In several genera evolutionary chromosome change involves variation in DNA amount in diploids and genome downsizing in polyploids. In a new study in AoB PLANTS, Poggio et al. analysed the genome size and karyotypical parameters of Hippeastrum species with different ploidy levels.The constancy of bimodal karyotypes, even with changes in ploidy level, and DNA content per basic genome indicate that the distribution of DNA within the complement is not random and suggest the presence of mechanisms selecting for constancy, or against change, in the karyotype morphology.
