Paternal care as a source of key skin microbiota in a poison frog

Parental care is a well-established mechanism for the vertical transfer of gut microbiota, yet its role in shaping offspring skin microbial communities remains largely unexplored. Using a cross-fostering experiment in a Neotropical poison frog, we demonstrate that paternal tadpole transport is a critical vector for the transmission of skin microbiota. Tadpoles transported by both biological and foster fathers acquired microbial communities that persisted through metamorphosis, maintaining a stable membership despite shifts in relative abundance. Notably, the paternal contribution included multiple bacterial genera known to inhibit the lethal pathogen Batrachochytrium dendrobatidis (Bd). In contrast, tadpoles deprived of paternal transport and manually transferred to water bodies exhibited depauperate communities with a significantly lower prevalence of these protective bacteria. Our findings reveal that parental care is a multifaceted behaviour that not only ensures offspring survival but also actively provisions them with a tailored, protective skin microbiome, highlighting a novel mechanism by which parental care influences offspring fitness and resilience to disease.