Phylogenetic relationship of silkmoths inferred from sequence data of the arylphorin gene

A portion of the arylphorin gene from 11 silkmoth species belonging to the families Saturniidae and Bombycidae was amplified by a polymerase chain reaction. Approximately 460 bp corresponding to the third exon, the third intron, and the fourth exon were successfully amplified, sequenced, and compared. Sequences corresponding to the third and fourth exons were the most conserved, whereas sequences corresponding to the third intron were conserved only between species belonging to the same genus. We also analyzed differences of substitution rates among codon positions and between synonymous and nonsynonymous sites. Phylogenetic trees were constructed using the entire nucleotide sequences, the first and second codon positions, nonsynonymous sites, transversions, and the inferred amino acid sequences in the exons by the neighbor-joining method. These trees supported the monophyly of the families Saturniidae and Bombycidae as well as the monophyly of the genera Actias, Bombyx, Antheraea, and Samia.