Supplementary data from 'Predicting the distribution of Australian frogs and their overlap with Batrachochytrium dendrobatidis under climate change'

Aim: Amphibians, with over 40% of assessed species listed as threatened,
are disproportionately at risk in the global extinction crisis. Among the
many factors implicated in the current and ongoing loss of
amphibian biodiversity are climate change and the disease
chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis
(Bd). These two threats are of particular concern in Australia, where Bd
has been implicated in the declines of at least 43 frog species, and
climate change is emerging as an additional threat. Here, we explore how
climate change is likely to affect the distributions of Australian frog
species and Bd to the year 2100, as well as how the spatial and climatic
niche overlap between chytridiomycosis-declined frogs and Bd could shift.
Location: Australia Methods: We used species distribution modelling to
infer the current and future distribution of 141 Australian frog species
and Bd, under two emissions scenarios. We used metrics of niche
similarity, including Schoener’s D and the Niche Margin Index, to quantify
predicted alterations to spatial interactions between Bd and frog species.
Results: Climate change is likely to have a variable impact on frog
distributions in Australia, with some 23 and 47 species, primarily in
southern Australia, predicted to lose at least 30% of their current
distributions under low and high emissions scenarios, respectively. In
contrast, 69 and 68 species, respectively, have potential to increase
their distributions, primarily in northern Australia. While the
distribution of Bd is predicted to decrease, the proportional spatial and
niche overlap between Bd and susceptible frog species is predicted to
remain little changed, and in some cases, to increase. Main
conclusions: Although effects will be variable across the continent,
climate change is likely to be a threatening factor to a number of
Australian frog species. Additionally, chytridiomycosis is likely to
remain a significant threat to many frog species, as any reductions to the
pathogen’s distribution largely coincide with geographic range
contractions of chytridiomycosis-susceptible species.