Variation is the spice of life or, in the case of evolution, variation is the necessary material on which selection can act to enable adaptation. Karyotypic variation in ploidy (the number of homologous chromosome sets) and aneuploidy (imbalance in the number of chromosomes) are fundamentally different than other types of genomic variants. Karyotypic variation emerges through different molecular mechanisms than other mutational events, and unlike mutations that alter the genome at the base pair level, rapid reversion to the wild type chromosome number is often possible. Although karyotypic variation has long been noted and discussed by biologists, interest in the importance of karyotypic variants in evolutionary processes has spiked in recent years, and much remains to be discovered about how karyotypic variants are produced and subsequently selected.
Bibliographical noteFunding Information:
We thank Anna Selmecki for helpful discussions. This work was supported by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) REA grant agreement number 303635; by an European Research Council Advanced Award, number 340087, RAPLODAPT, grants from the Israel Science foundation (340/13.), and by the National Institute of Allergy and Infectious Disease (R01AI075096 and R01AI0624273) to JB. ACG was supported by fellowship awards from the National Sciences and Engineering Research Council of Canada, the Canadian Institutes for Health Research, and the Azrieli Foundation.
© 2015 Elsevier Ltd.