Polygenic and directional regulatory evolution across pathways in Saccharomyces

We assess the prevalence of polygenic evolution in pathways between the yeasts S. cerevisiae and S. bayanus. We first established short-read sequencing methods to detect cis-regulatory variation in a diploid hybrid between the species. We then formulated an analytic strategy to test for the scenario in which selective pressure in one species, to increase or decrease the activity of a pathway, has driven the accumulation of cis-regulatory variants that act in the same direction on gene expression. Application of this test revealed a variety of yeast pathways with evidence for directional regulatory evolution. Overall design: Measurement of allele-specific expression of each ortholog in a diploid hybrid between Saccharomyces species