Metamorphosis and seasonality are major determinants of chytrid infection in a paedomorphic salamander

Abstract

Chytridiomycosis, an emerging disease caused mostly by the pathogen Batrachochytrium dendrobatidis, has caused massive amphibian population declines and extinctions worldwide. The ecology of this disease is mainly explained by the interaction of environmental factors, pathogen biology, and host traits including development. For paedomorphic salamanders, differences in B. dendrobatidis infection may be explained by metamorphosis and water physicochemical conditions. In this study, we aimed to determine the influence of environmental and host factors on B. dendrobatidis prevalence and infection intensity in the facultative paedomorphic salamander Ambystoma altamirani. We determined B. dendrobatidis prevalence and infection load in four populations of A. altamirani along 1 year (four seasons) and assessed their relationship with environmental factors and host metamorphic status (gilled or non-gilled). We found that B. dendrobatidis prevalence and infection load are largely explained by metamorphic status and environmental factors such as elevation, seasonality, water temperature, pH, conductivity, and dissolved oxygen. To our knowledge, this is the first study to empirically show the effect of metamorphosis on B. dendrobatidis infection status across locations and seasons. This information may be used to understand the temporal dynamics of B. dendrobatidis–host interactions and to identify potential disease outbreaks that may cause cryptic sublethal effects on salamander populations. Our results will help in the development of conservation strategies for paedomorphic salamanders that are already considered threatened by anthropogenic factors such as habitat loss and climate change.