FIG 9.

Status of syncytin-Mar1 during the radiation of the Sciuridae. Phylogenetic tree of the squirrel-related clade, with the families Sciuridae, Aplodontidae, and Gliridae, as well as the outgroup species Cavia porcellus and Mus musculus (dates and branching positions are from references 29, 30, 31, and 38), with the time scale at bottom left. Branches of the family Sciuridae whose interrelationships are still unresolved are represented as polytomies. The names of the species tested for the presence of the syncytin-Mar1 gene are indicated, together with the length (in amino acids) of the Syncytin-Mar1 proteins that were identified for each species (all of the sequences were deposited in GenBank under accession numbers KJ145238 to KJ145244, KJ670373, and KJ670374). Brackets indicate that only partial sequences could be retrieved. aa, amino acids; [c], coding sequence; [nc], noncoding sequence; –, no syncytin-Mar1 homologous sequence identified, by either PCR amplification or database search; nd, not done. The fusogenic activity of each cloned gene, as determined by the fusion assay in Fig. 7, is indicated.