Evolution of LTR-retrotransposons and phylogeny of hemiascomycetous yeasts based on 26S rDNA sequences. This cladogram was constructed by the neighbor-joining method using ClustalX and visualized with TreeView. Bootstrap values on 1000 replications are shown next to the nodes. Arrows indicate on the host phylogeny the evolutionary period corresponding to the exceptional event leading to the apparition of a new type of LTR-retrotransposon. A schematic representation of the evolution of the structural features of the LTR-retrotransposons is shown below the name of the retrotransposon types. LTRs are represented by boxes containing a black triangle, ORF1 by white boxes and ORF2 by gray boxes. The tRNA genes complementary to PBS are indicated above ORF1. The star in Tca2-like elements represents the stop codon separating ORF1 and ORF2.
