Karyotypic changes as drivers and catalyzers of cellular evolvability: A perspective from non-pathogenic yeasts

In spite of the existence of multiple cellular mechanisms that ensure genome stability, thanks to the advent of quantitative genomic assays in the last decade, an unforeseen level of plasticity in cellular genomes has begun to emerge in many different fields of cell biology. Eukaryotic cells not only have a remarkable ability to change their karyotypes in response to various perturbations, but also these karyotypic changes impact cellular fitness and in some circumstances enable evolutionary adaptation. In this review, we focus on recent findings in non-pathogenic yeasts indicating that karyotypic changes generate selectable phenotypic variation and alter genomic instability. Based on these findings, we propose that in highly stressful and thus strongly selective environments karyotypic changes could act both as a driver and as a catalyzer of cellular adaptation, i.e. karyotypic changes drive large phenotypic leaps and at the same time catalyze the accumulation of even more genotypic and karyotypic changes.

► We provide a theory of how karyotypic changes contribute to cellular adaptation.
► All karyotypic changes lead to some phenotypic changes.
► Some karyotypic changes lead to genome instability.
► Karyotypic changes act as a driver and as a catalyzer of phenotypic variation.
► Increased phenotypic variation underlies adaptation of cells to harsh conditions.