Saccharomyces paradoxus and Saccharomyces cerevisiae reside on oak trees in New Zealand: evidence for migration from Europe and interspecies hybrids

Saccharomyces cerevisiae and Saccharomyces paradoxus are used as model systems for molecular, cell and evolutionary biology; yet we know comparatively little of their ecology. One niche from which these species have been isolated is oak bark. There are no reports of these species from oak in the Southern Hemisphere. We describe the recovery of both S. cerevisiae and S. paradoxus from oak in New Zealand (NZ), and provide evidence for introgression between the species. Genetic inference shows that the oak S. cerevisiae are closely related to strains isolated from NZ and Australian vineyards, but that the S. paradoxus strains are very closely related to European isolates. This discovery is surprising as the current model of S. paradoxus biogeography suggests that global dispersal is rare. We test one idea to explain how members of the European S. paradoxus population might come to be in NZ: they were transported here along with acorns brought by migrants similar to 200 years ago. We show that S. paradoxus is associated with acorns and thus provide a potential mechanism for the unwitting global dispersal of S. paradoxus by humans.