201
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Searle CL, Belden LK, Bancroft BA, Han BA, Biga LM, Blaustein AR. Experimental examination of the effects of ultraviolet-B radiation in combination with other stressors on frog larvae. Oecologia 2009; 162:237-45. [PMID: 19727829 DOI: 10.1007/s00442-009-1440-8] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2009] [Accepted: 08/05/2009] [Indexed: 11/26/2022]
Abstract
Ultraviolet-B radiation (UVB) is a ubiquitous stressor with negative effects on many aquatic organisms. In amphibians, ambient levels of UVB can result in impaired growth, slowed development, malformations, altered behavior and mortality. UVB can also interact with other environmental stressors to amplify these negative effects on individuals. In outdoor mesocosm and laboratory experiments we studied potential synergistic effects of UVB, a pathogenic fungus, Batrachochytrium dendrobatidis (Bd), and varying temperatures on larval Cascades frogs (Rana cascadae). First, we compared survivorship, growth and development in two mesocosm experiments with UVB- and Bd-exposure treatments. We then investigated the effects of UVB on larvae in the laboratory under two temperature regimes, monitoring survival and behavior. We found reduced survival of R. cascadae larvae with exposure to UVB radiation in all experiments. In the mesocosm experiments, growth and development were not affected in either treatment, and no effect of Bd was found. In the laboratory experiment, larvae exposed to UVB demonstrated decreased activity levels. We also found a trend towards reduced survival when UVB and cold temperatures were combined. Our results show that amphibian larvae can suffer both lethal and sublethal effects when exposed to UVB radiation.
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202
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Puschendorf R, Carnaval AC, VanDerWal J, Zumbado-Ulate H, Chaves G, Bolaños F, Alford RA. Distribution models for the amphibian chytridBatrachochytrium dendrobatidisin Costa Rica: proposing climatic refuges as a conservation tool. DIVERS DISTRIB 2009. [DOI: 10.1111/j.1472-4642.2008.00548.x] [Citation(s) in RCA: 125] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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203
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204
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Skin microbes on frogs prevent morbidity and mortality caused by a lethal skin fungus. ISME JOURNAL 2009; 3:818-24. [PMID: 19322245 DOI: 10.1038/ismej.2009.27] [Citation(s) in RCA: 358] [Impact Index Per Article: 23.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Emerging infectious diseases threaten human and wildlife populations. Altered ecological interactions between mutualistic microbes and hosts can result in disease, but an understanding of interactions between host, microbes and disease-causing organisms may lead to management strategies to affect disease outcomes. Many amphibian species in relatively pristine habitats are experiencing dramatic population declines and extinctions due to the skin disease chytridiomycosis, which is caused by the chytrid fungus Batrachochytrium dendrobatidis. Using a randomized, replicated experiment, we show that adding an antifungal bacterial species, Janthinobacterium lividum, found on several species of amphibians to the skins of the frog Rana muscosa prevented morbidity and mortality caused by the pathogen. The bacterial species produces the anti-chytrid metabolite violacein, which was found in much higher concentrations on frog skins in the treatments where J. lividum was added. Our results show that cutaneous microbes are a part of amphibians' innate immune system, the microbial community structure on frog skins is a determinant of disease outcome and altering microbial interactions on frog skins can prevent a lethal disease outcome. A bioaugmentation strategy may be an effective management tool to control chytridiomycosis in amphibian survival assurance colonies and in nature.
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205
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Murphy PJ, St-Hilaire S, Bruer S, Corn PS, Peterson CR. Distribution and pathogenicity of Batrachochytrium dendrobatidis in boreal toads from the Grand Teton area of western Wyoming. ECOHEALTH 2009; 6:109-120. [PMID: 19418097 DOI: 10.1007/s10393-009-0230-4] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2008] [Revised: 08/01/2008] [Accepted: 08/02/2008] [Indexed: 05/27/2023]
Abstract
The pathogen Batrachochytrium dendrobatidis (Bd), which causes the skin disease chytridiomycosis, has been linked to amphibian population declines and extinctions worldwide. Bd has been implicated in recent declines of boreal toads, Bufo boreas boreas, in Colorado but populations of boreal toads in western Wyoming have high prevalence of Bd without suffering catastrophic mortality. In a field and laboratory study, we investigated the prevalence of Bd in boreal toads from the Grand Teton ecosystem (GRTE) in Wyoming and tested the pathogenicity of Bd to these toads in several environments. The pathogen was present in breeding adults at all 10 sites sampled, with a mean prevalence of 67%. In an experiment with juvenile toadlets housed individually in wet environments, 10(6) zoospores of Bd isolated from GRTE caused lethal disease in all Wyoming and Colorado animals within 35 days. Survival time was longer in toadlets from Wyoming than Colorado and in toadlets spending more time in dry sites. In a second trial involving Colorado toadlets exposed to 35% fewer Bd zoospores, infection peaked and subsided over 68 days with no lethal chytridiomycosis in any treatment. However, compared with drier aquaria with dry refuges, Bd infection intensity was 41% higher in more humid aquaria and 81% higher without dry refuges available. Our findings suggest that although widely infected in nature, Wyoming toads may escape chytridiomycosis due to a slight advantage in innate resistance or because their native habitat hinders Bd growth or provides more opportunities to reduce pathogen loads behaviorally than in Colorado.
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Affiliation(s)
- Peter J Murphy
- Department of Biological Sciences, Idaho State University, Pocatello, ID 83209-8007, USA.
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206
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Fisher MC, Bosch J, Yin Z, Stead DA, Walker J, Selway L, Brown AJP, Walker LA, Gow NAR, Stajich JE, Garner TWJ. Proteomic and phenotypic profiling of the amphibian pathogen Batrachochytrium dendrobatidis shows that genotype is linked to virulence. Mol Ecol 2009; 18:415-29. [PMID: 19161465 DOI: 10.1111/j.1365-294x.2008.04041.x] [Citation(s) in RCA: 113] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Population genetics of the amphibian pathogen Batrachochytrium dendrobatidis (Bd) show that isolates are highly related and globally homogenous, data that are consistent with the recent epidemic spread of a previously endemic organism. Highly related isolates are predicted to be functionally similar due to low levels of heritable genetic diversity. To test this hypothesis, we took a global panel of Bd isolates and measured (i) the genetic relatedness among isolates, (ii) proteomic profiles of isolates, (iii) the susceptibility of isolates to the antifungal drug caspofungin, (iv) the variation among isolates in growth and phenotypic characteristics, and (v) the virulence of isolates against the European common toad Bufo bufo. Our results show (i) genotypic differentiation among isolates, (ii) proteomic differentiation among isolates, (iii) no significant differences in susceptibility to caspofungin, (iv) differentiation in growth and phenotypic/morphological characters, and (v) differential virulence in B. bufo. Specifically, our data show that Bd isolates can be profiled by their genotypic and proteomic characteristics, as well as by the size of their sporangia. Bd genotypic and phenotypic distance matrices are significantly correlated, showing that less-related isolates are more biologically unique. Mass spectrometry has identified a set of candidate genes associated with inter-isolate variation. Our data show that, despite its rapid global emergence, Bd isolates are not identical and differ in several important characters that are linked to virulence. We argue that future studies need to clarify the mechanism(s) and rate at which Bd is evolving, and the impact that such variation has on the host-pathogen dynamic.
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Affiliation(s)
- Matthew C Fisher
- Department of Infectious Disease Epidemiology, Imperial College London, St. Mary's Hospital, Norfolk Place, London W21PG, UK.
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207
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Evaluating the links between climate, disease spread, and amphibian declines. Proc Natl Acad Sci U S A 2008; 105:17436-41. [PMID: 18987318 DOI: 10.1073/pnas.0806368105] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Human alteration of the environment has arguably propelled the Earth into its sixth mass extinction event and amphibians, the most threatened of all vertebrate taxa, are at the forefront. Many of the worldwide amphibian declines have been caused by the chytrid fungus, Batrachochytrium dendrobatidis (Bd), and two contrasting hypotheses have been proposed to explain these declines. Positive correlations between global warming and Bd-related declines sparked the chytrid-thermal-optimum hypothesis, which proposes that global warming increased cloud cover in warm years that drove the convergence of daytime and nighttime temperatures toward the thermal optimum for Bd growth. In contrast, the spatiotemporal-spread hypothesis states that Bd-related declines are caused by the introduction and spread of Bd, independent of climate change. We provide a rigorous test of these hypotheses by evaluating (i) whether cloud cover, temperature convergence, and predicted temperature-dependent Bd growth are significant positive predictors of amphibian extinctions in the genus Atelopus and (ii) whether spatial structure in the timing of these extinctions can be detected without making assumptions about the location, timing, or number of Bd emergences. We show that there is spatial structure to the timing of Atelopus spp. extinctions but that the cause of this structure remains equivocal, emphasizing the need for further molecular characterization of Bd. We also show that the reported positive multi-decade correlation between Atelopus spp. extinctions and mean tropical air temperature in the previous year is indeed robust, but the evidence that it is causal is weak because numerous other variables, including regional banana and beer production, were better predictors of these extinctions. Finally, almost all of our findings were opposite to the predictions of the chytrid-thermal-optimum hypothesis. Although climate change is likely to play an important role in worldwide amphibian declines, more convincing evidence is needed of a causal link.
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208
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KRIGER KERRYM, HERO JEANMARC. Altitudinal distribution of chytrid (Batrachochytrium dendrobatidis) infection in subtropical Australian frogs. AUSTRAL ECOL 2008. [DOI: 10.1111/j.1442-9993.2008.01872.x] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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209
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Global gene expression profiles for life stages of the deadly amphibian pathogen Batrachochytrium dendrobatidis. Proc Natl Acad Sci U S A 2008; 105:17034-9. [PMID: 18852473 DOI: 10.1073/pnas.0804173105] [Citation(s) in RCA: 84] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Amphibians around the world are being threatened by an emerging pathogen, the chytrid fungus Batrachochytrium dendrobatidis (Bd). Despite intensive ecological study in the decade since Bd was discovered, little is known about the mechanism by which Bd kills frogs. Here, we compare patterns of global gene expression in controlled laboratory conditions for the two phases of the life cycle of Bd: the free-living zoospore and the substrate-embedded sporangia. We find zoospores to be transcriptionally less complex than sporangia. Several transcripts more abundant in zoospores provide clues about how this motile life stage interacts with its environment. Genes with higher levels of expression in sporangia provide new hypotheses about the molecular pathways involved in metabolic activity, flagellar function, and pathogenicity in Bd. We highlight expression patterns for a group of fungalysin metallopeptidase genes, a gene family thought to be involved in pathogenicity in another group of fungal pathogens that similarly cause cutaneous infection of vertebrates. Finally we discuss the challenges inherent in developing a molecular toolkit for chytrids, a basal fungal lineage separated by vast phylogenetic distance from other well characterized fungi.
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210
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Ancient behaviors of larval amphibians in response to an emerging fungal pathogen, Batrachochytrium dendrobatidis. Behav Ecol Sociobiol 2008. [DOI: 10.1007/s00265-008-0655-8] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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211
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Symonds EP, Trott DJ, Bird PS, Mills P. Growth Characteristics and Enzyme Activity in Batrachochytrium dendrobatidis Isolates. Mycopathologia 2008; 166:143-7. [DOI: 10.1007/s11046-008-9135-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2008] [Accepted: 05/17/2008] [Indexed: 10/21/2022]
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212
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Ruthig GR. The influence of temperature and spatial distribution on the susceptibility of southern leopard frog eggs to disease. Oecologia 2008; 156:895-903. [DOI: 10.1007/s00442-008-1026-x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2007] [Accepted: 03/03/2008] [Indexed: 11/30/2022]
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213
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Alemu I JB, Cazabon MNE, Dempewolf L, Hailey A, Lehtinen RM, Mannette RP, Naranjit KT, Roach ACJ. Presence of the chytrid fungus Batrachochytrium dendrobatidis in populations of the critically endangered frog Mannophryne olmonae in Tobago, West Indies. ECOHEALTH 2008; 5:34-39. [PMID: 18648795 DOI: 10.1007/s10393-008-0154-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Revised: 11/13/2007] [Accepted: 11/19/2007] [Indexed: 05/26/2023]
Abstract
The emerging infectious disease chytridiomycosis is prevalent in Central and South America, and has caused catastrophic declines of amphibian populations in the Neotropics. The responsible organism, Batrachochytrium dendrobatidis, has been recorded on three West Indian islands, but the whole of the Caribbean region is predicted to offer a suitable environment for the disease. Monitoring the spread of chytridiomycosis is thus a priority in this region, which has exceptionally high levels of amphibian endemism. PCR analysis of 124 amphibian skin swabs in Tobago (Republic of Trinidad and Tobago) demonstrated the presence of B. dendrobatidis in three widely separated populations of the frog Mannophryne olmonae, which is listed as Critically Endangered on the basis of recent population declines. Chytridiomycosis is presently endemic in this species, with a prevalence of about 20% and no associated clinical disease. Increased susceptibility to chytridiomycosis from climate change is unlikely in amphibian populations in Tobago, as this island does not have high montane environments, but remains a possibility in the sister island of Trinidad. Preventing the spread of chytridiomycosis within and between these and other Caribbean islands should be a major goal of practical conservation measures for amphibians in the region.
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Affiliation(s)
- Jahson B Alemu I
- Project L.E.A.P., c/o Department of Life Sciences, University of the West Indies, St. Augustine, Trinidad and Tobago.
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214
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Frías-Alvarez P, Vredenburg VT, Familiar-López M, Longcore JE, González-Bernal E, Santos-Barrera G, Zambrano L, Parra-Olea G. Chytridiomycosis survey in wild and captive mexican amphibians. ECOHEALTH 2008; 5:18-26. [PMID: 18648793 DOI: 10.1007/s10393-008-0155-3] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2007] [Revised: 10/22/2007] [Accepted: 10/30/2007] [Indexed: 05/26/2023]
Abstract
Mexico, a rich country in terms of amphibian diversity, hosts about 375 described species. Population declines have been documented for several species where it is evident that their habitat is being destroyed or modified. However, other species which inhabit pristine areas are declining as well. It has been suggested that the chytrid fungus Batrachochytrium dendrobatidis (B.d.) may be one of the causes of the enigmatic declines in Mexico. We surveyed a total of 45 localities, in 12 states across Mexico, examining a total of 360 specimens representing 14 genera and 30 species. We also examined 91 specimens of Ambystoma mexicanum from a captive population in Mexico City as well as one Pachymedusa dacnicolor obtained in a pet shop. We used a two-tiered technique to detect the pathogen. For wild-caught specimens, we utilized light microscopy to identify presence of B.d. sporangia in amphibian skin. Then, to verify the infection, we used a quantitative real-time PCR assay on collected skin sections which is specific for B.d. For captive animals, we used a nonlethal version of the real-time PCR technique. We found evidence of B.d. infection in 111 animals comprising 14 species in 13 localities. A large percentage (84%) of Ambystoma mexicanum from the colony were infected with B.d. The two most highly infected individuals were the endangered Ambystoma mexicanum, from a captive colony, and Pachymedusa dacnicolor, purchased at a pet shop.
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Affiliation(s)
- Patricia Frías-Alvarez
- Departamento de Zoología, Instituto de Biología, UNAM, Tercer Circuito exterior s/n, Ciudad Universitaria, AP-70-153, CP 04510, México, DF, México
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215
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Kriger KM, Pereoglou F, Hero JM. Latitudinal variation in the prevalence and intensity of chytrid (Batrachochytrium dendrobatidis) infection in eastern Australia. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2007; 21:1280-90. [PMID: 17883493 DOI: 10.1111/j.1523-1739.2007.00777.x] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
Chytridiomycosis is a recently emerged, infectious skin disease of amphibians that has been linked directly to mass mortalities, population declines, and species extinctions worldwide. An understanding of the factors that limit the distribution and abundance of Batrachochytrium dendrobatidis (the etiological agent of chytridiomycosis) is urgently required. We conducted disease surveys at 31 lowland sites distributed north-south along 2315 km of the Australian east coast that encompassed 20.8 degrees of latitude. A total of 863 adult male stony creek frogs (Litoria lesueuri complex) were sampled, and the overall prevalence of B. dendrobatidis infection was 26%. B. dendrobatidis was detected at 77% of the sites, including sites at the northern and southern limits of the latitudinal transect. Frogs from temperate regions, however, had significantly more intense infections than did their tropical counterparts, often carrying an order of magnitude more B. dendrobatidis zoospores, suggesting that at low elevations, temperate frogs are at higher risk of chytridiomycosis-induced mortality than are tropical frogs. The prevalence and intensity of B. dendrobatidis infections were significantly greater at sites with high rainfall (>33 mm in the 30 days prior to sampling) and cool temperatures (stream temperature 1 h after sunset < 23 degrees C). Although climatic variables explained much of the variation in the prevalence and intensity of B. dendrobatidis infections between infected and uninfected sites, frog snout-vent length was consistently the best predictor of infection levels across infected sites. Small frogs were more likely to be infected and carried more intense infections than larger frogs, suggesting either that frogs can outgrow their chytrid infections or that the disease induces developmental stress that limits growth. Our results will directly assist amphibian disease researchers and wildlife managers, whose conservation efforts should focus on those amphibian populations living within the B. dendrobatidis climatic envelope that we have described.
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Affiliation(s)
- Kerry M Kriger
- Griffith University, Centre for Innovative Conservation Strategies, PMB 50 Gold Coast Mail Centre, QLD 9726, Australia.
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216
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Kriger KM, Hero JM. The chytrid fungus Batrachochytrium dendrobatidis is non-randomly distributed across amphibian breeding habitats. DIVERS DISTRIB 2007. [DOI: 10.1111/j.1472-4642.2007.00394.x] [Citation(s) in RCA: 112] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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217
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YOUNG S, BERGER L, SPEARE R. Amphibian chytridiomycosis: strategies for captive management and conservation. ACTA ACUST UNITED AC 2007. [DOI: 10.1111/j.1748-1090.2007.00010.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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218
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Bosch J, Carrascal LM, Durán L, Walker S, Fisher MC. Climate change and outbreaks of amphibian chytridiomycosis in a montane area of Central Spain; is there a link? Proc Biol Sci 2007; 274:253-60. [PMID: 17148254 PMCID: PMC1685858 DOI: 10.1098/rspb.2006.3713] [Citation(s) in RCA: 179] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Amphibian species are declining at an alarming rate on a global scale in large part owing to an infectious disease caused by the chytridiomycete fungus, Batrachochytrium dendrobatidis. This disease of amphibians has recently emerged within Europe, but knowledge of its effects on amphibian assemblages remains poor. Importantly, little is known about the environmental envelope that is associated with chytridiomycosis in Europe and the potential for climate change to drive future disease dynamics. Here, we use long-term observations on amphibian population dynamics in the Peñalara Natural Park, Spain, to investigate the link between climate change and chytridiomycosis. Our analysis shows a significant association between change in local climatic variables and the occurrence of chytridiomycosis within this region. Specifically, we show that rising temperature is linked to the occurrence of chytrid-related disease, consistent with the chytrid-thermal-optimum hypothesis. We show that these local variables are driven by general circulation patterns, principally the North Atlantic Oscillation. Given that B. dendrobatidis is known to be broadly distributed across Europe, there is now an urgent need to assess the generality of our finding and determine whether climate-driven epidemics may be expected to impact on amphibian species across the wider region.
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Affiliation(s)
- Jaime Bosch
- Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias NaturalesCSIC, José Gutiérrez Abascal, 2 28006 Madrid, Spain
- Author for correspondence ()
| | - Luís M Carrascal
- Departamento de Biodiversidad y Biología Evolutiva, Museo Nacional de Ciencias NaturalesCSIC, José Gutiérrez Abascal, 2 28006 Madrid, Spain
| | - Luis Durán
- Departamento de Fisica y Matemática, Universidad Europea de Madrid28670 Villaviciosa de Odón, Madrid, Spain
| | - Susan Walker
- Department of Infectious Disease Epidemiology, Imperial College Faculty of MedicineSt Mary's Campus, Norfolk Place, London W2 1PG, UK
| | - Matthew C Fisher
- Department of Infectious Disease Epidemiology, Imperial College Faculty of MedicineSt Mary's Campus, Norfolk Place, London W2 1PG, UK
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219
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Garner TWJ, Perkins MW, Govindarajulu P, Seglie D, Walker S, Cunningham AA, Fisher MC. The emerging amphibian pathogen Batrachochytrium dendrobatidis globally infects introduced populations of the North American bullfrog, Rana catesbeiana. Biol Lett 2007; 2:455-9. [PMID: 17148429 PMCID: PMC1686185 DOI: 10.1098/rsbl.2006.0494] [Citation(s) in RCA: 209] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Batrachochytrium dendrobatidis is the chytridiomycete fungus which has been implicated in global amphibian declines and numerous species extinctions. Here, we show that introduced North American bullfrogs (Rana catesbeiana) consistently carry this emerging pathogenic fungus. We detected infections by this fungus on introduced bullfrogs from seven of eight countries using both PCR and microscopic techniques. Only native bullfrogs from eastern Canada and introduced bullfrogs from Japan showed no sign of infection. The bullfrog is the most commonly farmed amphibian, and escapes and subsequent establishment of feral populations regularly occur. These factors taken together with our study suggest that the global threat of B. dendrobatidis disease transmission posed by bullfrogs is significant.
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Affiliation(s)
- Trenton W J Garner
- Institute of Zoology, Zoological Society of London, Regent's Park, London NW1 4RY, UK.
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220
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Kriger KM, Hero JM. Large-scale seasonal variation in the prevalence and severity of chytridiomycosis. J Zool (1987) 2006. [DOI: 10.1111/j.1469-7998.2006.00220.x] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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221
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Parris MJ, Reese E, Storfer A. Antipredator behavior of chytridiomycosis-infected northern leopard frog (Rana pipiens) tadpoles. CAN J ZOOL 2006. [DOI: 10.1139/z05-175] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the effects of Batrachochytrium dendrobatidis Longcore, Pessier & Nichols, a pathogen implicated in global amphibian population declines, on antipredator behavior of northern leopard frog (Rana pipiens Schreber, 1782) tadpoles in response to visual and chemical cues of a fish predator, bluegill sunfish (Lepomis macrochirus Rafinesque, 1819). We placed infected and uninfected tadpoles in containers partitioned with a transparent divider and measured tadpole activity and distance from the center. Infected tadpoles had significantly lower activity levels across all treatments. When exposed to only visual cues, uninfected tadpoles positioned themselves farther from the center divider (and thus the predator) than infected animals. All tadpoles were at similar distances from the center when exposed to chemical cues only, likely because chemical cues alone do not provide spatial information on the location of predators. Infected tadpoles were significantly farther from the center divider than uninfected ones when exposed to visual and chemical cues together, suggesting that, although the mechanism is unknown, both cues are necessary to stimulate predator avoidance behavior for infected animals. In a second experiment, infected tadpoles experienced lower mortality than uninfected ones in the lethal presence of fish. Thus, effects of infection on behavioral antipredator responses are complex, but lower host susceptibility to predation, low activity, and greater distance from predators when both chemical and visual predator cues are present likely benefits B. dendrobatidis, which relies on host survival for transmission.
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222
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Pounds JA, Bustamante MR, Coloma LA, Consuegra JA, Fogden MPL, Foster PN, La Marca E, Masters KL, Merino-Viteri A, Puschendorf R, Ron SR, Sánchez-Azofeifa GA, Still CJ, Young BE. Widespread amphibian extinctions from epidemic disease driven by global warming. Nature 2006; 439:161-7. [PMID: 16407945 DOI: 10.1038/nature04246] [Citation(s) in RCA: 805] [Impact Index Per Article: 44.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2005] [Accepted: 09/21/2005] [Indexed: 11/09/2022]
Abstract
As the Earth warms, many species are likely to disappear, often because of changing disease dynamics. Here we show that a recent mass extinction associated with pathogen outbreaks is tied to global warming. Seventeen years ago, in the mountains of Costa Rica, the Monteverde harlequin frog (Atelopus sp.) vanished along with the golden toad (Bufo periglenes). An estimated 67% of the 110 or so species of Atelopus, which are endemic to the American tropics, have met the same fate, and a pathogenic chytrid fungus (Batrachochytrium dendrobatidis) is implicated. Analysing the timing of losses in relation to changes in sea surface and air temperatures, we conclude with 'very high confidence' (> 99%, following the Intergovernmental Panel on Climate Change, IPCC) that large-scale warming is a key factor in the disappearances. We propose that temperatures at many highland localities are shifting towards the growth optimum of Batrachochytrium, thus encouraging outbreaks. With climate change promoting infectious disease and eroding biodiversity, the urgency of reducing greenhouse-gas concentrations is now undeniable.
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Affiliation(s)
- J Alan Pounds
- Golden Toad Laboratory for Conservation, Monteverde Cloud Forest Preserve and Tropical Science Center, Santa Elena, Puntarenas 5655-73, Costa Rica.
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Lips KR, Burrowes PA, Mendelson JR, Parra-Olea G. Amphibian Declines in Latin America: Widespread Population Declines, Extinctions, and Impacts1. Biotropica 2005. [DOI: 10.1111/j.1744-7429.2005.00023.x] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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La Marca E, Lips KR, Lotters S, Puschendorf R, Ibanez R, Rueda-Almonacid JV, Schulte R, Marty C, Castro F, Manzanilla-Puppo J, Garcia-Perez JE, Bolanos F, Chaves G, Pounds JA, Toral E, Young BE. Catastrophic Population Declines and Extinctions in Neotropical Harlequin Frogs (Bufonidae: Atelopus)1. Biotropica 2005. [DOI: 10.1111/j.1744-7429.2005.00026.x] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Ron SR. Predicting the Distribution of the Amphibian Pathogen Batrachochytrium dendrobatidis in the New World1. Biotropica 2005. [DOI: 10.1111/j.1744-7429.2005.00028.x] [Citation(s) in RCA: 145] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Lips KR, Burrowes PA, Mendelson JR, Parra-Olea G. Amphibian Population Declines in Latin America: A Synthesis1. Biotropica 2005. [DOI: 10.1111/j.1744-7429.2005.00029.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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Retallick RWR, McCallum H, Speare R. Endemic infection of the amphibian chytrid fungus in a frog community post-decline. PLoS Biol 2004; 2:e351. [PMID: 15502873 PMCID: PMC521176 DOI: 10.1371/journal.pbio.0020351] [Citation(s) in RCA: 184] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2004] [Accepted: 08/12/2004] [Indexed: 11/17/2022] Open
Abstract
The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985-1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985-1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.
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Affiliation(s)
- Richard W. R Retallick
- 1School of Tropical Biology, James Cook UniversityTownsville, QueenslandAustralia
- 2Department of Zoology and Entomology, University of QueenslandSt Lucia, QueenslandAustralia
- 3School of Life Sciences—Biology, Arizona State UniversityTempe, ArizonaUnited States of America
| | - Hamish McCallum
- 2Department of Zoology and Entomology, University of QueenslandSt Lucia, QueenslandAustralia
| | - Rick Speare
- 4Amphibian Diseases Group, School of Public Health and Tropical Medicine, James Cook UniversityTownsville, QueenslandAustralia
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