Epidemiological landscape of Batrachochytrium dendrobatidis and its
impact on amphibian diversity at global scale
Abstract
Chytridiomycosis caused by the fungal pathogen Batrachochytrium
dendrobatidis (Bd) is a major driver of amphibian decline worldwide. The
global presence of Bd is driven by a synergy of factors, such as
climate, species life history, and amphibian host susceptibility. Here,
using a Bayesian data-mining approach, we modelled the epidemiological
landscape of Bd to evaluate how the infection varies across several
spatial, ecological, and phylogenetic scales. We compiled global
information on Bd occurrence, climate, species ranges, and phylogenetic
diversity to infer the potential distribution and prevalence of Bd. By
calculating the degree of co-distribution between Bd and our set of
environmental and biological variables (e.g., climate and species), we
identified which factors could potentially be related to Bd presence and
prevalence using a geographic correlation metric, epsilon (ε). We fitted
five ecological models based on: i) amphibian species identity, ii)
phylogenetic species variability values for a given species assemblage,
iii) temperature, iv) precipitation, and v) all variables together. Our
results extend the findings of previous studies by identifying the
epidemiological landscape features of the presence of Bd. This
ecological modelling framework allowed us to generate explicit spatial
predictions for Bd prevalence at global scale and a ranked list of
species with high/low probability of Bd presence. Our geographic model
was able to identify areas with high potential for Bd prevalence as
potential risk areas and areas with low potential Bd prevalence as
potential refuges (free Bd). At the amphibian assemblage level, we found
a non-relationship with amphibian phylogenetic signals, but a
significantly negative correlation between observed species richness and
Bd prevalence indicated a potential dilution effect at the landscape
scale. Our model may identify potential susceptible species and areas at
risk of Bd presence which could be used to prioritize regions for
amphibian conservation efforts and assess species and assemblage risk