Ecological and mutation-order speciation in digital organisms

Reproductive isolation between populations often evolves as a by-product of independent adaptation to new environments, but the selective pressures of these environments may be divergent (“ecological speciation” or uniform (“mutation-order speciation.” In this study, we use an artificial life platform to directly compare the strength of reproductive isolation (specifically, postzygotic) generated by ecological and mutation-order processes. We also tested the effect of gene flow as well as the dimensionality (i.e., number of selective pressures) of the environments on the strength of postzygotic isolation. We found that ecological speciation generally formed stronger isolation than mutation-order speciation, mutation-order speciation was more sensitive to gene flow than ecological speciation, and environments with high dimensionality formed stronger reproductive isolation than those with low dimensionality. How various factors affect the strength of reproductive isolation has been difficult to test in biological organisms, but the use of artificial life, which provides its own genetic system that evolves, allowed us to computationally test the effect of these factors more easily.