Animals were animals, plants were plants, and microbes…they were something entirely unrelated to the biology, ecology, and evolution of Eukaryotes. Their point of intersection was when some pesty, ill-advised microbe caused disease in an animal, plant, or even us. That was the overwhelming view on host-microbe interactions for centuries: microbes are pathogenic when they are present. This view changed drastically not long ago, when we began using novel technologies and a phylogenetic marker gene to profile the microbial communities that associated with eukaryotic hosts. What was found was stagging: a new principle of life on Earth; eukaryotes live in harmony with diverse communities of microbial symbionts and that these partnerships change in predictable ways. This course walks through how each field within the life science intersects with host-microbe symbiosis and go branch to branch along the tree-of-life to explore the dominant types of symbioses at an ecological as well as molecular level. This course will partially be flipped to allow you—the student—to co-lead a topic within symbiosis that you are either curious or passionate about. This is a special topic course that is currently being offered at the University of North Carolina at Charlotte.

This practial course--informally called Where is Susy the symbiont?--focuses on determining factors that underly variation in the abundance of the primary symbiont of the breadcrumb sponge Halichondria panicea. Students will lead a series of collections that aim to outline the primary 'rules' of host-microbe symbiosis. Specifically, they will determine the specificity of the symbiont to H. panicea, assess variation between individuals, determine whether captivity affects symbiont abundance, and quantify how the environment impacts symbiont abundance. Students will design experiments, perform collections, extract and amplify DNA, estimate symbiont abundance, and perform statistical analyses to test their hypotheses. This course was taught at the GEOMAR Helmholtz Centre for Ocean Research (Kiel, Germany) in Spring 2022 with Ute Hentschel and Sabrina Jung.

The