Genome rocks. The genome of each species consists of a defined number of chromosomes. However, this number can change in cells, leading to chromosome copy number variations (aneuploidy) with large phenotypic consequence. Interestingly, aneuploidy is associated with both adaptation and pathogenesis. On pages 893–900 of this issue Guangbo Chen et al. review the widespread existence of aneuploidy in different species under different conditions. To reconcile the seemingly contradictory role of aneuploidy in both adaptation and pathogenesis, the review highlights the difference between organismal versus cellular evolution in multi-cellular species. The proposed mathematical model suggests that aneuploidy drives rapid evolution through phenotypic leap in cell populations with restricted size. The production of chromosome number variation can be further increased by stress- or mutation-induced chromosomal instability, fueling rapid cellular adaptation. The comparative genomic hybridization data of aneuploid cells is presented as music spectrum.
Cover by Xiang Yuan and Guangbo Chen.