1
|
Spranger RR, Raffel TR, Sinervo BR. Canopy coverage, light, and moisture affect thermoregulatory trade-offs in an amphibian breeding habitat. J Therm Biol 2024; 122:103864. [PMID: 38852487 DOI: 10.1016/j.jtherbio.2024.103864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 04/19/2024] [Accepted: 04/27/2024] [Indexed: 06/11/2024]
Abstract
When amphibians thermoregulate, they face a fundamental trade-off between the ability to maintain activity and an increased rate of dehydration at higher temperatures. Canopy coverage affects both the thermal and hydric conditions of the environment and can therefore influence amphibian thermoregulation. Frogs require proper conditions to thermoregulate to successfully grow, survive, and reproduce. But while we know how canopy and environmental variables typically affect operative temperature, less is known about effects on amphibian water loss rates. In this study, we measure the effect of canopy coverage on the conditions available for thermoregulation at a breeding pond of the California red-legged frog, Rana draytonii. We use agar frog models to estimate the thermal and hydric capacities frogs would experience in locations with different canopy coverage and microhabitats. At each site, we deployed models under four microhabitat treatments: wet/sun, wet/shade, dry/sun, and dry/shade. We modeled how environmental variables affected operative temperature and evaporative water loss from agar frogs. We found positive effects of air temperature, the sun treatment, and reduced canopy cover on operative temperature, and negative direct or indirect effects of these variables on evaporative water loss, consistent with the hypothesized trade-off between thermoregulatory behavior to increase temperature and the increased desiccation risk due to higher water loss. Additionally, our results indicate that the availability of wet microhabitats can allow frogs to reduce water loss, potentially mitigating the risk of desiccation when thermoregulating to achieve higher operative temperatures. Our findings suggest, that with access to proper microhabitats, amphibians can mitigate the fundamental trade-off and receive benefits of thermoregulating at high temperatures.
Collapse
Affiliation(s)
- Regina R Spranger
- Department of Ecology and Evolutionary Biology, University of California, 1156 High St, Santa Cruz, CA, 95064, USA.
| | - Thomas R Raffel
- Department of Biological Sciences, Oakland University, 2200 N Squirrel Rd, Rochester Hills, MI, 48309, USA.
| | - Barry R Sinervo
- Department of Ecology and Evolutionary Biology, University of California, 1156 High St, Santa Cruz, CA, 95064, USA
| |
Collapse
|
2
|
Pereira KE, Bletz MC, McCartney JA, Woodhams DC, Woodley SK. Effects of exogenous elevation of corticosterone on immunity and the skin microbiome of eastern newts ( Notophthalmus viridescens). Philos Trans R Soc Lond B Biol Sci 2023; 378:20220120. [PMID: 37305906 PMCID: PMC10258667 DOI: 10.1098/rstb.2022.0120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2022] [Accepted: 12/15/2022] [Indexed: 06/13/2023] Open
Abstract
The amphibian chytrid fungus, Batrachochytrium salamandrivorans (Bsal) threatens salamander biodiversity. The factors underlying Bsal susceptibility may include glucocorticoid hormones (GCs). The effects of GCs on immunity and disease susceptibility are well studied in mammals, but less is known in other groups, including salamanders. We used Notophthalmus viridescens (eastern newts) to test the hypothesis that GCs modulate salamander immunity. We first determined the dose required to elevate corticosterone (CORT; primary GC in amphibians) to physiologically relevant levels. We then measured immunity (neutrophil lymphocyte ratios, plasma bacterial killing ability (BKA), skin microbiome, splenocytes, melanomacrophage centres (MMCs)) and overall health in newts following treatment with CORT or an oil vehicle control. Treatments were repeated for a short (two treatments over 5 days) or long (18 treatments over 26 days) time period. Contrary to our predictions, most immune and health parameters were similar for CORT and oil-treated newts. Surprisingly, differences in BKA, skin microbiome and MMCs were observed between newts subjected to short- and long-term treatments, regardless of treatment type (CORT, oil vehicle). Taken together, CORT does not appear to be a major factor contributing to immunity in eastern newts, although more studies examining additional immune factors are necessary. This article is part of the theme issue 'Amphibian immunity: stress, disease and ecoimmunology'.
Collapse
Affiliation(s)
- Kenzie E. Pereira
- Department of Biology, Duquesne University, Pittsburgh, PA 15282, USA
| | - Molly C. Bletz
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Julia A. McCartney
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Douglas C. Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Sarah K. Woodley
- Department of Biology, Duquesne University, Pittsburgh, PA 15282, USA
| |
Collapse
|
3
|
King KC, Hall MD, Wolinska J. Infectious disease ecology and evolution in a changing world. Philos Trans R Soc Lond B Biol Sci 2023; 378:20220002. [PMID: 36744560 PMCID: PMC9900701 DOI: 10.1098/rstb.2022.0002] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 01/13/2023] [Indexed: 02/07/2023] Open
Affiliation(s)
- Kayla C. King
- Department of Biology, University of Oxford, Oxford OX1 3SZ, UK
| | - Matthew D. Hall
- School of Biological Sciences, Monash University, Melbourne 3800, Australia
| | - Justyna Wolinska
- Department of Evolutionary and Integrative Ecology, Leibniz Institute of Freshwater Ecology and Inland Fisheries (IGB), 12587 Berlin, Germany
- Department of Biology, Chemistry, and Pharmacy, Institute of Biology, Freie Universität Berlin (FU), 14195 Berlin, Germany
| |
Collapse
|
4
|
Cooke SJ, Madliger CL, Lennox RJ, Olden JD, Eliason EJ, Cramp RL, Fuller A, Franklin CE, Seebacher F. Biological mechanisms matter in contemporary wildlife conservation. iScience 2023; 26:106192. [PMID: 36895647 PMCID: PMC9988666 DOI: 10.1016/j.isci.2023.106192] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/16/2023] Open
Abstract
Given limited resources for wildlife conservation paired with an urgency to halt declines and rebuild populations, it is imperative that management actions are tactical and effective. Mechanisms are about how a system works and can inform threat identification and mitigation such that conservation actions that work can be identified. Here, we call for a more mechanistic approach to wildlife conservation and management where behavioral and physiological tools and knowledge are used to characterize drivers of decline, identify environmental thresholds, reveal strategies that would restore populations, and prioritize conservation actions. With a growing toolbox for doing mechanistic conservation research as well as a suite of decision-support tools (e.g., mechanistic models), the time is now to fully embrace the concept that mechanisms matter in conservation ensuring that management actions are tactical and focus on actions that have the potential to directly benefit and restore wildlife populations.
Collapse
Affiliation(s)
- Steven J. Cooke
- Fish Ecology and Conservation Physiology Laboratory, Department of Biology and Institute of Environmental and Interdisciplinary Science, Carleton University, 1125 Colonel By Dr., Ottawa, ON K1S 5B6, Canada
- Corresponding author
| | - Christine L. Madliger
- Department of Biology, Algoma University, 1520 Queen St. East, Sault Ste. Marie, ON P6A 2G4, Canada
| | - Robert J. Lennox
- Norwegian Research Centre (NORCE), Laboratory for Freshwater Ecology and Inland Fisheries, 5008 Bergen, Norway
| | - Julian D. Olden
- School of Aquatic and Fishery Sciences, University of Washington, Seattle, WA 98195-5020, USA
| | - Erika J. Eliason
- Department of Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA 93106, USA
| | - Rebecca L. Cramp
- School of Biological Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Andrea Fuller
- Brain Function Research Group, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Parktown 2193, South Africa
| | - Craig E. Franklin
- School of Biological Sciences, University of Queensland, Brisbane, QLD 4072, Australia
| | - Frank Seebacher
- School of Life and Environmental Sciences A08, University of Sydney, Sydney, NSW 2006, Australia
| |
Collapse
|
5
|
Human impact modulates chytrid fungus occurrence in amphibians in the Brazilian Atlantic Forest. Perspect Ecol Conserv 2022. [DOI: 10.1016/j.pecon.2022.05.002] [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] Open
|
6
|
Kásler A, Ujszegi J, Holly D, Jaloveczki B, Gál Z, Hettyey A. In vitro thermal tolerance of a hypervirulent lineage of Batrachochytrium dendrobatidis: Growth arrestment by elevated temperature and recovery following thermal treatment. Mycologia 2022; 114:661-669. [PMID: 35666647 DOI: 10.1080/00275514.2022.2065443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Chytridiomycosis, an emerging infectious disease caused by Batrachochytrium dendrobatidis (Bd), poses a serious threat to amphibians. The thermal optimum of Bd is lower than that of most amphibians, providing an opportunity to cure infected individuals with elevated temperature. However, this approach presupposes detailed knowledge about the thermal tolerance of the fungus. To determine the temperature that may effectively reduce infection burdens in vivo, detailed in vitro studies are needed to characterize thermal tolerance of the fungus without complexities introduced by the species-specific characteristics of hosts' immune systems. The aim of our study was to evaluate the thermal tolerance of a hypervirulent isolate of Bd, considering the limits of its thermal tolerance and its capacity to rebound following heat treatment. We incubated Bd cell cultures at five different temperatures (21, 25.5, 27, 29, or 30.5 C) for one of six exposure durations (3, 4, 5, 6, 7, or 8 days) and subsequently counted the number of zoospores to assess the temperature dependence of Bd growth. We observed intensive Bd growth at 21 C. At 25.5 C, the number of zoospores also increased over time, but the curve plateaued at about half of the maximum values observed in the lower temperature treatment. At temperatures of 27 C and above, the fungus showed no measurable growth. However, when we moved the cultures back to 21 C after the elevated temperature treatments, we observed recovery of Bd growth in all cultures previously treated at 27 C. At 29 C, a treatment duration of 8 days was necessary to prevent recovery of Bd growth, and at 30.5 C a treatment duration of 5 days was needed to achieve the same result, revealing that these moderately elevated temperatures applied for only a few days have merely a fungistatic rather than a fungicidal effect under in vitro conditions.
Collapse
Affiliation(s)
- Andrea Kásler
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest 1117, Hungary
| | - János Ujszegi
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Department of Systematic Zoology and Ecology, Eötvös Loránd University, Budapest 1117, Hungary
| | - Dóra Holly
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Doctoral School of Biology, Institute of Biology, ELTE Eötvös Loránd University, Budapest 1117, Hungary
| | - Boglárka Jaloveczki
- Department of Zoology, Centre for Agricultural Research, Plant Protection Institute, Budapest 1029, Hungary
| | - Zoltán Gál
- Institute of Genetics and Biotechnology, Animal Biotechnology Department, Hungarian University of Agriculture and Life Sciences, Gödöllő 2100, Hungary
| | - Attila Hettyey
- Lendület Evolutionary Ecology Research Group, Centre for Agricultural Research, Plant Protection Institute, Eötvös Loránd Research Network, Nagykovácsi str. 26-30., Budapest 1029, Hungary.,Department of Ecology, University of Veterinary Medicine, Budapest 1078, Hungary
| |
Collapse
|
7
|
Rumschlag SL, Roth SA, McMahon TA, Rohr JR, Civitello DJ. Variability in environmental persistence but not per capita transmission rates of the amphibian chytrid fungus leads to differences in host infection prevalence. J Anim Ecol 2021; 91:170-181. [PMID: 34668575 DOI: 10.1111/1365-2656.13612] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2021] [Accepted: 09/27/2021] [Indexed: 11/28/2022]
Abstract
Heterogeneities in infections among host populations may arise through differences in environmental conditions through two mechanisms. First, environmental conditions may alter host exposure to pathogens via effects on survival. Second, environmental conditions may alter host susceptibility, making infection more or less likely if contact between a host and pathogen occurs. Further, host susceptibility might be altered through acquired resistance, which hosts can develop, in some systems, through exposure to dead or decaying pathogens and their metabolites. Environmental conditions may alter the rates of pathogen decomposition, influencing the likelihood of hosts developing acquired resistance. The present study primarily tests how environmental context influences the relative contributions of pathogen survival and per capita transmission on host infection prevalence using the amphibian chytrid fungus (Batrachochytrium dendrobatidis; Bd) as a model system. Secondarily, we evaluate how environmental context influences the decomposition of Bd because previous studies have shown that dead Bd and its metabolites can illicit acquired resistance in hosts. We conducted Bd survival and infection experiments and then fit models to discern how Bd mortality, decomposition and per capita transmission rates vary among water sources [e.g. artificial spring water (ASW) or water from three ponds]. We found that infection prevalence differed among water sources, which was driven by differences in mortality rates of Bd, rather than differences in per capita transmission rates. Bd mortality rates varied among pond water treatments and were lower in ASW compared to pond water. These results suggest that variation in Bd infection dynamics could be a function of environmental factors in waterbodies that result in differences in exposure of hosts to live Bd. In contrast to the persistence of live Bd, we found that the rates of decomposition of dead Bd did not vary among water sources, which may suggest that exposure of hosts to dead Bd or its metabolites might not commonly vary among nearby sites. Ultimately, a mechanistic understanding of the environmental dependence of free-living pathogens could lead to a deeper understanding of the patterns of outbreak heterogeneity, which could inform surveillance and management strategies.
Collapse
Affiliation(s)
- Samantha L Rumschlag
- Department of Biological Sciences, Environmental Change Initiative, and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.,Department of Integrative Biology, University of South Florida, Tampa, FL, USA
| | - Sadie A Roth
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA.,Department of Natural Resources Management, Texas Tech University, Lubbock, TX, USA
| | - Taegan A McMahon
- Department of Biology, University of Tampa, Tampa, FL, USA.,Department of Biology, Connecticut College, New London, CT, USA
| | - Jason R Rohr
- Department of Biological Sciences, Environmental Change Initiative, and Eck Institute for Global Health, University of Notre Dame, Notre Dame, IN, USA.,Department of Integrative Biology, University of South Florida, Tampa, FL, USA
| | | |
Collapse
|
8
|
Alvarado-Rybak M, Lepe-Lopez M, Peñafiel-Ricaurte A, Valenzuela-Sánchez A, Valdivia C, Mardones FO, Bacigalupe LD, Puschendorf R, Cunningham AA, Azat C. Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient. Sci Rep 2021; 11:17383. [PMID: 34462470 PMCID: PMC8405646 DOI: 10.1038/s41598-021-96535-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2021] [Accepted: 08/05/2021] [Indexed: 02/07/2023] Open
Abstract
Amphibian chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), has caused the greatest known loss of biodiversity due to an infectious disease. We used Bd infection data from quantitative real-time PCR (qPCR) assays of amphibian skin swabs collected across Chile during 2008-2018 to model Bd occurrence with the aim to determine bioclimatic and anthropogenic variables associated with Bd infection. Also, we used Bd presence/absence records to identify geographical Bd high-risk areas and compare Bd prevalence and infection loads between amphibian families, ecoregions, and host ecology. Data comprised 4155 Bd-specific qPCR assays from 162 locations across a latitudinal gradient of 3700 km (18º to 51ºS). Results showed a significant clustering of Bd associated with urban centres and anthropogenically highly disturbed ecosystems in central-south Chile. Both Bd prevalence and Bd infection loads were higher in aquatic than terrestrial amphibian species. Our model indicated positive associations of Bd prevalence with altitude, temperature, precipitation and human-modified landscapes. Also, we found that macroscale drivers, such as land use change and climate, shape the occurrence of Bd at the landscape level. Our study provides with new evidence that can improve the effectiveness of strategies to mitigate biodiversity loss due to amphibian chytridiomycosis.
Collapse
Affiliation(s)
- Mario Alvarado-Rybak
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
- Núcleo de Ciencias Aplicadas en Ciencias Veterinarias y Agronómicas, Universidad de las Américas, Echaurren 140, Santiago, Chile
| | - Manuel Lepe-Lopez
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
| | - Alexandra Peñafiel-Ricaurte
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
| | - Andrés Valenzuela-Sánchez
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
- ONG Ranita de Darwin, Nataniel Cox 152, Santiago, Chile
- Instituto de Conservación, Biodiversidad y Territorio, Facultad de Ciencias Forestales y Recursos Naturales, Universidad Austral de Chile, 5110566, Valdivia, Chile
| | - Catalina Valdivia
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile
| | - Fernando O Mardones
- Escuela de Medicina Veterinaria, Facultad de Agronomía e Ingeniería Forestal, Facultad de Ciencias Biológicas y Facultad de Medicina, Pontificia Universidad Católica de Chile, Santiago, Chile
| | - Leonardo D Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia, Chile
| | - Robert Puschendorf
- School of Biological and Marine Sciences, University of Plymouth, Plymouth, PL4 8AA, UK
| | - Andrew A Cunningham
- Institute of Zoology, Zoological Society of London, Regent's Park, London, NW1 4RY, UK
| | - Claudio Azat
- Sustainability Research Centre & PhD Programme in Conservation Medicine, Life Sciences Faculty, Universidad Andres Bello, Republica 252, Santiago, Chile.
| |
Collapse
|
9
|
TEMPERATURE AS A DRIVER OF THE PATHOGENICITY AND VIRULENCE OF AMPHIBIAN CHYTRID FUNGUS BATRACHOCHYTRIUM DENDROBATIDIS: A SYSTEMATIC REVIEW. J Wildl Dis 2021; 57:477-494. [PMID: 34019674 DOI: 10.7589/jwd-d-20-00105] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 02/10/2021] [Indexed: 11/20/2022]
Abstract
Chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), is a leading cause of global amphibian declines. Severe infections with Bd can lead to cardiac arrest, and mass deaths during epidemics have been reported. Temperature, pH, salinity, and moisture are important determinants of the survival, growth, reproduction, and pathogenicity of Bd, as well as its effect on amphibian populations. Here, we synthesize current knowledge on the role of temperature as a driver of the pathogenicity and virulence of Bd to better understand the effects of temperature on amphibian defense mechanisms against infection. This review advises on research direction and management approaches to benefit amphibian populations affected by Bd. We conclude by offering guidelines for four levels of temperature monitoring in amphibian field studies to improve consistency between studies: regional climate, habitat, microhabitat, and amphibian host.
Collapse
|
10
|
Delazeri F, Ernetti JR, De Bastiani VIM, Lingnau R, Toledo LF, Lucas EM. Forest cover influences chytrid infections in populations of Boana curupi, a threatened treefrog of south Brazil. DISEASES OF AQUATIC ORGANISMS 2021; 144:133-142. [PMID: 33955851 DOI: 10.3354/dao03585] [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
Complex interactions among hosts, pathogens, and the environment affect the vulnerability of amphibians to the emergence of infectious diseases such as chytridiomycosis, caused by Batrachochytrium dendrobatidis (Bd). Boana curupi is a forest-dwelling amphibian endemic to the southern Atlantic Forest of South America, a severely fragmented region. Here, we evaluated whether abiotic factors (including air and water temperature, relative air humidity, and landscape) are correlated with chytrid infection intensity and prevalence in B. curupi. We found individuals infected with Bd in all populations sampled. Prevalence ranged from 25-86%, and the infection burden ranged from 1 to over 130000 zoospore genomic equivalents (g.e.) (mean ± SD: 4913 ± 18081 g.e.). The infection load differed among populations and was influenced by forest cover at scales of 100, 500, and 1000 m, with the highest infection rates recorded in areas with a higher proportion of forest cover. Our results suggest that the fungus is widely distributed in the populations of B. curupi in southern Brazil. Population and disease monitoring are necessary to better understand the relationships between host, pathogen, and environment, especially when, as in the case of B. curupi, threatened species are involved.
Collapse
Affiliation(s)
- Francieli Delazeri
- Programa de Pós-graduação em Ciências Ambientais, Universidade Comunitária da Região de Chapecó, Chapecó, Santa Catarina 89809-900, Brazil
| | | | | | | | | | | |
Collapse
|
11
|
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.
Collapse
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.
| |
Collapse
|
12
|
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.
Collapse
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
| |
Collapse
|
13
|
Barrile GM, Chalfoun AD, Walters AW. Infection Status as the Basis for Habitat Choices in a Wild Amphibian. Am Nat 2021; 197:128-137. [PMID: 33417518 DOI: 10.1086/711927] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
AbstractAnimals challenged with disease may select specific habitat conditions that help prevent or reduce infection. Whereas preinfection avoidance of habitats with a high risk of disease exposure has been documented in both captive and free-ranging animals, evidence of switching habitats after infection to support the clearing of the infection is limited to laboratory experiments. The extent to which wild animals proximately modify habitat choices in response to infection status thus remains unclear. We investigated preinfection behavioral avoidance and postinfection habitat switching using wild, radio-tracked boreal toads (Anaxyrus boreas boreas) in a population challenged with Batrachochytrium dendrobatidis (Bd), a pathogenic fungus responsible for a catastrophic panzootic affecting hundreds of amphibian species worldwide. Boreal toads did not preemptively avoid microhabitats with conditions conducive to Bd growth. Infected individuals, however, selected warmer, more open habitats, which were associated with elevated body temperature and the subsequent clearing of infection. Our results suggest that disease can comprise an important selective pressure on animal habitat and space use. Habitat selection models, therefore, may be greatly improved by including variables that quantify infection risk and/or the infection status of individuals through time.
Collapse
|
14
|
Beukema W, Pasmans F, Van Praet S, Ferri-Yáñez F, Kelly M, Laking AE, Erens J, Speybroeck J, Verheyen K, Lens L, Martel A. Microclimate limits thermal behaviour favourable to disease control in a nocturnal amphibian. Ecol Lett 2020; 24:27-37. [PMID: 33022129 DOI: 10.1111/ele.13616] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/15/2020] [Accepted: 09/07/2020] [Indexed: 11/28/2022]
Abstract
While epizootics increasingly affect wildlife, it remains poorly understood how the environment shapes most host-pathogen systems. Here, we employ a three-step framework to study microclimate influence on ectotherm host thermal behaviour, focusing on amphibian chytridiomycosis in fire salamanders (Salamandra salamandra) infected with the fungal pathogen Batrachochytrium salamandrivorans (Bsal). Laboratory trials reveal that innate variation in thermal preference, rather than behavioural fever, can inhibit infection and facilitate salamander recovery under humidity-saturated conditions. Yet, a 3-year field study and a mesocosm experiment close to the invasive Bsal range show that microclimate constraints suppress host thermal behaviour favourable to disease control. A final mechanistic model, that estimates range-wide, year-round host body temperature relative to microclimate, suggests that these constraints are rule rather than exception. Our results demonstrate how innate host defences against epizootics may remain constrained in the wild, which predisposes to range-wide disease outbreaks and population declines.
Collapse
Affiliation(s)
- Wouter Beukema
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| | - Frank Pasmans
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| | - Sarah Van Praet
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| | - Francisco Ferri-Yáñez
- Department of Community Ecology, Helmholtz Centre for Environmental Research (UFZ), Theodor-Lieser-Strasse 4, Halle, 06120, Germany
| | - Moira Kelly
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| | - Alexandra E Laking
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| | - Jesse Erens
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| | - Jeroen Speybroeck
- Research Institute for Nature and Forest - INBO, Havenlaan 88 bus 73, Brussels, 1000, Belgium
| | - Kris Verheyen
- Forest & Nature Lab, Department of Forest and Water Management, Ghent University, Geraardsbergsesteenweg 267, Gontrode, 9090, Belgium
| | - Luc Lens
- Terrestrial Ecology Unit, Ghent University, K. L, Ledeganckstraat 35, Ghent, 9000, Belgium
| | - An Martel
- Wildlife Health Ghent, Department of Pathology, Bacteriology and Avian Diseases, Ghent University, Salisburylaan 133, Merelbeke, 9820, Belgium
| |
Collapse
|
15
|
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
| |
Collapse
|
16
|
Forti LR, Pontes MR, Alcantara EP, Morais DH, Silva RJ, Dodonov P, Toledo LF. Torrent frogs have fewer macroparasites but higher rates of chytrid infection in landscapes with smaller forest cover. Ecosphere 2020. [DOI: 10.1002/ecs2.3169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Affiliation(s)
- Lucas Rodriguez Forti
- Instituto de Biologia Universidade Federal da Bahia Campus de Ondina Salvador Bahia40170‐115Brazil
| | - Mariana Retuci Pontes
- Laboratório Multiusuário de Bioacústica (LMBio) e Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB) Departamento de Biologia Animal Instituto de Biologia Universidade Estadual de Campinas Campinas Sao Paulo13083‐970Brazil
- Programa de Pós‐Graduação em Ecologia Instituto de Biologia Universidade Estadual de Campinas Campinas Sao Paulo13083‐970Brazil
| | - Edna Paulino Alcantara
- Setor de Parasitologia, Instituto de Biologia Universidade Estadual de São Paulo/UNESP Rua Professor Doutor Antônio Celso Wagner Zanin, s/n Botucatu Sao Paulo18618‐689Brazil
| | - Drausio Honorio Morais
- Instituto de Ciências Agrárias UFU – Universidade Federal de Uberlândia LMG‐746, Km 1 Monte Carmelo Minas Gerais38500‐000Brazil
| | - Reinaldo José Silva
- Setor de Parasitologia, Instituto de Biologia Universidade Estadual de São Paulo/UNESP Rua Professor Doutor Antônio Celso Wagner Zanin, s/n Botucatu Sao Paulo18618‐689Brazil
| | - Pavel Dodonov
- Instituto de Biologia Universidade Federal da Bahia Campus de Ondina Salvador Bahia40170‐115Brazil
| | - Luís Felipe Toledo
- Laboratório Multiusuário de Bioacústica (LMBio) e Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB) Departamento de Biologia Animal Instituto de Biologia Universidade Estadual de Campinas Campinas Sao Paulo13083‐970Brazil
| |
Collapse
|
17
|
A subtle threat: behavioral and phenotypic consequences of invasive mosquitofish on a native paedomorphic newt. Biol Invasions 2019. [DOI: 10.1007/s10530-019-02181-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
18
|
Sonn JM, Utz RM, Richards‐Zawacki CL. Effects of latitudinal, seasonal, and daily temperature variations on chytrid fungal infections in a North American frog. Ecosphere 2019. [DOI: 10.1002/ecs2.2892] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Julia M. Sonn
- Department of Ecology and Evolutionary Biology Tulane University New Orleans Louisiana USA
| | - Ryan M. Utz
- Falk School of Sustainability Chatham University Gibsonia Pennsylvania USA
| | | |
Collapse
|
19
|
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.
Collapse
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
| |
Collapse
|
20
|
Shocket MS, Magnante A, Duffy MA, Cáceres CE, Hall SR. Can hot temperatures limit disease transmission? A test of mechanisms in a zooplankton–fungus system. Funct Ecol 2019. [DOI: 10.1111/1365-2435.13403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
| | | | - Meghan A. Duffy
- Department of Ecology and Evolutionary Biology University of Michigan Ann Arbor MI USA
| | - Carla E. Cáceres
- School of Integrative Biology University of Illinois at Urbana‐Champaign Urbana IL USA
| | | |
Collapse
|
21
|
Price SJ, Leung WTM, Owen CJ, Puschendorf R, Sergeant C, Cunningham AA, Balloux F, Garner TWJ, Nichols RA. Effects of historic and projected climate change on the range and impacts of an emerging wildlife disease. GLOBAL CHANGE BIOLOGY 2019; 25:2648-2660. [PMID: 31074105 DOI: 10.1111/gcb.14651] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 02/13/2019] [Indexed: 06/09/2023]
Abstract
The global trend of increasing environmental temperatures is often predicted to result in more severe disease epidemics. However, unambiguous evidence that temperature is a driver of epidemics is largely lacking, because it is demanding to demonstrate its role among the complex interactions between hosts, pathogens, and their shared environment. Here, we apply a three-pronged approach to understand the effects of temperature on ranavirus epidemics in UK common frogs, combining in vitro, in vivo, and field studies. Each approach suggests that higher temperatures drive increasing severity of epidemics. In wild populations, ranavirosis incidents were more frequent and more severe at higher temperatures, and their frequency increased through a period of historic warming in the 1990s. Laboratory experiments using cell culture and whole animal models showed that higher temperature increased ranavirus propagation, disease incidence, and mortality rate. These results, combined with climate projections, predict severe ranavirosis outbreaks will occur over wider areas and an extended season, possibly affecting larval recruitment. Since ranaviruses affect a variety of ectothermic hosts (amphibians, reptiles, and fish), wider ecological damage could occur. Our three complementary lines of evidence present a clear case for direct environmental modulation of these epidemics and suggest management options to protect species from disease.
Collapse
Affiliation(s)
- Stephen J Price
- UCL Genetics Institute, London, United Kingdom
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | - William T M Leung
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | | | - Robert Puschendorf
- School of Biological and Marine Sciences, University of Plymouth, Devon, United Kingdom
| | - Chris Sergeant
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | | | | | - Trenton W J Garner
- Institute of Zoology, Zoological Society of London, London, United Kingdom
| | | |
Collapse
|
22
|
Hettyey A, Ujszegi J, Herczeg D, Holly D, Vörös J, Schmidt BR, Bosch J. Mitigating Disease Impacts in Amphibian Populations: Capitalizing on the Thermal Optimum Mismatch Between a Pathogen and Its Host. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00254] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
23
|
Longo AV, Fleischer RC, Lips KR. Double trouble: co-infections of chytrid fungi will severely impact widely distributed newts. Biol Invasions 2019. [DOI: 10.1007/s10530-019-01973-3] [Citation(s) in RCA: 31] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
24
|
Draft Genome Sequences of Violacein-Producing Duganella sp. Isolates from a Waterway in Eastern Pennsylvania. Microbiol Resour Announc 2018; 7:MRA01196-18. [PMID: 30533678 PMCID: PMC6256701 DOI: 10.1128/mra.01196-18] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 08/31/2018] [Indexed: 12/03/2022] Open
Abstract
Five Duganella sp. bacterial isolates that synthesize violacein were cultured from a central Pennsylvania waterway. Five Duganella sp. bacterial isolates that synthesize violacein were cultured from a central Pennsylvania waterway. Violacein has antimicrobial potential, including chytrid-killing effects, relevant to amphibian declines worldwide. Whole-genome analysis of these five microbial isolates may provide insights to better protect amphibian communities from fungal infections using bioremediation.
Collapse
|
25
|
Pathogen invasion and non-epizootic dynamics in Pacific newts in California over the last century. PLoS One 2018; 13:e0197710. [PMID: 29965970 PMCID: PMC6028104 DOI: 10.1371/journal.pone.0197710] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Accepted: 05/07/2018] [Indexed: 11/19/2022] Open
Abstract
Emerging infectious disease is a growing threat to global biodiversity. The infectious disease chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd) has led to the decline and extinction of hundreds of amphibian species. Severe Bd-caused epizootics have been documented in North, Central and South America—with many of the research focused on anurans. California, where Bd-related epizootics and amphibian declines have been reported, has some of the highest diversity of salamanders. After more than a decade since the first known epizootic in California, little is known about Bd disease dynamics in salamanders. Pacific newts (Genus: Taricha) are ideal study species because of their abundance, wide geographic range, occurrence in both aquatic and terrestrial habitats, and how little is known about Bd infection dynamics for this group. We conducted a retrospective study to determine the relationship between Pacific newts and the fungal pathogen. We tested 1895 specimens collected between 1889–2009 and found no evidence of Bd-infected Pacific newts until the late 1940’s. Although we estimate that Bd emerged in this genus and rapidly spread geographically throughout California, we did not find evidence for epizootic dynamics. Bd infection prevalence and intensity, two measures commonly used to estimate dynamics, remained consistently low over time; suggesting Pacific newts may not be highly susceptible. Also, we found the timing of first Bd emergence in Pacific newts predate Bd emergence in other California salamander species. In addition, we found several environmental and anthropogenic factors correlated with Bd prevalence which may help explain Bd disease dynamics in the genus Taricha. Pacific newts may be a reservoir species that signal pathogen invasion into California salamanders, though further studies are needed.
Collapse
|
26
|
Affiliation(s)
- Thomas R. Raffel
- Department of Biological Sciences Oakland University Rochester MI USA
| |
Collapse
|
27
|
Greenspan SE, Bower DS, Webb RJ, Berger L, Rudd D, Schwarzkopf L, Alford RA. White blood cell profiles in amphibians help to explain disease susceptibility following temperature shifts. DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2017; 77:280-286. [PMID: 28870450 DOI: 10.1016/j.dci.2017.08.018] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2017] [Revised: 08/30/2017] [Accepted: 08/30/2017] [Indexed: 06/07/2023]
Abstract
Temperature variability, and in particular temperature decreases, can increase susceptibility of amphibians to infections by the fungus Batrachochytrium dendrobatidis (Bd). However, the effects of temperature shifts on the immune systems of Bd-infected amphibians are unresolved. We acclimated frogs to 16 °C and 26 °C (baseline), simultaneously transferred them to an intermediate temperature (21 °C) and inoculated them with Bd (treatment), and tracked their infection levels and white blood cell profiles over six weeks. Average weekly infection loads were consistently higher in 26°C-history frogs, a group that experienced a 5 °C temperature decrease, than in 16°C-history frogs, a group that experienced a 5 °C temperature increase, but this pattern only approached statistical significance. The 16°C-acclimated frogs had high neutrophil:lymphocyte (N:L) ratios (suggestive of a hematopoietic stress response) at baseline, which were conserved post-treatment. In contrast, the 26°C-acclimated frogs had low N:L ratios at baseline which reversed to high N:L ratios post-treatment (suggestive of immune system activation). Our results suggest that infections were less physiologically taxing for the 16°C-history frogs than the 26°C-history frogs because they had already adjusted immune parameters in response to challenging conditions (cold). Our findings provide a possible mechanistic explanation for observations that amphibians are more susceptible to Bd infection following temperature decreases compared to increases and underscore the consensus that increased temperature variability associated with climate change may increase the impact of infectious diseases.
Collapse
Affiliation(s)
- Sasha E Greenspan
- College of Science and Engineering, James Cook University, Townsville, Queensland 4811, Australia.
| | - Deborah S Bower
- College of Science and Engineering, James Cook University, Townsville, Queensland 4811, Australia
| | - Rebecca J Webb
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Donna Rudd
- College of Public Health, Medical and Veterinary Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Lin Schwarzkopf
- College of Science and Engineering, James Cook University, Townsville, Queensland 4811, Australia
| | - Ross A Alford
- College of Science and Engineering, James Cook University, Townsville, Queensland 4811, Australia
| |
Collapse
|
28
|
Clulow S, Gould J, James H, Stockwell M, Clulow J, Mahony M. Elevated salinity blocks pathogen transmission and improves host survival from the global amphibian chytrid pandemic: Implications for translocations. J Appl Ecol 2017. [DOI: 10.1111/1365-2664.13030] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Simon Clulow
- School of Environmental and Life Sciences; University of Newcastle; Callaghan NSW Australia
| | - John Gould
- School of Environmental and Life Sciences; University of Newcastle; Callaghan NSW Australia
| | - Hugh James
- School of Environmental and Life Sciences; University of Newcastle; Callaghan NSW Australia
| | - Michelle Stockwell
- School of Environmental and Life Sciences; University of Newcastle; Callaghan NSW Australia
| | - John Clulow
- School of Environmental and Life Sciences; University of Newcastle; Callaghan NSW Australia
| | - Michael Mahony
- School of Environmental and Life Sciences; University of Newcastle; Callaghan NSW Australia
| |
Collapse
|
29
|
Bacigalupe LD, Soto-Azat C, García-Vera C, Barría-Oyarzo I, Rezende EL. Effects of amphibian phylogeny, climate and human impact on the occurrence of the amphibian-killing chytrid fungus. GLOBAL CHANGE BIOLOGY 2017; 23:3543-3553. [PMID: 28055125 DOI: 10.1111/gcb.13610] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 12/20/2016] [Indexed: 06/06/2023]
Abstract
Chytridiomycosis, due to the fungus Batrachochytrium dendrobatidis (Bd), has been associated with the alarming decline and extinction crisis of amphibians worldwide. Because conservation programs are implemented locally, it is essential to understand how the complex interactions among host species, climate and human activities contribute to Bd occurrence at regional scales. Using weighted phylogenetic regressions and model selection, we investigated geographic patterns of Bd occurrence along a latitudinal gradient of 1500 km within a biodiversity hot spot in Chile (1845 individuals sampled from 253 sites and representing 24 species), and its association with climatic, socio-demographic and economic variables. Analyses show that Bd prevalence decreases with latitude although it has increased by almost 10% between 2008 and 2013, possibly reflecting an ongoing spread of Bd following the introduction of Xenopus laevis. Occurrence of Bd was higher in regions with high gross domestic product (particularly near developed centers) and with a high variability in rainfall regimes, whereas models including other bioclimatic or geographic variables, including temperature, exhibited substantially lower fit and virtually no support based on Akaike weights. In addition, Bd prevalence exhibited a strong phylogenetic signal, with five species having high numbers of infected individuals and higher prevalence than the average of 13.3% across all species. Taken together, our results highlight that Bd in Chile might still be spreading south, facilitated by a subset of species that seem to play an important epidemiological role maintaining this pathogen in the communities, in combination with climatic and human factors affecting the availability and quality of amphibian breeding sites. This information may be employed to design conservation strategies and mitigate the impacts of Bd in the biodiversity hot spot of southern Chile, and similar studies may prove useful to disentangle the role of different factors contributing to the emergence and spread of this catastrophic disease.
Collapse
Affiliation(s)
- Leonardo D Bacigalupe
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Avda. Rector Eduardo Morales s/n, Edificio Pugín, Valdivia, Chile
| | - Claudio Soto-Azat
- Centro de Investigación para la Sustentabilidad, Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, República 440, Santiago, Chile
| | - Cristobal García-Vera
- Dirección General de Aguas, Ministerio de Obras Públicas, Riquelme 465, Coyhaique, Chile
| | - Ismael Barría-Oyarzo
- Instituto de Ciencias Ambientales y Evolutivas, Facultad de Ciencias, Universidad Austral de Chile, Avda. Rector Eduardo Morales s/n, Edificio Pugín, Valdivia, Chile
| | - Enrico L Rezende
- Facultad de Ecología y Recursos Naturales, Universidad Andres Bello, República 440, Santiago, Chile
| |
Collapse
|
30
|
Greenspan SE, Bower DS, Webb RJ, Roznik EA, Stevenson LA, Berger L, Marantelli G, Pike DA, Schwarzkopf L, Alford RA. Realistic heat pulses protect frogs from disease under simulated rainforest frog thermal regimes. Funct Ecol 2017. [DOI: 10.1111/1365-2435.12944] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Affiliation(s)
- Sasha E. Greenspan
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Deborah S. Bower
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Rebecca J. Webb
- One Health Research Group College of Public Health Medical and Veterinary Sciences James Cook University Douglas Qld Australia
| | | | - Lisa A. Stevenson
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Lee Berger
- One Health Research Group College of Public Health Medical and Veterinary Sciences James Cook University Douglas Qld Australia
| | | | | | - Lin Schwarzkopf
- College of Science and Engineering James Cook University Townsville Qld Australia
| | - Ross A. Alford
- College of Science and Engineering James Cook University Townsville Qld Australia
| |
Collapse
|
31
|
Chytrid Infection Dynamics in Cricket Frogs on Military and Public Lands in the Midwestern United States. JOURNAL OF FISH AND WILDLIFE MANAGEMENT 2017. [DOI: 10.3996/012017-jfwm-003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Abstract
The pathogenic chytrid fungus Batrachochytrium dendrobatidis (hereafter, Bd) is a causal agent in amphibian decline and extinction events. Sampling for Bd in the Midwestern United States has largely been opportunistic and haphazard, so little information exists on the true occurrence and prevalence of the disease. We repeatedly tested Cricket Frogs Acris blanchardi or A. crepitans at 54 wetlands in 2009 and 15 wetlands in 2011 on both public and military lands to estimate Bd occurrence and prevalence rates between different land-use types, sampling seasons (spring, summer, autumn) and sampling years. We found Bd occurred in 100% of wetlands we sampled in 2009 and 2011, and overall prevalence was 22.7% in 2009 and 40.5% in 2011. Batrachochytrium dendrobatidis prevalence in 2011 was significantly higher than in 2009 and was significantly higher during the spring season than in the summer or autumn. We also found Bd prevalence was not significantly different on military versus public-use sites and was most affected by the average 30-d maximum temperature prior to sampling. This study provides data on the occurrence and prevalence of Bd in the United States and fills an important gap in the Midwest, while also corroborating prior research findings of increased prevalence in the cooler spring season.
Collapse
|
32
|
Lambertini C, Becker CG, Bardier C, da Silva Leite D, Toledo LF. Spatial distribution of Batrachochytrium dendrobatidis in South American caecilians. DISEASES OF AQUATIC ORGANISMS 2017; 124:109-116. [PMID: 28425424 DOI: 10.3354/dao03114] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
The amphibian-killing fungus Batrachochytrium dendrobatidis (Bd) is linked to population declines in anurans and salamanders globally. To date, however, few studies have attempted to screen Bd in live caecilians; Bd-positive caecilians have only been reported in Africa and French Guiana. Here, we performed a retrospective survey of museum preserved specimens to (1) describe spatial patterns of Bd infection in Gymnophiona across South America and (2) test whether areas of low climatic suitability for Bd in anurans predict Bd spatial epidemiology in caecilians. We used quantitative PCR to detect Bd in preserved caecilians collected over a 109 yr period, and performed autologistic regressions to test the effect of bioclimatic metrics of temperature and precipitation, vegetation density, and elevation on the likelihood of Bd occurrence. We detected an overall Bd prevalence of 12.4%, with positive samples spanning the Uruguayan savanna, Brazil's Atlantic Forest, and the Amazon basin. Our autologistic models detected a strong effect of macroclimate, a weaker effect of vegetation density, and no effect of elevation on the likelihood of Bd occurrence. Although most of our Bd-positive records overlapped with reported areas of high climatic suitability for the fungus in the Neotropics, many of our new Bd-positive samples extend far into areas of poor suitability for Bd in anurans. Our results highlight an important gap in the study of amphibian chytridiomycosis: the potential negative impact of Bd on Neotropical caecilians and the hypothetical role of caecilians as Bd reservoirs.
Collapse
Affiliation(s)
- Carolina Lambertini
- Laboratório de História Natural de Anfíbios Brasileiros (LaHNAB), Departamento de Biologia Animal, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo 13083-862, Brazil
| | | | | | | | | |
Collapse
|
33
|
Voyles J, Johnson LR, Rohr J, Kelly R, Barron C, Miller D, Minster J, Rosenblum EB. Diversity in growth patterns among strains of the lethal fungal pathogen Batrachochytrium dendrobatidis across extended thermal optima. Oecologia 2017; 184:363-373. [PMID: 28424893 PMCID: PMC5487841 DOI: 10.1007/s00442-017-3866-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2016] [Accepted: 04/05/2017] [Indexed: 12/27/2022]
Abstract
The thermal sensitivities of organisms regulate a wide range of ecological interactions, including host–parasite dynamics. The effect of temperature on disease ecology can be remarkably complex in disease systems where the hosts are ectothermic and where thermal conditions constrain pathogen reproductive rates. Amphibian chytridiomycosis, caused by the pathogen Batrachochytrium dendrobatidis (Bd), is a lethal fungal disease that is influenced by temperature. However, recent temperature studies have produced contradictory findings, suggesting that our current understanding of thermal effects on Bd may be incomplete. We investigated how temperature affects three different Bd strains to evaluate diversity in thermal responses. We quantified growth across the entire thermal range of Bd, and beyond the known thermal limits (Tmax and Tmin). Our results show that all Bd strains remained viable and grew following 24 h freeze (−12 °C) and heat shock (28 °C) treatments. Additionally, we found that two Bd strains had higher logistic growth rates (r) and carrying capacities (K) at the upper and lower extremities of the temperature range, and especially in low temperature conditions (2–3 °C). In contrast, a third strain exhibited relatively lower growth rates and carrying capacities at these same thermal extremes. Overall, our results suggest that there is considerable variation among Bd strains in thermal tolerance, and they establish a new thermal sensitivity profile for Bd. More generally, our findings point toward important questions concerning the mechanisms that dictate fungal thermal tolerances and temperature-dependent pathogenesis in other fungal disease systems.
Collapse
Affiliation(s)
- Jamie Voyles
- Department of Biology, University of Nevada-Reno, Reno, NV, 87801, USA.
| | - Leah R Johnson
- Department of Integrative Biology, University of South Florida, Tampa, FL, 33620, USA
- Department of Statistics, Virginia Polytechnic Institute and State University, Blacksburg, VA, 24061, USA
| | - Jason Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL, 33620, USA
| | - Rochelle Kelly
- Department of Biology, University of Washington, Seattle, WA, 98195, USA
| | - Carley Barron
- Department of Biology, New Mexico Tech, 801 Leroy Place, Socorro, NM, 87801, USA
| | - Delaney Miller
- Department of Biology, New Mexico Tech, 801 Leroy Place, Socorro, NM, 87801, USA
| | - Josh Minster
- Department of Biology, New Mexico Tech, 801 Leroy Place, Socorro, NM, 87801, USA
| | - Erica Bree Rosenblum
- Department of Environmental Science, Policy and Management, University of California- Berkeley, Berkeley, CA, 94720-3144, USA
| |
Collapse
|
34
|
Adams AJ, Kupferberg SJ, Wilber MQ, Pessier AP, Grefsrud M, Bobzien S, Vredenburg VT, Briggs CJ. Extreme drought, host density, sex, and bullfrogs influence fungal pathogen infection in a declining lotic amphibian. Ecosphere 2017. [DOI: 10.1002/ecs2.1740] [Citation(s) in RCA: 43] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Andrea J. Adams
- Department of Ecology, Evolution, and Marine Biology; University of California; Santa Barbara California 93106 USA
| | - Sarah J. Kupferberg
- Department of Integrative Biology; University of California; Berkeley California 94720 USA
| | - Mark Q. Wilber
- Department of Ecology, Evolution, and Marine Biology; University of California; Santa Barbara California 93106 USA
| | - Allan P. Pessier
- Department of Veterinary Microbiology and Pathology; College of Veterinary Medicine; Washington State University; Pullman Washington 99164 USA
| | - Marcia Grefsrud
- California Department of Fish and Wildlife; Bay Delta Region Napa California 94558 USA
| | - Steve Bobzien
- East Bay Regional Park District; Oakland California 94605 USA
| | | | - Cheryl J. Briggs
- Department of Ecology, Evolution, and Marine Biology; University of California; Santa Barbara California 93106 USA
| |
Collapse
|
35
|
Nowakowski AJ, Whitfield SM, Eskew EA, Thompson ME, Rose JP, Caraballo BL, Kerby JL, Donnelly MA, Todd BD. Infection risk decreases with increasing mismatch in host and pathogen environmental tolerances. Ecol Lett 2016; 19:1051-61. [PMID: 27339786 DOI: 10.1111/ele.12641] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2016] [Revised: 04/07/2016] [Accepted: 05/23/2016] [Indexed: 01/14/2023]
Abstract
The fungal pathogen Batrachochytrium dendrobatidis (Bd) has caused the greatest known wildlife pandemic, infecting over 500 amphibian species. It remains unclear why some host species decline from disease-related mortality whereas others persist. We introduce a conceptual model that predicts that infection risk in ectotherms will decrease as the difference between host and pathogen environmental tolerances (i.e. tolerance mismatch) increases. We test this prediction using both local-scale data from Costa Rica and global analyses of over 11 000 Bd infection assays. We find that infection prevalence decreases with increasing thermal tolerance mismatch and with increasing host tolerance of habitat modification. The relationship between environmental tolerance mismatches and Bd infection prevalence is generalisable across multiple amphibian families and spatial scales, and the magnitude of the tolerance mismatch effect depends on environmental context. These findings may help explain patterns of amphibian declines driven by a global wildlife pandemic.
Collapse
Affiliation(s)
- A Justin Nowakowski
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| | | | - Evan A Eskew
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| | - Michelle E Thompson
- Department of Biological Sciences, Florida International University, Miami, FL, 33199, USA
| | - Jonathan P Rose
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| | - Benjamin L Caraballo
- Science Department, Renaissance Charter High School for Innovation, 410 E. 100 St., New York, NY, 10029, USA
| | - Jacob L Kerby
- Biology Department, University of South Dakota, 414 E. Clark St., Vermillion, SD, 57069, USA
| | - Maureen A Donnelly
- Department of Biological Sciences, Florida International University, Miami, FL, 33199, USA
| | - Brian D Todd
- Department of Wildlife, Fish, and Conservation Biology, University of California, Davis, One Shields Ave., Davis, CA, 95616, USA
| |
Collapse
|
36
|
Petersen CE, Lovich RE, Phillips CA, Dreslik MJ, Lannoo MJ. Prevalence and Seasonality of the Amphibian Chytrid Fungus Batrachochytrium dendrobatidis Along Widely Separated Longitudes Across the United States. ECOHEALTH 2016; 13:368-382. [PMID: 26935823 DOI: 10.1007/s10393-016-1101-4] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 12/14/2015] [Accepted: 12/14/2015] [Indexed: 06/05/2023]
Abstract
The chytrid fungus Batrachochytrium dendrobatidis (Bd) has been implicated in amphibian declines on almost all continents. We report on prevalence and intensity of Bd in the United States amphibian populations across three longitudinally separated north-to-south transects conducted at 15 Department of Defense installations during two sampling periods (late-spring/early summer and mid to late summer). Such a standardized approach minimizes the effects of sampling and analytical bias, as well as human disturbance (by sampling restricted military bases), and therefore permits a cleaner interpretation of environmental variables known to affect chytrid dynamics such as season, temperature, rainfall, latitude, and longitude. Our prevalence of positive samples was 20.4% (137/670), and our mean intensity was 3.21 zoospore equivalents (SE = 1.03; range 0.001-103.59). Of the 28 amphibian species sampled, 15 tested positive. Three sites had no evidence of Bd infection; across the remaining 12 Bd-positive sites, neither infection prevalence nor intensity varied systematically. We found a more complicated pattern of Bd prevalence than anticipated. Early season samples showed no trend associated with increasing temperature and precipitation and decreasing (more southerly) latitudes; while in late season samples, the proportion of infected individuals decreased with increasing temperature and precipitation and decreasing latitudes. A similar pattern held for the east-west gradient, with the highest prevalence associated with more easterly/recently warmer sites in the early season then shifting to more westerly/recently cooler sites in the later season. Bd intensity across bases and sampling periods was comparatively low. Some of the trends in our data have been seen in previous studies, and our results offer further continental-level Bd sampling over which more concentrated local sampling efforts can be overlaid.
Collapse
Affiliation(s)
- Christopher E Petersen
- Naval Facilities Engineering Command Atlantic, Code EV52CP, 6506 Hampton Blvd., Norfolk, VA, 23508, USA.
| | - Robert E Lovich
- Naval Facilities Engineering Command Southwest, 1220 Pacific Highway, San Diego, CA, 92132, USA
| | - Christopher A Phillips
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA
| | - Michael J Dreslik
- Illinois Natural History Survey, Prairie Research Institute, University of Illinois at Urbana-Champaign, Champaign, IL, 61820, USA
| | - Michael J Lannoo
- Indiana University School of Medicine, Terre Haute, IN, 47802, USA
| |
Collapse
|
37
|
Valencia-Aguilar A, Toledo LF, Vital MV, Mott T. Seasonality, Environmental Factors, and Host Behavior Linked to Disease Risk in Stream-Dwelling Tadpoles. HERPETOLOGICA 2016. [DOI: 10.1655/herpetologica-d-15-00013] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
38
|
Stoler AB, Berven KA, Raffel TR. Leaf Litter Inhibits Growth of an Amphibian Fungal Pathogen. ECOHEALTH 2016; 13:392-404. [PMID: 26935822 DOI: 10.1007/s10393-016-1106-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Revised: 01/29/2016] [Accepted: 02/09/2016] [Indexed: 06/05/2023]
Abstract
Past studies have found a heterogeneous distribution of the amphibian chytrid fungal pathogen, Batrachochytrium dendrobatidis (Bd). Recent studies have accounted for some of this heterogeneity through a positive association between canopy cover and Bd abundance, which is attributed to the cooling effect of canopy cover. We questioned whether leaf litter inputs that are also associated with canopy cover might also alter Bd growth. Leaf litter inputs exhibit tremendous interspecific chemical variation, and we hypothesized that Bd growth varies with leachate chemistry. We also hypothesized that Bd uses leaf litter as a growth substrate. To test these hypotheses, we conducted laboratory trials in which we exposed cultures of Bd to leachate of 12 temperate leaf litter species at varying dilutions. Using a subset of those 12 litter species, we also exposed Bd to pre-leached litter substrate. We found that exposure to litter leachate and substrate reduced Bd spore and sporangia densities, although there was substantial variation among treatments. In particular, Bd densities were inversely correlated with concentrations of phenolic acids. We conducted a field survey of phenolic concentrations in natural wetlands which verified that the leachate concentrations in our lab study are ecologically relevant. Our study reinforces prior indications that positive associations between canopy cover and Bd abundance are likely mediated by water temperature effects, but this phenomenon might be counteracted by changes in aquatic chemistry from leaf litter inputs.
Collapse
Affiliation(s)
- Aaron B Stoler
- Department of Biological Sciences, Oakland University, Rochester, MI, USA.
- 1115 Center for Biotechnology and Integrative Sciences, Department of Biological Sciences, Rensselaer Polytechnic Institute, 110 8th St, Troy, NY, 12180, USA.
| | - Keith A Berven
- Department of Biological Sciences, Oakland University, Rochester, MI, USA
| | - Thomas R Raffel
- Department of Biological Sciences, Oakland University, Rochester, MI, USA
| |
Collapse
|
39
|
Preuss JF, Lambertini C, Leite DDS, Toledo LF, Lucas EM. Crossing the threshold: an amphibian assemblage highly infected withBatrachochytrium dendrobatidisin the southern Brazilian Atlantic forest. STUDIES ON NEOTROPICAL FAUNA AND ENVIRONMENT 2016. [DOI: 10.1080/01650521.2016.1163857] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
|
40
|
Rothermel BB, Miller DL, Travis ER, Gonynor McGuire JL, Jensen JB, Yabsley MJ. Disease dynamics of red-spotted newts and their anuran prey in a montane pond community. DISEASES OF AQUATIC ORGANISMS 2016; 118:113-127. [PMID: 26912042 DOI: 10.3354/dao02965] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Long-term monitoring of amphibians is needed to clarify population-level effects of ranaviruses (Rv) and the fungal pathogen Batrachochytrium dendrobatidis (Bd). We investigated disease dynamics of co-occurring amphibian species and potential demographic consequences of Rv and Bd infections at a montane site in the Southern Appalachians, Georgia, USA. Our 3-yr study was unique in combining disease surveillance with intensive population monitoring at a site where both pathogens are present. We detected sub-clinical Bd infections in larval and adult red-spotted newts Notophthalmus viridescens viridescens, but found no effect of Bd on body condition of adult newts. Bd infections also occurred in larvae of 5 anuran species that bred in our fishless study pond, and we detected co-infections with Bd and Rv in adult newts and larval green frogs Lithobates clamitans. However, all mortality and clinical signs in adult newts and larval anurans were most consistent with ranaviral disease, including a die-off of larval wood frogs Lithobates sylvaticus in small fish ponds located near our main study pond. During 2 yr of drift fence monitoring, we documented high juvenile production in newts, green frogs and American bullfrogs L. catesbeianus, but saw no evidence of juvenile recruitment in wood frogs. Larvae of this susceptible species may have suffered high mortality in the presence of both Rv and predators. Our findings were generally consistent with results of Rv-exposure experiments and support the purported role of red-spotted newts, green frogs, and American bullfrogs as common reservoirs for Bd and/or Rv in permanent and semi-permanent wetlands.
Collapse
|
41
|
|
42
|
Ortega N, Price W, Campbell T, Rohr J. Acquired and introduced macroparasites of the invasive Cuban treefrog, Osteopilus septentrionalis. INTERNATIONAL JOURNAL FOR PARASITOLOGY-PARASITES AND WILDLIFE 2015; 4:379-84. [PMID: 26759792 PMCID: PMC4683551 DOI: 10.1016/j.ijppaw.2015.10.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 10/02/2015] [Accepted: 10/07/2015] [Indexed: 11/28/2022]
Abstract
Because shifts in host–parasite relationships can alter host populations, attention should be given to the parasites that introduced species take with them or acquire in their introduced range. The Cuban treefrog, Osteopilus septentrionalis, is a successful invasive species in Florida with its parasites in the native range being well-documented, but there is a void in the literature regarding what parasites were lost or introduced in its expansion. We necropsied 330 O. septentrionalis from Tampa, FL and compared their macroparasites to those of O. septentrionalis in their native range and to the parasites of anurans native to the Tampa, FL area to determine the species O. septentrionalis likely introduced or acquired in Florida. At least nine parasite species (Aplectana sp., Oswaldocruzia lenteixeirai, Cylindrotaenia americana, Physaloptera sp., Rhabdias sp., Centrorhynchus sp., unidentified trematode metacercariae, unidentified larval acuariids, and unidentified pentastomids) were isolated. We found no differences in parasite communities of adult male and female frogs, which averaged 19.36 parasite individuals and 1.39 parasite species per adult frog, and had an overall prevalence of 77.52%. Acuariid larvae were likely acquired by O. septentrionalis in FL because they are not found in their native range. O. lenteixeirai was likely introduced because it is commonly reported in O. septentrionalis' native range but has never been reported in FL-native anurans. Aplectana sp. is also likely introduced because it has been reported in several anurans in Cuba but only reported once in Florida. O. septentrionalis tended to harbor fewer of its native parasites in the introduced range, which is consistent with the enemy release hypothesis and potentially creates an immunological advantage for this invasive host. Because native populations can be threatened by introduced parasites, there is a need to further explore the frequency and rate at which non-native hosts introduce parasites. We found at least six new host records of parasites in the Cuban treefrog. Host type significantly affected parasite mean abundance and mean intensity. Hosts were infected with fewer species of parasites than in their native range. Introduced parasite prevalence is eight-fifteen times higher in its native range.
Collapse
Affiliation(s)
- Nicole Ortega
- Department of Integrative Biology, University of South Florida, 4202 E. Fowler Ave - SCA 110, Tampa, FL 33620-5150, United States
| | - Wayne Price
- Department of Biology, 401 W. Kennedy Blvd., University of Tampa, Tampa, FL 33606, United States
| | - Todd Campbell
- Department of Biology, 401 W. Kennedy Blvd., University of Tampa, Tampa, FL 33606, United States
| | - Jason Rohr
- Department of Integrative Biology, University of South Florida, 4202 E. Fowler Ave - SCA 110, Tampa, FL 33620-5150, United States
| |
Collapse
|
43
|
Raffel TR, Halstead NT, McMahon TA, Davis AK, Rohr JR. Temperature variability and moisture synergistically interact to exacerbate an epizootic disease. Proc Biol Sci 2015; 282:20142039. [PMID: 25567647 DOI: 10.1098/rspb.2014.2039] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Climate change is altering global patterns of precipitation and temperature variability, with implications for parasitic diseases of humans and wildlife. A recent study confirmed predictions that increased temperature variability could exacerbate disease, because of lags in host acclimation following temperature shifts. However, the generality of these host acclimation effects and the potential for them to interact with other factors have yet to be tested. Here, we report similar effects of host thermal acclimation (constant versus shifted temperatures) on chytridiomycosis in red-spotted newts (Notophthalmus viridescens). Batrachochytrium dendrobatidis (Bd) growth on newts was greater following a shift to a new temperature, relative to newts already acclimated to this temperature (15°C versus 25°C). However, these acclimation effects depended on soil moisture (10, 16 and 21% water) and were only observed at the highest moisture level, which induced greatly increased Bd growth and infection-induced mortality. Acclimation effects were also greater following a decrease rather than an increase in temperature. The results are consistent with previous findings that chytridiomycosis is associated with precipitation, lower temperatures and increased temperature variability. This study highlights host acclimation as a potentially general mediator of climate-disease interactions, and the need to account for context-dependencies when testing for acclimation effects on disease.
Collapse
Affiliation(s)
- Thomas R Raffel
- Department of Biology, Oakland University, Rochester, MI, USA
| | - Neal T Halstead
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA
| | | | - Andrew K Davis
- Odum School of Ecology, University of Georgia, Athens, GA, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL, USA
| |
Collapse
|
44
|
Roznik EA, Sapsford SJ, Pike DA, Schwarzkopf L, Alford RA. Natural disturbance reduces disease risk in endangered rainforest frog populations. Sci Rep 2015; 5:13472. [PMID: 26294048 PMCID: PMC4544035 DOI: 10.1038/srep13472] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2015] [Accepted: 07/28/2015] [Indexed: 11/27/2022] Open
Abstract
Natural disturbances can drive disease dynamics in animal populations by altering the microclimates experienced by hosts and their pathogens. Many pathogens are highly sensitive to temperature and moisture, and therefore small changes in habitat structure can alter the microclimate in ways that increase or decrease infection prevalence and intensity in host populations. Here we show that a reduction of rainforest canopy cover caused by a severe tropical cyclone decreased the risk of endangered rainforest frogs (Litoria rheocola) becoming infected by a fungal pathogen (Batrachochytrium dendrobatidis). Reductions in canopy cover increased the temperatures and rates of evaporative water loss in frog microhabitats, which reduced B. dendrobatidis infection risk in frogs by an average of 11–28% in cyclone-damaged areas, relative to unaffected areas. Natural disturbances to the rainforest canopy can therefore provide an immediate benefit to frogs by altering the microclimate in ways that reduce infection risk. This could increase host survival and reduce the probability of epidemic disease outbreaks. For amphibian populations under immediate threat from this pathogen, targeted manipulation of canopy cover could increase the availability of warmer, drier microclimates and therefore tip the balance from host extinction to coexistence.
Collapse
Affiliation(s)
- Elizabeth A Roznik
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Sarah J Sapsford
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - David A Pike
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Lin Schwarzkopf
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| | - Ross A Alford
- College of Marine and Environmental Sciences, James Cook University, Townsville, Queensland 4811, Australia
| |
Collapse
|
45
|
Scheele BC, Driscoll DA, Fischer J, Fletcher AW, Hanspach J, Vörös J, Hartel T. Landscape context influences chytrid fungus distribution in an endangered European amphibian. Anim Conserv 2015. [DOI: 10.1111/acv.12199] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Affiliation(s)
- B. C. Scheele
- Fenner School of Environment and Society; Australian National University; Canberra Australia
| | - D. A. Driscoll
- Fenner School of Environment and Society; Australian National University; Canberra Australia
| | - J. Fischer
- Faculty of Sustainability; Leuphana University Lueneburg; Lueneburg Germany
| | - A. W. Fletcher
- Faculty of Sustainability; Leuphana University Lueneburg; Lueneburg Germany
| | - J. Hanspach
- Faculty of Sustainability; Leuphana University Lueneburg; Lueneburg Germany
| | - J. Vörös
- Department of Zoology; Hungarian Natural History Museum; Budapest Hungary
| | - T. Hartel
- Faculty of Sustainability; Leuphana University Lueneburg; Lueneburg Germany
- Environmental Science Department; Sapientia Hungarian University of Transylvania; Cluj-Napoca Romania
| |
Collapse
|
46
|
McMahon TA, Rohr JR. Transition of chytrid fungus infection from mouthparts to hind limbs during amphibian metamorphosis. ECOHEALTH 2015; 12:188-193. [PMID: 25384612 DOI: 10.1007/s10393-014-0989-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2013] [Revised: 09/04/2014] [Accepted: 10/12/2014] [Indexed: 06/04/2023]
Abstract
The chytrid fungus, Batrachochytrium dendrobatidis (Bd), is implicated in worldwide amphibian declines. Bd has been shown to qualitatively transition from the mouthparts of tadpoles to the hindlimbs during metamorphosis, but we lack evidence of consistency in the timing of this transition across amphibian species. We also do not have predictive functions for the abundance of Bd in mouthparts and limbs as tadpoles develop or for the relationship between keratin and Bd abundance. Hence, researchers presently have little guidance on where to sample developing amphibians to maximize Bd detection, which could affect the accuracy of prevalence and abundance estimates for this deadly pathogen. Here, we show consistency in the timing of the transition of Bd from mouthparts to hind limbs across two frog species (Osteopilus septentrionalis and Mixophyes fasciolatus). Keratin and Bd simultaneously declined from the mouthparts starting at approximately Gosner stage 40. However, keratin on the hindlimbs began to appear at approximately stage 38 but, on average, Bd was not detectable on the hindlimbs until approximately stage 40, suggesting a lag between keratin and Bd arrival. Predictive functions for the relationships between developmental stage and keratin and developmental stage and Bd for mouthparts and hind limbs are provided so that researchers can optimize sampling designs and minimize erroneous conclusions associated with missing Bd infections or misestimating Bd abundance.
Collapse
Affiliation(s)
- Taegan A McMahon
- Department of Biology, University of Tampa, 401 W. Kennedy Ave, Tampa, FL, 33606, USA,
| | | |
Collapse
|
47
|
Evidence of a salt refuge: chytrid infection loads are suppressed in hosts exposed to salt. Oecologia 2014; 177:901-910. [PMID: 25416999 DOI: 10.1007/s00442-014-3157-6] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2013] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
Abstract
With the incidence of emerging infectious diseases on the rise, it is becoming increasingly important to identify refuge areas that protect hosts from pathogens and therefore prevent population declines. For the chytrid fungus Batrachochytrium dendrobatidis, temperature and humidity refuge areas for amphibian hosts exist but are difficult to manipulate. Other environmental features that may affect the outcome of infection include water quality, drying regimes, abundance of alternate hosts and isolation from other hosts. We identified relationships between water bodies with these features and infection levels in the free-living hosts inhabiting them. Where significant relationships were identified, we used a series of controlled experiments to test for causation. Infection loads were negatively correlated with the salt concentration of the aquatic habitat and the degree of water level fluctuation and positively correlated with fish abundance. However, only the relationship with salt was confirmed experimentally. Free-living hosts inhabiting water bodies with mean salinities of up to 3.5 ppt had lower infection loads than those exposed to less salt. The experiment confirmed that exposure to sodium chloride concentrations >2 ppt significantly reduced host infection loads compared to no exposure (0 ppt). These results suggest that the exposure of amphibians to salt concentrations found naturally in lentic habitats may be responsible for the persistence of some susceptible species in the presence of B. dendrobatidis. By manipulating the salinity of water bodies, it may be possible to create refuges for declining amphibians, thus allowing them to be reintroduced to their former ranges.
Collapse
|
48
|
Scheele BC, Hunter DA, Grogan LF, Berger L, Kolby JE, McFadden MS, Marantelli G, Skerratt LF, Driscoll DA. Interventions for reducing extinction risk in chytridiomycosis-threatened amphibians. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2014; 28:1195-1205. [PMID: 24975971 DOI: 10.1111/cobi.12322] [Citation(s) in RCA: 90] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2013] [Accepted: 02/21/2014] [Indexed: 06/03/2023]
Abstract
Wildlife diseases pose an increasing threat to biodiversity and are a major management challenge. A striking example of this threat is the emergence of chytridiomycosis. Despite diagnosis of chytridiomycosis as an important driver of global amphibian declines 15 years ago, researchers have yet to devise effective large-scale management responses other than biosecurity measures to mitigate disease spread and the establishment of disease-free captive assurance colonies prior to or during disease outbreaks. We examined the development of management actions that can be implemented after an epidemic in surviving populations. We developed a conceptual framework with clear interventions to guide experimental management and applied research so that further extinctions of amphibian species threatened by chytridiomycosis might be prevented. Within our framework, there are 2 management approaches: reducing Batrachochytrium dendrobatidis (the fungus that causes chytridiomycosis) in the environment or on amphibians and increasing the capacity of populations to persist despite increased mortality from disease. The latter approach emphasizes that mitigation does not necessarily need to focus on reducing disease-associated mortality. We propose promising management actions that can be implemented and tested based on current knowledge and that include habitat manipulation, antifungal treatments, animal translocation, bioaugmentation, head starting, and selection for resistance. Case studies where these strategies are being implemented will demonstrate their potential to save critically endangered species.
Collapse
Affiliation(s)
- Ben C Scheele
- ARC Centre of Excellence for Environmental Decisions, National Environmental Research Program Environmental Decisions Hub, Fenner School of Environment and Society, Forestry Building [48], Australian National University, Canberra, ACT 0200, Australia; NSW Office of Environment and Heritage, Queanbeyan, NSW 2620, Australia.
| | | | | | | | | | | | | | | | | |
Collapse
|
49
|
Chestnut T, Anderson C, Popa R, Blaustein AR, Voytek M, Olson DH, Kirshtein J. Heterogeneous occupancy and density estimates of the pathogenic fungus Batrachochytrium dendrobatidis in waters of North America. PLoS One 2014; 9:e106790. [PMID: 25222122 PMCID: PMC4164359 DOI: 10.1371/journal.pone.0106790] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 08/06/2014] [Indexed: 01/15/2023] Open
Abstract
Biodiversity losses are occurring worldwide due to a combination of stressors. For example, by one estimate, 40% of amphibian species are vulnerable to extinction, and disease is one threat to amphibian populations. The emerging infectious disease chytridiomycosis, caused by the aquatic fungus Batrachochytrium dendrobatidis (Bd), is a contributor to amphibian declines worldwide. Bd research has focused on the dynamics of the pathogen in its amphibian hosts, with little emphasis on investigating the dynamics of free-living Bd. Therefore, we investigated patterns of Bd occupancy and density in amphibian habitats using occupancy models, powerful tools for estimating site occupancy and detection probability. Occupancy models have been used to investigate diseases where the focus was on pathogen occurrence in the host. We applied occupancy models to investigate free-living Bd in North American surface waters to determine Bd seasonality, relationships between Bd site occupancy and habitat attributes, and probability of detection from water samples as a function of the number of samples, sample volume, and water quality. We also report on the temporal patterns of Bd density from a 4-year case study of a Bd-positive wetland. We provide evidence that Bd occurs in the environment year-round. Bd exhibited temporal and spatial heterogeneity in density, but did not exhibit seasonality in occupancy. Bd was detected in all months, typically at less than 100 zoospores L(-1). The highest density observed was ∼3 million zoospores L(-1). We detected Bd in 47% of sites sampled, but estimated that Bd occupied 61% of sites, highlighting the importance of accounting for imperfect detection. When Bd was present, there was a 95% chance of detecting it with four samples of 600 ml of water or five samples of 60 mL. Our findings provide important baseline information to advance the study of Bd disease ecology, and advance our understanding of amphibian exposure to free-living Bd in aquatic habitats over time.
Collapse
Affiliation(s)
- Tara Chestnut
- Oregon State University, Environmental Science Graduate Program, Corvallis, Oregon, United States of America
- US Geological Survey, Oregon Water Science Center, Portland, Oregon, United States of America
| | - Chauncey Anderson
- US Geological Survey, Oregon Water Science Center, Portland, Oregon, United States of America
| | - Radu Popa
- Biological Sciences, University of Southern California, Los Angeles, California, United States of America
| | - Andrew R. Blaustein
- Oregon State University, Department of Integrative Biology, Corvallis, Oregon, United States of America
| | - Mary Voytek
- Astrobiology Program, National Aeronautics and Space Administration Headquarters, Washington DC, United States of America
| | - Deanna H. Olson
- US Forest Service, Pacific Northwest Research Station, Corvallis, Oregon, United States of America
| | - Julie Kirshtein
- US Geological Survey, National Research Program, Reston, Virginia, United States of America
| |
Collapse
|
50
|
Lenker MA, Savage AE, Becker CG, Rodriguez D, Zamudio KR. Batrachochytrium dendrobatidis infection dynamics vary seasonally in upstate New York, USA. DISEASES OF AQUATIC ORGANISMS 2014; 111:51-60. [PMID: 25144117 DOI: 10.3354/dao02760] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The amphibian disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis (Bd), is a major cause of worldwide amphibian declines and extinctions. Although several studies indicate that Bd prevalence and infection intensity vary seasonally, temporal variation of Bd at high-latitude sites, such as the northeastern USA, is still poorly characterized. We screened amphibians for Bd monthly at 2 study sites in New York State from April to October 2011 and used quantitative polymerase chain reaction (qPCR) to detect and quantify temporal variability in Bd infection prevalence and intensity. We found pronounced seasonal variation in both Bd infection prevalence and intensity at the community level, and our data indicate that this pattern is due to a few species (Lithobates catesbeianus, L. clamitans, and Notophthalmus viridescens) that drive temporal variability in disease dynamics. Amphibian body mass and sex were significant predictors of infection intensity but not infection prevalence. Understanding the temporal dynamics of Bd host-pathogen interactions provides important insight into regional, seasonal, and host-specific determinants of disease outbreaks. Further, our study elucidates the most relevant and informative timing for Bd surveys in temperate amphibian assemblages. Seasonal variation of infection dynamics suggests that Bd surveys from different sampling time points are not comparable, and summer surveys to evaluate chytridiomycosis may significantly underestimate Bd prevalence and intensity, leading to false conclusions about the severity of chytridiomycosis-induced amphibian mortality and population decline.
Collapse
Affiliation(s)
- Melissa A Lenker
- Cornell University, Department of Ecology and Evolutionary Biology, Ithaca, NY 14853, USA
| | | | | | | | | |
Collapse
|