Persistence with Chytridiomycosis Does Not Assure Survival of Direct-developing Frogs

Longo, Ana V.; Burrowes, Patricia A.

doi:10.1007/s10393-010-0327-9

Cited by 65 publications

(61 citation statements)

References 34 publications

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“…Studies on some amphibian-Bd systems have reported similar results: surveyors have observed chytridiomycosis-induced mortality in the field but subsequent CMR studies have found no evidence that Bd infection reduced frog survival (Retallick et al 2004;Voordouw et al 2010). In contrast, studies on other species have found the expected negative effects of Bd infection on frog survival (Murray et al 2009;Longo and Burrowes 2010;Pilliod et al 2010). The lack of a negative effect of Bd on the populationlevel survival of L. rheocola seems paradoxical because some individual frogs are killed by chytridiomycosis at lowland sites in the Wet Tropics (Woodhams and Alford 2005;Phillott et al 2013).…”

Section: Survival Ratementioning

confidence: 65%

“…For example, populations of the Australian hylid frog Litoria wilcoxii have a high prevalence of Bd but infection has no negative effect on adult survival in this species (Kriger and Hero 2006). In other species, however, survival of infected individuals can be lower than uninfected individuals (Murray et al 2009;Longo and Burrowes 2010;Pilliod et al 2010). Thus, the effects of infection by Bd are species-specific, and there are some species in which the host-pathogen relationship has apparently changed.…”

Section: Electronic Supplementary Materialsmentioning

confidence: 91%

“…We had an a priori expectation that season, population or site type, and possibly their interactions, would influence the survival and recapture rates, as previous work on other frog populations has demonstrated such effects (Longo and Burrowes 2010;Sapsford et al 2013). We also wanted to test whether Bd infection influenced the survival and recapture rates of L. rheocola, as it can in other species (e.g.…”

Section: Multi-state Capture-mark-recapture Statistical Analysismentioning

confidence: 98%

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Infection dynamics in frog populations with different histories of decline caused by a deadly disease

et al. 2015

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Pathogens can drive host population dynamics. Chytridiomycosis is a fungal disease of amphibians that is caused by the fungus Batrachochytrium dendrobatidis (Bd). This pathogen has caused declines and extinctions in some host species whereas other host species coexist with Bd without suffering declines. In the early 1990s, Bd extirpated populations of the endangered common mistfrog, Litoria rheocola, at high-elevation sites, while populations of the species persisted at low-elevation sites. Today, populations have reappeared at many high-elevation sites where they presently co-exist with the fungus. We conducted a capture-mark-recapture (CMR) study of six populations of L. rheocola over 1 year, at high and low elevations. We used multistate CMR models to determine which factors (Bd infection status, site type, and season) influenced rates of frog survival, recapture, infection, and recovery from infection. We observed Bd-induced mortality of individual frogs, but did not find any significant effect of Bd infection on the survival rate of L. rheocola at the population level. Survival and recapture rates depended on site type and season. Infection rate was highest in winter when temperatures were favourable for pathogen growth, and differed among site types. The recovery rate was high (75.7-85.8%) across seasons, and did not differ among site types. The coexistence of L. rheocola with Bd suggests that (1) frog populations are becoming resistant to the fungus, (2) Bd may have evolved lower virulence, or (3) current environmental conditions may be inhibiting outbreaks of the fatal disease.

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Section: Survival Ratementioning

confidence: 65%

Section: Electronic Supplementary Materialsmentioning

confidence: 91%

Section: Multi-state Capture-mark-recapture Statistical Analysismentioning

confidence: 98%

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Infection dynamics in frog populations with different histories of decline caused by a deadly disease

et al. 2015

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“…The infection was associated with juveniles; juveniles had higher prevalence than adults, and populations with Bd had more juveniles than other populations. Several hypotheses might explain this association between population structure and presence of Bd infection: densitydependence (Briggs et al 2010), greater in fectivity of juveniles (Kriger et al 2007, Longo & Burrowes 2010, or pathogen-induced change of behavior making juveniles stay near water rather than dispersing into the terrestrial habitat. Most juveniles were not infected, so the latter is a less likely explanation.…”

Section: Discussionmentioning

confidence: 99%

Presence of the chytrid fungus Batrachochytrium dendrobatidis in a Vulnerable frog in Trinidad, West Indies

Alemu¹,

Cazabon-Mannette²,

Cunningham³

et al. 2013

Endang. Species. Res.

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Amphibian chytridiomycosis occurs on a small proportion of West Indian islands, but the entire Caribbean region, including Trinidad, offers a suitable environment for the infection. We report the presence of the causative agent Batrachochytrium dendrobatidis (Bd) in 2 out of 12 populations sampled of the Vulnerable Trinidad stream frog, Mannophryne trinitatis. We analyzed 184 skin swabs collected from wild frogs using real-time PCR analysis. Follow-up sampling determined a prevalence of Bd infection of 3 and 23% in these 2 populations. We did not find any evidence of associated clinical disease. Bd-positive populations were located at the highest elevations studied (425 to 450 m). These 2 populations had more juveniles than other populations, and juveniles were more likely to be infected than adults. Our results suggest that sampling juveniles may provide the greatest sensitivity for any future monitoring for the presence of Bd in M. trinitatis populations in Trinidad.

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“…Of course, a range of responses to infection occurs within species as well, with differences in susceptibility arising between individuals and populations. This may be driven by body condition (Beldomenico & Begon 2010;Ramsey et al 2010), age or life stage (Longo & Burrowes 2010), and the capacity of the host to thermally acclimate relative to the pathogen , or behaviourally thermoregulate (Richards-Zawacki 2010), in given environmental conditions. In addition, body size is thought to influence susceptibility within species, with smaller animals succumbing to Bd infection faster (Carey et al 2006;).…”

Section: Variation In Susceptibility To Chytridiomycosismentioning

confidence: 99%

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

Ohmer¹

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Worldwide, there has been an unprecedented rise in emerging infectious diseases of wildlife, and this has contributed to a widespread biodiversity crisis. Amphibian populations, in particular, are threatened by the fungal pathogen Batrachochytrium dendrobatidis (Bd), which in post-metamorphic animals only infects the skin, and causes the potentially lethal disease chytridiomycosis. Amphibians regularly slough their skin, and in doing so remove many skinassociated microbes. Thus, skin sloughing may play an important role in the pathogenesis of chytridiomycosis. To investigate this association, the influence of Bd infection on amphibian skin sloughing, and the role of sloughing in regulating infection, was examined. Furthermore, to better understand the variation in skin sloughing rates across species and ecological groups, and make inferences about the role of this process in susceptibility to this fungal disease, amphibian skin structure and function was investigated within a phylogenetic context. To determine the relationship between skin sloughing and disease progression (chapter 2), adult green tree frogs (Litoria caerulea) were exposed to an Australian Bd strain, and sloughing rates and infection load were monitored on a naturalistic cycling temperature regime (15 -23˚C).Sloughing rates were determined by filming frogs and infection intensity was monitored before and after sloughing with conventional swabbing and quantitative PCR. Sloughing rate was found to increase with Bd infection load in infected frogs, but sloughing itself did not affect Bd load on the ventral skin surface. Although a faster sloughing rate might be considered advantageous for Bdinfected animals, it does not appear to curb the progression of disease in susceptible species. In fact, sloughing may actually contribute to the loss of physiological homeostasis seen in terminally ill frogs by further inhibiting water and electrolyte transport across the skin.In some species less susceptible to chytridiomycosis, it has been demonstrated that Bd growth remains epibiotic, without penetrating the underlying epidermal layers. Therefore, sloughing may more effectively remove Bd zoospores in less susceptible species (chapter 3). To test this hypothesis, five Australian frog species, Lit. caerulea, Platyplectrum ornatum, Lechriodus fletcheri, Limnodynastes peronii, and Lim. tasmaniensis, were exposed to an Australian Bd strain, and their sloughing rates and infection loads monitored over time. Utilising an improved methodology to remove any artefacts from the swabbing itself, sloughing was found to reduce Bd load on the ventral skin surface, in all five species, despite wide ranging variation in susceptibility to Bd infection and subsequent disease. In less susceptible species, sloughing reduced Bd load up to 100%, leading to infection clearance. However, the drop in Bd load was only temporary in susceptible species, potentially due to the invasive growth of Bd in skin layers underlying the ii stratum corneum in these species. If less suscept...

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Persistence with Chytridiomycosis Does Not Assure Survival of Direct-developing Frogs

Cited by 65 publications

References 34 publications

Infection dynamics in frog populations with different histories of decline caused by a deadly disease

Infection dynamics in frog populations with different histories of decline caused by a deadly disease

Presence of the chytrid fungus Batrachochytrium dendrobatidis in a Vulnerable frog in Trinidad, West Indies

Interactions between amphibian skin sloughing and a cutaneous fungal disease: infection progression, immune defence, and phylogenetic patterns

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