Thermal biology of newts (Notophthalmus viridescens) chronically infected with a naturally occurring pathogen

Sherman, Elizabeth

doi:10.1016/j.jtherbio.2007.09.005

Cited by 21 publications

(16 citation statements)

References 24 publications

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“…Fungal diseases are currently emerging at record rates, posing a direct threat to global biodiversity in the face of climate change 18 . Reduced maximum thermal tolerance can be a major side effect of infections in amphibians 19 , fish 20 , 21 , and mollusks 22 – 28 . For example, ill newts Notophthalmus viridescens infected with a mesomycetozoan parasite had lower CT max than uninfected newts (by 0.6–1.7 °C) 19 .…”

Section: Introductionmentioning

confidence: 99%

Infection increases vulnerability to climate change via effects on host thermal tolerance

Greenspan

Bower

Roznik

et al. 2017

Sci Rep

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Unprecedented global climate change and increasing rates of infectious disease emergence are occurring simultaneously. Infection with emerging pathogens may alter the thermal thresholds of hosts. However, the effects of fungal infection on host thermal limits have not been examined. Moreover, the influence of infections on the heat tolerance of hosts has rarely been investigated within the context of realistic thermal acclimation regimes and potential anthropogenic climate change. We tested for effects of fungal infection on host thermal tolerance in a model system: frogs infected with the chytrid Batrachochytrium dendrobatidis. Infection reduced the critical thermal maxima (CTmax) of hosts by up to ~4 °C. Acclimation to realistic daily heat pulses enhanced thermal tolerance among infected individuals, but the magnitude of the parasitism effect usually exceeded the magnitude of the acclimation effect. In ectotherms, behaviors that elevate body temperature may decrease parasite performance or increase immune function, thereby reducing infection risk or the intensity of existing infections. However, increased heat sensitivity from infections may discourage these protective behaviors, even at temperatures below critical maxima, tipping the balance in favor of the parasite. We conclude that infectious disease could lead to increased uncertainty in estimates of species’ vulnerability to climate change.

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Section: Introductionmentioning

confidence: 99%

Infection increases vulnerability to climate change via effects on host thermal tolerance

Greenspan

Bower

Roznik

et al. 2017

Sci Rep

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“…First, malformed frogs could select warmer habitats in order to raise their body temperature and induce ''behavioral fevers,'' as noted for other amphibian species in response to parasite infection (Sherman et al 1991). While cases of dose-dependent behavioral fever (i.e., only chronically infected individuals elevate body temperature) are known for amphibians (Sherman 2008), we argue that this is unlikely to be the case here. Despite the absence of malformations, all individuals (malformed and normal) were infected with comparable levels of Ribeiroia, suggesting that differences in infection alone do not explain the observed behavioral differences in thermoregulation.…”

Section: Discussionmentioning

confidence: 80%

Ecomorphology and disease: cryptic effects of parasitism on host habitat use, thermoregulation, and predator avoidance

Goodman

Johnson

2011

Ecology

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Abstract. Parasites can cause dramatic changes in the phenotypes of their hosts, sometimes leading to a higher probability of predation and parasite transmission. Because an organism's morphology directly affects its locomotion, even subtle changes in key morphological traits may affect survival and behavior. However, despite the ubiquity of parasites in natural communities, few studies have incorporated parasites into ecomorphological research. Here, we evaluated the effects of parasite-induced changes in host phenotype on the habitat use, thermal biology, and simulated predator-escape ability of Pacific chorus frogs (Pseudacris regilla) in natural environments. Frogs with parasite-induced limb malformations were more likely to use ground microhabitats relative to vertical refugia and selected less-angled perches closer to the ground in comparison with normal frogs. Although both groups had similar levels of infection, malformed frogs used warmer microhabitats, which resulted in higher body temperatures. Likely as a result of their morphological abnormalities, malformed frogs allowed a simulated predator to approach closer before escaping and escaped shorter distances relative to normal frogs. These data indicate that parasite-induced morphological changes can significantly alter host behavior and habitat use, highlighting the importance of incorporating the ubiquitous, albeit cryptic, role of parasites into ecomorphological research.

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“…We sent several apparently infected newts to the National Wildlife Health Center in Madison, Wisconsin, which identified the lesions as having been caused by an Ichthyophonus-like organism. Thereafter, we used visual inspection to designate newts as either uninfected or infected (Raffel et al, 2006;Sherman, 2008). It is unlikely that apparently healthy newts had subclinical infections (Raffel et al, 2006).…”

Section: Methodsmentioning

confidence: 99%

“…infection as a predictor of FA, we followed Sherman's (2008) procedure for indexing infection. Characteristically, the lesions were arrayed along the long axis of the newt and could affect one side or both right and left sides of the animal.…”

Section: Extent Of Lesionsmentioning

confidence: 99%

Fluctuating asymmetry in Ichthyophonus-sp. infected newts, Notophthalmus viridescens, from Vermont

2009

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Measures of fluctuating asymmetry (FA) have been used to assess the significance of stress in amphibian populations. When animals with bilateral body plans are challenged by environmental stressors, departures from bilateral symmetry can emerge during development. The tendency for FA to develop has been linked to greater susceptibility to pathogens in many organisms. In our study, newts (Notophthalmus viridescens) infected with Ichthyophonus-sp. exhibited greater size-corrected FA of the hind limbs than uninfected animals from the same population. Among infected animals, however, the intensity of infection and the extent of hind limb asymmetry were not correlated, suggesting that asymmetry did not arise following infection, but rather that newts having greater FA may have been more susceptible to infection as a result of the same stresses that produced the increase in FA. There was no relationship between dorsal spot pattern FA and infection status or hind limb FA. We suggest that spot pattern may be less canalized than hind limb development. Newts are widely distributed and important components of freshwater communities in eastern North America and, thus, any change in their vitality may affect the composition of those communities. Analyses of hind limb FA may be a useful and non-invasive tool for identifying potentially vulnerable amphibian populations.

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Thermal biology of newts (Notophthalmus viridescens) chronically infected with a naturally occurring pathogen

Cited by 21 publications

References 24 publications

Infection increases vulnerability to climate change via effects on host thermal tolerance

Infection increases vulnerability to climate change via effects on host thermal tolerance

Ecomorphology and disease: cryptic effects of parasitism on host habitat use, thermoregulation, and predator avoidance

Fluctuating asymmetry in Ichthyophonus-sp. infected newts, Notophthalmus viridescens, from Vermont

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