51
|
Orlofske SA, Belden LK, Hopkins WA. Effects of Echinostoma trivolvis metacercariae infection during development and metamorphosis of the wood frog (Lithobates sylvaticus). Comp Biochem Physiol A Mol Integr Physiol 2016; 203:40-48. [PMID: 27543422 DOI: 10.1016/j.cbpa.2016.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2016] [Revised: 07/28/2016] [Accepted: 08/05/2016] [Indexed: 11/27/2022]
Abstract
Many organisms face energetic trade-offs between defense against parasites and other host processes that may determine overall consequences of infection. These trade-offs may be particularly evident during unfavorable environmental conditions or energetically demanding life history stages. Amphibian metamorphosis, an ecologically important developmental period, is associated with drastic morphological and physiological changes and substantial energetic costs. Effects of the trematode parasite Echinostoma trivolvis have been documented during early amphibian development, but effects during later development and metamorphosis are largely unknown. Using a laboratory experiment, we examined the energetic costs of late development and metamorphosis coupled with E. trivolvis infection in wood frogs, Lithobates [=Rana] sylvaticus. Echinostoma infection intensity did not differ between tadpoles examined prior to and after completing metamorphosis, suggesting that metacercariae were retained through metamorphosis. Infection with E. trivolvis contributed to a slower growth rate and longer development period prior to the initiation of metamorphosis. In contrast, E. trivolvis infection did not affect energy expenditure during late development or metamorphosis. Possible explanations for these results include the presence of parasites not interfering with pronephros degradation during metamorphosis or the mesonephros compensating for any parasite damage. Overall, the energetic costs of metamorphosis for wood frogs were comparable to other species with similar life history traits, but differed from a species with a much shorter duration of metamorphic climax. Our findings contribute to understanding the possible role of energetic trade-offs between parasite defense and host processes by considering parasite infection with simultaneous energetic demands during a sensitive period of development.
Collapse
Affiliation(s)
- Sarah A Orlofske
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA.
| | - Lisa K Belden
- Department of Biological Sciences, Virginia Tech, Blacksburg, VA 24061, USA
| | - William A Hopkins
- Department of Fish and Wildlife Conservation, Virginia Tech, Blacksburg, VA 24061, USA
| |
Collapse
|
52
|
MONITORING RANAVIRUS-ASSOCIATED MORTALITY IN A DUTCH HEATHLAND IN THE AFTERMATH OF A RANAVIRUS DISEASE OUTBREAK. J Wildl Dis 2016; 52:817-827. [PMID: 27455198 DOI: 10.7589/2015-04-104] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The ranaviruses are an emerging group of viruses that infect amphibians, fish, and reptiles. Although ranaviruses have not been linked to extinctions, emergence in amphibian communities has resulted in population declines for some species. We present the results of ranavirus-associated mortality in a Dutch national park in the aftermath of an outbreak associated with a common midwife toad virus (CMTV)-like ranavirus. We monitored five bodies of water across Dwingelderveld National Park, the Netherlands, in 2011-13. Dead and live amphibians were counted weekly July-September and every 2 wk in June and October. Dead amphibians were collected and tested for ranavirus infection. In addition, we measured biologic, chemical, and physical site characteristics to test for a correlation with ranavirus-associated mortality. Ranavirus infection was widespread in our study area and we observed nearly continuous presence of dead, ranavirus-infected amphibians in the presence of asymptomatic, live amphibians throughout our study. Fatalities occurred in larval, subadult, and adult amphibians. Ranavirus infection prevalence (based on fatal cases) was significantly associated with increasing fractions of adults and subadults compared to juveniles and larvae in the population, but was unrelated to any other measured site characteristics. Our findings showed that a CMTV-like ranavirus can persist long term in an ecosystem, affecting a diversity of amphibian species and life stages for a prolonged period. This study illustrates the importance of monitoring the modes of spread for ranaviruses and their impact on amphibian populations.
Collapse
|
53
|
Martin LB, Burgan SC, Adelman JS, Gervasi SS. Host Competence: An Organismal Trait to Integrate Immunology and Epidemiology. Integr Comp Biol 2016; 56:1225-1237. [DOI: 10.1093/icb/icw064] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
|
54
|
Kirschman LJ, Haslett S, Fritz KA, Whiles MR, Warne RW. Influence of Physiological Stress on Nutrient Stoichiometry in Larval Amphibians. Physiol Biochem Zool 2016; 89:313-21. [DOI: 10.1086/687047] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
|
55
|
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
|
56
|
Warne RW, LaBumbard B, LaGrange S, Vredenburg VT, Catenazzi A. Co-Infection by Chytrid Fungus and Ranaviruses in Wild and Harvested Frogs in the Tropical Andes. PLoS One 2016; 11:e0145864. [PMID: 26726999 PMCID: PMC4701007 DOI: 10.1371/journal.pone.0145864] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2015] [Accepted: 12/09/2015] [Indexed: 11/18/2022] Open
Abstract
While global amphibian declines are associated with the spread of Batrachochytrium dendrobatidis (Bd), undetected concurrent co-infection by other pathogens may be little recognized threats to amphibians. Emerging viruses in the genus Ranavirus (Rv) also cause die-offs of amphibians and other ectotherms, but the extent of their distribution globally, or how co-infections with Bd impact amphibians are poorly understood. We provide the first report of Bd and Rv co-infection in South America, and the first report of Rv infections in the amphibian biodiversity hotspot of the Peruvian Andes, where Bd is associated with extinctions. Using these data, we tested the hypothesis that Bd or Rv parasites facilitate co-infection, as assessed by parasite abundance or infection intensity within individual adult frogs. Co-infection occurred in 30% of stream-dwelling frogs; 65% were infected by Bd and 40% by Rv. Among terrestrial, direct-developing Pristimantis frogs 40% were infected by Bd, 35% by Rv, and 20% co-infected. In Telmatobius frogs harvested for the live-trade 49% were co-infected, 92% were infected by Bd, and 53% by Rv. Median Bd and Rv loads were similar in both wild (Bd = 101.2 Ze, Rv = 102.3 viral copies) and harvested frogs (Bd = 103.1 Ze, Rv = 102.7 viral copies). While neither parasite abundance nor infection intensity were associated with co-infection patterns in adults, these data did not include the most susceptible larval and metamorphic life stages. These findings suggest Rv distribution is global and that co-infection among these parasites may be common. These results raise conservation concerns, but greater testing is necessary to determine if parasite interactions increase amphibian vulnerability to secondary infections across differing life stages, and constitute a previously undetected threat to declining populations. Greater surveillance of parasite interactions may increase our capacity to contain and mitigate the impacts of these and other wildlife diseases.
Collapse
Affiliation(s)
- Robin W. Warne
- Southern Illinois University, Department of Zoology, 1125 Lincoln Dr., MC6501, Carbondale, IL, 62901, United States of America
- * E-mail:
| | - Brandon LaBumbard
- Southern Illinois University, Department of Zoology, 1125 Lincoln Dr., MC6501, Carbondale, IL, 62901, United States of America
| | - Seth LaGrange
- Southern Illinois University, Department of Zoology, 1125 Lincoln Dr., MC6501, Carbondale, IL, 62901, United States of America
| | - Vance T. Vredenburg
- Department of Biology, San Francisco State University, San Francisco, CA, 94132, United States of America
| | - Alessandro Catenazzi
- Southern Illinois University, Department of Zoology, 1125 Lincoln Dr., MC6501, Carbondale, IL, 62901, United States of America
| |
Collapse
|
57
|
Hing S, Narayan EJ, Thompson RCA, Godfrey SS. The relationship between physiological stress and wildlife disease: consequences for health and conservation. WILDLIFE RESEARCH 2016. [DOI: 10.1071/wr15183] [Citation(s) in RCA: 94] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Wildlife populations are under increasing pressure from a variety of threatening processes, ranging from climate change to habitat loss, that can incite a physiological stress response. The stress response influences immune function, with potential consequences for patterns of infection and transmission of disease among and within wildlife, domesticated animals and humans. This is concerning because stress may exacerbate the impact of disease on species vulnerable to extinction, with consequences for biodiversity conservation globally. Furthermore, stress may shape the role of wildlife in the spread of emerging infectious diseases (EID) such as Hendra virus (HeV) and Ebola virus. However, we still have a limited understanding of the influence of physiological stress on infectious disease in wildlife. We highlight key reasons why an improved understanding of the relationship between stress and wildlife disease could benefit conservation, and animal and public health, and discuss approaches for future investigation. In particular, we recommend that increased attention be given to the influence of anthropogenic stressors including climate change, habitat loss and management interventions on disease dynamics in wildlife populations.
Collapse
|
58
|
Buck JC, Rohr JR, Blaustein AR. Effects of nutrient supplementation on host-pathogen dynamics of the amphibian chytrid fungus: a community approach. FRESHWATER BIOLOGY 2016; 61:110-120. [PMID: 28956554 PMCID: PMC4857202 DOI: 10.1111/fwb.12685] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
Anthropogenic stressors may influence hosts and their pathogens directly or may alter host-pathogen dynamics indirectly through interactions with other species. For example, in aquatic ecosystems, eutrophication may be associated with increased or decreased disease risk. Conversely, pathogens can influence community structure and function and are increasingly recognised as important members of the ecological communities in which they exist.In outdoor mesocosms, we experimentally manipulated nutrients (nitrogen and phosphorus) and the presence of a fungal pathogen, Batrachochytrium dendrobatidis (Bd), and examined the effects on Bd abundance on larval amphibian hosts (Pseudacris regilla: Hylidae), amphibian traits and community dynamics. We predicted that resource supplementation would mitigate negative effects of Bd on tadpole growth and development and that indirect effects of treatments would propagate through the community.Nutrient additions caused changes in algal growth, which benefitted tadpoles through increased mass, development and survival. Bd-exposed tadpoles metamorphosed sooner than unexposed individuals, but their mass at metamorphosis was not affected by Bd exposure. We detected additive rather than interactive effects of nutrient supplementation and Bd in this experiment.Nutrient supplementation was not a significant predictor of infection load of larval amphibians. However, a structural equation model revealed that resource supplementation and exposure of amphibians to Bd altered the structure of the aquatic community. This is the first demonstration that sublethal effects of Bd on amphibians can alter aquatic community dynamics.
Collapse
Affiliation(s)
- Julia C Buck
- Texas Research Institute for Environmental Studies, Sam Houston State University, Huntsville, TX, U.S.A
- Department of Integrative Biology, Oregon State University, Corvallis, OR, U.S.A
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL, U.S.A
| | - Andrew R Blaustein
- Department of Integrative Biology, Oregon State University, Corvallis, OR, U.S.A
| |
Collapse
|
59
|
Hall EM, Crespi EJ, Goldberg CS, Brunner JL. Evaluating environmental DNA-based quantification of ranavirus infection in wood frog populations. Mol Ecol Resour 2015; 16:423-33. [PMID: 26308150 DOI: 10.1111/1755-0998.12461] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 08/13/2015] [Accepted: 08/21/2015] [Indexed: 11/26/2022]
Abstract
A variety of challenges arise when monitoring wildlife populations for disease. Sampling tissues can be invasive to hosts, and obtaining sufficient sample sizes can be expensive and time-consuming, particularly for rare species and when pathogen prevalence is low. Environmental DNA (eDNA)-based detection of pathogens is an alternative approach to surveillance for aquatic communities that circumvents many of these issues. Ranaviruses are emerging pathogens of ectothermic vertebrates linked to die-offs of amphibian populations. Detecting ranavirus infections is critical, but nonlethal methods have the above issues and are prone to false negatives. We report on the feasibility and effectiveness of eDNA-based ranavirus detection in the field. We compared ranavirus titres in eDNA samples collected from pond water to titres in wood frog (Lithobates sylvaticus; n = 5) tadpoles in sites dominated by this one species (n = 20 pond visits). We examined whether ranavirus DNA can be detected in eDNA from pond water when infections are present in the pond and if viral titres detected in eDNA samples correlate with the prevalence or intensity of ranavirus infections in tadpoles. With three 250 mL water samples, we were able to detect the virus in all visits with infected larvae (0.92 diagnostic sensitivity). Also, we found a strong relationship between the viral eDNA titres and titres in larval tissues. eDNA titres increased prior to observed die-offs and declined afterwards, and were two orders of magnitude higher in ponds with a die-off. Our results suggest that eDNA is useful for detecting ranavirus infections in wildlife and aquaculture.
Collapse
Affiliation(s)
- Emily M Hall
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
| | - Erica J Crespi
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
| | - Caren S Goldberg
- School of the Environment, Washington State University, PO Box 646410, Pullman, WA, 99164-2812, USA
| | - Jesse L Brunner
- School of Biological Sciences, Washington State University, PO Box 644236, Pullman, WA, 99164-4236, USA
| |
Collapse
|
60
|
Echaubard P, Pauli BD, Trudeau VL, Lesbarrères D. Ranavirus infection in northern leopard frogs: the timing and number of exposures matter. J Zool (1987) 2015. [DOI: 10.1111/jzo.12281] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- P. Echaubard
- Genetics and Ecology of Amphibians Research Group (GEARG); Department of Biology; Laurentian University; Sudbury Ontario Canada
- WHO Collaborating Center for Research and Control of Opisthorchiasis; Tropical Disease Research laboratory; Faculty of Medicine; Khon Kaen University; Khon Kaen Thailand
| | - B. D. Pauli
- Environment Canada; Science and Technology Branch, National Wildlife Research Centre; Carleton University; Ottawa Ontario Canada
| | - V. L. Trudeau
- Centre for Advanced Research in Environmental Genomics; Department of Biology; University of Ottawa; Ottawa Ontario Canada
| | - D. Lesbarrères
- Genetics and Ecology of Amphibians Research Group (GEARG); Department of Biology; Laurentian University; Sudbury Ontario Canada
| |
Collapse
|
61
|
Kolby JE, Smith KM, Ramirez SD, Rabemananjara F, Pessier AP, Brunner JL, Goldberg CS, Berger L, Skerratt LF. Rapid Response to Evaluate the Presence of Amphibian Chytrid Fungus (Batrachochytrium dendrobatidis) and Ranavirus in Wild Amphibian Populations in Madagascar. PLoS One 2015; 10:e0125330. [PMID: 26083349 PMCID: PMC4471163 DOI: 10.1371/journal.pone.0125330] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Accepted: 03/11/2015] [Indexed: 12/03/2022] Open
Abstract
We performed a rapid response investigation to evaluate the presence and distribution of amphibian pathogens in Madagascar following our identification of amphibian chytrid fungus (Batrachochytrium dendrobatidis, Bd) and ranavirus in commercially exported amphibians. This targeted risk-based field surveillance program was conducted from February to April 2014 encompassing 12 regions and 47 survey sites. We simultaneously collected amphibian and environmental samples to increase survey sensitivity and performed sampling both in wilderness areas and commercial amphibian trade facilities. Bd was not detected in any of 508 amphibian skin swabs or 68 water filter samples, suggesting pathogen prevalence was below 0.8%, with 95% confidence during our visit. Ranavirus was detected in 5 of 97 amphibians, including one adult Mantidactylus cowanii and three unidentified larvae from Ranomafana National Park, and one adult Mantidactylus mocquardi from Ankaratra. Ranavirus was also detected in water samples collected from two commercial amphibian export facilities. We also provide the first report of an amphibian mass-mortality event observed in wild amphibians in Madagascar. Although neither Bd nor ranavirus appeared widespread in Madagascar during this investigation, additional health surveys are required to disentangle potential seasonal variations in pathogen abundance and detectability from actual changes in pathogen distribution and rates of spread. Accordingly, our results should be conservatively interpreted until a comparable survey effort during winter months has been performed. It is imperative that biosecurity practices be immediately adopted to limit the unintentional increased spread of disease through the movement of contaminated equipment or direct disposal of contaminated material from wildlife trade facilities. The presence of potentially introduced strains of ranaviruses suggests that Madagascar's reptile species might also be threatened by disease. Standardized population monitoring of key amphibian and reptile species should be established with urgency to enable early detection of potential impacts of disease emergence in this global biodiversity hotspot.
Collapse
Affiliation(s)
- Jonathan E. Kolby
- One Health Research Group, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
- EcoHealth Alliance, New York, New York, United States of America
- * E-mail:
| | | | - Sara D. Ramirez
- Sustainability Studies Program, Ramapo College of New Jersey, Mahwah, New Jersey, United States of America
| | | | - Allan P. Pessier
- Amphibian Disease Laboratory, Institute for Conservation Research, San Diego Zoo Global, San Diego, California, United States of America
| | - Jesse L. Brunner
- School of Biological Sciences, Washington State University, Pullman, Washington, United States of America
| | - Caren S. Goldberg
- School of the Environment, Washington State University, Pullman, Washington, United States of America
| | - Lee Berger
- One Health Research Group, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| | - Lee F. Skerratt
- One Health Research Group, College of Public Health, Medical, and Veterinary Sciences, James Cook University, Townsville, Queensland, Australia
| |
Collapse
|
62
|
Gabor CR, Fisher MC, Bosch J. Elevated Corticosterone Levels and Changes in Amphibian Behavior Are Associated with Batrachochytrium dendrobatidis (Bd) Infection and Bd Lineage. PLoS One 2015; 10:e0122685. [PMID: 25893675 PMCID: PMC4404099 DOI: 10.1371/journal.pone.0122685] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Accepted: 02/06/2015] [Indexed: 11/24/2022] Open
Abstract
Few studies have examined the role hormones play in mediating clinical changes associated with infection by the parasite Batrachochytrium dendrobatidis (Bd). Glucocorticoid (GC) hormones such as corticosteroids (CORT) regulate homeostasis and likely play a key role in response to infection in amphibians. We explore the relationship between CORT release rates and Bd infection in tadpoles of the common midwife toad, Alytes obstetricians, using a non-invasive water-borne hormone collection method across seven populations. We further examined whether tadpoles of A. muletensis infected with a hypervirulent lineage of Bd, BdGPL, had greater CORT release rates than those infected with a hypovirulent lineage, BdCAPE. Finally, we examined the relationship between righting reflex and CORT release rates in infected metamorphic toads of A. obstetricans. We found an interaction between elevation and Bd infection status confirming that altitude is associated with the overall severity of infection. In tandem, increasing elevation was associated with increasing CORT release rates. Tadpoles infected with the hypervirulent BdGPL had significantly higher CORT release rates than tadpoles infected with BdCAPE showing that more aggressive infections lead to increased CORT release rates. Infected metamorphs with higher CORT levels had an impaired righting reflex, our defined experimental endpoint. These results provide evidence that CORT is associated with an amphibian’s vulnerability to Bd infection, and that CORT is also affected by the aggressiveness of infection by Bd. Together these results indicate that CORT is a viable biomarker of amphibian stress.
Collapse
Affiliation(s)
- Caitlin R. Gabor
- Department of Biology, Texas State University, San Marcos, Texas, United States of America
| | - Matthew C. Fisher
- Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London, United Kingdom
- * E-mail:
| | - Jaime Bosch
- Museo Nacional de Ciencias Naturales, CSIC, c/ José Gutiérrez Abascal 2, Madrid, Spain
| |
Collapse
|
63
|
Warne RW, Crespi EJ. Larval growth rate and sex determine resource allocation and stress responsiveness across life stages in juvenile frogs. ACTA ACUST UNITED AC 2015; 323:191-201. [DOI: 10.1002/jez.1911] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2014] [Revised: 12/04/2014] [Accepted: 12/04/2014] [Indexed: 11/06/2022]
Affiliation(s)
- Robin W. Warne
- Department of Biology; Vassar College; Poughkeepsie New York
| | - Erica J. Crespi
- Department of Biology; Vassar College; Poughkeepsie New York
| |
Collapse
|
64
|
Sutton WB, Gray MJ, Hardman RH, Wilkes RP, Kouba AJ, Miller DL. High susceptibility of the endangered dusky gopher frog to ranavirus. DISEASES OF AQUATIC ORGANISMS 2014; 112:9-16. [PMID: 25392038 DOI: 10.3354/dao02792] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Amphibians are one of the most imperiled vertebrate groups, with pathogens playing a role in the decline of some species. Rare species are particularly vulnerable to extinction because populations are often isolated and exist at low abundance. The potential impact of pathogens on rare amphibian species has seldom been investigated. The dusky gopher frog Lithobates sevosus is one of the most endangered amphibian species in North America, with 100-200 individuals remaining in the wild. Our goal was to determine whether adult L. sevosus were susceptible to ranavirus, a pathogen responsible for amphibian die-offs worldwide. We tested the relative susceptibility of adult L. sevosus to ranavirus (103 plaque-forming units) isolated from a morbid bullfrog via 3 routes of exposure: intra-coelomic (IC) injection, oral (OR) inoculation, and water bath (WB) exposure. We observed 100% mortality of adult L. sevosus in the IC and WB treatments after 10 and 19 d, respectively. Ninety-five percent mortality occurred in the OR treatment over the 28 d evaluation period. No mortality was observed in the control treatment after 28 d. Our results indicate that L. sevosus is susceptible to ranavirus, and if adults in the wild are exposed to this pathogen, significant mortality could occur. Additionally, our study demonstrates that some adult amphibian species can be very susceptible to ranavirus, which has been often overlooked in North American studies. We recommend that conservation planners consider testing the susceptibility of rare amphibian species to ranavirus and that the adult age class is included in future challenge experiments.
Collapse
Affiliation(s)
- William B Sutton
- Center for Wildlife Health, Department of Forestry, Wildlife and Fisheries, University of Tennessee, Knoxville, TN 37996, USA
| | | | | | | | | | | |
Collapse
|
65
|
Ferrie GM, Alford VC, Atkinson J, Baitchman E, Barber D, Blaner WS, Crawshaw G, Daneault A, Dierenfeld E, Finke M, Fleming G, Gagliardo R, Hoffman EA, Karasov W, Klasing K, Koutsos E, Lankton J, Lavin SR, Lentini A, Livingston S, Lock B, Mason T, McComb A, Morris C, Pessier AP, Olea-Popelka F, Probst T, Rodriguez C, Schad K, Semmen K, Sincage J, Stamper MA, Steinmetz J, Sullivan K, Terrell S, Wertan N, Wheaton CJ, Wilson B, Valdes EV. Nutrition and health in amphibian husbandry. Zoo Biol 2014; 33:485-501. [PMID: 25296396 PMCID: PMC4685711 DOI: 10.1002/zoo.21180] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Revised: 08/11/2014] [Accepted: 09/09/2014] [Indexed: 12/25/2022]
Abstract
Amphibian biology is intricate, and there are many inter-related factors that need to be understood before establishing successful Conservation Breeding Programs (CBPs). Nutritional needs of amphibians are highly integrated with disease and their husbandry needs, and the diversity of developmental stages, natural habitats, and feeding strategies result in many different recommendations for proper care and feeding. This review identifies several areas where there is substantial room for improvement in maintaining healthy ex situ amphibian populations specifically in the areas of obtaining and utilizing natural history data for both amphibians and their dietary items, achieving more appropriate environmental parameters, understanding stress and hormone production, and promoting better physical and population health. Using a scientific or research framework to answer questions about disease, nutrition, husbandry, genetics, and endocrinology of ex situ amphibians will improve specialists' understanding of the needs of these species. In general, there is a lack of baseline data and comparative information for most basic aspects of amphibian biology as well as standardized laboratory approaches. Instituting a formalized research approach in multiple scientific disciplines will be beneficial not only to the management of current ex situ populations, but also in moving forward with future conservation and reintroduction projects. This overview of gaps in knowledge concerning ex situ amphibian care should serve as a foundation for much needed future research in these areas.
Collapse
Affiliation(s)
- Gina M. Ferrie
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
- Department of Biology, University of Central Florida, Orlando, FL
| | - Vance C. Alford
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Jim Atkinson
- Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada
| | | | | | | | | | - Andy Daneault
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | | | | | - Greg Fleming
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | | | - Eric A. Hoffman
- Department of Biology, University of Central Florida, Orlando, FL
| | - William Karasov
- Department of Forest and Wildlife Ecology, University of Wisconsin-Madison, Madison, WI
| | - Kirk Klasing
- Department of Animal Science, Graduate Program in Avian Sciences, UC Davis, Davis, CA
| | | | - Julia Lankton
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
- Department of Animal Sciences, University of Florida, Gainesville, FL
| | - Shana R. Lavin
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
- Department of Animal Sciences, University of Florida, Gainesville, FL
| | | | - Shannon Livingston
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | | | | | | | | | - Allan P. Pessier
- Wildlife Disease Laboratories, Institute for Conservation Research, San Diego Zoo Global, San Diego, CA
- Department of Clinical Sciences, College of Veterinary Medicine and Biomedical Sciences, Colorado State University, Fort Collins, CO
| | | | - Tom Probst
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Carlos Rodriguez
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Kristine Schad
- European Association of Zoos and Aquaria, Amsterdam, The Netherlands
| | - Kent Semmen
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Jamie Sincage
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - M. Andrew Stamper
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Jason Steinmetz
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Kathleen Sullivan
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Scott Terrell
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Nina Wertan
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Catharine J. Wheaton
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
| | - Brad Wilson
- Amphibian Ark, Woodland Park Zoo, Seattle, WA
| | - Eduardo V. Valdes
- Animals, Science and Environment, Walt Disney World Resort, Lake Buena Vista, FL
- Department of Biology, University of Central Florida, Orlando, FL
- Department of Animal and Poultry Science, University of Guelph, Guelph, ON, Canada
- Department of Animal Sciences, University of Florida, Gainesville, FL
| |
Collapse
|
66
|
Searle CL, Belden LK, Du P, Blaustein AR. Stress and chytridiomycosis: exogenous exposure to corticosterone does not alter amphibian susceptibility to a fungal pathogen. ACTA ACUST UNITED AC 2014; 321:243-53. [PMID: 24610865 DOI: 10.1002/jez.1855] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Revised: 12/19/2013] [Accepted: 01/15/2014] [Indexed: 11/11/2022]
Abstract
Recent emergence and spread of the amphibian fungal pathogen, Batrachochytrium dendrobatidis (Bd) has been attributed to a number of factors, including environmental stressors that increase host susceptibility to Bd. Physiological stress can increase circulating levels of the hormone, corticosterone, which can alter a host's physiology and affect its susceptibility to pathogens. We experimentally elevated whole-body levels of corticosterone in both larval and post-metamorphic amphibians, and subsequently tested their susceptibility to Bd. Larvae of three species were tested (Anaxyrus boreas, Rana cascadae, and Lithobates catesbeianus) and one species was tested after metamorphosis (R. cascadae). After exposure to Bd, we measured whole-body corticosterone, infection, mortality, growth, and development. We found that exposure to exogenous corticosterone had no effect on Bd infection in any species or at either life stage. Species varied in whole-body corticosterone levels and exposure to corticosterone reduced mass in A. boreas and R. cascadae larvae. Exposure to Bd did not affect mortality, but had a number of sublethal effects. Across species, larvae exposed to Bd had higher corticosterone levels than unexposed larvae, but the opposite pattern was found in post-metamorphic R. cascadae. Bd exposure also increased larval length in all species and increased mass in R. cascadae larvae. Our results indicate that caution is warranted in assuming a strong link between elevated levels of corticosterone and disease susceptibility in amphibians. The role of physiological stress in altering Bd prevalence in amphibian populations is likely much more complicated than can be explained by examining a single "stress" endpoint.
Collapse
Affiliation(s)
- Catherine L Searle
- Department of Ecology and Evolutionary Biology, University of Michigan, Ann Arbor, Michigan; Department of Zoology, Oregon State University, Corvallis, Oregon
| | | | | | | |
Collapse
|
67
|
Gervasi SS, Hunt EG, Lowry M, Blaustein AR. Temporal patterns in immunity, infection load and disease susceptibility: understanding the drivers of host responses in the amphibian‐chytrid fungus system. Funct Ecol 2013. [DOI: 10.1111/1365-2435.12194] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Affiliation(s)
- Stephanie S. Gervasi
- Department of Zoology Oregon State University 3029 Cordley Hall Corvallis OR 97330 USA
| | - Emily G. Hunt
- Environmental Sciences Graduate Program Oregon State University 104 Wilkinson Hall Corvallis OR 97330 USA
| | - Malcolm Lowry
- Microbiology Department Oregon State University 220 Nash Hall Corvallis OR 97331 USA
| | - Andrew R. Blaustein
- Department of Zoology Oregon State University 3029 Cordley Hall Corvallis OR 97330 USA
- Environmental Sciences Graduate Program Oregon State University 104 Wilkinson Hall Corvallis OR 97330 USA
| |
Collapse
|
68
|
Marino JA, Holland MP, Middlemis Maher J. Predators and trematode parasites jointly affect larval anuran functional traits and corticosterone levels. OIKOS 2013. [DOI: 10.1111/j.1600-0706.2013.00896.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
|
69
|
Warne RW, Kardon A, Crespi EJ. Physiological, behavioral and maternal factors that contribute to size variation in larval amphibian populations. PLoS One 2013; 8:e76364. [PMID: 24143188 PMCID: PMC3797114 DOI: 10.1371/journal.pone.0076364] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2013] [Accepted: 08/25/2013] [Indexed: 11/24/2022] Open
Abstract
Size variance among similarly aged individuals within populations is a pattern common to many organisms that is a result of interactions between intrinsic and extrinsic traits of individuals. While genetic and maternal effects, as well as physiological and behavioral traits have been shown to contribute to size variation in animal populations, teasing apart the influence of such factors on individual growth rates remain a challenge. Furthermore, tracing the effects of these interactions across life stages and in shaping adult phenotypes also requires further exploration. In this study we investigated the relationship between genetics, hatching patterns, behaviors, neuroendocrine stress axis activity and variance in growth and metamorphosis among same-aged larval amphibians. Through parallel experiments we found that in the absence of conspecific interactions, hatch time and to a lesser extent egg clutch identity (i.e. genetics and maternal effects) influenced the propensity for growth and development in individual tadpoles and determined metamorphic traits. Within experimental groups we found that variance in growth rates was associated with size-dependent foraging behaviors and responses to food restriction. We also found an inverse relationship between glucocorticoid (GC) hormone levels and body mass and developmental stage among group-reared tadpoles, which suggests that GC expression plays a role in regulating differing within-population growth trajectories in response to density-dependent conditions. Taken together these findings suggest that factors that influence hatching conditions can have long-term effects on growth and development. These results also raise compelling questions regarding the extent to which maternal and genetic factors influence physiological and behavioral profiles in amphibians.
Collapse
Affiliation(s)
- Robin W. Warne
- Biology Department, Vassar College, Poughkeepsie, New York, United States of America
- * E-mail:
| | - Adam Kardon
- Biology Department, Vassar College, Poughkeepsie, New York, United States of America
| | - Erica J. Crespi
- Biology Department, Vassar College, Poughkeepsie, New York, United States of America
| |
Collapse
|
70
|
Reeve BC, Crespi EJ, Whipps CM, Brunner JL. Natural stressors and ranavirus susceptibility in larval wood frogs (Rana sylvatica). ECOHEALTH 2013; 10:190-200. [PMID: 23579812 DOI: 10.1007/s10393-013-0834-6] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2012] [Revised: 03/18/2013] [Accepted: 03/19/2013] [Indexed: 06/02/2023]
Abstract
Chronic exposure to stressors has been shown to suppress immune function in vertebrates, making them more susceptible to pathogens. It is less clear, however, whether many natural stressors are immunosuppressive. Moreover, whether stressors make disease more likely or more severe in populations is unclear because animals respond to stressors both behaviorally and physiologically. We tested whether chronic exposure to three natural stressors of wood frog tadpoles-high-densities, predator-cues, and low-food conditions-influence their susceptibility to a lethal ranavirus both individually in laboratory experiments, and collectively in outdoor mesocosms. Prior to virus exposure, we observed elevated corticosterone only in low-food treatments, although other treatments altered rates of growth and development as well as tadpole behavior. None of the treatments, however, increased susceptibility to ranavirus as measured by the proportion of tadpoles that became infected or died, or the time to death compared to controls. In fact, mortality in the mesocosms was actually lower in the high-density treatment even though most individuals became infected, largely because of increased rates of metamorphosis. Overall we find no support for the hypothesis that chronic exposure to common, ecologically relevant challenges necessarily elevates corticosterone levels in a population or leads to more severe ranaviral disease or epidemics. Conditions may, however, conspire to make ranavirus infection more common in metamorphosing amphibians.
Collapse
Affiliation(s)
- Brooke C Reeve
- Department of Environmental and Forest Biology, State University of New York College of Environmental Science and Forestry (SUNY-ESF), Syracuse, NY, USA
| | | | | | | |
Collapse
|
71
|
Peterson JD, Steffen JE, Reinert LK, Cobine PA, Appel A, Rollins-Smith L, Mendonça MT. Host stress response is important for the pathogenesis of the deadly amphibian disease, Chytridiomycosis, in Litoria caerulea. PLoS One 2013; 8:e62146. [PMID: 23630628 PMCID: PMC3632538 DOI: 10.1371/journal.pone.0062146] [Citation(s) in RCA: 52] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2012] [Accepted: 03/18/2013] [Indexed: 02/05/2023] Open
Abstract
Chytridiomycosis, a disease caused by Batrachochytrium dendrobatidis, has contributed to worldwide amphibian population declines; however, the pathogenesis of this disease is still somewhat unclear. Previous studies suggest that infection disrupts cutaneous sodium transport, which leads to hyponatremia and cardiac failure. However, infection is also correlated with unexplained effects on appetite, skin shedding, and white blood cell profiles. Glucocorticoid hormones may be the biochemical connection between these disparate effects, because they regulate ion homeostasis and can also influence appetite, skin shedding, and white blood cells. During a laboratory outbreak of B. dendrobatidis in Australian Green Tree Frogs, Litoria caerulea, we compared frogs showing clinical signs of chytridiomycosis to infected frogs showing no signs of disease and determined that diseased frogs had elevated baseline corticosterone, decreased plasma sodium and potassium, and altered WBC profiles. Diseased frogs also showed evidence of poorer body condition and elevated metabolic rates compared with frogs showing no signs of disease. Prior to displaying signs of disease, we also observed changes in appetite, body mass, and the presence of shed skin associated with infected but not yet diseased frogs. Collectively, these results suggest that elevated baseline corticosterone is associated with chytridiomycosis and correlates with some of the deleterious effects observed during disease development.
Collapse
Affiliation(s)
- John D Peterson
- Department of Biological Sciences, Auburn University, Auburn, Alabama, United States of America.
| | | | | | | | | | | | | |
Collapse
|
72
|
Bayley AE, Hill BJ, Feist SW. Susceptibility of the European common frog Rana temporaria to a panel of ranavirus isolates from fish and amphibian hosts. DISEASES OF AQUATIC ORGANISMS 2013; 103:171-183. [PMID: 23574703 DOI: 10.3354/dao02574] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Ranaviruses are an emerging group of viruses and have been implicated in an increase of epidemics in susceptible species. They have a wide host range, infecting fish, amphibians and reptiles, with some isolates able to infect multiple species from different animal classes. Whilst some information exists on the pathogenicity of ranaviruses to novel hosts, there is none on the pathogenicity of fish ranaviruses to amphibians; this information is needed to develop measures to prevent the further spread of ranaviral disease in the aquatic environment. We undertook bath infection trials to assess the susceptibility of the European common frog Rana temporaria to 9 ranavirus isolates comprising doctor fish virus (DFV), European sheatfish virus (ESV), epizootic haematopoietic necrosis virus (EHNV), guppy virus 6 (GV6), pike-perch iridovirus (PPIV) and short-finned eel ranavirus (SERV) from fish hosts, and Bohle iridovirus (BIV), frog virus 3 (FV3) and Rana esculenta virus 282/I02 (REV) from amphibians. Animals were challenged as tadpoles at 15 and 20°C and as recent metamorphs at room temperature (20 ± 1°C) to investigate the effect of temperature and amphibian developmental stage on virus pathogenicity. Tadpoles were susceptible to FV3, PPIV and REV, but refractory to the other ranaviruses. Post-metamorphs were susceptible to FV3 and REV but refractory to BIV (the other ranaviruses were not tested). Significant mortality occurred in post-metamorphs and in tadpoles challenged at 20°C but was low in tadpoles challenged at 15°C. This study presents the first evidence of mortality in an amphibian species after challenge with ranavirus originally isolated from fish.
Collapse
Affiliation(s)
- Amanda E Bayley
- Centre for Environment, Fisheries and Aquaculture Science (Cefas), Barrack Road, The Nothe, Weymouth, Dorset DT4 8UB, UK.
| | | | | |
Collapse
|
73
|
Stöhr AC, Fleck J, Mutschmann F, Marschang RE. Ranavirus infection in a group of wild-caught Lake Urmia newts Neurergus crocatus imported from Iraq into Germany. DISEASES OF AQUATIC ORGANISMS 2013; 103:185-189. [PMID: 23574704 DOI: 10.3354/dao02556] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
High mortality, in association with anorexia and skin ulcerations, occurred in a group of wild-caught Lake Urmia newts Neurergus crocatus, imported from Iraq in 2011. Predominant findings in the pathological examinations consisted of systemic hemorrhages and ulcerative dermatitis. Ranavirus DNA was detected via PCR in 2 of 3 dead animals, and a part of the major capsid protein (MCP) gene was sequenced. The analyzed portion of the MCP gene was 99% identical to the corresponding portion of the frog virus 3 genome. This is the first description of a ranavirus in Lake Urmia newts and in wild-caught amphibians from Iraq, as well as the first description of ranavirus infection in a urodele from the Middle East.
Collapse
Affiliation(s)
- Anke C Stöhr
- Fachgebiet für Umwelt und Tierhygiene, University of Hohenheim, Garbenstr. 30, 70599 Stuttgart, Germany
| | | | | | | |
Collapse
|
74
|
Gabor CR, Fisher MC, Bosch J. A non-invasive stress assay shows that tadpole populations infected with Batrachochytrium dendrobatidis have elevated corticosterone levels. PLoS One 2013; 8:e56054. [PMID: 23418508 PMCID: PMC3572145 DOI: 10.1371/journal.pone.0056054] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2012] [Accepted: 01/08/2013] [Indexed: 12/23/2022] Open
Abstract
Batrachochytrium dendrobatidis (Bd) is a fungus that causes the disease chytridiomycosis and is associated with widespread amphibian declines. Populations vary in their susceptibility to Bd infections, and the virulence of the infecting lineage can also vary. Both of these factors may manifest as a differential physiological stress response. In addition, variation in disease susceptibility across amphibian populations may be influenced by immunosuppression caused by chronic stress imposed by environmental factors. Here, we use a non-invasive water-borne hormone technique to assess stress levels (corticosterone) of free-living tadpole populations that are infected by Bd. We found that corticosterone release rates were higher in infected populations of two species of tadpoles (Alytes obstetricans and A. muletensis) than in an uninfected population for both species. The relationship between corticosterone and the intensity of infection differed between species, with only the infected A. obstetricans population showing a significant positive correlation. The higher corticosterone release rates found in A. obstetricans may be an outcome of infection by a highly virulent lineage of Bd (BdGPL), whereas A. muletensis is infected with a less virulent lineage (BdCAPE). These results suggest that different lineages of Bd impose different levels of stress on the infected animals, and that this may influence survival. The next step is to determine whether higher corticosterone levels make individuals more susceptible to Bd or if Bd infections drive the higher corticosterone levels.
Collapse
Affiliation(s)
- Caitlin R Gabor
- Department of Biology, Texas State University, San Marcos, Texas, United States of America.
| | | | | |
Collapse
|
75
|
Blaustein AR, Gervasi SS, Johnson PTJ, Hoverman JT, Belden LK, Bradley PW, Xie GY. Ecophysiology meets conservation: understanding the role of disease in amphibian population declines. Philos Trans R Soc Lond B Biol Sci 2012; 367:1688-707. [PMID: 22566676 DOI: 10.1098/rstb.2012.0011] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Infectious diseases are intimately associated with the dynamics of biodiversity. However, the role that infectious disease plays within ecological communities is complex. The complex effects of infectious disease at the scale of communities and ecosystems are driven by the interaction between host and pathogen. Whether or not a given host-pathogen interaction results in progression from infection to disease is largely dependent on the physiological characteristics of the host within the context of the external environment. Here, we highlight the importance of understanding the outcome of infection and disease in the context of host ecophysiology using amphibians as a model system. Amphibians are ideal for such a discussion because many of their populations are experiencing declines and extinctions, with disease as an important factor implicated in many declines and extinctions. Exposure to pathogens and the host's responses to infection can be influenced by many factors related to physiology such as host life history, immunology, endocrinology, resource acquisition, behaviour and changing climates. In our review, we discuss the relationship between disease and biodiversity. We highlight the dynamics of three amphibian host-pathogen systems that induce different effects on hosts and life stages and illustrate the complexity of amphibian-host-parasite systems. We then review links between environmental stress, endocrine-immune interactions, disease and climate change.
Collapse
Affiliation(s)
- Andrew R Blaustein
- Department of Zoology, Oregon State University, 3029 Cordley Hall, Corvallis, OR 97331-2914, USA.
| | | | | | | | | | | | | |
Collapse
|
76
|
Haislip N, Hoverman J, Miller D, Gray M. Natural stressors and disease risk: does the threat of predation increase amphibian susceptibility to ranavirus? CAN J ZOOL 2012. [DOI: 10.1139/z2012-060] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Emerging infectious diseases have been identified as threats to biodiversity, yet our understanding of the factors contributing to host susceptibility to pathogens within natural populations remains limited. It has been proposed that species interactions within communities affect host susceptibility to pathogens, thereby contributing to disease emergence. In particular, predation risk is a common natural stressor that has been hypothesized to compromise immune function of prey through chronic stress responses possibly leading to increased susceptibility to pathogens. We examined whether predation risk experienced during the development of four larval anuran species increases susceptibility (mortality and infection) to ranaviruses, a group of viruses responsible for amphibian die-offs. Using controlled laboratory experiments, we exposed each species to a factorial combination of two virus treatments (no virus or virus) crossed with three predator-cue treatments (no predators, larval dragonflies, or adult water bugs). All four amphibian species reduced activity by 22%–48% following continuous exposure to predator cues. In addition, virus exposure significantly reduced survival by 17%–100% across all species. However, exposure to predator cues did not interact with the virus treatments to elevate mortality or viral load. Our results suggest that the expression of predator-induced plasticity in anuran larvae does not increase ranaviral disease risk.
Collapse
Affiliation(s)
- N.A. Haislip
- Center for Wildlife Health, Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Knoxville, TN 37996, USA
| | - J.T. Hoverman
- Center for Wildlife Health, Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Knoxville, TN 37996, USA
| | - D.L. Miller
- Center for Wildlife Health, Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Knoxville, TN 37996, USA
- Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia, Tifton, GA 31793, USA
- Department of Biomedical and Diagnostic Sciences, College of Veterinary Medicine, University of Tennessee, Knoxville, TN 37996, USA
| | - M.J. Gray
- Center for Wildlife Health, Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Knoxville, TN 37996, USA
| |
Collapse
|
77
|
Urinary corticosterone metabolites and chytridiomycosis disease prevalence in a free-living population of male Stony Creek frogs (Litoria wilcoxii). Comp Biochem Physiol A Mol Integr Physiol 2012; 162:171-6. [DOI: 10.1016/j.cbpa.2012.02.018] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2011] [Revised: 02/13/2012] [Accepted: 02/16/2012] [Indexed: 11/20/2022]
|
78
|
Hoverman JT, Gray MJ, Haislip NA, Miller DL. Phylogeny, life history, and ecology contribute to differences in amphibian susceptibility to ranaviruses. ECOHEALTH 2011; 8:301-19. [PMID: 22071720 DOI: 10.1007/s10393-011-0717-7] [Citation(s) in RCA: 100] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2011] [Revised: 09/27/2011] [Accepted: 10/11/2011] [Indexed: 05/23/2023]
Abstract
Research that identifies the potential host range of generalist pathogens as well as variation in host susceptibility is critical for understanding and predicting the dynamics of infectious diseases within ecological communities. Ranaviruses have been linked to amphibian die-off events worldwide with the greatest number of reported mortality events occurring in the United States. While reports of ranavirus-associated mortality events continue to accumulate, few data exist comparing the relative susceptibility of different species. Using a series of laboratory exposure experiments and comparative phylogenetics, we compared the susceptibilities of 19 amphibian species from two salamander families and five anurans families for two ranavirus isolates: frog virus 3 (FV3) and an FV3-like isolate from an American bullfrog culture facility. We discovered that ranaviruses were capable of infecting 17 of the 19 larval amphibian species tested with mortality ranging from 0 to 100%. Phylogenetic comparative methods demonstrated that species within the anuran family Ranidae were generally more susceptible to ranavirus infection compared to species from the other five families. We also found that susceptibility to infection was associated with species that breed in semi-permanent ponds, develop rapidly as larvae, and have limited range sizes. Collectively, these results suggest that phylogeny, life history characteristics, and habitat associations of amphibians have the potential to impact susceptibility to ranaviruses.
Collapse
Affiliation(s)
- Jason T Hoverman
- Department of Ecology and Evolutionary Biology, University of Colorado, Boulder, CO 80309, USA.
| | | | | | | |
Collapse
|
79
|
Haislip NA, Gray MJ, Hoverman JT, Miller DL. Development and disease: how susceptibility to an emerging pathogen changes through anuran development. PLoS One 2011; 6:e22307. [PMID: 21799820 PMCID: PMC3142128 DOI: 10.1371/journal.pone.0022307] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2011] [Accepted: 06/23/2011] [Indexed: 01/31/2023] Open
Abstract
Ranaviruses have caused die-offs of amphibians across the globe. In North America, these pathogens cause more amphibian mortality events than any other pathogen. Field observations suggest that ranavirus epizootics in amphibian communities are common during metamorphosis, presumably due to changes in immune function. However, few controlled studies have compared the relative susceptibility of amphibians to ranaviruses across life stages. Our objectives were to measure differences in mortality and infection prevalence following exposure to ranavirus at four developmental stages and determine whether the differences were consistent among seven anuran species. Based on previous studies, we hypothesized that susceptibility to ranavirus would be greatest at metamorphosis. Our results did not support this hypothesis, as four of the species were most susceptible to ranavirus during the larval or hatchling stages. The embryo stage had the lowest susceptibility among species probably due to the protective membranous layers of the egg. Our results indicate that generalizations should be made cautiously about patterns of susceptibility to ranaviruses among amphibian developmental stages and species. Further, if early developmental stages of amphibians are susceptible to ranaviruses, the impact of ranavirus epizootic events may be greater than realized due to the greater difficulty of detecting morbid hatchlings and larvae compared to metamorphs.
Collapse
Affiliation(s)
- Nathan A. Haislip
- Department of Forestry, Wildlife, and Fisheries, Center for Wildlife Health, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Matthew J. Gray
- Department of Forestry, Wildlife, and Fisheries, Center for Wildlife Health, University of Tennessee, Knoxville, Tennessee, United States of America
| | - Jason T. Hoverman
- Department of Forestry, Wildlife, and Fisheries, Center for Wildlife Health, University of Tennessee, Knoxville, Tennessee, United States of America
- * E-mail:
| | - Debra L. Miller
- Department of Forestry, Wildlife, and Fisheries, Center for Wildlife Health, University of Tennessee, Knoxville, Tennessee, United States of America
- Veterinary Diagnostic and Investigational Laboratory, College of Veterinary Medicine, University of Georgia, Tifton, Georgia, United States of America
| |
Collapse
|