Symbiotic interactions are fundamental to life as we know it, and range across a spectrum from parasitism to mutualism. Animals rely on microbes for nutrient acquisition, immune system regulation and protection, while microbial parasites challenge fitness. The line between who is a mutualist and who is a parasite may depend on small variations in the environment, such as resources and the presence of additional symbionts. Technological advances, in e.g. sequencing and imaging, facilitates the study of symbioses at an increasingly finer scale. This allows for answering key questions in the animal-microbe symbioses field – the who’s who of interacting partners, which resources and services are being exchanged within an interaction network, and at what cost. Naturally these insights open up new research avenues.

Areas: biology, microbiology, ecology, medicine, chemistry, animal-microbe symbioses.