Disruptive selection can lead to the evolution of discrete morphs. We show that particular genetic architectures, in terms of dominance, epistasis, and linkage, are likely to evolve to produce discrete morphs under disruptive selection. Recent genomic studies have revealed that causative mutations tend to cluster, sometimes as a result of chromosomal rearrangements, but we still know little about the molecular mechanisms of dominance and epistasis. Although disruptive selection can also lead to speciation, once an optimal genetic architecture has evolved, disruptive selection no longer promotes the evolution of assortative mating. For a better understanding of the conditions that promote or constrain speciation, it is necessary to address how fast such a genetic architecture can evolve.
Figure: Although they look different, they are all polymorphic forms within the same species.
