Community-Wide Genotyping of Batrachochytrium dendrobatidis in Ecuadorian Forests

Abstract

The amphibian chytrid fungus Batrachochytrium dendrobatidis (Bd) is a cosmopolitan pathogen with numerous distinct lineages. The global panzootic lineage (Bd-GPL) is the most widespread and virulent lineage and is responsible for many recorded amphibian declines. Mapping the extent of Bd-GPL and other more established lineages is important for predicting disease dynamics in amphibian communities. Ecuador is the most biodiverse country per unit area for amphibian taxa and, thus, a priority for studies on genotypic diversity of Bd. In this study, we tested skin swab samples collected from 464 individual amphibians across coastal, Andean montane, and Amazonian forests, for the presence of two Bd lineages known to be present in South America: the globally-distributed Bd-GPL and the Brazilian-endemic Bd-Asia2/Brazil lineage. By using a discriminatory qPCR SNP assay, we found widespread prevalence of Bd-GPL in Ecuador in diverse host taxa. Genotyping efficiency was 36% in this study, meaning that one in every three swabs that tested positive for Bd in infection assays were successfully genotyped. Through this study, we provide further support for the presence of a single Bd lineage in this neotropical biodiversity hotspot.