We present FloTree, a multi-user simulation that illustrates key dynamic processes underlying evolutionary change. Our intention is to create a informal learning environment that links micro-level evolutionary processes to macro-level outcomes of speciation and biodiversity. On a multi-touch table, the simulation represents change from generation to generation in a population of organisms. By placing hands or arms on the surface, visitors can add environmental barriers, thus interrupting the genetic flow between the separated populations. This results in sub-populations that accumulate genetic differences independently over time, sometimes leading to the formation of new species. Learners can morph the result of the simulation into a corresponding phylogenetic tree. The free-form hand and body touch gestures invite creative input from users, encourages social interaction, and provides an opportunity for deep engagement.