Almost every suppressor that she studied could rescue the TS mutant in all genetic backgrounds. Despite this high conservation, the fitness of the mutants, and thus the “strength” of the suppression, did vary across the genetic backgrounds

The identified modifiers are quite different from spontaneous bypass suppressor mutations that were isolated in a laboratory. These differences are likely due to the deleteriousness of the laboratory suppressor mutations, suggesting that these are unlikely to become fixed in natural populations

In most cases, a single gene was responsible for the change in essentiality. This genetic “simplicity” is somewhat surprising given the focus on complex genotype-to-phenotype relationships in scientific literature, but can be explained by the rare and extreme nature of the phenotype we are studying

We selected 18 natural yeast strains, whose genomes are about as different from each other as those of two human beings, and asked whether ~800 genes that are required for viability in a laboratory yeast strain were also essential in these wild yeast strains. We found 39 genes that were not