(A) A phylogenetic tree of S. cerevisiae isolates, adapted from (Wang et al., 2012). The main worldwide and Chinese lineages (denoted, CHN I-V) are highlighted. Lineages CHN-I, CHN-III, CHN-V were mostly isolated from Fagaceae trees in the rainforest of the tropical Hainan Island in the South China Sea. Lineages CHN-II and CHN-IV were isolated from temperate areas in north China (Shaanxi province and Beijing province, respectively). (B) Sequence similarity plots of the Y55 and SK1 laboratory strains showing the relationships to the five, worldwide genetically distinct lineages (listed on the right) along chromosome II. Similarity is defined as N/(D+1), where N is the number of positions in a chromosomal window and D is the number of those positions where the nucleotides differ. The genomes of both Y55 and SK1 are mostly derived from the West African lineage (red line). However, large blocks of the chromosome show drops in similarity to the West African lineage and higher similarity to other lineages. Y55 has three segments (0–50 kb, around 400 kb, from 650 kb to the right telomere) with high similarity to the Wine/European genome (yellow line). Likewise, SK1 has a large segment (650–750 kb) with higher similarity to the Sake lineage (light green line). This type of analysis has revealed the mosaic genome structure of many S. cerevisiae isolates (Liti et al., 2009). Image credit: Anders Bergström and Gianni Liti.