A novel laboratory activity for teaching about the evolution of multicellularity

The evolution of complexity remains one of the most challenging topics in biology to teach effectively. We present a novel laboratory activity, modeled on a recent experimental breakthrough, in which students experimentally evolve simple multicellularity using single-celled yeast (Saccharomyces cerevisiae). By simply selecting for faster settling through liquid media, yeast evolve to form snowflakeshaped multicelled clusters that continue to evolve as multicellular individuals. We present core experimental and curriculum tools, including discussion topics and assessment instruments, and provide suggestions for teacher customization. Prelab and postlab assessments demonstrate that this lab effectively teaches fundamental concepts about the transition to multicellularity. Yeast strains, the student lab manual, and an introductory presentation are available free of charge.