  Recent studies on epistatic networks of model organisms have unveiled a
certain type of modular property called monochromaticity in which the networks
are clusterable into functional modules that interact with each other through
the same type of epistasis. Here we propose and study three epistatic network
models that are inspired by the Duplication-Divergence mechanism to gain
insight into the evolutionary basis of monochromaticity and to test if it can
be explained as the outcome of a neutral evolutionary hypothesis. We show that
the epistatic networks formed by these stochastic evolutionary models have
monochromaticity conflict distributions that are centered close to zero and are
statistically significantly different from their randomized counterparts. In
particular, the last model we propose yields a strictly monochromatic solution.
Our results agree with the monochromaticity findings in real organisms and
point toward the possible role of a neutral mechanism in the evolution of this
phenomenon.
