Figure 4

Schematic illustration of different evolutionary processes. Examples of fitness distributions corresponding to different processes. The variation in fitness for each phenotype is due to pure demographic stochasticity. The dashed gray lines show the regression of expected fitness ($\widehat{w}$) on phenotype. Below each fitness distribution are diagrams illustrating both the probability of the trait increasing or decreasing (indicated by the thickness of each arrow) and the magnitude of change in each direction (indicated by the length of each arrow).