Despite their deleterious effects on hybrids, epistatic genetic interactions in the form of Dobzhansky-Muller incompatibilities (DMIs) seem to persist, and potentially even accumulate, in populations in the presence of gene flow.

In this paper, we provide a rigorous theoretical framework to study this phenomenon. We determine the maximum amount of gene flow that allows for the accumulation or maintenance of DMIs, and interpret our results with respect to the relative importance of ecological and mutation-order speciation; two concepts that are controversially discussed in the field of speciation.

Link to our paper in Genetics: The limits to parapatric speciation: Dobzhansky-Muller incompatibilities in a continent-island model