Molecular Specificity, Convergence and Constraint Shape Adaptive Evolution in Nutrient-Poor Environments

摘要: One of the central goals evolutionary biology is to explain and predict molecular basis adaptive evolution. We studied evolution genetic networks in Saccharomyces cerevisiae (budding yeast) populations propagated for more than 200 generations different nitrogen-limiting conditions. find that rapid nitrogen-poor environments dominated by de novo generation selection copy number variants (CNVs), a large fraction which contain genes encoding specific nitrogen transporters including PUT4, DUR3 DAL4. The fitness increases associated with these alleles limits heterogeneity adapting even multiple sources. Complete identification acquired point mutations, individual lineages entire populations, identified at level loci but common themes functional modules, controlling phosphatidylinositol-3-phosphate metabolism vacuole biogenesis. Adaptive strategies shared other nutrient-limited variation TORC1 Ras/PKA signaling pathways as general mechanism underlying improved growth environments. Within single population we observed repeated independent multi-locus genotype, comprised functionally related GAT1, MEP2 LST4. By studying alleles, their combination, well history evolving population, order mutations are constrained epistasis. repeatedly selected interact epistatically suggests gene network polymorphisms (GNPs) may be frequent outcome Our results provide insight into mechanistic cells adapt suggest knowledge selective environment regulatory mechanisms important survival greatly increase predictability