Evolution and development of budding by stem cells: Ascidian coloniality as a case study

► We review the evolution of budding and coloniality in ascidians. ► We compare somatic and germline stem cells in solitary and colonial ascidians. ► We discuss how ascidians evolved different ways of budding, which are derived from different stem cell progenitors. ► We suggest that brooding may have allowed plasticity in stem cell lineage determination. ► We propose heterochrony and plasticity of stem cell lineages as means to evolve budding.