Bioclimatic and anthropogenic variables shape the occurrence of Batrachochytrium dendrobatidis over a large latitudinal gradient

<jats:title>Abstract</jats:title><jats:p>Amphibian chytridiomycosis, caused by the fungus <jats:italic>Batrachochytrium dendrobatidis</jats:italic> (<jats:italic>Bd</jats:italic>), has caused the greatest known loss of biodiversity due to an infectious disease. We used <jats:italic>Bd</jats:italic> infection data from quantitative real-time PCR (qPCR) assays of amphibian skin swabs collected across Chile during 2008–2018 to model <jats:italic>Bd</jats:italic> occurrence with the aim to determine bioclimatic and anthropogenic variables associated with <jats:italic>Bd</jats:italic> infection. Also, we used <jats:italic>Bd</jats:italic> presence/absence records to identify geographical <jats:italic>Bd</jats:italic> high-risk areas and compare <jats:italic>Bd</jats:italic> prevalence and infection loads between amphibian families, ecoregions, and host ecology. Data comprised 4155 <jats:italic>Bd</jats:italic>-specific qPCR assays from 162 locations across a latitudinal gradient of 3700 km (18º to 51ºS). Results showed a significant clustering of <jats:italic>Bd</jats:italic> associated with urban centres and anthropogenically highly disturbed ecosystems in central-south Chile. Both <jats:italic>Bd</jats:italic> prevalence and <jats:italic>Bd</jats:italic> infection loads were higher in aquatic than terrestrial amphibian species. Our model indicated positive associations of <jats:italic>Bd</jats:italic> prevalence with altitude, temperature, precipitation and human-modified landscapes. Also, we found that macroscale drivers, such as land use change and climate, shape the occurrence of <jats:italic>Bd</jats:italic> at the landscape level. Our study provides with new evidence that can improve the effectiveness of strategies to mitigate biodiversity loss due to amphibian chytridiomycosis.</jats:p>