In a new paper in Trends in Ecology and Evolution, Dr Gabriel Jamie and Dr Joana Meier explore the phenomenon that the same polymorphisms often recur in many members of a species radiation (e.g. colour/pattern morphs, heterostyly, mating types, shell chirality). This phenomenon is puzzling because speciation often represents a barrier to the inheritance of the ancestral genetic variation underpinning polymorphisms. Generally, only a subset of the ancestral population go on to become founders of the new species. They outline the characteristics of polymorphisms that help their underlying genetic variation get inherited from ancestral standing variation, re-introduced through introgression or re-invented through mutation and also explore the factors influencing whether the requisite balancing selection operates widely across daughter species so that polymorphisms are maintained in many members of the radiation.