An End to Endless Forms: Epistasis, Phenotype Distribution Bias, and Nonuniform Evolution
(A) The percentage of visible phenotypes out of the potential phenotypes as a function of the number of regulatory layers. The regulatory dimension, r, and the phenotypic dimension, k, are both set to 14. For a single regulatory layer, the visible phenotypes already constitute only 8.2% of the 214 potential phenotypes, in accordance with our results for the basic model. Introducing additional recurrent layers dramatically decreases the number of visible phenotypes (note the logarithmic scale), reaching 0.06% (approximately 10 phenotypes) with 50 layers. Furthermore, if each regulatory layer incorporates a different developmental plan, the reduction in the number of visible phenotypes as a function of the number of layers is even more extreme. (B) The distribution of the number of unique phenotypes that remain visible when the systems reaches steady state.