modularity
Kashtan N, Parter M, Dekel E, Mayo AE & Alon U 2009 Extinctions in heterogeneous environments and the evolution of modularity. Evolution 63:1964-1975.
- in the absence of extinction events, the evolved computational networks are typically highly optimal for their localities with a nonmodular structure
- when local populations go extinct from time to time, we find that the evolved networks are modular in structure
- modular circuitry is selected because of its ability to adapt rapidly to the conditions of the free niche following an extinction event
- this rapid adaptation is mainly achieved through genetic recombination of modules between immigrants from neighboring local populations
- extinctions in heterogeneous environments promote the evolution of modular biological network structure
- allowing populations to effectively recombine their modules to recolonize niches
- modularity is not an inevitable feature but may be selected by evolution under certain conditions
- evolution in simulations almost always converges toward a nonmodular design
- the nonmodular designs are commonly selected in simulations due to the fact that modular designs are very rare and often less optimal than the nonmodular designs
- explanations for the emergence of modularity can be divided into two classes
- the first class suggests that modularity emerges as a result of a direct selective advantage such as selection for stability, robustness, or evolvability
- in the second class of explanations, no direct selective advantage is associated with modularity
- instead modularity arises as a dynamical side effect of evolution
