Bias and Evolution of the Mutationally Accessible Phenotypic Space in a Developmental System

摘要: Genetic and developmental architecture may bias the mutationally available phenotypic spectrum. Although such asymmetries in introduction of variation influence possible evolutionary trajectories, we lack quantitative characterization biases inducible variation, their genotype-dependence, underlying molecular causes. Here quantify accessible spectrum vulval system using mutation accumulation (MA) lines derived from four wild isolates nematodes Caenorhabditis elegans C. briggsae. The results confirm that on average, spontaneous mutations degrade precision, with MA showing a low, yet consistently increased, proportion defects variants. This result indicates strong purifying selection acting to maintain an invariant phenotype. Both genotype significantly First, irrespective genotype, there is bias, certain variants are commonly induced by MA, while others very rarely or never induced. Second, found both degree genotype-dependent. Overall, briggsae exhibited two-fold higher decline precision than lines. Moreover, propensity generate specific depended genetic background. We show genotype-specific likely due cryptic activities cascades. analysis allowed us identify most sensitive elements system, which indicate axes potential variation. Consistent this scenario, trends concern characters easily affected mutation. study provides empirical assessment evolution phenotypes supports notion directions change.