| description |
The natural biology of Saccharomyces cerevisiae, the best known unicellular model eukaryote, remains poorly documented and understood. In the Northern Hemisphere, wild populations of S. cerevisiae have recently been found in association with oak trees but in spite of these advances, it has until now not been possible to determine the natural distribution of S. cerevisiae at a global scale. Here we investigate the occurrence of S. cerevisiae in Brazil, a tropical region where oaks and other Fagaceae are absent. We report a candidate natural niche of S. cerevisiae in South America and, using whole genome data, we uncover new lineages that appear to have as closest relatives the wild populations found in North America and Japan. A population structure analysis revealed the penetration of the wine genotype into the wild Brazilian population, a first observation of the impact of domesticated microbe lineages on the genetic structure of wild populations. Unexpectedly, the Brazilian population shows conspicuous evidence of hybridization with population B of S. paradoxus. Introgressions from S. paradoxus were significantly enriched in genes encoding secondary active transmembrane transporters. We hypothesize that hybridization in tropical wild lineages may have facilitated the niche transition accompanying the colonization of the tropical ecosystem. |