I just had a new paper come out (read in in the American Journal of Botany or download a PDF) exploring the question of why triploid aspen are common in western North America. This pattern is initially difficult to explain because triploids typically have low fertility due to chromosome segregation problems. The study does a detailed exploration of possible population-level mechanisms enabling coexistence of different ploidy levels. It shows that clonality is probably the main force maintaining triploids (so that long lifespan can balance out low reproduction), though numerous other mechanisms are also plausible. The study helps to give some clarity to an apparent paradox, and helps me understand better the unique life history of this common tree species.