"The causes of global decline of amphibian population is still unclear, however it is apparent that this animal group is susceptible to opportunistic infections. Two important infectious agents have been identified: a fungus and a virus, both of which are responsible for mass mortalities. However, since 2003, new mass mortality events have been recorded through out the USA and have been attributed to infection by a protist of the Superphylum Alveolata. This parasite preferentially infects liver tissue leading to the presence of hundred of thousand small spherical cells. In parallel, environmental sequencing of freshwater environments targeting the smallest size of eukaryotic plankton has revealed that this group of protists is globally distributed and has a free-living stage. We have performed a pilot test on 28 tadpoles specimens from the collection of the Natural History Museum of London (UK) in order to confirm the association between the protist and frogs and found three positive cases in distantly related frog taxa. We therefore hypothesise that this protist group represents a global threat to frogs and has a complex lifecycle involving both infectious and freeliving phases and has acquired cellular phenotypes and molecular innovations associated with host infection. Using a combination of molecular pathology of global tadpole samples, microscopy with cell biological staining, and comparative transcriptomics this project will identify the geographic and taxonomic prevalence of this pathogen and how and by what molecular mechanism it infects tadpole cells. As such the project will underpin advanced training in: collection management, histology, immuno-microscopy, comparative genomics and microbial parasitology of animal hosts. This project will provide information important for understanding the diversity of microbial eukaryotic forms, evolution of parasitic mechanisms and understanding disease threats to frogs in order to assists conservation planning."