The Emergence of Overlapping Scale-free
Genetic Architecture in Digital Organisms

Philip Gerlee and Torbjörn Lundh

Abstract
We have studied the evolution of genetic architecture in digital organisms and
found that the gene overlap follows a scale-free distribution, which is commonly
found in metabolic networks of many organisms. Our results show that the slope
of the scale-free distribution depends on the mutation rate and that the gene
development is driven by expansion of already existing genes, which is in direct
correspondence to the preferential growth algorithm that gives rise to
scale-free networks. To further validate our results we have constructed a
simple model of gene development, which recapitulates the results from the
evolutionary process and shows that the mutation rate affects the tendency of
genes to cluster. In addition we could relate the slope of the scale-free
distribution to the genetic complexity of the organisms and show that a high
mutation rate gives rise to a more complex genetic architecture.