Trait variation in yeast is defined by population history

Area of Science:

• Evolutionary biology
• Genomics
• Yeast biology

Background:

• Understanding the interplay between ecological variation, trait evolution, and genetic underpinnings is crucial in biology.
• Mapping natural genomic and phenomic variation is key to bridging genotype-phenotype gaps.

Purpose of the Study:

• To map natural trait variation in Saccharomyces cerevisiae and its relatives.
• To trace the genetic basis and evolutionary timing of major phenotype changes.
• To investigate the influence of ecological variation and population history on trait evolution.

Main Methods:

• High-resolution phenotyping of Saccharomyces cerevisiae and related species.
• Genomic analysis to identify genetic variants.
• Tracing evolutionary history and population dynamics.

Main Results:

• Natural trait variation in S. cerevisiae is extensive, exceeding that of its relatives despite limited genetic diversity.
• Phenotypic variation correlates with population history, not environmental origin.
• The West African population is phenotypically distinct, with numerous low-performance alleles, including a premature stop codon in GAL3 affecting galactose metabolism.
• Many traits appear to result from genetic drift, consistent with population bottlenecks.
• The standard lab strain S288C is atypical, cautioning against generalizing findings from domesticated strains.

Conclusions:

• Ecological variation's role in driving trait divergence and genetic fixation in yeast is complex and influenced by population history.
• Genetic drift plays a significant role in shaping yeast phenotypes, particularly in bottlenecked populations.
• Findings underscore the importance of studying diverse natural isolates and highlight the limitations of using atypical lab strains for understanding species-wide gene-trait relationships.