología, Universidad de Costa Rica, San Pedro, Costa Rica
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Gilbert Alvarado
- Escuela de Biología, Universidad de Costa Rica, San Pedro, Costa Rica
- Faculdade de Medicina Veterinária e Zootecnia, Universidade de São Paulo, São Paulo, Brazil
| | - Hasan Sulaeman
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
| | - Federico Bolaños
- Escuela de Biología, Universidad de Costa Rica, San Pedro, Costa Rica
| | - Vance T. Vredenburg
- Department of Biology, San Francisco State University, San Francisco, California, United States of America
- Museum of Vertebrate Zoology, University of California Berkeley, Berkeley, California, United States of America
- * E-mail:
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79
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LETHAL AND SUBLETHAL AMPHIBIAN HOST RESPONSES TO BATRACHOCHYTRIUM DENDROBATIDIS EXPOSURE ARE DETERMINED BY THE ADDITIVE INFLUENCE OF HOST RESOURCE AVAILABILITY. J Wildl Dis 2019. [PMID: 31769713 DOI: 10.7589/2019-01-021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Host species may differ in their responses to pathogen exposures based on host energy reserves, which could be important for long-term trends in host population growth. Batrachochytrium dendrobatidis (BD) is a pathogen associated with amphibian population declines but also occurs without causing mass mortalities. The impact of BD in populations without associated declines is not well understood, and food abundance could play a role in determining the magnitude of its effects. We exposed American toad (Anaxyrus americanus), northern leopard frog (Lithobates pipiens), and cricket frog (Acris blanchardi) metamorphs to BD under low or high food treatments. Overall, anuran species responded differently to BD exposure and the combined effect of BD exposure and food abundance was additive. American toad survival was lowered by BD exposure and low food availability. Based on these results, we developed a population model for American toads to estimate how reductions in survival could influence population growth. We found that BD could reduce population growth by 14% with high food availability and 21% with low food availability. In contrast, survival of northern leopard frogs was high across all treatments, but their growth was negatively impacted by the additive effects of BD exposure and low food availability. Cricket frog growth and survival were unaffected by BD exposure, suggesting that this species is not sensitive to the effects of this pathogen in terms of growth and survival across environments of different quality in the time period examined. Our results showed that low food availability additively increased the species-specific lethal and sublethal impacts of BD on hosts, which could have implications for long-term host population dynamics.
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80
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Wilkins LGE, Matthews KR, Steel ZL, Nusslé SC, Carlson SM. Population dynamics of
Rana sierrae
at Dusy Basin: influence of non‐native predators, drought, and restoration potential. Ecosphere 2019. [DOI: 10.1002/ecs2.2951] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Affiliation(s)
- Laetitia G. E. Wilkins
- Department of Environmental Science, Policy & Management University of California, Berkeley Berkeley California USA
- Genome and Biomedical Sciences Facility University of California, Davis Davis California USA
| | | | - Zachary L. Steel
- Department of Environmental Science, Policy & Management University of California, Berkeley Berkeley California USA
- Department of Environmental Science & Policy University of California, Davis Davis California USA
| | - Sébastien C. Nusslé
- Department of Environmental Science, Policy & Management University of California, Berkeley Berkeley California USA
| | - Stephanie M. Carlson
- Department of Environmental Science, Policy & Management University of California, Berkeley Berkeley California USA
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81
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Amorim FO, Pimentel LA, Machado LF, Cavalcanti ADC, Napoli MF, Juncá FA. New records of Batrachochytrium dendrobatidis in the state of Bahia, Brazil: histological analysis in anuran amphibian collections. DISEASES OF AQUATIC ORGANISMS 2019; 136:147-155. [PMID: 31621647 DOI: 10.3354/dao03402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Infection caused by the fungus Batrachochytrium dendrobatidis (Bd) produces chytridiomycosis, a disease considered one of the main causes of amphibian population declines in the world. In Brazil, Bd has been recorded in several regions, but mainly in the Atlantic Forest biome. This study aimed to investigate the occurrence of Bd in amphibian species in Bahia State to test the hypothesis that Bd is widespread in other Brazilian biomes. Using histological analysis, we evaluated the skin of 190 anurans of 85 species preserved in herpetological collections. Based on these analyses, the distribution of Bd was extended approximately 400 km to the west, 150 km to the north and 105 km to the east in the state of Bahia. Of the 190 specimens analyzed, Bd infection was diagnosed in 16 individuals, from 14 species, with the earliest record from a specimen collected in 1996 in the Caatinga biome. We identified Bd in 13 adult specimens, including 2 individuals showing suggestive signs of the disease (loss of skin pigmentation). In tadpoles, we recorded fungal structures in the oral region and on the epidermis adjacent to the rows of teeth. The results of this study corroborate the prediction that Bd is widespread in the Atlantic Forest biome, and suggest that it is widespread in the other biomes of the state (Cerrado and Caatinga, at least since 1996). Conservation efforts should involve long-term studies aimed at providing information on the dynamics of the infection, its relationship with its host and its effect on amphibian populations.
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Affiliation(s)
- F O Amorim
- Institute of Biology, Federal University of Bahia - UFBA, Rua Barão de Jeremoabo, s/n, Ondina Campus, CEP 40170-115, Salvador, Bahia, Brazil
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82
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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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83
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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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84
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Bolom‐Huet R, Pineda E, Díaz‐Fleischer F, Muñoz‐Alonso AL, Galindo‐González J. Known and estimated distribution in Mexico of
Batrachochytrium dendrobatidis,
a pathogenic fungus of amphibians. Biotropica 2019. [DOI: 10.1111/btp.12697] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
| | - Eduardo Pineda
- Red de Biología y Conservación de Vertebrados Instituto de Ecología A. C. Xalapa Veracruz México
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85
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Keiser CN, Wantman T, Rebollar EA, Harris RN. Tadpole body size and behaviour alter the social acquisition of a defensive bacterial symbiont. ROYAL SOCIETY OPEN SCIENCE 2019; 6:191080. [PMID: 31598324 PMCID: PMC6774948 DOI: 10.1098/rsos.191080] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 08/01/2019] [Indexed: 05/29/2023]
Abstract
Individual differences in host phenotypes can generate heterogeneity in the acquisition and transmission of microbes. Although this has become a prominent factor of disease epidemiology, host phenotypic variation might similarly underlie the transmission of microbial symbionts that defend against pathogen infection. Here, we test whether host body size and behaviour influence the social acquisition of a skin bacterium, Janthinobacterium lividum, which in some hosts can confer protection against infection by Batrachochytrium dendrobatidis, the causative agent of the amphibian skin disease chytridiomycosis. We measured body size and boldness (time spent in an open field) of green frog tadpoles and haphazardly constructed groups of six individuals. In some groups, we exposed one individual in each group to J. lividum and, in other groups, we inoculated a patch of aquarium pebbles to J. lividum. After 24 h, we swabbed each individual to estimate the presence of J. lividum on their skin. On average, tadpoles acquired nearly four times more bacteria when housed with an exposed individual compared to those housed with a patch of inoculated substrate. When tadpoles were housed with an exposed group-mate, larger and 'bolder' individuals acquired more bacteria. These data suggest that phenotypically biased acquisition of defensive symbionts might generate biased patterns of mortality from the pathogens against which they protect.
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Affiliation(s)
- Carl N. Keiser
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Trina Wantman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA 15260, USA
| | - Eria A. Rebollar
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mor, Mexico
| | - Reid N. Harris
- Amphibian Survival Alliance, London SW7 2HQ, UK
- Department of Biology, James Madison University, Harrisonburg, VA 22807, USA
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86
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Scheele BC, Pasmans F, Skerratt LF, Berger L, Martel A, Beukema W, Acevedo AA, Burrowes PA, Carvalho T, Catenazzi A, De la Riva I, Fisher MC, Flechas SV, Foster CN, Frías-Álvarez P, Garner TWJ, Gratwicke B, Guayasamin JM, Hirschfeld M, Kolby JE, Kosch TA, La Marca E, Lindenmayer DB, Lips KR, Longo AV, Maneyro R, McDonald CA, Mendelson J, Palacios-Rodriguez P, Parra-Olea G, Richards-Zawacki CL, Rödel MO, Rovito SM, Soto-Azat C, Toledo LF, Voyles J, Weldon C, Whitfield SM, Wilkinson M, Zamudio KR, Canessa S. Amphibian fungal panzootic causes catastrophic and ongoing loss of biodiversity. Science 2019; 363:1459-1463. [PMID: 30923224 DOI: 10.1126/science.aav0379] [Citation(s) in RCA: 568] [Impact Index Per Article: 113.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2018] [Accepted: 02/06/2019] [Indexed: 12/18/2022]
Abstract
Anthropogenic trade and development have broken down dispersal barriers, facilitating the spread of diseases that threaten Earth's biodiversity. We present a global, quantitative assessment of the amphibian chytridiomycosis panzootic, one of the most impactful examples of disease spread, and demonstrate its role in the decline of at least 501 amphibian species over the past half-century, including 90 presumed extinctions. The effects of chytridiomycosis have been greatest in large-bodied, range-restricted anurans in wet climates in the Americas and Australia. Declines peaked in the 1980s, and only 12% of declined species show signs of recovery, whereas 39% are experiencing ongoing decline. There is risk of further chytridiomycosis outbreaks in new areas. The chytridiomycosis panzootic represents the greatest recorded loss of biodiversity attributable to a disease.
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Affiliation(s)
- Ben C Scheele
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia. .,National Environmental Science Programme, Threatened Species Recovery Hub, Canberra, ACT 2601, Australia.,One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Frank Pasmans
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Lee F Skerratt
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Lee Berger
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - An Martel
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Wouter Beukema
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
| | - Aldemar A Acevedo
- Programa de Doctorado en Ciencias Biológicas, Laboratorio de Biología Evolutiva, Pontificia Universidad Católica de Chile, Avenida Libertador Bernardo O'Higgins 340, Santiago, Chile.,Grupo de Investigación en Ecología y Biogeografía, Universidad de Pamplona, Barrio El Buque, Km 1, Vía a Bucaramanga, Pamplona, Colombia
| | - Patricia A Burrowes
- Department of Biology, University of Puerto Rico, P.O. Box 23360, San Juan, Puerto Rico
| | - Tamilie Carvalho
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Alessandro Catenazzi
- Department of Biological Sciences, Florida International University, Miami, FL 33199, USA
| | - Ignacio De la Riva
- Museo Nacional de Ciencias Naturales-CSIC, C/ José Gutiérrez Abascal 2, Madrid 28006, Spain
| | - Matthew C Fisher
- MRC Centre for Global Infectious Disease Analysis, School of Public Health, Imperial College London, London W2 1PG, UK
| | - Sandra V Flechas
- Department of Biological Sciences, Universidad de los Andes, Bogotá, Colombia.,Instituto de Investigación de Recursos Biológicos Alexander von Humboldt, Sede Venado de Oro, Paseo Bolívar 16-20, Bogotá, Colombia
| | - Claire N Foster
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia
| | - Patricia Frías-Álvarez
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia
| | - Trenton W J Garner
- Institute of Zoology, Zoological Society London, Regents Park, London NW1 4RY, UK.,Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Brian Gratwicke
- Smithsonian National Zoological Park and Conservation Biology Institute, Washington, DC 20008, USA
| | - Juan M Guayasamin
- Universidad San Francisco de Quito USFQ, Colegio de Ciencias Biológicas y Ambientales COCIBA, Instituto de Investigaciones Biológicas y Ambientales BIOSFERA, Laboratorio de Biología Evolutiva, Campus Cumbayá, Quito, Ecuador.,Centro de Investigación de la Biodiversidad y Cambio Climático (BioCamb), Ingeniería en Biodiversidad y Cambio Climático, Facultad de Medio Ambiente, Universidad Tecnológica Indoamérica, Calle Machala y Sabanilla, Quito, Ecuador.,Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
| | - Mareike Hirschfeld
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, Berlin 10115, Germany
| | - Jonathan E Kolby
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia.,Honduras Amphibian Rescue and Conservation Center, Lancetilla Botanical Garden and Research Center, Tela, Honduras.,The Conservation Agency, Jamestown, RI 02835, USA
| | - Tiffany A Kosch
- One Health Research Group, Melbourne Veterinary School, The University of Melbourne, Werribee, VIC 3030, Australia.,AL Rae Centre for Genetics and Breeding, Massey University, Palmerston North 4442, New Zealand
| | - Enrique La Marca
- School of Geography, Faculty of Forestry Engineering and Environmental Sciences, University of Los Andes, Merida, Venezuela
| | - David B Lindenmayer
- Fenner School of Environment and Society, Australian National University, Canberra, ACT 2601, Australia.,National Environmental Science Programme, Threatened Species Recovery Hub, Canberra, ACT 2601, Australia
| | - Karen R Lips
- Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Ana V Longo
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
| | - Raúl Maneyro
- Laboratorio de Sistemática e Historia Natural de Vertebrados. Facultad de Ciencias, Universidad de la República. Igua 4225, CP 11400, Montevideo, Uruguay
| | - Cait A McDonald
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Joseph Mendelson
- Zoo Atlanta, Atlanta, GA 30315, USA.,School of Biological Sciences, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | - Gabriela Parra-Olea
- Departamento de Zoología, Instituto de Biología, Universidad Nacional Autónoma de México, Mexico City, México
| | | | - Mark-Oliver Rödel
- Museum für Naturkunde, Leibniz Institute for Evolution and Biodiversity Science, Invalidenstr. 43, Berlin 10115, Germany
| | - Sean M Rovito
- Unidad de Genómica Avanzada (Langebio), Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional, km 9.6 Libramiento Norte Carretera Irapuato-León, Irapuato, Guanajuato CP36824, México
| | - Claudio Soto-Azat
- Centro de Investigación para la Sustentabilidad, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago 8370251, Chile
| | - Luís Felipe Toledo
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, Brazil
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV 89557, USA
| | - Ché Weldon
- Unit for Environmental Sciences and Management, North-West University, Potchefstroom 2520, South Africa
| | - Steven M Whitfield
- Zoo Miami, Conservation and Research Department, Miami, FL 33177, USA.,Florida International University School of Earth, Environment, and Society, 11200 SW 8th St., Miami, FL 33199, USA
| | - Mark Wilkinson
- Department of Life Sciences, The Natural History Museum, London SW7 5BD, UK
| | - Kelly R Zamudio
- Department of Ecology and Evolutionary Biology, Cornell University, Ithaca, NY 14853, USA
| | - Stefano Canessa
- Wildlife Health Ghent, Department of Pathology, Bacteriology, and Avian Diseases, Faculty of Veterinary Medicine, Ghent University, B-9820 Merelbeke, Belgium
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87
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Wu NC, McKercher C, Cramp RL, Franklin CE. Mechanistic basis for loss of water balance in green tree frogs infected with a fungal pathogen. Am J Physiol Regul Integr Comp Physiol 2019; 317:R301-R311. [PMID: 31141416 DOI: 10.1152/ajpregu.00355.2018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Chytridiomycosis, a lethal skin disease caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), disrupts skin function of amphibians, interfering with ionic and osmotic regulation. To regulate fungal loads, amphibians increase their rate of skin sloughing. However, sloughing also causes a temporary loss of ionic and osmotic homeostasis due to disruption of the skin, a key osmoregulatory organ. The combined effects of increased sloughing frequency and chytridiomycosis contribute to the high rates of mortality from Bd infections. However, the mechanisms responsible for the loss of cutaneous osmotic regulation remain unknown. We measured the changes in whole animal water uptake rates, in vitro transcutaneous water fluxes across the ventral skin, and the mRNA expression of epithelial water transport proteins (aquaporins, AQPs) and junctional proteins in Bd-infected and uninfected Litoria caerulea skin. We hypothesize that infected frogs would show reduction/inhibition in cutaneous water transporters responsible for regulating water balance, and sloughing would exacerbate cutaneous water fluxes. We found that infected, nonsloughing frogs had an impaired rate of water uptake and showed increased rates of in vitro water efflux across the ventral skin. In uninfected frogs, the expression of AQPs and junction genes increased significantly with sloughing, which may assist in regulating cutaneous water movements and barrier function in the newly exposed skin. In contrast, infected frogs did not show this postsloughing increase in AQP gene expression. The combination of increased sloughing frequency, impaired water uptake rates, and increased rates of water loss likely contributes to the loss of osmotic homeostasis in frogs infected with Bd.
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Affiliation(s)
- Nicholas C Wu
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Callum McKercher
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Rebecca L Cramp
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Craig E Franklin
- School of Biological Sciences, University of Queensland, Brisbane, Queensland, Australia
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88
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Survey of Ranavirus and Batrachochytrium dendrobatidis in Introduced Frogs in Hawaii, USA. J Wildl Dis 2019. [DOI: 10.7589/2018-05-137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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89
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Doody KA, Ohmer ME, Cramp RL, Franklin CE. Do Frogs Infected with Batrachochytrium dendrobatidis Avoid Water While Sloughing? HERPETOLOGICA 2019. [DOI: 10.1655/d-18-00014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Kathleen A. Doody
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Michel E.B. Ohmer
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
| | - Rebecca L. Cramp
- School of Biological Sciences, The University of Queensland, St. Lucia, QLD 4072, Australia
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90
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Rivera B, Cook K, Andrews K, Atkinson MS, Savage AE. Pathogen Dynamics in an Invasive Frog Compared to Native Species. ECOHEALTH 2019; 16:222-234. [PMID: 31332577 DOI: 10.1007/s10393-019-01432-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 04/10/2019] [Accepted: 05/09/2019] [Indexed: 06/10/2023]
Abstract
Emerging infectious diseases threaten the survival of wildlife populations and species around the world. In particular, amphibians are experiencing population declines and species extinctions primarily in response to two pathogens, the fungus Batrachochytrium dendrobatidis (Bd) and the iridovirus Ranavirus (Rv). Here, we use field surveys and quantitative (q)PCR to compare infection intensity and prevalence of Bd and Rv across species and seasons on Jekyll Island, a barrier island off the coast of Georgia, USA. We collected oral and skin swabs for 1 year from four anuran species and three families, including two native hylids (Hyla cinerea and Hyla squirella), a native ranid (Rana sphenocephala), and the invasive rain frog Eleutherodactylus planirostris. Bd infection dynamics did not vary significantly over sampling months, but Rv prevalence and intensity were significantly higher in fall 2014 compared to spring 2015. Additionally, Rv prevalence and intensity were significantly higher in E. planirostris than in the other three species. Our study highlights the potential role of invasive amphibians as drivers of disease dynamics and demonstrates the importance of pathogen surveillance across multiple time periods and species to accurately capture the infectious disease landscape.
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Affiliation(s)
- Brenda Rivera
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL, 32816, USA
| | - Katrina Cook
- Wyoming Natural Diversity Database, University of Wyoming, 1000 E. University Ave, Laramie, WY, 82071, USA
| | - Kimberly Andrews
- Odum School of Ecology, University of Georgia, UGA Marine Extension, Brunswick, GA, 31520, USA
| | - Matthew S Atkinson
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL, 32816, USA
| | - Anna E Savage
- Department of Biology, University of Central Florida, 4110 Libra Dr, Orlando, FL, 32816, USA.
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91
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Abney CR, Balzer SW, Dueckman A, Baylis A, Clements DR. Early Spring and Early Vanishing Wetlands as Harbingers of the Future? The Climate Change Trap for Ephemeral Pond-Breeding Frogs. NORTHWEST SCIENCE 2019. [DOI: 10.3955/046.093.0105] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- Curtis R. Abney
- Department of Biological Sciences, Brock University, 1812 Sir Isaac Brock Way, St. Catharines, Ontario, L2S 3A1, Canada
| | - Sterling W. Balzer
- Department of Biology, Trinity Western University, 7600 Glover Rd., Langley, British Columbia, V2Y 1Y1, Canada
| | - Ashley Dueckman
- Department of Biology, Trinity Western University, 7600 Glover Rd., Langley, British Columbia, V2Y 1Y1, Canada
| | - Andrew Baylis
- A Rocha Canada, 1620 192 Street, Surrey, British Columbia V3Z 9V2, Canada
| | - David R. Clements
- Department of Biology, Trinity Western University, 7600 Glover Rd., Langley, British Columbia, V2Y 1Y1, Canada
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92
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93
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Stroud JT, Thompson ME. Looking to the past to understand the future of tropical conservation: The importance of collecting basic data. Biotropica 2019. [DOI: 10.1111/btp.12665] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- James T. Stroud
- Department of Biology Washington University St. Louis Missouri
| | - Michelle E. Thompson
- Department of Science & Education Field Museum of Natural History Chicago Illinois
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94
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Calderon MR, Almeida CA, González P, Jofré MB. Influence of water quality and habitat conditions on amphibian community metrics in rivers affected by urban activity. Urban Ecosyst 2019. [DOI: 10.1007/s11252-019-00862-w] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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95
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Frenken T, Agha R, Schmeller DS, van West P, Wolinska J. Biological Concepts for the Control of Aquatic Zoosporic Diseases. Trends Parasitol 2019; 35:571-582. [PMID: 31076352 DOI: 10.1016/j.pt.2019.04.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2019] [Revised: 04/04/2019] [Accepted: 04/06/2019] [Indexed: 12/26/2022]
Abstract
Aquatic zoosporic diseases are threatening global biodiversity and ecosystem services, as well as economic activities. Current means of controlling zoosporic diseases are restricted primarily to chemical treatments, which are usually harmful or likely to be ineffective in the long term. Furthermore, some of these chemicals have been banned due to adverse effects. As a result, there is a need for alternative methods with minimal side-effects on the ecosystem or environment. Here, we integrate existing knowledge of three poorly interconnected areas of disease research - amphibian conservation, aquaculture, and plankton ecology - and arrange it into seven biological concepts to control zoosporic diseases. These strategies may be less harmful and more sustainable than chemical approaches. However, more research is needed before safe application is possible.
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Affiliation(s)
- Thijs Frenken
- Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany.
| | - Ramsy Agha
- Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Dirk S Schmeller
- ECOLAB, Université de Toulouse, CNRS, INPT, UPS, Toulouse, France
| | - Pieter van West
- Aberdeen Oomycete Laboratory, College of Life Sciences and Medicine, Institute of Medical Sciences, University of Aberdeen, Aberdeen, UK
| | - Justyna Wolinska
- Department of Ecosystem Research, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany; Institute of Biology, Freie Universität Berlin, Berlin, Germany
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96
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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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97
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Kärvemo S, Laurila A, Höglund J. Urban environment and reservoir host species are associated with Batrachochytrium dendrobatidis infection prevalence in the common toad. DISEASES OF AQUATIC ORGANISMS 2019; 134:33-42. [PMID: 32132271 DOI: 10.3354/dao03359] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Human-induced changes of the environment, including landscape alteration and habitat loss, may affect wildlife disease dynamics and have important ramifications for wildlife conservation. Amphibians are among the vertebrate taxa most threatened by anthropogenic habitat change. The emerging fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused extinctions and population declines in hundreds of anuran species globally. We studied how the urban landscape is associated with the prevalence of Bd infections by sampling 655 anurans of 3 species (mainly the common toad Bufo bufo) in 42 ponds surrounded by different amounts of urban habitat (defined as towns, cities or villages). We also examined the association between Bd infections and a potential reservoir host species (the moor frog Rana arvalis). We found that 38% of the sites were positive for Bd with an infection prevalence of 4.4%. The extent of urban landscape was negatively correlated with Bd infection prevalence. However, the positive association of Bd with the presence of the possible reservoir species was substantially stronger than the urban effects. The body condition index of B. bufo was negatively associated with Bd infection. This Bd effect was stronger than the negative effect of urban landscape on body condition. Our results suggest that urban environments in Sweden have a negative impact on Bd infections, while the presence of the reservoir species has a positive impact on Bd prevalence. Our study also highlights the potential importance of Bd infection on host fitness, especially in rural landscapes.
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Affiliation(s)
- Simon Kärvemo
- Department of Ecology and Genetics/Animal Ecology, Uppsala University, 75236 Uppsala, Sweden
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98
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Grant SA, Bienentreu JF, Vilaça ST, Brunetti CR, Lesbarrères D, Murray DL, Kyle CJ. Low intraspecific variation of Frog virus 3 with evidence for novel FV3-like isolates in central and northwestern Canada. DISEASES OF AQUATIC ORGANISMS 2019; 134:1-13. [PMID: 32132268 DOI: 10.3354/dao03354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Frog virus 3 (FV3) and FV3-like ranaviruses can infect a variety of cold-blooded aquatic species and present a primary threat to amphibians across the globe. Previous studies of FV3-like viruses have largely investigated higher-level phylogenetic distinctions of these pathogens via portions of the conserved major capsid protein (MCP), and the putative virulence gene vIF-2α. Few studies, however, have investigated the spatial distribution of FV3 variants at the population level3-data that can be used to further understand the spatial epidemiology of this disease. In this study, we sequenced the MCP and vIF-2α of 127 FV3-positive amphibians sampled from Canadian water bodies in Ontario, northeastern Alberta, and southern Northwest Territories to explore whether intraspecific genetic variation exists within FV3. There was a lack of variation at the 2 markers across these regions, suggesting that there is a lack of FV3 sequence diversity in Canada, which may hint at a single source of infection that has spread. However, an undocumented variant termed Wood Buffalo ranavirus (WBRV) was detected in samples from 3 sites in Alberta and Northwest Territories that clustered within the FV3-like lineage with 99.3% sequence homology for MCP. For vIF-2α, all sequences were the expected truncated variant except for 6 samples in Ontario. These latter sequences were suggestive of recombination with common midwife toad virus (CMTV). The lack of variation suggests that higher-resolution genome analyses will be required to further explore the spatial spread and intraspecific variation of the disease.
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Affiliation(s)
- Samantha A Grant
- Environmental and Life Sciences Graduate Program, Trent University, Peterborough, Ontario K9J 7B8, Canada
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99
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Zumbado‐Ulate H, García‐Rodríguez A, Vredenburg VT, Searle C. Infection with Batrachochytrium dendrobatidis is common in tropical lowland habitats: Implications for amphibian conservation. Ecol Evol 2019; 9:4917-4930. [PMID: 31031954 PMCID: PMC6476760 DOI: 10.1002/ece3.5098] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2018] [Revised: 02/25/2019] [Accepted: 02/28/2019] [Indexed: 11/24/2022] Open
Abstract
Numerous species of amphibians declined in Central America during the 1980s and 1990s. These declines mostly affected highland stream amphibians and have been primarily linked to chytridiomycosis, a deadly disease caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd). Since then, the majority of field studies on Bd in the Tropics have been conducted in midland and highland environments (>800 m) mainly because the environmental conditions of mountain ranges match the range of ideal abiotic conditions for Bd in the laboratory. This unbalanced sampling has led researchers to largely overlook host-pathogen dynamics in lowlands, where other amphibian species declined during the same period. We conducted a survey testing for Bd in 47 species (n = 348) in four lowland sites in Costa Rica to identify local host-pathogen dynamics and to describe the abiotic environment of these sites. We detected Bd in three sampling sites and 70% of the surveyed species. We found evidence that lowland study sites exhibit enzootic dynamics with low infection intensity and moderate to high prevalence (55% overall prevalence). Additionally, we found evidence that every study site represents an independent climatic zone, where local climatic differences may explain variations in Bd disease dynamics. We recommend more detection surveys across lowlands and other sites that have been historically considered unsuitable for Bd occurrence. These data can be used to identify sites for potential disease outbreaks and amphibian rediscoveries.
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Affiliation(s)
| | - Adrián García‐Rodríguez
- Departamento de Zoología, Instituto de BiologíaUniversidad Nacional Autónoma de México (UNAM)Ciudad de MéxicoMéxico
- Escuela de BiologíaUniversidad de Costa RicaSan JoséCosta Rica
- Departamento de EcologiaUniversidade Federal do Rio Grande do NorteNatalBrazil
| | | | - Catherine Searle
- Department of Biological SciencesPurdue UniversityWest LafayetteIndiana
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100
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Cádiz A, Reytor ML, Díaz LM, Chestnut T, Burns JA, Amato G. The Chytrid Fungus, Batrachochytrium dendrobatidis, is Widespread Among Cuban Amphibians. ECOHEALTH 2019; 16:128-140. [PMID: 30377876 DOI: 10.1007/s10393-018-1383-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 10/04/2018] [Accepted: 10/09/2018] [Indexed: 06/08/2023]
Abstract
The fungus Batrachochytrium dendrobatidis (Bd) is a generalist amphibian pathogen responsible for chytridiomycosis. It was documented for the first time in Cuba in 2007, the apparent cause of the decline in one species of toad. In a recent survey, Bd was reported only for the highlands of Central Cuba. In the present study, we reexamined the geographic distribution and level of impact of Bd in Cuba by conducting an island-wide sampling in 10 localities and collecting skin swabs from 18 species and 28 environmental samples. We report detection of Bd in 60% of sampled sites and in 58% of sampled taxa. We show that Bd is associated with riparian, arboreal and terrestrial species, and it was estimated to occur in approximately 30% of the aquatic habitats we sampled. In addition, we confirmed that a dying individual of the species Eleutherodactylus casparii was severely infected with Bd. We also rise concern about the endanger toad Peltophryne longinasus and about three species of endemic riparian frogs that were not detected during our surveys. This study demonstrates that this pathogen is widespread throughout Cuba and provides relevant evidence to advance our understanding of its detection in amphibians and the aquatic environment in Cuba and about the occurrence of Bd in species with different ecologies. We provide valuable baseline information for Bd risk assessment and decision-making processes to mitigate its negative impact on Cuban amphibians.
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Affiliation(s)
- Antonio Cádiz
- Faculty of Biology, Havana University, La Havana, Cuba.
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, USA.
- , Weehawken, USA.
| | | | - Luis M Díaz
- National Museum of Natural History of Cuba, La Havana, Cuba
| | | | - John A Burns
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, USA
| | - George Amato
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, USA
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