March 19, 2015
Polyploidization ‐ where the chromosome number is more than double the normal or haploid number ‐ is common in fungi, plants and animals, but its influence on evolution is unclear. The Dowell Lab study describes bench-top evolution experiments on haploid, diploid and tetraploid asexual yeast strains showing that polyploidy can accelerate adaptation to growth on a poor carbon source, with tetraploids adapting the fastest. This go-faster evolution is driven by the acquisition of more and more beneficial mutations. Polyploidy can be unstable however, but aneuploidy, concerted chromosome loss and point mutations all provide substantial gains in fitness in this context.