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Cabanzo-Olarte LC, Cardoso Bícego K, Navas Iannini CA. Behavioral responses during sickness in amphibians and reptiles: Concepts, experimental design, and implications for field studies. J Therm Biol 2024; 123:103889. [PMID: 38897001 DOI: 10.1016/j.jtherbio.2024.103889] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Revised: 06/09/2024] [Accepted: 06/10/2024] [Indexed: 06/21/2024]
Abstract
In ectothermic vertebrates, behavioral fever, where an individual actively seeks warmer areas, seems to be a primary response to pathogens. This is considered a broad and evolutionarily conserved response among vertebrates. Recent population declines in amphibians are associated with an increase of infectious disease driven largely by climate change, habitat degradation, and pollution. Immediate action through research is required to better understand and inform conservation efforts. The literature available, does not provide unifying concepts that can guide adequate experimental protocols and interpretation of data, especially when studying animals in the field. The aim of this review is to promote common understanding of terminology and facilitating improved comprehension and application of key concepts about the occurrence of both sickness behavior or behavioral fever in ectothermic vertebrates. We start with a conceptual synthesis of sickness behavior and behavioral fever, with examples in different taxa. Through this discussion we present possible paths to standardize terminology, starting from original use in endothermic tetrapods which was expanded to ectothermic vertebrates, particularly amphibians and reptiles. This conceptual expansion from humans (endothermic vertebrates) and then to ectothermic counterparts, gravitates around the concept of 'normality'. Thus, following this discussion, we highlight caveats with experimental protocols and state the need of a reference value considered normal (RVCN), which is different from experimental control and make recommendations regarding experimental procedures and stress the value of detailed documentation of behavioral responses. We also propose some future directions that could enhance interaction among disciplines, emphasizing relationships at different levels of biological organization. This is crucial given the increasing convergence of fields such as thermal physiology, immunology, and animal behavior due to emerging diseases and other global crises impacting biodiversity.
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Affiliation(s)
- Laura Camila Cabanzo-Olarte
- Physiology Department, Biosciences Institute, University of São Paulo, Trav. 14, N 321, CEP 05508-090 São Paulo, SP, Brazil.
| | - Kênia Cardoso Bícego
- Department of Animal Morphology and Physiology, São Paulo State University (FCAV-UNESP), Via de Acesso Prof. Paulo Donato Castellane s/n, Jaboticabal, SP 14884-900, Brazil.
| | - Carlos Arturo Navas Iannini
- Physiology Department, Biosciences Institute, University of São Paulo, Trav. 14, N 321, CEP 05508-090 São Paulo, SP, Brazil.
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Wu NC. Pathogen load predicts host functional disruption: A meta‐analysis of an amphibian fungal panzootic. Funct Ecol 2023. [DOI: 10.1111/1365-2435.14245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Affiliation(s)
- Nicholas C. Wu
- Hawkesbury Institute for the Environment Western Sydney University Richmond New South Wales Australia
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Ortega‐Chinchilla JE, Cabanzo‐Olarte LC, Vaz R, Lamadrid‐Feris F, Bevier CR, Navas CA. Behavioral models of hydrothermal regulation in anurans: A field study in the Atlantic Forest, Brazil. Biotropica 2022. [DOI: 10.1111/btp.13187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Affiliation(s)
- Jesús Eduardo Ortega‐Chinchilla
- Laboratório de Ecofisiologia e Fisiologia Evolutiva, Departamento de Fisiologia geral, Instituto de Biociências Universidade de São Paulo São Paulo Brazil
| | - Laura Camila Cabanzo‐Olarte
- Laboratório de Ecofisiologia e Fisiologia Evolutiva, Departamento de Fisiologia geral, Instituto de Biociências Universidade de São Paulo São Paulo Brazil
| | - Renata Vaz
- Laboratório de Ecofisiologia e Fisiologia Evolutiva, Departamento de Fisiologia geral, Instituto de Biociências Universidade de São Paulo São Paulo Brazil
| | - Faride Lamadrid‐Feris
- Laboratório de Fisiologia Evolutiva e Comportamento, Departamento de Fisiologia geral, Instituto de Biociências Universidade de São Paulo São Paulo Brazil
| | | | - Carlos A. Navas
- Laboratório de Ecofisiologia e Fisiologia Evolutiva, Departamento de Fisiologia geral, Instituto de Biociências Universidade de São Paulo São Paulo Brazil
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Bakewell L, Kelehear C, Graham S. Impacts of temperature on immune performance in a desert anuran (
Anaxyrus punctatus
). J Zool (1987) 2021. [DOI: 10.1111/jzo.12891] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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TEMPERATURE AS A DRIVER OF THE PATHOGENICITY AND VIRULENCE OF AMPHIBIAN CHYTRID FUNGUS BATRACHOCHYTRIUM DENDROBATIDIS: A SYSTEMATIC REVIEW. J Wildl Dis 2021; 57:477-494. [PMID: 34019674 DOI: 10.7589/jwd-d-20-00105] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 02/10/2021] [Indexed: 11/20/2022]
Abstract
Chytridiomycosis, caused by the chytrid fungus Batrachochytrium dendrobatidis (Bd), is a leading cause of global amphibian declines. Severe infections with Bd can lead to cardiac arrest, and mass deaths during epidemics have been reported. Temperature, pH, salinity, and moisture are important determinants of the survival, growth, reproduction, and pathogenicity of Bd, as well as its effect on amphibian populations. Here, we synthesize current knowledge on the role of temperature as a driver of the pathogenicity and virulence of Bd to better understand the effects of temperature on amphibian defense mechanisms against infection. This review advises on research direction and management approaches to benefit amphibian populations affected by Bd. We conclude by offering guidelines for four levels of temperature monitoring in amphibian field studies to improve consistency between studies: regional climate, habitat, microhabitat, and amphibian host.
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Lopes PC, French SS, Woodhams DC, Binning SA. Sickness behaviors across vertebrate taxa: proximate and ultimate mechanisms. J Exp Biol 2021; 224:260576. [PMID: 33942101 DOI: 10.1242/jeb.225847] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
There is nothing like a pandemic to get the world thinking about how infectious diseases affect individual behavior. In this respect, sick animals can behave in ways that are dramatically different from healthy animals: altered social interactions and changes to patterns of eating and drinking are all hallmarks of sickness. As a result, behavioral changes associated with inflammatory responses (i.e. sickness behaviors) have important implications for disease spread by affecting contacts with others and with common resources, including water and/or sleeping sites. In this Review, we summarize the behavioral modifications, including changes to thermoregulatory behaviors, known to occur in vertebrates during infection, with an emphasis on non-mammalian taxa, which have historically received less attention. We then outline and discuss our current understanding of the changes in physiology associated with the production of these behaviors and highlight areas where more research is needed, including an exploration of individual and sex differences in the acute phase response and a greater understanding of the ecophysiological implications of sickness behaviors for disease at the population level.
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Affiliation(s)
- Patricia C Lopes
- Schmid College of Science and Technology, Chapman University, Orange, CA 92866, USA
| | - Susannah S French
- Department of Biology and The Ecology Center, Utah State University, Logan, UT 84322, USA
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Sandra A Binning
- Département de Sciences Biologiques, Université de Montréal, Montréal, QC, Canada, H3C 3J7
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Feeding alters the preferred body temperature of Cururu toads, Rhinella diptycha (Anura, Bufonidae). Comp Biochem Physiol A Mol Integr Physiol 2020; 249:110771. [PMID: 32711161 DOI: 10.1016/j.cbpa.2020.110771] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 07/15/2020] [Accepted: 07/15/2020] [Indexed: 02/06/2023]
Abstract
Ectothermic organisms depend primarily on external heat sources and behavioural adjustments to regulate body temperature. Under controlled conditions, in a thermal gradient, body temperature often clusters around a more or less defined range of preferred body temperatures (Tpref). However, Tpref may be modified in response to environmental parameters and/or physiological state. For example, meal ingestion is sometimes followed by a post-prandial thermophilic response leading to a transient increment in Tpref. Although thought to optimize digestive processes, its occurrence, magnitude, and possible determinants remains scarcely documented for anuran amphibians. Herein, we investigated whether the Cururu toad, Rhinella diptycha, exhibits a post-prandial thermophilic response by monitoring the body temperature of fasting and fed toads while they were maintained in a thermal gradient. We found that the toads' Tpref increased by about 13% from day 2 to 4 after feeding, in comparison with the Tpref recorded under fasting. Also, fed animals exhibited a broader range for Tpref at days 2 and 3 post-prandial, which reflects a greater level of locomotor activity compared to fasting individuals. We conclude that R. diptycha is capable to exhibit a post-prandial thermophilic response under the controlled conditions of a thermal gradient. Although this thermoregulatory adjustment is thought to optimize meal digestion yielding important energetic and ecological benefits, its occurrence in anuran amphibians in nature remains uncertain.
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Hettyey A, Ujszegi J, Herczeg D, Holly D, Vörös J, Schmidt BR, Bosch J. Mitigating Disease Impacts in Amphibian Populations: Capitalizing on the Thermal Optimum Mismatch Between a Pathogen and Its Host. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00254] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
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Sauer EL, Fuller RC, Richards-Zawacki CL, Sonn J, Sperry JH, Rohr JR. Variation in individual temperature preferences, not behavioural fever, affects susceptibility to chytridiomycosis in amphibians. Proc Biol Sci 2018; 285:rspb.2018.1111. [PMID: 30135162 DOI: 10.1098/rspb.2018.1111] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2018] [Accepted: 07/27/2018] [Indexed: 11/12/2022] Open
Abstract
The ability of wildlife populations to mount rapid responses to novel pathogens will be critical for mitigating the impacts of disease outbreaks in a changing climate. Field studies have documented that amphibians preferring warmer temperatures are less likely to be infected with the fungal pathogen Batrachochytrium dendrobatidis (Bd). However, it is unclear whether this phenomenon is driven by behavioural fever or natural variation in thermal preference. Here, we placed frogs in thermal gradients, tested for temperature preferences and measured Bd growth, prevalence, and the survival of infected animals. Although there was significant individual- and species-level variation in temperature preferences, we found no consistent evidence of behavioural fever across five frog species. Interestingly, for species that preferred warmer temperatures, the preferred temperatures of individuals were negatively correlated with Bd growth on hosts, while the opposite correlation was true for species preferring cooler temperatures. Our results suggest that variation in thermal preference, but not behavioural fever, might shape the outcomes of Bd infections for individuals and populations, potentially resulting in selection for individual hosts and host species whose temperature preferences minimize Bd growth and enhance host survival during epidemics.
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Affiliation(s)
- Erin L Sauer
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
| | - Rebecca C Fuller
- Department of Animal Biology, University of Illinois, Champaign, IL 61820, USA
| | | | - Julia Sonn
- Department of Ecology and Evolutionary Biology, Tulane University, New Orleans, LA 70118, USA
| | - Jinelle H Sperry
- US Army Engineer Research and Development Center, Champaign, IL 61826, USA
| | - Jason R Rohr
- Department of Integrative Biology, University of South Florida, Tampa, FL 33620, USA
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Effects of Emerging Infectious Diseases on Amphibians: A Review of Experimental Studies. DIVERSITY-BASEL 2018. [DOI: 10.3390/d10030081] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Numerous factors are contributing to the loss of biodiversity. These include complex effects of multiple abiotic and biotic stressors that may drive population losses. These losses are especially illustrated by amphibians, whose populations are declining worldwide. The causes of amphibian population declines are multifaceted and context-dependent. One major factor affecting amphibian populations is emerging infectious disease. Several pathogens and their associated diseases are especially significant contributors to amphibian population declines. These include the fungi Batrachochytrium dendrobatidis and B. salamandrivorans, and ranaviruses. In this review, we assess the effects of these three pathogens on amphibian hosts as found through experimental studies. Such studies offer valuable insights to the causal factors underpinning broad patterns reported through observational studies. We summarize key findings from experimental studies in the laboratory, in mesocosms, and from the field. We also summarize experiments that explore the interactive effects of these pathogens with other contributors of amphibian population declines. Though well-designed experimental studies are critical for understanding the impacts of disease, inconsistencies in experimental methodologies limit our ability to form comparisons and conclusions. Studies of the three pathogens we focus on show that host susceptibility varies with such factors as species, host age, life history stage, population and biotic (e.g., presence of competitors, predators) and abiotic conditions (e.g., temperature, presence of contaminants), as well as the strain and dose of the pathogen, to which hosts are exposed. Our findings suggest the importance of implementing standard protocols and reporting for experimental studies of amphibian disease.
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Finnerty PB, Shine R, Brown GP. Survival of the feces: Does a nematode lungworm adaptively manipulate the behavior of its cane toad host? Ecol Evol 2018; 8:4606-4618. [PMID: 29760901 PMCID: PMC5938457 DOI: 10.1002/ece3.3870] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Revised: 12/27/2017] [Accepted: 01/02/2018] [Indexed: 01/07/2023] Open
Abstract
Parasites can enhance their fitness by modifying the behavior of their hosts in ways that increase rates of production and transmission of parasite larvae. We used an antihelminthic drug to experimentally alter infections of lungworms (Rhabdias pseudosphaerocephala) in cane toads (Rhinella marina). We then compared subsequent behaviors of dewormed toads versus toads that retained infections. Both in the laboratory and in the field, the presence of parasites induced hosts to select higher body temperatures (thereby increasing rates of lungworm egg production), to defecate in moister sites, and to produce feces with higher moisture content (thereby enhancing survival of larvae shed in feces). Because those behavioral modifications enhance rather than decrease parasite fitness, they are likely to have arisen as adaptive manipulations of host behavior rather than as host adaptations to combat infection or as nonadaptive consequences of infection on host physiology. However, the mechanisms by which lungworms alter cane toad thermal preference and defecation are not known. Although many examples of host manipulation by parasites involve intermediate hosts facilitating their own demise, our findings indicate that manipulation of definitive hosts can be as subtle as when and where to defecate.
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Affiliation(s)
- Patrick B Finnerty
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - Richard Shine
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
| | - Gregory P Brown
- School of Life and Environmental Sciences University of Sydney Sydney NSW Australia
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