The budding yeast, Saccharomyces cerevisiae, has long provided us with beer, bread and wine. Although S. paradoxus, the closest known relative of S. cerevisae, has been found present in some wine musts, it has predominantly been found in association with tree sap exudate, presumably mediated by insect vectors. In contrast, S. cerevisiae has most often been found in association with beer, breed or wine production. However, strains of S. cerevisiae have also been found in association with tree sap exudate, raising the possibility that there are both wild and domesticated strains of S. cerevisae. Consistent with this idea, we have found extensive population structure between strains isolated from vineyards and tree sap exudate. However, it is also possible that much of the population structure is a simple consequence of a complex population history, unrelated to habitat-specific adaptation. To distinguish between these hypotheses, we are investigating the genetic and phenotypic variation that differentiates vineyard and non-vineyard strains of yeast.