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Hardy BM, Muths E, Funk WC, Bailey LL. Quantifying intraspecific variation in host resistance and tolerance to a lethal pathogen. J Anim Ecol 2024. [PMID: 38773788 DOI: 10.1111/1365-2656.14106] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2024] [Accepted: 03/14/2024] [Indexed: 05/24/2024]
Abstract
Testing for intraspecific variation for host tolerance or resistance in wild populations is important for informing conservation decisions about captive breeding, translocation, and disease treatment. Here, we test the importance of tolerance and resistance in multiple populations of boreal toads (Anaxyrus boreas boreas) against Batrachochytrium dendrobatidis (Bd), the amphibian fungal pathogen responsible for the greatest host biodiversity loss due to disease. Boreal toads have severely declined in Colorado (CO) due to Bd, but toad populations challenged with Bd in western Wyoming (WY) appear to be less affected. We used a common garden infection experiment to expose post-metamorphic toads sourced from four populations (2 in CO and 2 in WY) to Bd and monitored changes in mass, pathogen burden and survival for 8 weeks. We used a multi-state modelling approach to estimate weekly survival and transition probabilities between infected and cleared states, reflecting a dynamic infection process that traditional approaches fail to capture. We found that WY boreal toads are more tolerant to Bd infection with higher survival probabilities than those in CO when infected with identical pathogen burdens. WY toads also appeared more resistant to Bd with a higher probability of infection clearance and an average of 5 days longer to reach peak infection burdens. Our results demonstrate strong intraspecific differences in tolerance and resistance that likely contribute to why population declines vary regionally across this species. Our multi-state framework allowed us to gain inference on typically hidden disease processes when testing for host tolerance or resistance. Our findings demonstrate that describing an entire host species as 'tolerant' or 'resistant' (or lack thereof) is unwise without testing for intraspecific variation.
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Affiliation(s)
- Bennett M Hardy
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Erin Muths
- United States Geological Survey, Fort Collins Science Center, Fort Collins, Colorado, USA
| | - W Chris Funk
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
- Department of Biology, Colorado State University, Fort Collins, Colorado, USA
| | - Larissa L Bailey
- Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA
- Department of Fish, Wildlife, and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA
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2
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Barrile GM, Cross PC, Stewart C, Malmberg J, Jakopak RP, Binfet J, Monteith KL, Werner B, Jennings‐Gaines J, Merkle JA. Chronic wasting disease alters the movement behavior and habitat use of mule deer during clinical stages of infection. Ecol Evol 2024; 14:e11418. [PMID: 38779534 PMCID: PMC11108800 DOI: 10.1002/ece3.11418] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2023] [Revised: 04/13/2024] [Accepted: 05/02/2024] [Indexed: 05/25/2024] Open
Abstract
Integrating host movement and pathogen data is a central issue in wildlife disease ecology that will allow for a better understanding of disease transmission. We examined how adult female mule deer (Odocoileus hemionus) responded behaviorally to infection with chronic wasting disease (CWD). We compared movement and habitat use of CWD-infected deer (n = 18) to those that succumbed to starvation (and were CWD-negative by ELISA and IHC; n = 8) and others in which CWD was not detected (n = 111, including animals that survived the duration of the study) using GPS collar data from two distinct populations collared in central Wyoming, USA during 2018-2022. CWD and predation were the leading causes of mortality during our study (32/91 deaths attributed to CWD and 27/91 deaths attributed to predation). Deer infected with CWD moved slower and used lower elevation areas closer to rivers in the months preceding death compared with uninfected deer that did not succumb to starvation. Although CWD-infected deer and those that died of starvation moved at similar speeds during the final months of life, CWD-infected deer used areas closer to streams with less herbaceous biomass than starved deer. These behavioral differences may allow for the development of predictive models of disease status from movement data, which will be useful to supplement field and laboratory diagnostics or when mortalities cannot be quickly retrieved to assess cause-specific mortality. Furthermore, identifying individuals who are sick before predation events could help to assess the extent to which disease mortality is compensatory with predation. Finally, infected animals began to slow down around 4 months prior to death from CWD. Our approach for detecting the timing of infection-induced shifts in movement behavior may be useful in application to other disease systems to better understand the response of wildlife to infectious disease.
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Affiliation(s)
- Gabriel M. Barrile
- Department of Zoology and PhysiologyUniversity of WyomingLaramieWyomingUSA
| | - Paul C. Cross
- U.S. Geological Survey, Northern Rocky Mountain Science CenterBozemanMontanaUSA
| | | | - Jennifer Malmberg
- Department of Veterinary SciencesUniversity of WyomingLaramieWyomingUSA
- USDA‐APHIS, Wildlife Services, National Wildlife Research CenterFort CollinsColoradoUSA
| | - Rhiannon P. Jakopak
- Haub School of Environment and Natural ResourcesUniversity of WyomingLaramieWyomingUSA
| | | | - Kevin L. Monteith
- Haub School of Environment and Natural Resources, Department of Zoology and Physiology, Wyoming Cooperative Fish and Wildlife Research UnitUniversity of WyomingLaramieWyomingUSA
| | | | | | - Jerod A. Merkle
- Department of Zoology and PhysiologyUniversity of WyomingLaramieWyomingUSA
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3
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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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4
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Gomes FR, Madelaire CB, Moretti EH, Titon SCM, Assis VR. Immunoendocrinology and Ecoimmunology in Brazilian Anurans. Integr Comp Biol 2022; 62:1654-1670. [PMID: 35411921 DOI: 10.1093/icb/icac014] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
This paper reviews several aspects of immunoendocrinology and ecoimmunology in Brazilian species of anurans under investigation for more than a decade, including (1) patterns of annual covariation of circulating steroids, calling behavior and innate immunity, (2) endocrine and immune correlates of calling performance, (3) behavioral and physiological correlates of parasite load, (4) thermal sensitivity of immune function, and (5) endocrine and immunomodulation by experimental exposure to acute and chronic stressors, as well as to endocrine manipulations and simulated infections. Integrated results have shown an immunoprotective role of increased steroid plasma levels during reproductive activity in calling males. Moreover, a higher helminth parasite load is associated with changes in several behavioral and physiological traits under field conditions. We also found anuran innate immunity is generally characterized by eurythermy, with maximal performance observed in temperatures close to normal and fever thermal preferendum. Moreover, the aerobic scope of innate immune response is decreased at fever thermal preferendum. Experimental exposure to stressors results in increased corticosterone plasma levels and immune redistribution, with an impact on immune function depending on the duration of the stress exposure. Interestingly, the fate of immunomodulation by chronic stressors also depends in part on individual body condition. Acute treatment with corticosterone generally enhances immune function, while prolonged exposure results in immunosuppression. Still, the results of hormonal treatment are complex and depend on the dose, duration of treatment, and the immune variable considered. Finally, simulated infection results in complex modulation of the expression of cytokines, increased immune function, activation of the Hypothalamus-Pituitary-Interrenal axis, and decreased activity of the Hypothalamus-Pituitary-Gonadal axis, as well as reduced melatonin plasma levels, suggesting that anurans have a functional Immune-Pineal axis, homologous to that previously described for mammals. These integrated and complementary approaches have contributed to a better understanding of physiological mechanisms and processes, as well as ecological and evolutionary implications of anuran immunoendocrinology.
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Affiliation(s)
- Fernando Ribeiro Gomes
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brasil
| | - Carla Bonetti Madelaire
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brasil.,School of Life Sciences, University of Nevada Las Vegas, Las Vegas, NV 89154, USA
| | - Eduardo Hermógenes Moretti
- Departamento de Imunologia, Instituto de Ciências Biomédicas, Universidade de São Paulo, Av. Professor Lineu Prestes, 1730, São Paulo, SP 05508-900, Brasil
| | - Stefanny Christie Monteiro Titon
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brasil
| | - Vania Regina Assis
- Departamento de Fisiologia, Instituto de Biociências, Universidade de São Paulo, Rua do Matão, trav. 14, 101, São Paulo, SP 05508-090, Brasil
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5
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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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Wilber MQ, Knapp RA, Smith TC, Briggs CJ. Host density has limited effects on pathogen invasion, disease-induced declines and within-host infection dynamics across a landscape of disease. J Anim Ecol 2022; 91:2451-2464. [PMID: 36285540 DOI: 10.1111/1365-2656.13823] [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: 05/26/2022] [Accepted: 09/20/2022] [Indexed: 12/14/2022]
Abstract
1. Host density is hypothesized to be a major driver of variability in the responses and outcomes of wildlife populations following pathogen invasion. While the effects of host density on pathogen transmission have been extensively studied, these studies are dominated by theoretical analyses and small-scale experiments. This focus leads to an incomplete picture regarding how host density drives observed variability in disease outcomes in the field. 2. Here, we leveraged a dataset of hundreds of replicate amphibian populations that varied by orders of magnitude in host density. We used these data to test the effects of host density on three outcomes following the arrival of the amphibian-killing fungal pathogen Batrachochytrium dendrobatidis (Bd): the probability that Bd successfully invaded a host population and led to a pathogen outbreak, the magnitude of the host population-level decline following an outbreak and within-host infection dynamics that drive population-level outcomes in amphibian-pathogen systems. 3. Based on previous small-scale transmission experiments, we expected that populations with higher densities would be more likely to experience Bd outbreaks and would suffer larger proportional declines following outbreaks. To test these predictions, we developed and fitted a Hidden Markov Model that accounted for imperfectly observed disease outbreak states in the amphibian populations we surveyed. 4. Contrary to our predictions, we found minimal effects of host density on the probability of successful Bd invasion, the magnitude of population decline following Bd invasion and the dynamics of within-host infection intensity. Environmental conditions, such as summer temperature, winter severity and the presence of pathogen reservoirs, were more predictive of variability in disease outcomes. 5. Our results highlight the limitations of extrapolating findings from small-scale transmission experiments to observed disease trajectories in the field and provide strong evidence that variability in host density does not necessarily drive variability in host population responses following pathogen arrival. In an applied context, we show that feedbacks between host density and disease will not necessarily affect the success of reintroduction efforts in amphibian-Bd systems of conservation concern.
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Affiliation(s)
- Mark Q Wilber
- Department of Forestry, Wildlife, and Fisheries, University of Tennessee Institute of Agriculture, Knoxville, Tennessee, USA
| | - Roland A Knapp
- Earth Research Institute, University of California, Santa Barbara, California, USA.,Sierra Nevada Aquatic Research Laboratory, University of California, Mammoth Lakes, California, USA
| | - Thomas C Smith
- Earth Research Institute, University of California, Santa Barbara, California, USA.,Sierra Nevada Aquatic Research Laboratory, University of California, Mammoth Lakes, California, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, California, USA
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7
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Schwarzer AC, Cox WA, Tornwall B. Habitat selection of nesting and fledgling salt marsh songbirds in northeast Florida. J Wildl Manage 2022. [DOI: 10.1002/jwmg.22260] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Affiliation(s)
- Amy C. Schwarzer
- Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission 1105 SW Williston Road Gainesville FL 32601 USA
| | - W. Andrew Cox
- Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission 1105 SW Williston Road Gainesville FL 32601 USA
| | - Brett Tornwall
- Fish and Wildlife Research Institute, Florida Fish and Wildlife Conservation Commission 1105 SW Williston Road Gainesville FL 32601 USA
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8
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Barrile GM, Chalfoun AD, Estes‐Zumpf WA, Walters AW. Wildfire influences individual growth and breeding dispersal, but not survival and recruitment in a montane amphibian. Ecosphere 2022. [DOI: 10.1002/ecs2.4212] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Affiliation(s)
- Gabriel M. Barrile
- Wyoming Cooperative Fish and Wildlife Research Unit, Program in Ecology, Department of Zoology and Physiology University of Wyoming Laramie Wyoming USA
| | - Anna D. Chalfoun
- U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology and Program in Ecology University of Wyoming Laramie Wyoming USA
| | | | - Annika W. Walters
- U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology and Program in Ecology University of Wyoming Laramie Wyoming USA
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9
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Wilber MQ, Ohmer MEB, Altman KA, Brannelly LA, LaBumbard BC, Le Sage EH, McDonnell NB, Muñiz Torres AY, Nordheim CL, Pfab F, Richards-Zawacki CL, Rollins-Smith LA, Saenz V, Voyles J, Wetzel DP, Woodhams DC, Briggs CJ. Once a reservoir, always a reservoir? Seasonality affects the pathogen maintenance potential of amphibian hosts. Ecology 2022; 103:e3759. [PMID: 35593515 DOI: 10.1002/ecy.3759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2021] [Revised: 03/18/2022] [Accepted: 03/31/2022] [Indexed: 11/10/2022]
Abstract
Host species that can independently maintain a pathogen in a host community and contribute to infection in other species are important targets for disease management. However, the potential of host species to maintain a pathogen is not fixed over time, and an important challenge is understanding how within- and across-season variability in host maintenance potential affects pathogen persistence over longer time scales relevant for disease management (e.g., years). Here, we sought to understand the causes and consequences of seasonal infection dynamics in leopard frogs (Rana sphenocephala and R. pipiens) infected with the fungal pathogen Batrachochytrium dendrobatidis (Bd). We addressed three questions broadly applicable to seasonal host-parasite systems. First, to what degree are observed seasonal patterns in infection driven by temperature-dependent infection processes compared to seasonal host demographic processes? Second, how does seasonal variation in maintenance potential affect long-term pathogen persistence in multihost communities? Third, does high deterministic maintenance potential relate to the long-term stochastic persistence of pathogens in host populations with seasonal infection dynamics? To answer these questions, we used field data collected over three years on >1400 amphibians across four geographic locations, laboratory and mesocosm experiments, and a novel mathematical model. We found that the mechanisms that drive seasonal prevalence were different than those driving seasonal infection intensity. Seasonal variation in Bd prevalence was driven primarily by changes in host contact rates associated with breeding migrations to and from aquatic habitat. In contrast, seasonal changes in infection intensity were driven by temperature-induced changes in Bd growth rate. Using our model, we found that the maintenance potential of leopard frogs varied significantly throughout the year and that seasonal troughs in infection prevalence made it unlikely that leopard frogs were responsible for long-term Bd persistence in these seasonal amphibian communities, highlighting the importance of alternative pathogen reservoirs for Bd persistence. Our results have broad implications for management in seasonal host-pathogen systems, showing that seasonal changes in host and pathogen vital rates, rather than the depletion of susceptible hosts, can lead to troughs in pathogen prevalence and stochastic pathogen extirpation.
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Affiliation(s)
- Mark Q Wilber
- Department of Forestry, Wildlife, and Fisheries, University of Tennessee, Institute of Agriculture, Knoxville, TN.,Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
| | - Michel E B Ohmer
- Living Earth Collaborative, Washington University in St. Louis, St. Louis, MO.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, University of Mississippi, Oxford, MS
| | - Karie A Altman
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Department of Biology, St. Bonaventure University, St Bonaventure, NY
| | - Laura A Brannelly
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA.,Melbourne Veterinary School, Faculty of Veterinary and Agricultural Sciences, The University of Melbourne, Werribee, Victoria, Australia
| | - Brandon C LaBumbard
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Emily H Le Sage
- Department of Pathology Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Nina B McDonnell
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Aura Y Muñiz Torres
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Caitlin L Nordheim
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA.,Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Ferdinand Pfab
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
| | | | - Louise A Rollins-Smith
- Department of Pathology Microbiology, and Immunology, Vanderbilt University School of Medicine, Nashville, TN
| | - Veronica Saenz
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Jamie Voyles
- Department of Biology, University of Nevada, Reno, Reno, NV
| | - Daniel P Wetzel
- Department of Biological Sciences, University of Pittsburgh, Pittsburgh, PA
| | - Douglas C Woodhams
- Department of Biology, University of Massachusetts Boston, Boston, Massachusetts, USA
| | - Cheryl J Briggs
- Ecology, Evolution and Marine Biology, University of California, Santa Barbara, Santa Barbara, CA
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10
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Stage-Specific Environmental Correlates of Reproductive Success in Boreal Toads (Anaxyrus boreas boreas). J HERPETOL 2022. [DOI: 10.1670/21-023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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11
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Brophy T, Luong LT. The influence of infection status and parasitism risk on host dispersal and susceptibility to infection in Drosophila nigrospiracula. Parasitology 2021:1-6. [PMID: 35260204 DOI: 10.1017/s0031182021001979] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
For many organisms, habitat avoidance provides the first line of defence against parasitic infection. Changes in infection status can shift the cost-benefit ratio of remaining in a given habitat vs dispersing. The aim of this study was to test the hypothesis that the propensity to disperse in Drosophila nigrospiracula is mediated by current parasite load and the risk of further infection by an ectoparasitic mite (Macrocheles subbadius). An activity monitor was used to assess dispersal propensity among infected and uninfected flies. The activity level of uninfected females increased threefold upon exposure to a mite, whereas the activity among uninfected males increased by 17-fold in the presence of a questing mite. Among infected flies, the risk of further infection also generated a change in activity, but the magnitude of the response was dependent on host sex. Current infection status influenced the probability of acquiring more parasites due to increased susceptibility to infection with mite load. The probability of acquiring additional mites among males increased more rapidly compared to female flies. Current infection status can potentially determine the risk of further infection, the host propensity and ability to disperse, with consequence for hosts and parasites at the individual, population and species level.
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Affiliation(s)
- Taylor Brophy
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Lien T Luong
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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12
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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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13
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Barrile GM, Walters A, Webster M, Chalfoun AD. Informed breeding dispersal following stochastic changes to patch quality in a pond-breeding amphibian. J Anim Ecol 2021; 90:1878-1890. [PMID: 33884620 DOI: 10.1111/1365-2656.13503] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Accepted: 04/06/2021] [Indexed: 11/28/2022]
Abstract
The unidirectional movement of animals between breeding patches (i.e. breeding dispersal) has profound implications for the ecological and evolutionary dynamics of spatially structured populations. In spatiotemporally variable environments, individuals are expected to adjust their dispersal decisions according to information gathered on the environmental and/or social cues that reflect the fitness prospects in a given breeding patch (i.e. informed dispersal). A paucity of empirical work limited our understanding of the ability of animals to depart from low-quality breeding patches and settle in high-quality breeding patches. We examined the capacity of individuals to respond to stochastic changes in habitat quality via informed breeding dispersal in a pond-breeding amphibian. We conducted a 5-year (2015-2019) capture-recapture study of boreal toads Anaxyrus boreas boreas (n = 1,100) that breed in beaver ponds in western Wyoming, USA. During early spring of 2017, an extreme flooding event destroyed several beaver dams and resulted in the loss of breeding habitat. We used multi-state models to investigate how temporal changes in pond characteristics influenced breeding dispersal, and determine whether movement decisions were in accordance with prospects for reproductive fitness. Boreal toads more often departed from low-quality breeding ponds (without successful metamorphosis) and settled in high-quality breeding ponds (with successful metamorphosis). Movement decisions were context-dependent and associated with pond characteristics altered by beaver dam destruction. Individuals were more likely to depart from shallow ponds with high vegetation cover and settle in deep ponds with low vegetation cover. The probability of metamorphosis was related to the same environmental cues, suggesting that boreal toads assess the fitness prospects of a breeding patch and adjust movement decisions accordingly (i.e. informed breeding dispersal). We demonstrated that stochastic variability in environmental conditions and habitat quality can underpin dispersal behaviour in amphibians. Our study highlighted the mechanistic linkages between habitat change, movement behaviour and prospects for reproductive performance, which is critical for understanding how wild animals respond to rapid environmental change.
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Affiliation(s)
- Gabriel M Barrile
- Wyoming Cooperative Fish and Wildlife Research Unit, Program in Ecology, Department of Zoology and Physiology, University of Wyoming, Laramie, WY, USA
| | - Annika Walters
- U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology and Program in Ecology, University of Wyoming, Laramie, WY, USA
| | - Matthew Webster
- Wyoming Cooperative Fish and Wildlife Research Unit, University of Wyoming, Laramie, WY, USA
| | - Anna D Chalfoun
- U.S. Geological Survey, Wyoming Cooperative Fish and Wildlife Research Unit, Department of Zoology and Physiology and Program in Ecology, University of Wyoming, Laramie, WY, USA
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