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Krueger SK, Williams SC, O’Keefe JM, Zirkle GA, Haase CG. White-nose syndrome, winter duration, and pre-hibernation climate impact abundance of reproductive female bats. PLoS One 2024; 19:e0298515. [PMID: 38669238 PMCID: PMC11051637 DOI: 10.1371/journal.pone.0298515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2023] [Accepted: 01/26/2024] [Indexed: 04/28/2024] Open
Abstract
White-nose syndrome (WNS) is an infectious disease that disrupts hibernation in bats, leading to premature exhaustion of fat stores. Though we know WNS does impact reproduction in hibernating female bats, we are unsure how these impacts are exacerbated by local climate factors. We compiled data from four southeastern U.S. states and used generalized linear mixed effects models to compare effects of WNS, pre-hibernation climate variables, and winter duration on the number of reproductive females in species across the range of WNS susceptibility. We predicted we would see a decline in the number of reproductive females in WNS-susceptible species, with the effect exaggerated by longer winter durations and pre-hibernation climate variables that lead to reductions in foraging. We found that the number of reproductive females in WNS-susceptible species was positively correlated with pre-hibernation local climate conditions conducive to foraging; however, WNS-susceptible species experienced an overall decline with the presence of WNS and as winter duration increased. Our long-term dataset provides evidence that pre-hibernation climate, specifically favorable summer weather conditions for foraging, greatly influences the reproduction, regardless of WNS status.
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Affiliation(s)
- Sarah K. Krueger
- Department of Biology, Austin Peay State University, Clarksville, Tennessee, United States of America
| | - Sarah C. Williams
- Environmental Division, US Army Fort Campbell, Fort Campbell, Kentucky, United States of America
| | - Joy M. O’Keefe
- Department of Natural Resources and Environmental Sciences, University of Illinois, Urbana, Illinois, United States of America
| | - Gene A. Zirkle
- Environmental Division, US Army Fort Campbell, Fort Campbell, Kentucky, United States of America
| | - Catherine G. Haase
- Department of Biology, Austin Peay State University, Clarksville, Tennessee, United States of America
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2
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Whiting-Fawcett F, Blomberg AS, Troitsky T, Meierhofer MB, Field KA, Puechmaille SJ, Lilley TM. A Palearctic view of a bat fungal disease. CONSERVATION BIOLOGY : THE JOURNAL OF THE SOCIETY FOR CONSERVATION BIOLOGY 2024:e14265. [PMID: 38616727 DOI: 10.1111/cobi.14265] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/20/2023] [Revised: 01/02/2024] [Accepted: 01/20/2024] [Indexed: 04/16/2024]
Abstract
The fungal infection causing white-nose disease in hibernating bats in North America has resulted in dramatic population declines of affected species, since the introduction of the causative agent Pseudogymnoascus destructans. The fungus is native to the Palearctic, where it also infects several bat species, yet rarely causes severe pathology or the death of the host. Pseudogymnoascus destructans infects bats during hibernation by invading and digesting the skin tissue, resulting in the disruption of torpor patterns and consequent emaciation. Relations among pathogen, host, and environment are complex, and individuals, populations, and species respond to the fungal pathogen in different ways. For example, the Nearctic Myotis lucifugus responds to infection by mounting a robust immune response, leading to immunopathology often contributing to mortality. In contrast, the Palearctic M. myotis shows no significant immunological response to infection. This lack of a strong response, resulting from the long coevolution between the hosts and the pathogen in the pathogen's native range, likely contributes to survival in tolerant species. After more than 15 years since the initial introduction of the fungus to North America, some of the affected populations are showing signs of recovery, suggesting that the fungus, hosts, or both are undergoing processes that may eventually lead to coexistence. The suggested or implemented management methods of the disease in North America have encompassed, for example, the use of probiotics and fungicides, vaccinations, and modifying the environmental conditions of the hibernation sites to limit the growth of the pathogen, intensity of infection, or the hosts' responses to it. Based on current knowledge from Eurasia, policy makers and conservation managers should refrain from disrupting the ongoing evolutionary processes and adopt a holistic approach to managing the epizootic.
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Affiliation(s)
- F Whiting-Fawcett
- Department of Evolution, Ecology and Behaviour, University of Liverpool, Liverpool, UK
- BatLab Finland, Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
| | - A S Blomberg
- BatLab Finland, Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
| | - T Troitsky
- BatLab Finland, Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
| | - M B Meierhofer
- BatLab Finland, Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
| | - K A Field
- Department of Biology, Bucknell University, Lewisburg, Pennsylvania, USA
| | - S J Puechmaille
- Institut des Sciences de l'Évolution Montpellier (ISEM), University of Montpellier, CNRS, EPHE, IRD, Montpellier, France
- Institut Universitaire de France, Paris, France
| | - T M Lilley
- BatLab Finland, Finnish Museum of Natural History, University of Helsinki, Helsinki, Finland
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3
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Forney R, Rios-Sotelo G, Lindauer A, Willis CKR, Voyles J. Temperature shifts associated with bat arousals during hibernation inhibit the growth of Pseudogymnoascus destructans. ROYAL SOCIETY OPEN SCIENCE 2022; 9:211986. [PMID: 36425515 PMCID: PMC9682300 DOI: 10.1098/rsos.211986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 11/06/2022] [Indexed: 06/16/2023]
Abstract
Temperature is a critically important factor in many infectious disease systems, because it can regulate responses in both the host and the pathogen. White-nose syndrome (WNS) in bats is a severe infectious disease caused by the temperature-sensitive fungus, Pseudogymnoascus destructans (Pd). One feature of WNS is an increase in the frequency of arousal bouts (i.e. when bat body temperatures are elevated) in Pd-infected bats during hibernation. While several studies have proposed that increased frequency of arousals may play a role in the pathophysiology of WNS, it is unknown if the temperature fluctuations might mediate Pd growth. We hypothesized that exposure to a high frequency of elevated temperatures would reduce Pd growth due to thermal constraints on the pathogen. We simulated the thermal conditions for arousal bouts of uninfected and infected bats during hibernation (fluctuating from 8 to 25°C at two different rates) and quantified Pd growth in vitro. We found that increased exposure to high temperatures significantly reduced Pd growth. Because temperature is one of the most critical abiotic factors mediating host-pathogen interactions, resolving how Pd responds to fluctuating temperatures will provide insights for understanding WNS in bats and other fungal diseases.
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Affiliation(s)
- Ronny Forney
- Department of Biology, University of Nevada, Reno, NV, USA
| | | | - Alexa Lindauer
- Department of Biology, University of Nevada, Reno, NV, USA
- Sierra Nevada Aquatic Research Laboratory, University of California, Santa Barbara, Mammoth Lakes, CA, USA
| | - Craig K. R. Willis
- Department of Biology, University of Winnipeg, Winnipeg, Manitoba, Canada
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, NV, USA
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4
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Grimaudo AT, Hoyt JR, Yamada SA, Herzog CJ, Bennett AB, Langwig KE. Host traits and environment interact to determine persistence of bat populations impacted by white-nose syndrome. Ecol Lett 2022; 25:483-497. [PMID: 34935272 PMCID: PMC9299823 DOI: 10.1111/ele.13942] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 08/26/2021] [Accepted: 11/17/2021] [Indexed: 11/27/2022]
Abstract
Emerging infectious diseases have resulted in severe population declines across diverse taxa. In some instances, despite attributes associated with high extinction risk, disease emergence and host declines are followed by host stabilisation for unknown reasons. While host, pathogen, and the environment are recognised as important factors that interact to determine host-pathogen coexistence, they are often considered independently. Here, we use a translocation experiment to disentangle the role of host traits and environmental conditions in driving the persistence of remnant bat populations a decade after they declined 70-99% due to white-nose syndrome and subsequently stabilised. While survival was significantly higher than during the initial epidemic within all sites, protection from severe disease only existed within a narrow environmental space, suggesting host traits conducive to surviving disease are highly environmentally dependent. Ultimately, population persistence following pathogen invasion is the product of host-pathogen interactions that vary across a patchwork of environments.
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Affiliation(s)
| | - Joseph R. Hoyt
- Department of Biological SciencesVirginia TechBlacksburgVirginiaUSA
| | | | - Carl J. Herzog
- New York State Department of Environmental ConservationAlbanyNew YorkUSA
| | | | - Kate E. Langwig
- Department of Biological SciencesVirginia TechBlacksburgVirginiaUSA
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5
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McGuire LP, Johnson EM, Frick WF, Boyles JG. Temperature alone is insufficient to understand hibernation energetics. J Exp Biol 2021; 224:269251. [PMID: 34160026 DOI: 10.1242/jeb.239772] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 06/16/2021] [Indexed: 11/20/2022]
Abstract
Energy conservation has long been a focal point in hibernation research. A long-standing assumption is that ambient temperature (Ta) largely defines the rate of energy expenditure because of well-known relationships between Ta, metabolic rate and frequency of arousal from torpor. Body condition and humidity also affect energy expenditure but are usually considered secondary factors. We held tricolored bats (Perimyotis subflavus) in captivity under multiple environmental conditions to directly compare the importance of Ta, fat mass and humidity for hibernation energy expenditure. Fat mass was the best predictor of female mass loss, followed by Ta and humidity. However, males had less fat and adopted a more energetically conservative hibernation strategy. Our results demonstrate that understanding the evolution of behavior, physiology and ecology of hibernation requires disentangling the relative contributions of multiple drivers of hibernation energetics, and that Ta is not always the most important factor driving energy expenditure.
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Affiliation(s)
- Liam P McGuire
- Department of Biology, University of Waterloo, Waterloo, ON, Canada, N2L 3G1.,Department of Biological Sciences, Texas Tech University, Lubbock, TX 79401, USA
| | - Emily M Johnson
- Department of Biological Sciences, Texas Tech University, Lubbock, TX 79401, USA
| | - Winifred F Frick
- Bat Conservation International, Austin, TX 78746, USA.,Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95060, USA
| | - Justin G Boyles
- Cooperative Wildlife Research Laboratory and School of Biological Sciences, Southern Illinois University, Carbondale, IL62901, USA
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6
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Integrating Multiple Survey Techniques to Document a Shifting Bat Community in the Wake of White-Nose Syndrome. JOURNAL OF FISH AND WILDLIFE MANAGEMENT 2021. [DOI: 10.3996/jfwm-20-043] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Abstract
The long-term study of bat communities often depends on a diverse set of sampling methodologies that are chosen based on the species or habitat management priorities of the research project. Integrating the data from a diverse set of methodologies (such as acoustic monitoring and mist net sampling) would improve our ability to characterize changes in community structure or composition over time, such as one would expect following an emergent infectious disease such as white-nose syndrome. We developed a Bayesian state-space model to integrate these disparate data into a common currency (relative abundance). We collected both acoustic monitoring and mist net capture data over an 8-y period (2006–2014) to document shifts in the bat community in central New England, USA, in response to the onset of white-nose syndrome in 2009. The integrated data model shows a significant decline in the abundance of little brown bat Myotis lucifugus, northern long-eared bat Myotis septentrionalis, and hoary bat Lasiurus cinereus, and an increase in abundance of the eastern small-footed bat Myotis leibii and the eastern red bat Lasiurus borealis. There was no evidence for a change in abundance in the big brown bat Eptesicus fuscus since the onset of white-nose syndrome. The consistency of this model with regional estimates of decline over the same time period support the validity of our relative abundance estimate. This model provides the opportunity to quantify shifts in other communities where multiple sampling methodologies were employed, and therefore provides natural resource managers with a robust tool to integrate existing sampling data to quantify changes in community composition that can inform conservation and management recommendations.
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7
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Meierhofer MB, Lilley TM, Ruokolainen L, Johnson JS, Parratt SR, Morrison ML, Pierce BL, Evans JW, Anttila J. Ten-year projection of white-nose syndrome disease dynamics at the southern leading-edge of infection in North America. Proc Biol Sci 2021; 288:20210719. [PMID: 34074117 PMCID: PMC8170204 DOI: 10.1098/rspb.2021.0719] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Predicting the emergence and spread of infectious diseases is critical for the effective conservation of biodiversity. White-nose syndrome (WNS), an emerging infectious disease of bats, has resulted in high mortality in eastern North America. Because the fungal causative agent Pseudogymnoascus destructans is constrained by temperature and humidity, spread dynamics may vary by geography. Environmental conditions in the southern part of the continent are different than the northeast, where disease dynamics are typically studied, making it difficult to predict how the disease will manifest. Herein, we modelled WNS pathogen spread in Texas based on cave densities and average dispersal distances of hosts, projecting these results out to 10 years. We parameterized a predictive model of WNS epidemiology and its effects on bat populations with observed cave environmental data. Our model suggests that bat populations in northern Texas will be more affected by WNS mortality than southern Texas. As such, we recommend prioritizing the preservation of large overwintering colonies of bats in north Texas through management actions. Our model illustrates that infectious disease spread and infectious disease severity can become uncoupled over a gradient of environmental variation and highlight the importance of understanding host, pathogen and environmental conditions across a breadth of environments.
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Affiliation(s)
- Melissa B Meierhofer
- Department of Rangeland, Wildlife and Fisheries Management, Texas A&M University, 534 John Kimbrough Boulevard, College Station, TX 77843, USA.,Natural Resources Institute, Texas A&M University, 534 John Kimbrough Boulevard, College Station, TX 77843, USA.,Finnish Museum of Natural History, University of Helsinki, Pohjoinen Rautatiekatu 13, 00100 Helsinki, Finland
| | - Thomas M Lilley
- Finnish Museum of Natural History, University of Helsinki, Pohjoinen Rautatiekatu 13, 00100 Helsinki, Finland
| | - Lasse Ruokolainen
- Department of Biosciences, University of Helsinki, Yliopistonkatu 4, 00100 Helsinki, Finland
| | - Joseph S Johnson
- Department of Biological Sciences, Ohio University, Athens, OH 45701, USA
| | - Steven R Parratt
- Department of Ecology and Evolution, University of Liverpool, Liverpool L69 7BE, UK
| | - Michael L Morrison
- Department of Rangeland, Wildlife and Fisheries Management, Texas A&M University, 534 John Kimbrough Boulevard, College Station, TX 77843, USA
| | - Brian L Pierce
- Natural Resources Institute, Texas A&M University, 534 John Kimbrough Boulevard, College Station, TX 77843, USA
| | - Jonah W Evans
- Wildlife Diversity Program, Texas Parks and Wildlife, 4200 Smith School Road, Austin, TX 78744, USA
| | - Jani Anttila
- Natural Resources Institute Finland (Luke), Latokartanonkaari 9, 00790 Helsinki, Finland
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8
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Affiliation(s)
- Justin G. Boyles
- Cooperative Wildlife Research Laboratory Center for Ecology, and School of Biological Sciences Southern Illinois University Carbondale IL USA
| | | | - Anna Blomberg
- Department of Biology University of Turku Vesilinnantie 520100Turku Finland
| | - Thomas M. Lilley
- Finnish Museum of Natural History University of Helsinki P. Rautatiekatu 1300100Helsinki Finland
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Haase CG, Fuller NW, Hranac CR, Hayman DTS, McGuire LP, Norquay KJO, Silas KA, Willis CKR, Plowright RK, Olson SH. Incorporating evaporative water loss into bioenergetic models of hibernation to test for relative influence of host and pathogen traits on white-nose syndrome. PLoS One 2019; 14:e0222311. [PMID: 31671100 PMCID: PMC6822741 DOI: 10.1371/journal.pone.0222311] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 10/08/2019] [Indexed: 12/29/2022] Open
Abstract
Hibernation consists of extended durations of torpor interrupted by periodic arousals. The ‘dehydration hypothesis’ proposes that hibernating mammals arouse to replenish water lost through evaporation during torpor. Arousals are energetically expensive, and increased arousal frequency can alter survival throughout hibernation. Yet we lack a means to assess the effect of evaporative water loss (EWL), determined by animal physiology and hibernation microclimate, on torpor bout duration and subsequent survival. White-nose syndrome (WNS), a devastating disease impacting hibernating bats, causes increased frequency of arousals during hibernation and EWL has been hypothesized to contribute to this increased arousal frequency. WNS is caused by a fungus, which grows well in humid hibernaculum environments and damages wing tissue important for water conservation. Here, we integrated the effect of EWL on torpor expression in a hibernation energetics model, including the effects of fungal infection, to determine the link between EWL and survival. We collected field data for Myotis lucifugus, a species that experiences high mortality from WNS, to gather parameters for the model. In saturating conditions, we predicted healthy bats experience minimal mortality. Infected bats, however, suffer high fungal growth in highly saturated environments, leading to exhaustion of fat stores before spring. Our results suggest that host adaptation to humid environments leads to increased arousal frequency from infection, which drives mortality across hibernaculum conditions. Our modified hibernation model provides a tool to assess the interplay between host physiology, hibernaculum microclimate, and diseases such as WNS on winter survival.
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Affiliation(s)
- Catherine G. Haase
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, United States of America
- * E-mail:
| | - Nathan W. Fuller
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | - C. Reed Hranac
- Molecular Epidemiology and Public Health Laboratory, Hopkirk Research Institute, Massey University, Palmerston North, New Zealand
| | - David T. S. Hayman
- Molecular Epidemiology and Public Health Laboratory, Hopkirk Research Institute, Massey University, Palmerston North, New Zealand
| | - Liam P. McGuire
- Department of Biological Sciences, Texas Tech University, Lubbock, Texas, United States of America
| | | | - Kirk A. Silas
- Wildlife Conservation Society, Wildlife Health Program, Bronx, New York, United States of America
| | | | - Raina K. Plowright
- Department of Microbiology and Immunology, Montana State University, Bozeman, Montana, United States of America
| | - Sarah H. Olson
- Wildlife Conservation Society, Wildlife Health Program, Bronx, New York, United States of America
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10
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O’Keefe JM, Pettit JL, Loeb SC, Stiver WH. White-nose syndrome dramatically altered the summer bat assemblage in a temperate Southern Appalachian forest. Mamm Biol 2019. [DOI: 10.1016/j.mambio.2019.09.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
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11
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Haase CG, Fuller NW, Hranac CR, Hayman DTS, Olson SH, Plowright RK, McGuire LP. Bats are not squirrels: Revisiting the cost of cooling in hibernating mammals. J Therm Biol 2019; 81:185-193. [PMID: 30975417 DOI: 10.1016/j.jtherbio.2019.01.013] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 12/18/2018] [Accepted: 01/21/2019] [Indexed: 01/23/2023]
Abstract
Many species use stored energy to hibernate through periods of resource limitation. Hibernation, a physiological state characterized by depressed metabolism and body temperature, is critical to winter survival and reproduction, and therefore has been extensively quantified and modeled. Hibernation consists of alternating phases of extended periods of torpor (low body temperature, low metabolic rate), and energetically costly periodic arousals to normal body temperature. Arousals consist of multiple phases: warming, euthermia, and cooling. Warming and euthermic costs are regularly included in energetic models, but although cooling to torpid body temperature is an important phase of the torpor-arousal cycle, it is often overlooked in energetic models. When included, cooling cost is assumed to be 67% of warming cost, an assumption originally derived from a single study that measured cooling cost in ground squirrels. Since this study, the same proportional value has been assumed across a variety of hibernating species. However, no additional values have been derived. We derived a model of cooling cost from first principles and validated the model with empirical energetic measurements. We compared the assumed 67% proportional cooling cost with our model-predicted cooling cost for 53 hibernating mammals. Our results indicate that using 67% of warming cost only adequately represents cooling cost in ground squirrel-sized mammals. In smaller species, this value overestimates cooling cost and in larger species, the value underestimates cooling cost. Our model allows for the generalization of energetic costs for multiple species using species-specific physiological and morphometric parameters, and for predictions over variable environmental conditions.
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Affiliation(s)
- Catherine G Haase
- Department of Microbiology and Immunology, Montana State University, 109 Lewis Hall, PO Box 173520, Bozeman, MT 59717, USA.
| | - Nathan W Fuller
- Department of Biological Sciences, Texas Tech University, 2901 Main St., Lubbock, TX 79409, USA
| | - C Reed Hranac
- Molecular Epidemiology and Public Health Laboratory, Hopkirk Research Institute, Massey University, Private Bag, 11 222, Palmerston North 4442, New Zealand
| | - David T S Hayman
- Molecular Epidemiology and Public Health Laboratory, Hopkirk Research Institute, Massey University, Private Bag, 11 222, Palmerston North 4442, New Zealand
| | - Sarah H Olson
- Wildlife Conservation Society, 2300 Southern Boulevard, Bronx, NY 10460, USA
| | - Raina K Plowright
- Department of Microbiology and Immunology, Montana State University, 109 Lewis Hall, PO Box 173520, Bozeman, MT 59717, USA
| | - Liam P McGuire
- Department of Biological Sciences, Texas Tech University, 2901 Main St., Lubbock, TX 79409, USA
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Holz P, Hufschmid J, Boardman WSJ, Cassey P, Firestone S, Lumsden LF, Prowse TAA, Reardon T, Stevenson M. Does the fungus causing white-nose syndrome pose a significant risk to Australian bats? WILDLIFE RESEARCH 2019. [DOI: 10.1071/wr18194] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Abstract
ContextPseudogymnoascus destructans is the fungus responsible for white-nose syndrome (WNS), which has killed millions of hibernating bats in North America, but also occurs in bats in Europe and China without causing large-scale population effects. This is likely to be due to differences in species susceptibility and behaviour, and environmental factors, such as temperature and humidity. Pseudogymnoascus destructans is currently believed to be absent from Australia.
AimsTo ascertain the level of risk that white-nose syndrome poses for Australian bats.
Methods This risk analysis examines the likelihood that P. destructans enters Australia, the likelihood of the fungus coming in contact with native bats on successful entry, and the potential consequences should this occur.
Key results This risk assessment concluded that it is very likely to almost certain that P. destructans will enter Australia, and it is likely that bats will be exposed to the fungus over the next 10 years. Eight cave-dwelling bat species from southern Australia are the ones most likely to be affected.
ConclusionsThe risk was assessed as medium for the critically endangered southern bent-winged bat (Miniopterus orianae bassanii), because any increase in mortality could affect its long-term survival. The risk to other species was deemed to range from low to very low, owing to their wider distribution, which extends beyond the P. destructans risk zone.
Implications Although Australia’s milder climate may preclude the large mortality events seen in North America, the fungus could still significantly affect Australian bat populations, particularly bent-winged bats. Active surveillance is required to confirm Australia’s continuing WNS-free status, and to detect the presence of P. destructans should it enter the country. Although White-nose Syndrome Response Guidelines have been developed by Wildlife Health Australia to assist response agencies in the event of an incursion of WNS into bats in Australia, these guidelines would be strengthened by further research to characterise Australian cave temperatures and hibernating bat biology, such as length of torpor bouts and movement over winter. Risk-mitigation strategies should focus on education programs that target cavers, show-cave managers and tourists, particularly those who have visited regions where WNS is known to occur.
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Boyles JG, Boyles E, Dunlap RK, Johnson SA, Brack V. Long-term microclimate measurements add further evidence that there is no “optimal” temperature for bat hibernation. Mamm Biol 2017. [DOI: 10.1016/j.mambio.2017.03.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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14
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Reynolds HT, Raudabaugh D, Lilje O, Allender M, Miller AN, Gleason FH. Chapter 27 Emerging Mycoses and Fungus-Like Diseases of Vertebrate Wildlife. Mycology 2017. [DOI: 10.1201/9781315119496-28] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
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15
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Affiliation(s)
- Justin G. Boyles
- Cooperative Wildlife Research Laboratory; Department of Zoology; Southern Illinois University; Carbondale IL 62901 USA
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16
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Klüg-Baerwald BJ, Brigham RM. Hung out to dry? Intraspecific variation in water loss in a hibernating bat. Oecologia 2017; 183:977-985. [PMID: 28213638 DOI: 10.1007/s00442-017-3837-0] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 02/07/2017] [Indexed: 02/05/2023]
Abstract
Hibernation is a period of water deficit for some small mammals, and humidity strongly influences hibernation patterns. Dry conditions reduce length of torpor bouts, stimulate arousals, and decrease overwinter survival. To mitigate these effects, many small mammals hibernate in near saturated (100% RH) conditions. However, big brown bats (Eptesicus fuscus) hibernate in a wider variety of conditions and tolerate lower humidity than most other bats. To assess arid tolerance in this species, we compared torpid metabolic rates (TMR) and rates of total evaporative water loss (TEWL) between two populations of E. fuscus with differing winter ecologies: one that hibernates in humid karst caves and one that hibernates in relatively dry rock crevices. We used flow-through respirometry to measure TMR and TEWL of bats in humid and dry conditions. Torpid metabolic rates did not differ between populations or with humidity treatments. Rates of TEWL were similar between populations in humid conditions, but higher for cave-hibernating bats than crevice-hibernating bats in dry conditions. Our results suggest that E. fuscus hibernating in arid environments have mechanisms to decrease evaporative water loss that are not evident at more humid sites. Drought tolerance may facilitate the sedentary nature of the species, allowing them to tolerate more variable microclimates during hibernation and thus increasing the availability of overwintering habitat. The ability to survive arid conditions may also lessen the susceptibility of E. fuscus to diseases that affect water balance.
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Affiliation(s)
| | - R Mark Brigham
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK, Canada
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17
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Hayman DTS, Pulliam JRC, Marshall JC, Cryan PM, Webb CT. Environment, host, and fungal traits predict continental-scale white-nose syndrome in bats. SCIENCE ADVANCES 2016; 2:e1500831. [PMID: 27152322 PMCID: PMC4846429 DOI: 10.1126/sciadv.1500831] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/23/2015] [Accepted: 11/30/2015] [Indexed: 06/05/2023]
Abstract
White-nose syndrome is a fungal disease killing bats in eastern North America, but disease is not seen in European bats and is less severe in some North American species. We show that how bats use energy during hibernation and fungal growth rates under different environmental conditions can explain how some bats are able to survive winter with infection and others are not. Our study shows how simple but nonlinear interactions between fungal growth and bat energetics result in decreased survival times at more humid hibernation sites; however, differences between species such as body size and metabolic rates determine the impact of fungal infection on bat survival, allowing European bat species to survive, whereas North American species can experience dramatic decline.
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Affiliation(s)
- David T. S. Hayman
- Molecular Epidemiology and Public Health Laboratory, Hopkirk Research Institute, Massey University, Private Bag, 11 222, Palmerston North 4442, New Zealand
| | - Juliet R. C. Pulliam
- Department of Biology, University of Florida, Gainesville, FL 32611, USA
- Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611, USA
- Fogarty International Center, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jonathan C. Marshall
- Molecular Epidemiology and Public Health Laboratory, Hopkirk Research Institute, Massey University, Private Bag, 11 222, Palmerston North 4442, New Zealand
- Institute of Fundamental Sciences, Massey University, Private Bag, 11 222, Palmerston North 4442, New Zealand
| | - Paul M. Cryan
- U.S. Geological Survey, Fort Collins Science Center, Fort Collins, CO 80526, USA
| | - Colleen T. Webb
- Department of Biology, Colorado State University, Fort Collins, CO 80523, USA
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Modeling the environmental growth of Pseudogymnoascus destructans and its impact on the white-nose syndrome epidemic. J Wildl Dis 2015; 51:318-31. [PMID: 25588008 DOI: 10.7589/2014-06-157] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
White-nose syndrome (WNS) has had a devastating effect on North American bat populations. The causal agent of WNS is the fungal pathogen, Pseudogymnoascus destructans (Pd), which has been shown to persist in caves after the eradication of host populations. As nonpathogenic Pseudogymnoascus spp. display saprophytic growth and are among the most commonly isolated fungi from caves, we examined whether Pd could grow in cave sediments and the contribution such growth could have to WNS disease progression. We inoculated a range of diverse cave sediments and demonstrated the growth of Pd in all sediments tested. These data indicate that environmental growth of Pd could lead to the accumulation of spores above the estimated infection threshold for WNS, allowing environment-to-bat infection. The obtained growth parameters were then used in a susceptible-infected-susceptible mathematic model to determine the possible contribution of environmental Pd growth to WNS disease progression in a colony of little brown bats (Myotis lucifugus). This model suggests that the environmental growth of Pd would increase WNS infection rates, particularly in colonies experiencing longer hibernation periods or in hibernacula with high levels of organic detritus. The model also suggests that once introduced, environmental Pd growth would allow the persistence of this pathogen within infected hibernacula for decades, greatly compromising the success of bat reintroduction strategies. Together these data suggest that Pd is not reliant on its host for survival and is capable of environmental growth and amplification that could contribute to the rapid progression and long-term persistence of WNS in the hibernacula of threatened North American bats.
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