Section: New Results

A Gondwanan imprint of S. uvarum diversity

Domestication of livestock and crops has been amply demonstrated through historical and archeological records, but domestication of microorganisms is much more difficult to establish. In a large-scale study [11] of the wine and cider yeast Saccharomyces uvarum conducted with colleagues from the Institut du Vigne et du Vin, Bordeaux and the Universidade Nova de Lisboa, Lisbon, we found the first indications of its domestication in the transition from its habitat in Nothofagus (southern beech) trees on the Gondwana mega-continent, to its present-day diversity in the Holarctic. The global phylogeography of these microorganisms was investigated through genome sequencing and comparison of 54 strains isolated on five continents, resulting in the identification of ${10}^5$ high-quality SNPs and a remarkable pattern of introgressions ([11] figure 3 http://dx.doi.org/10.1038/ncomms5044 ).

The 54 genomes in this study were isolated, selected, and sequenced, and both assembled and aligned against reference genomes. Phylogenies were based on concatenated SNP alignment of selected chromosomes. The structure of the population was investigated using model-based Bayesian clustering.

In addition to the biological result, this study illustrates the ubiquity of an experimental approach based on large-scale sequencing of highly related genomes, in order to isolate tiny differences linked to a trait of interest. This is in contrast to the strategy that was current eight years ago, based on sequencing of a modest number of genomes spanning a much greater evolutionary range.