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Unbeknownst to most brewers, we’ve been using hybrid yeast for years. Modern lager yeast (Saccharomyces pastorianus) are a hybrid of common ale yeast (Saccharomyces cerevisiae) and Saccharomyces eubayanus, a cryotolerant (i.e., cold-tolerant) yeast.
Transgressive segregation, or parental transgression, is the formation of phenotypes with more variation than is found in the parents. A simple illustration of this: kids who are taller than either of their parents.
Yeast labs are now taking advantage of this transgressive property of breeding to create new yeast strains and species for modern brewers. They hope either to combine the good qualities of two yeast strains—such as taking the flocculant properties of kveik and combining it with the flavors of a saison strain—or to create some new characteristic in yeast—such as enhancing the biotransformations sought in hazy IPAs.