Genomic Exploration of the Hemiascomycetous Yeasts: 18. Comparative analysis of chromosome maps and synteny with Saccharomyces cerevisiae

We have analyzed the evolution of chromosome maps of Hemiascomycetes by com paring gene order and orientation of the 13 yeast species partially sequenc ed in this program with the genome map of Saccharomyces cervisiae. From the analysis of nearly 8000 situations in which two distinct genes having homo logs in S.cervisiae could be identified on the sequenced inserts of another east species, we have quantified the loss of synteny, the frequency of sin gle gene deletion and the occurrence of gene inversion. Traces of ancestral duplications in the genome of S.cervisiae could be identified from the com parison with the other species that do not entirely coincide with those ide ntified from the comparison of S. cervisiae with itself. From such duplicat ions and from the correlation observed between gene inversion and loss of s ynteny, a model is proposed for the molecular evolution of Hemiascomycetes, This model, which can possibly be extended to other eukaryotes, is based o n the reiteration of events of duplication of chromosome segments, creating transient merodiploids that are subsequently resolved by single gene delet ion events. (C) 2000 Federation of European Biochemical Societies. Publishe d by Elsevier Science B.V. All rights reserved.