BREAKING THE SPECIES BARRIER. “That said, there are examples in which hybrids that have formed from cross-species cell–cell fusions have ultimately given rise to new species, such as the posited origin of S. cerevisiae from an ancestral whole genome duplication event following fusion of two related, but different, yeast species.”
http://cshperspectives.cshlp.org/content/6/3/a016154.full