Populations of a Susceptible Amphibian Species Can Grow despite the Presence of a Pathogenic Chytrid Fungus

Tobler, Ursina; Borgula, Adrian; Schmidt, Benedikt R.

doi:10.1371/journal.pone.0034667

Cited by 61 publications

(59 citation statements)

References 52 publications

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“…By contrast, infected populations were even able to increase despite the presence of the fungus. Thus, our observation in the yellowbellied toad population Baumbach marl pit/Hergerhausen stone pit with high prevalence of Bd but population growth confirms that of Tobler et al (2012), who also concluded that observed negative effects of Bd on survival of individuals do not necessarily translate into negative effects at the population level. In yet another study, Canestrelli et al (2013) showed that Bd has been present in Apennine yellow-bellied toad populations Bombina pachypus at least since the late 1970s, but strong declines only started after the mid-1990s.…”

Section: Discussionsupporting

confidence: 84%

“…Mass mortalities or obvious signs of disease in individuals were not observed. Conversely, we could show that Bd-in fected populations can even increase in size under favorable habitat conditions, supporting the findings of Tobler et al (2012). Apart from longterm monitoring of yellow-bellied toad populations, we therefore call for maintenance measures that improve aquatic and terrestrial habitat conditions to keep or bring populations into a favorable conservation status.…”

Section: Discussionsupporting

confidence: 80%

“…This increase was only visible due to monitoring data over 3 in stead of 2 yr, again pointing to the importance of long-term monitoring (see Meyer et al 1998). Tobler et al (2012) analyzed count data series of 26 Bd-infected and uninfected midwife toad Alytes obstetricans populations in Switzerland over 4 to 8 yr. The authors did not find any negative effects of the presence of Bd in a population on growth rate.…”

Section: Discussionmentioning

confidence: 99%

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No evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads

Wagner

Neubeck²,

Guicking³

et al. 2017

Dis. Aquat. Org.

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The parasitic chytrid fungus Batrachochytrium dendrobatidis (Bd ) can cause the lethal disease chytridiomycosis in amphibians and therefore may play a role in population declines. The yellow-bellied toad Bombina variegata suffered strong declines throughout western and northwestern parts of its range and is therefore listed as highly endangered for Germany and the federal state of Hesse. Whether chytridiomycosis may play a role in the observed local declines of this strictly protected anuran species has never been tested. We investigated 19 Hessian yellowbellied toad populations for Bd infection rates, conducted capture-mark-recapture studies in 4 of them over 2 to 3 yr, examined survival histories of recaptured infected individuals, and tested whether multi-locus heterozygosity of individuals as well as expected heterozygosity and different environmental variables of populations affect probabilities of Bd infection. Our results show high prevalence of Bd infection in Hessian yellow-bellied toad populations, but although significant decreases in 2 populations could be observed, no causative link to Bd as the reason for this can be established. Mass mortalities or obvious signs of disease in individuals were not observed. Conversely, we show that growth of Bd-infected populations is possible under favorable habitat conditions and that most infected individuals could be recaptured with improved body indices. Neither genetic diversity nor environmental variables appeared to affect Bd infection probabilities. Hence, genetically diverse amphibian specimens and populations may not automatically be less susceptible for Bd infection.

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Section: Discussionsupporting

confidence: 84%

Section: Discussionsupporting

confidence: 80%

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

No evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads

Wagner

Neubeck²,

Guicking³

et al. 2017

Dis. Aquat. Org.

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“…Further mechanisms for coexistence may operate at the population level, such that even observable negative effects of Bd on the individual host do not automatically translate to negative effects at the population level [4,43]. In our case, both populations appeared relatively stable over the study period.…”

Section: (B) Population-level Patternsmentioning

confidence: 58%

Fragile coexistence of a global chytrid pathogen with amphibian populations is mediated by environment and demography

et al. 2017

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Unravelling the multiple interacting drivers of host-pathogen coexistence is crucial in understanding how an apparently stable state of endemism may shift towards an epidemic and lead to biodiversity loss. Here, we investigate the apparent coexistence of the global amphibian pathogen Batrachochytrium dendrobatidis (Bd) with Bombina variegata populations in The Netherlands over a 7-year period. We used a multi-season mark-recapture dataset and assessed potential drivers of coexistence (individual condition, environmental mediation and demographic compensation) at the individual and population levels. We show that even in a situation with a clear cost incurred by endemic Bd, population sizes remain largely stable. Current environmental conditions and an over-dispersed pathogen load probably stabilize disease dynamics, but as higher temperatures increase infection probability, changing environmental conditions, for example a climate-change-driven rise in temperature, could unbalance the current fragile host-pathogen equilibrium. Understanding the proximate mechanisms of such environmental mediation and of site-specific differences in infection dynamics can provide vital information for mitigation actions.

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“…In other species with enzootic infections, the absence of negative effects of Bd in population growth rates, survival, and recruitment may indicate the evolution of tolerance (Muths et al, 2011;Tobler et al, 2012). However, this is not the case for E. coqui because populations are still declining, Bd infection hinders frog survival and juveniles are more susceptible than adults .…”

mentioning

confidence: 99%

Lability in Host Defenses: Terrestrial Frogs Die from Chytridiomycosis under Enzootic Conditions

Longo

Ossiboff

Zamudio

et al. 2013

Journal of Wildlife Diseases

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ABSTRACT:Chytridiomycosis-induced mortalities often occur upon the emergence of Batrachochytrium dendrobatidis (Bd) in naïve amphibian populations. We report chytridiomycosis-associated mortalities in the wild of the coqui (Eleutherodactylus coqui), a declining direct-developing frog with persistent Bd infections. These findings provide additional evidence of decreased host defenses during cool-dry seasons in Puerto Rico.

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Populations of a Susceptible Amphibian Species Can Grow despite the Presence of a Pathogenic Chytrid Fungus

Cited by 61 publications

References 52 publications

No evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads

No evidence for effects of infection with the amphibian chytrid fungus on populations of yellow-bellied toads

Fragile coexistence of a global chytrid pathogen with amphibian populations is mediated by environment and demography

Lability in Host Defenses: Terrestrial Frogs Die from Chytridiomycosis under Enzootic Conditions

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