1
|
Muise KA, Dzal YA, Fletcher QE, Willis CKR. Hibernating female big brown bats (Eptesicus fuscus) adjust huddling and drinking behaviour, but not arousal frequency, in response to low humidity. J Exp Biol 2024; 227:jeb246699. [PMID: 38353043 PMCID: PMC10949064 DOI: 10.1242/jeb.246699] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2023] [Accepted: 02/07/2024] [Indexed: 03/08/2024]
Abstract
Many mammals hibernate during winter, reducing energy expenditure via bouts of torpor. The majority of a hibernator's energy reserves are used to fuel brief, but costly, arousals from torpor. Although arousals likely serve multiple functions, an important one is to restore water stores depleted during torpor. Many hibernating bat species require high humidity, presumably to reduce torpid water loss, but big brown bats (Eptesicus fuscus) appear tolerant of a wide humidity range. We tested the hypothesis that hibernating female E. fuscus use behavioural flexibility during torpor and arousals to maintain water balance and reduce energy expenditure. We predicted: (1) E. fuscus hibernating in dry conditions would exhibit more compact huddles during torpor and drink more frequently than bats in high humidity conditions; and (2) the frequency and duration of torpor bouts and arousals, and thus total loss of body mass would not differ between bats in the two environments. We housed hibernating E. fuscus in temperature- and humidity-controlled incubators at 50% or 98% relative humidity (8°C, 110 days). Bats in the dry environment maintained a more compact huddle during torpor and drank more frequently during arousals. Bats in the two environments had a similar number of arousals, but arousal duration was shorter in the dry environment. However, total loss of body mass over hibernation did not differ between treatments, indicating that the two groups used similar amounts of energy. Our results suggest that behavioural flexibility allows hibernating E. fuscus to maintain water balance and reduce energy costs across a wide range of hibernation humidities.
Collapse
Affiliation(s)
- Kristina A. Muise
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MN, CanadaR3B 2E9
| | - Yvonne A. Dzal
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MN, CanadaR3B 2E9
| | - Quinn E. Fletcher
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MN, CanadaR3B 2E9
| | - Craig K. R. Willis
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MN, CanadaR3B 2E9
| |
Collapse
|
2
|
Jackson RT, Webala PW, Ogola JG, Lunn TJ, Forbes KM. Roost selection by synanthropic bats in rural Kenya: implications for human-wildlife conflict and zoonotic pathogen spillover. ROYAL SOCIETY OPEN SCIENCE 2023; 10:230578. [PMID: 37711150 PMCID: PMC10498048 DOI: 10.1098/rsos.230578] [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: 04/30/2023] [Accepted: 08/21/2023] [Indexed: 09/16/2023]
Abstract
Many wildlife species are synanthropic and use structures built by humans, creating a high-risk interface for human-wildlife conflict and zoonotic pathogen spillover. However, studies that investigate features of urbanizing areas that attract or repel wildlife are currently lacking. We surveyed 85 buildings used by bats and 172 neighbouring buildings unused by bats (controls) in southeastern Kenya during 2021 and 2022 and evaluated the role of microclimate and structural attributes in building selection. We identified eight bat species using buildings, with over 25% of building roosts used concurrently by multiple species. Bats selected taller cement-walled buildings with higher water vapour pressure and lower presence of permanent human occupants. However, roost selection criteria differed across the most common bat species: molossids selected structures like those identified by our main dataset whereas Cardioderma cor selected buildings with lower presence of permanent human occupants. Our results show that roost selection of synanthropic bat species is based on specific buildings attributes. Further, selection criteria that facilitate bat use of buildings are not homogeneous across species. These results provide information on the general mechanisms of bat-human contact in rural settings, as well as specific information on roost selection for synanthropic bats in urbanizing Africa.
Collapse
Affiliation(s)
- Reilly T. Jackson
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701-4002, USA
| | - Paul W. Webala
- Department of Forestry and Wildlife Management, Maasai Mara University, Narok, Kenya
| | - Joseph G. Ogola
- Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya
| | - Tamika J. Lunn
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701-4002, USA
| | - Kristian M. Forbes
- Department of Biological Sciences, University of Arkansas, Fayetteville, AR 72701-4002, USA
| |
Collapse
|
3
|
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.
Collapse
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
| |
Collapse
|
4
|
McGuire LP, Fuller NW, Dzal YA, Haase CG, Klüg-Baerwald BJ, Silas KA, Plowright RK, Lausen CL, Willis CKR, Olson SH. Interspecific variation in evaporative water loss and temperature response, but not metabolic rate, among hibernating bats. Sci Rep 2021; 11:20759. [PMID: 34675252 PMCID: PMC8531132 DOI: 10.1038/s41598-021-00266-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 10/08/2021] [Indexed: 11/30/2022] Open
Abstract
Hibernation is widespread among mammals in a variety of environmental contexts. However, few experimental studies consider interspecific comparisons, which may provide insight into general patterns of hibernation strategies. We studied 13 species of free-living bats, including populations spread over thousands of kilometers and diverse habitats. We measured torpid metabolic rate (TMR) and evaporative water loss (two key parameters for understanding hibernation energetics) across a range of temperatures. There was no difference in minimum TMR among species (i.e., all species achieved similarly low torpid metabolic rate) but the temperature associated with minimum TMR varied among species. The minimum defended temperature (temperature below which TMR increased) varied from 8 °C to < 2 °C among species. Conversely, evaporative water loss varied among species, with species clustered in two groups representing high and low evaporative water loss. Notably, species that have suffered population declines due to white-nose syndrome fall in the high evaporative water loss group and less affected species in the low evaporative water loss group. Documenting general patterns of physiological diversity, and associated ecological implications, contributes to broader understanding of biodiversity, and may help predict which species are at greater risk of environmental and anthropogenic stressors.
Collapse
Affiliation(s)
- Liam P McGuire
- Department of Biology, University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
- Department of Biological Sciences, Texas Tech University, 2901 Main St, Lubbock, TX, 79409, USA.
| | - Nathan W Fuller
- Department of Biological Sciences, Texas Tech University, 2901 Main St, Lubbock, TX, 79409, USA
- Nongame and Rare Species Program, Texas Parks and Wildlife, Austin, TX, 78744, USA
| | - Yvonne A Dzal
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MB, R3B 2E9, Canada
| | - Catherine G Haase
- Department of Microbiology and Immunology, Montana State University, PO Box 173520, Bozeman, MT, 59717, USA
- Department of Biology, Austin Peay State University, PO Box 4718, Clarkesville, TN, 37044, USA
| | - Brandon J Klüg-Baerwald
- Department of Biology, University of Regina, 3737 Wascana Parkway, Regina, SK, S4S 0A2, Canada
| | - Kirk A Silas
- Wildlife Conservation Society, Health Program, 2300 Southern Blvd, Bronx, NY, 10460, USA
| | - Raina K Plowright
- Department of Microbiology and Immunology, Montana State University, PO Box 173520, Bozeman, MT, 59717, USA
| | - Cori L Lausen
- Wildlife Conservation Society Canada, Bat Program, PO Box 606, Kaslo, BC, V0G 1M0, Canada
| | - Craig K R Willis
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MB, R3B 2E9, Canada
| | - Sarah H Olson
- Wildlife Conservation Society, Health Program, 2300 Southern Blvd, Bronx, NY, 10460, USA
| |
Collapse
|
5
|
Hranac CR, Haase CG, Fuller NW, McClure ML, Marshall JC, Lausen CL, McGuire LP, Olson SH, Hayman DTS. What is winter? Modeling spatial variation in bat host traits and hibernation and their implications for overwintering energetics. Ecol Evol 2021; 11:11604-11614. [PMID: 34522327 PMCID: PMC8427580 DOI: 10.1002/ece3.7641] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 03/31/2021] [Accepted: 04/09/2021] [Indexed: 01/05/2023] Open
Abstract
White-nose syndrome (WNS) has decimated hibernating bat populations across eastern and central North America for over a decade. Disease severity is driven by the interaction between bat characteristics, the cold-loving fungal agent, and the hibernation environment. While we further improve hibernation energetics models, we have yet to examine how spatial heterogeneity in host traits is linked to survival in this disease system. Here, we develop predictive spatial models of body mass for the little brown myotis (Myotis lucifugus) and reassess previous definitions of the duration of hibernation of this species. Using data from published literature, public databases, local experts, and our own fieldwork, we fit a series of generalized linear models with hypothesized abiotic drivers to create distribution-wide predictions of prehibernation body fat and hibernation duration. Our results provide improved estimations of hibernation duration and identify a scaling relationship between body mass and body fat; this relationship allows for the first continuous estimates of prehibernation body mass and fat across the species' distribution. We used these results to inform a hibernation energetic model to create spatially varying fat use estimates for M. lucifugus. These results predict WNS mortality of M. lucifugus populations in western North America may be comparable to the substantial die-off observed in eastern and central populations.
Collapse
Affiliation(s)
- C. Reed Hranac
- Molecular Epidemiology and Public Health LaboratoryHopkirk Research InstituteMassey UniversityPalmerston NorthNew Zealand
| | - Catherine G. Haase
- Department of Microbiology and ImmunologyMontana State UniversityBozemanMTUSA
- Present address:
Department of BiologyAustin Peay State UniversityClarksvilleTNUSA
| | - Nathan W. Fuller
- Department of Biological SciencesTexas Tech UniversityLubbockTXUSA
- Present address:
Texas Parks and Wildlife DepartmentNongame and Rare Species ProgramAustinTXUSA
| | | | | | | | - Liam P. McGuire
- Department of Biological SciencesTexas Tech UniversityLubbockTXUSA
- Present address:
Department of BiologyUniversity of WaterlooWaterlooONCanada
| | | | - David T. S. Hayman
- Molecular Epidemiology and Public Health LaboratoryHopkirk Research InstituteMassey UniversityPalmerston NorthNew Zealand
| |
Collapse
|
6
|
McGuire LP, Fuller NW, Dzal YA, Haase CG, Silas KA, Willis CKR, Olson SH, Lausen CL. Similar hibernation physiology in bats across broad geographic ranges. J Comp Physiol B 2021; 192:171-181. [PMID: 34426856 DOI: 10.1007/s00360-021-01400-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 06/28/2021] [Accepted: 08/07/2021] [Indexed: 11/26/2022]
Abstract
Species with broad geographic ranges may experience varied environmental conditions throughout their range leading to local adaptation. Variation among populations reflects potential adaptability or plasticity, with implications for populations impacted by disease, climate change, and other anthropogenic influences. However, behavior may counteract divergent selection among populations. We studied intraspecific variation in hibernation physiology of Myotis lucifugus (little brown myotis) and Corynorhinus townsendii (Townsend's big-eared bat), two species of bats with large geographic ranges. We studied M. lucifugus at three hibernacula which spanned a latitudinal gradient of 1500 km, and C. townsendii from 6 hibernacula spread across 1200 km latitude and 1200 km longitude. We found no difference in torpid metabolic rate among populations of either species, nor was there a difference in the effect of ambient temperature among sites. Evaporative water loss was similar among populations of both species, with the exception of one C. townsendii pairwise site difference and one M. lucifugus site that differed from the others. We suggest the general lack of geographic variation is a consequence of behavioral microhabitat selection. As volant animals, bats can travel relatively long distances in search of preferred microclimates for hibernation. Despite dramatic macroclimate differences among populations, hibernating bats are able to find preferred microclimate conditions within their range, resulting in similar selection pressures among populations spread across wide geographic ranges.
Collapse
Affiliation(s)
- Liam P McGuire
- Department of Biology, University of Waterloo, 200 University Ave W, Waterloo, ON, N2L 3G1, Canada.
- Department of Biological Sciences, Texas Tech University, 2901 Main St, Lubbock, TX, 79409, USA.
| | - Nathan W Fuller
- Department of Biological Sciences, Texas Tech University, 2901 Main St, Lubbock, TX, 79409, USA
- Nongame and Rare Species Program, Texas Parks and Wildlife, Austin, TX, 78744, USA
| | - Yvonne A Dzal
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MB, R3B 2E9, Canada
| | - Catherine G Haase
- Department of Microbiology and Immunology, Montana State University, PO Box 173520, Bozeman, MT, 59717, USA
- Department of Biology, Austin Peay State University, PO Box 4718, Clarkesville, TN, 37040, USA
| | - Kirk A Silas
- Health Program, Wildlife Conservation Society, Bronx, NY, USA
| | - Craig K R Willis
- Department of Biology, University of Winnipeg, 515 Portage Ave, Winnipeg, MB, R3B 2E9, Canada
| | - Sarah H Olson
- Health Program, Wildlife Conservation Society, Bronx, NY, USA
| | - Cori L Lausen
- Western Canada Bat Program, Wildlife Conservation Society Canada, PO Box 606, Kaslo, BC, V0G 1M0, Canada
| |
Collapse
|
7
|
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.
Collapse
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
| |
Collapse
|
8
|
Abstract
The recent introduction of Pseudogymnoascus destructans (the fungal pathogen that causes white-nose syndrome in bats) from Eurasia to North America has resulted in the collapse of North American bat populations and restructured species communities. The long evolutionary history between P. destructans and bats in Eurasia makes understanding host life history essential to uncovering the ecology of P. destructans. In this Review, we combine information on pathogen and host biology to understand the patterns of P. destructans spread, seasonal transmission ecology, the pathogenesis of white-nose syndrome and the cross-scale impact from individual hosts to ecosystems. Collectively, this research highlights how early pathogen detection and quantification of host impacts has accelerated the understanding of this newly emerging infectious disease.
Collapse
|
9
|
Haase CG, Fuller NW, Dzal YA, Hranac CR, Hayman DTS, Lausen CL, Silas KA, Olson SH, Plowright RK. Body mass and hibernation microclimate may predict bat susceptibility to white-nose syndrome. Ecol Evol 2021; 11:506-515. [PMID: 33437446 PMCID: PMC7790633 DOI: 10.1002/ece3.7070] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Revised: 10/31/2020] [Accepted: 11/06/2020] [Indexed: 12/15/2022] Open
Abstract
In multihost disease systems, differences in mortality between species may reflect variation in host physiology, morphology, and behavior. In systems where the pathogen can persist in the environment, microclimate conditions, and the adaptation of the host to these conditions, may also impact mortality. White-nose syndrome (WNS) is an emerging disease of hibernating bats caused by an environmentally persistent fungus, Pseudogymnoascus destructans. We assessed the effects of body mass, torpid metabolic rate, evaporative water loss, and hibernaculum temperature and water vapor deficit on predicted overwinter survival of bats infected by P. destructans. We used a hibernation energetics model in an individual-based model framework to predict the probability of survival of nine bat species at eight sampling sites across North America. The model predicts time until fat exhaustion as a function of species-specific host characteristics, hibernaculum microclimate, and fungal growth. We fit a linear model to determine relationships with each variable and predicted survival and semipartial correlation coefficients to determine the major drivers in variation in bat survival. We found host body mass and hibernaculum water vapor deficit explained over half of the variation in survival with WNS across species. As previous work on the interplay between host and pathogen physiology and the environment has focused on species with narrow microclimate preferences, our view on this relationship is limited. Our results highlight some key predictors of interspecific survival among western bat species and provide a framework to assess impacts of WNS as the fungus continues to spread into western North America.
Collapse
Affiliation(s)
- Catherine G. Haase
- Department of Microbiology and ImmunologyMontana State UniversityBozemanMTUSA
- Present address:
Department of BiologyAustin Peay State UniversityClarksvilleTNUSA
| | - Nathan W. Fuller
- Department of Biological SciencesTexas Tech UniversityLubbockTXUSA
- Present address:
Texas Parks and Wildlife DepartmentNongame and Rare Species ProgramAustinTXUSA
| | - Yvonne A. Dzal
- Department of BiologyCentre for Forest Interdisciplinary Research (C‐FIR)University of WinnipegWinnipegMBCanada
| | - C. Reed Hranac
- Molecular Epidemiology and Public Health LaboratoryMassey UniversityPalmerston NorthNew Zealand
| | - David T. S. Hayman
- Molecular Epidemiology and Public Health LaboratoryMassey UniversityPalmerston NorthNew Zealand
| | | | | | | | - Raina K. Plowright
- Department of Microbiology and ImmunologyMontana State UniversityBozemanMTUSA
| |
Collapse
|