EUKARYOTIC SPECIATION. “A signature feature of eukaryotes is that they speciate, segregating into closely related populations that fail to respond to each other’s mating cues to form zygotes (prezygotic isolation) and/or form zygotes that fail to produce a viable next generation (postzygotic isolation).”
http://cshperspectives.cshlp.org/content/6/3/a016154.full