Climatic and anthropogenic factors structuring the occurrence of Batrachochytrium dendrobatidis infection: 10 years of chytrid research in Chile
Mario Alvarado-RybakMuseo del Jade
Mario Alvardo-Rybak, Manuel Lepe, Alexandra Peñafiel-Ricaurte, Andrés Valenzuela, Fernando O. Mardones, Leonardo D. Bacigalupe, Andrew Cunningham, Claudio Soto-Azat
Chytridiomycosis, due to the fungus Batrachochytrium dendrobatidis (Bd), has been associated with the alarming decline and extinction of amphibians worldwide. This fungus infects all amphibian orders: Anura, Urodela and Gymnophiona, in which many species may develop lethal disease. In this context, by analysing Bd prevalence and geographic spread at a regional scale, it is possible to identify risk factors for Bd occurrence. Here, we used real-time quantitative PCR (qPCR) to detect Bd on anurans along a 4,000 km latitudinal gradient in Chile Chilean biodiversity hotspot and based on presence/absence data we performed spatial scan analyses and modelling to detect high-risk spatial areas and risk factors. We analysed information of 4,155 Bd-qPCR analyses from 162 study sites across Chile obtained from 2008 to 2018 to identify low and high-risk areas for Bd in Chile. Overall, Bd was found from 24 out of 40 species captured from 97 sites in Chile with an estimated prevalence of 19.1%. Also, results show significant clustering of Bd with the identification of a few local clusters aggregated in the central and south areas (i.e., Chilean Matorral and Valdivian temperate forest ecoregions) and with some clusters overlapping with the distribution of the invasive amphibian Xenopus laevis. Moreover, we found that risk factors such as annual mean temperature, annual precipitation, landcover and anthropogenic biomes explain the prevalence distribution. These relationship is not straightforward and will likely to be further complicated by a changing climate scenario. More importantly, this study provides information to assess the role of X.laevis in the epidemiology of Bd, to identify risk factors (e.g., anthropogenic variables) for Bd infection and the potential impacts of this pathogen on native amphibian populations decline. Identifying the factors structuring Bd occurrence and impacts inform adequate conservation management, with the ultimate goal of halting the biodiversity loss caused by chytridiomycosis.