Abstract
Genome duplications are important evolutionary events that impact the rate and spectrum of beneficial mutations and thus the rate of adaptation. Laboratory evolution experiments initiated with haploid Saccharomyces cerevisiae cultures repeatedly experience whole-genome duplication (WGD). We report recurrent genome duplication in 46 haploid yeast populations evolved for 4,000 generations. We find that WGD confers a fitness advantage, and this immediate fitness gain is accompanied by a shift in genomic and phenotypic evolution. The presence of ploidy-enriched targets of selection and structural variants reveals that autodiploids utilize adaptive paths inaccessible to haploids. We find that autodiploids accumulate recessive deleterious mutations, indicating an increased susceptibility for nonadaptive evolution. Finally, we report that WGD results in a reduced adaptation rate, indicating a trade-off between immediate fitness gains and long-term adaptability.
Highlights
The natural life cycle of budding yeast alternates between haploid and diploid phases
Evidence of ancient whole genome duplications can be seen in most modern genomes
Common, outcome of laboratory evolution experiments that start with haploid yeast populations is the emergence of diploid lineages via whole genome duplication
Summary
The natural life cycle of budding yeast alternates between haploid and diploid phases. Both ploidies can be stably propagated asexually through mitotic division. Repeated attempts at evolving experimental haploid populations have resulted in recurrent whole genome duplications yielding populations of autodiploids ([3,4,5], see Table 1). Proposed explanations of this phenomenon include artifacts of strain construction [6], unintended mating events [5], and an adaptive advantage of diploidy [3]. If most selection has occurred on these higher ploidy states, gene regulation and cell physiology of diploids should be better optimized relative to haploids
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call