Chytrid Fungus in Europe

Garner, Trenton W. J.; Walker, Susan L.; Bosch, Jaime; Hyatt, Alex D.; Cunningham, Andrew A.; Fisher, Matthew C.

doi:10.3201/eid1110.050109

Cited by 104 publications

(42 citation statements)

References 8 publications

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“…The results also show that Bd -associated mortality can be substantial in an area where Bd is widespread ([27], [28], U. Tobler and B. R. Schmidt, unpublished data) but where no mass mortalities or Bd -associated population declines have been reported [26]. Nevertheless, the high mortality rates we observed are likely to affect populations and suggest that Bd may be a cryptic driver of amphibian population dynamics.…”

Section: Discussionmentioning

confidence: 52%

Within- and Among-Population Variation in Chytridiomycosis-Induced Mortality in the Toad Alytes obstetricans

Tobler

Schmidt

2010

PLoS ONE

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BackgroundChytridiomycosis is a fungal disease linked to local and global extinctions of amphibians. Susceptibility to chytridiomycosis varies greatly between amphibian species, but little is known about between- and within-population variability. However, this kind of variability is the basis for the evolution of tolerance and resistance evolution to disease.Methodology/Principal FindingsIn a common garden experiment, we measured mortality after metamorphosis of Alytes obstetricans naturally infected with Batrachochytrium dendrobatidis. Mortality rates differed significantly among populations and ranged from 27 to 90%. Within populations, mortality strongly depended on mass at and time through metamorphosis.Conclusions/SignificanceAlthough we cannot rule out that the differences observed resulted from differences in skin microbiota, different pathogen strains or environmental effects experienced by the host or the pathogen prior to the start of the experiment, we argue that genetic differences between populations are a likely source of at least part of this variation. To our knowledge, this is the first study showing differences in survival between and within populations under constant laboratory conditions. Assuming that some of this intraspecific variation has a genetic basis, this may suggest that there is the potential for the evolution of resistance or tolerance, which might allow population persistence.

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Section: Discussionmentioning

confidence: 52%

Within- and Among-Population Variation in Chytridiomycosis-Induced Mortality in the Toad Alytes obstetricans

Tobler

Schmidt

2010

PLoS ONE

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“…This highway is very popular for fishing enthusiasts, and multiple camping stops and boat launches decorate the rivers' estuaries. Human involvement in the spread of pathogens has already been documented (Garner et al 2005, Fisher & Garner 2007, Phillott et al 2010. In wild tiger salamanders Ambystoma tigrinum from the western USA, ranavirus isolates were more closely related to sport fish strains than to amphibian strains, and strains cultured in salamanders in bait shops in Phoenix, Arizona, were also found in the wild .…”

Section: Discussionmentioning

confidence: 94%

Amphibian pathogens at northern latitudes: presence of chytrid fungus and ranavirus in northeastern Canada

D'Aoust‐Messier¹,

Echaubard²,

Billy³

et al. 2015

Dis. Aquat. Org.

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Infections by the fungal pathogen Batrachochytrium dendrobatidis (Bd) and members of the genus Ranavirus (Rv) are increasingly reported as significant determinants of amphibian population die-offs. The complexity associated with their transmission and spatial distribution leads to an increase in demand for comprehensive reporting systems and global mapping of their distribution. Here, we document the distribution of these 2 pathogens in a remote northern temperate lowland where environmental sensitivity is high, providing important insight into the pathogens' natural history and infection patterns. Wood frog Lithobates sylvaticus tissues were collected from the James Bay area in northeastern Canada and were screened for the presence of Bd and Rv using conventional and real-time PCR. Both pathogens were present in the study area, which is the northernmost record in eastern North America. Interestingly, different patterns of distribution were observed between the eastern and western coasts of James Bay, suggesting differences in the spatial and transmission dynamics for each pathogen. Anthropogenic introduction may still influence the distribution patterns observed, even at these latitudes. The presence of infections in this remote area also raises further questions on the risk these pathogens pose to northern amphibian communities. We encourage further research in remote locations for a better understanding of these pathogens, their transmission dynamics, and especially their respective impacts on amphibian populations worldwide.

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“…comm.). Given that Batrachochytrium dendrobatidis has been implicated in the extinction of numerous amphibian species worldwide (Garner et al 2005, 2006, Pounds et al 2006), our analysis highlights the potential danger of overlooking frequency‐dependence.…”

Section: Discussionmentioning

confidence: 97%

Host‐parasite population dynamics under combined frequency‐ and density‐dependent transmission

Ryder

Miller²,

White³

et al. 2007

Oikos

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Many host‐parasite models assume that transmission increases linearly with host population density (‘density‐dependent transmission’), but various alternative transmission functions have been proposed in an effort to capture the complexity of real biological systems. The most common alternative (usually applied to sexually transmitted parasites) assumes instead that the rate at which hosts contact one another is independent of population density, leading to ‘frequency‐dependent’ transmission. This straight‐forward distinction generates fundamentally different dynamics (e.g. deterministic, parasite‐driven extinction with frequency‐ but not density‐dependence). Here, we consider the situation where transmission occurs through two different types of contact, one of which is density‐dependent (e.g. social contacts), the other density‐independent (e.g. sexual contacts). Drawing on a range of biological examples, we propose that this type of contact structure may be widespread in natural populations. When our model is characterized mainly by density‐dependent transmission, we find that allowing even small amounts of transmission to occur through density‐independent contacts leads to the possibility of deterministic, parasite‐driven extinction (and lowers the threshold for parasite persistence). Contrastingly, allowing some density‐dependent transmission to occur in a model characterized mainly by density‐independent contacts (i.e. by frequency‐dependent transmission) does not affect the extinction threshold, but does increase the likelihood of parasite persistence. The idea that directly transmitted parasites exploit different types of host contact is not new, but here we show that the impact on dynamics can be fundamental even in the simplest cases. For example, in systems where density‐dependent transmission is normally assumed de facto, we show that parasite‐driven extinction can occur if a small amount of transmission occurs through density‐independent contacts. Many empirical studies are still guided by the traditional density/frequency dichotomy, but our combined transmission function may provide a better model for systems in which both types of transmission occur.

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Chytrid Fungus in Europe

Cited by 104 publications

References 8 publications

Within- and Among-Population Variation in Chytridiomycosis-Induced Mortality in the Toad Alytes obstetricans

Within- and Among-Population Variation in Chytridiomycosis-Induced Mortality in the Toad Alytes obstetricans

Amphibian pathogens at northern latitudes: presence of chytrid fungus and ranavirus in northeastern Canada

Host‐parasite population dynamics under combined frequency‐ and density‐dependent transmission

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