Starvation induces genomic rearrangements and starvation-resilient phenotypes in yeast

Evolution has shaped a wide variety of genomes across eukaryotic taxa. However, the forces that shape the genomes are generally unknown. Because organisms in nature commonly experience prolonged periods of nutrient depletion, we posit that diverse demographic, physiological, and genomic responses to starvation can occur. To test for these possibilities, we subjected replicate yeast populations to prolonged starvation. We observed that clones repeatedly gave rise to descendants that were karyotypically diverse. After a 1-month starvation period, approximately 70% of randomly isolated members of starved populations harbored one or more genomic rearrangements. Further, we found that 5 of 16 karyotypically differentiated groups of isolates from starved populations were more resilient to starvation than nonstarved clones and their common ancestor. Phylogenetic analysis of these isolates suggests that genomic rearrangements that arose during starvation can be adaptive in the context of a nutrient-depleted environment. Altogether our data illustrate the profound influence of environmental conditions on adaptive genome evolution in eukaryotes.