Molecular phylogeny and evolution of sex-chromosomal genes and SINE sequences in the family Mustelidae

In the present study, we determined nucleotide sequences of three sex-chromosomal genes (SRY, ZFY and ZFX) for nine species of the family Mustelidae distributed around Japan, and constructed molecular phylogenetic trees, compared with previously reported phylogenies which were examined based on maternally and biparentally inherited genes. The tree topologies by combined sequence data (about 1,800 bp) of two genes (SRY and ZFY) on Y chromosome were almost the same as those by maternal and biparental genes: the mustelid species were basically divided into five genus lineages (Mustela group, Martes group, Neovison, Lutra and Metes). The branching order of Neovison vison and Mustela erminea was different between sex-chromosomal DNA trees. The higher substitution ratio of Y-chromosomal DNA (926-1143 bp of ZFY) than X-chromosomal DNA (848 869 bp of ZFX), revealed by the present study, could be responsible for the topological difference. Meanwhile, in the ZFY final introns of Mustela erminea and Metes anakuma, insertions of carnivore-specific SINEs (CAN-SINEs) were found. This indicates that the two homologous SINEs evolved in the mustelid genome and that they were inserted to the ZFY final introns lineage-independently after species radiation of Mustelidae.