After the epidemic: Ongoing declines, stabilizations and recoveries in amphibians afflicted by chytridiomycosis

Scheele, Ben C.; Skerratt, Lee F.; Grogan, Laura F.; Hunter, David; Clemann, Nick; McFadden, Michael; Newell, David; Hoskin, Conrad J.; Gillespie, Graeme R.; Heard, Geoffrey W.; Brannelly, Laura A.; Roberts, A. W.; Berger, Lee

doi:10.1016/j.biocon.2016.12.010

Cited by 107 publications

(105 citation statements)

References 87 publications

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“…Our results also indicate that suitability for Bd decreases with elevation, which is opposite to what other authors have found regarding the best conditions for Bd growth (Woodhams and Alford , Scheele et al. ). Nevertheless, the high altitude areas where suitability is indeed very low (Andes mountains in blue in Fig.…”

Section: Discussioncontrasting

confidence: 99%

The amphibian‐killing fungus in a biodiversity hotspot: identifying and validating high‐risk areas and refugia

et al. 2019

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Amphibian chytridiomycosis, due to infection with the fungus Batrachochytrium dendrobatidis (Bd), has been associated with the alarming decline and extinction crisis of amphibians worldwide. It is essential for conservation management to identify regions with high or low suitability for Bd. We use a species distribution model to estimate the environmental suitability of Bd in the Chilean Winter Rainfall–Valdivian Forest biodiversity hotspot. Fourteen environmental variables were used as predictors in the statistical modeling (Maxent, generalized linear models, random forest) which also included 56 independent Bd+ localities. High‐risk areas (i.e., suitability above a defined threshold) were validated through prospective field surveys conducted in 2017. As results from Maxent, which only uses presence data, were the only results retained, refugia (i.e., suitability below a defined threshold) were validated with the Bd absences (N = 12) used in the GLM and RF modeling. Our results showed that (1) suitability for Bd increased with human footprint and with shorter distances to urban centers and water bodies and decreased with elevation; (2) climate was not a major factor shaping the current distribution of Bd; and (3) the model predicted high‐risk and refugia areas fairly well. Surveys of 24 new localities in high‐risk areas confirmed that 23 were Bd+; hence, these areas warrant consideration for long‐term Bd surveillance, population monitoring, and disease mitigation. In addition, five localities with apparent Bd absence were found in the predicted high‐risk areas. Our models showed that refugia can exist near high‐risk areas and Bd+ sites. Four localities with apparent Bd absence were located within the refugia predicted by the model. Preventing Bd transmission to such refugia is of paramount importance for persistence of Bd‐susceptible amphibian populations. The identification and validation through prospective field surveys of high‐risk areas and refugia are imperative to develop strategies to prevent further arrival and establishment of Bd and also, by identifying amphibian species or populations of conservation concern in such areas, will help to guide specific actions to reduce the biodiversity loss caused by chytridiomycosis.

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Section: Discussioncontrasting

confidence: 99%

The amphibian‐killing fungus in a biodiversity hotspot: identifying and validating high‐risk areas and refugia

et al. 2019

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“…Both species are threatened, and the Southern Corroboree Frog is critically endangered. For 40 years, Southern Corroboree Frogs have experienced a catastrophic population decline due, primarily, to living in sympatry with a chytridiomycosis reservoir species ( Crinia signifera ; Hunter, Marantelli, et al, ; Hunter, Speare, et al, ; Scheele et al, ). Southern Corroboree Frogs are now functionally extinct (Brannelly, Roberts, Skerratt, & Berger, ).…”

Section: Introductionmentioning

confidence: 99%

Educating the enemy: Harnessing learned avoidance behavior in wild predators to increase survival of reintroduced southern corroboree frogs

Umbers

Riley

Kelly

et al. 2019

Conservat Sci and Prac

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After decades of near‐complete extirpation, the yellow‐and‐black‐striped Southern Corroboree Frog (Pseudophryne corroboree) is being reintroduced into field enclosures that exclude all but avian predators. The frog's long absence means avian attack risk to reintroduced individuals is unknown, so we asked: does corroboree frog coloration make them vulnerable to predators? First, using painted clay frog models and humans as proxy predators, we found that, surprisingly, striped models were as difficult to detect as control black models, and were far less detectable than yellow models. Second, to quantify attack probabilities, we deployed 2,304 models twice in the species' former range. Of our recovered models, 18% of the striped models were attacked by birds, suggesting they are a significant threat. In our second deployment, we saw a significant reduction in attacks on all model colors with only 10% of striped models attacked. If predators generalize their avoidance learning to real corroboree frogs, strategically timed model deployment near release sites may enhance the probability of survival of reintroduced frogs. Our study suggests that model deployment could be an effective low‐cost technique to increase the survival of reintroduced prey species, including, but not limited to, those potentially conspicuous to their natural enemies.

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“…, Scheele et al. ). Hotter temperatures are less optimal for chytrid: temperatures above 26°C significantly slow growth, with a lethal thermal maximum at 28–29°C for Queensland‐derived chytrid (Stevenson et al.…”

Section: Methodsmentioning

confidence: 98%

“…, Scheele et al. ), and it is likely that in the future they will continue to recolonize up the elevation gradient. However, we could not build this into the models due to a lack of data on the rate or potential ultimate extent of this recolonization.…”

Section: Methodsmentioning

confidence: 99%

“…Disease.-Chytridiomycosis disease, caused by the "chytrid" fungus (Batrachochytrium dendrobatidis), has caused large losses to the populations of some frog species within the study area, so that they no longer occur in parts of their former ranges (Puschendorf et al 2011). Chytrid is present throughout the Wet Tropics but only impacts populations of susceptible species in cooler mid and upland rainforest (Puschendorf et al 2011, Scheele et al 2017. Hotter temperatures are less optimal for chytrid: temperatures above 26°C significantly slow growth, with a lethal thermal maximum at 28-29°C for Queensland-derived chytrid (Stevenson et al 2013).…”

Section: Post-workhop Model Refiningmentioning

confidence: 99%

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Beyond the model: expert knowledge improves predictions of species’ fates under climate change

Reside

Critchell

Crayn

et al. 2018

Ecological Applications

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The need to proactively manage landscapes and species to aid their adaptation to climate change is widely acknowledged. Current approaches to prioritizing investment in species conservation generally rely on correlative models, which predict the likely fate of species under different climate change scenarios. Yet, while model statistics can be improved by refining modeling techniques, gaps remain in understanding the relationship between model performance and ecological reality. To investigate this, we compared standard correlative species distribution models to highly accurate, fine‐scale, distribution models. We critically assessed the ecological realism of each species’ model, using expert knowledge of the geography and habitat in the study area and the biology of the study species. Using interactive software and an iterative vetting with experts, we identified seven general principles that explain why the distribution modeling under‐ or overestimated habitat suitability, under both current and predicted future climates. Importantly, we found that, while temperature estimates can be dramatically improved through better climate downscaling, many models still inaccurately reflected moisture availability. Furthermore, the correlative models did not account for biotic factors, such as disease or competitor species, and were unable to account for the likely presence of micro refugia. Under‐performing current models resulted in widely divergent future projections of species’ distributions. Expert vetting identified regions that were likely to contain micro refugia, even where the fine‐scale future projections of species distributions predicted population losses. Based on the results, we identify four priority conservation actions required for more effective climate change adaptation responses. This approach to improving the ecological realism of correlative models to understand climate change impacts on species can be applied broadly to improve the evidence base underpinning management responses.

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After the epidemic: Ongoing declines, stabilizations and recoveries in amphibians afflicted by chytridiomycosis

Cited by 107 publications

References 87 publications

The amphibian‐killing fungus in a biodiversity hotspot: identifying and validating high‐risk areas and refugia

The amphibian‐killing fungus in a biodiversity hotspot: identifying and validating high‐risk areas and refugia

Educating the enemy: Harnessing learned avoidance behavior in wild predators to increase survival of reintroduced southern corroboree frogs

Beyond the model: expert knowledge improves predictions of species’ fates under climate change

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