Fig. 4.

A schematic of the evolutionary dynamics between the 2 alleles of GPA1. The wild-type GPA1 allele has growth-rate advantage of ≈1% per generation, but a mating disadvantage of ≈30% per round of mating compared with the GPA1-G1406T allele. If these 2 strains are mixed and propagated in a regime where 1 round of mating occurs every 30 generations, these 2 strains would be equally fit (black trace). If mating occurs more frequently than every 30 generations, the GPA1-G1406T allele will win the competition (red trace). Conversely, if more than 30 generations pass between rounds of mating, the wild-type allele of GPA1 will win (blue trace). During long-term evolution, strains are typically propagated asexually. Under such a circumstance, sterile strains, which eliminate basal signaling through the mating pathway, will outcompete mating-proficient strains (green trace, on the secondary y axis to demonstrate the ≈2% advantage versus strains carrying the GPA1-G1406T allele).