The influence of the chytrid fungus on the vocalization of Dendropsophus minutus

The vocal repertoire of anurans can be categorised according to the social context, especially during the reproductive season, when acoustic communication is fundamental. It is known that some factors can influence these calling variations, such as the chytrid fungus, Batrachochytrium dendrobatidis (Bd), as studies show that some anurans infected with Bd have differences in calls when compared to healthy males. This study is focused on Dendropsophus minutus, a small treefrog whose reproductive cycle takes place during rainy seasons. It is possible that infection by Bd can affect their reproductive success, by affecting the vocalisation of males. Previously recorded call data and analyses, as well as skin swabs and qPCR experiments from D. minutus, were compiled to test the relationship between calling variables and Bd infection. We found no difference between infected and uninfected male’s calls. However, among infected individuals, Bd load was positively correlated to the number of notes and call duration. In this study, we propose that two hypotheses may explain the observed patterns: the terminal investment hypothesis and the Hamilton–Zuk hypothesis. The terminal investment hypothesis suggests that individuals with poor health may increase their current calling effort as a last attempt to reproduce. On the other hand, the Hamilton–Zuk hypothesis takes into account that D. minutus is resistant to the infection, and those with higher Bd loads may display enhanced call performance, as more intense vocalisations suggests that these individuals possess traits associated with Bd resistance. With these results, we advocate for further investigations on how Bd impacts the mating behaviour and female preferences of D. minutus, and how the infection alters their reproductive success.