Host-associated microbes can interact with macro-organisms in a number of ways that affect host health. Few studies of host-associated microbiomes, however, focus on fungi. This is partly because it is difficult to discern whether a fungal organism found in or on a host is associating in a durable, symbiotic interaction versus a transient one. We seek to define these interactions on an amphibian, the Colorado boreal toad (Anaxyrus boreas boreas), across its physiologically dynamic development. We asked: (1) how does the fungal community vary across the different life stages of the host, and (2) which fungal OTU’s are putatively symbiotically associated with toad skin, as opposed to transiently so? We sequenced the ITS1 region of the fungal community on the skin of wild toads (n=124) from four sites in the Colorado Rocky Mountains. We also sampled the common habitats used by boreal toads: water from their natal wetland, aquatic pond sediment, and upland soil surrounding the wetland. We then identified fungal taxa that could be putative symbionts of this host using an indicator species analysis on toad versus environmental samples.
Results/Conclusions
We identified seven fungal taxa that were indicators of toad skin, which were interpreted as putative symbionts. This approach leverages sequence data from host and habitat samples to predict which microbial taxa are potentially symbionts versus transient microbes, condensing a large sequence dataset to a smaller list of targets for future experimental investigation. The approach addresses the challenges associated with using microbiome data from wildlife to study host-symbiont interactions.