text: In Crabtree-negative species, respiration related genes are highly expressed in the presence of oxygen.  However, when S. cerevisiae is grown on glucose in aerobic conditions, respiration-related gene expression is repressed.  Mitochondrial ribosomal proteins expression is only induced under environmental stress conditions, specifically low glucose availability.  Genes involving mitochondrial energy generation and phosphorylation oxidation, which are involved in respiration, have the largest expression difference between aerobic fermentative yeast species and respiratory species.  In a comparative analysis between Sch. pombe and S. cerevisiae, both of which evolved aerobic fermentation independently, the expression pattern of these two fermentative yeasts were more similar to each other than a respiratory yeast, C. albicans.  However, S. cerevisiae is evolutionarily closer to C. albicans.  Regulatory rewiring was likely important in the evolution of aerobic fermentation in both lineages.