Paraphyletic status of Polychaeta suggested by phylogenetic analysis based on the amino acid sequences of elongation factor-1 alpha.

In order to judge whether or not Polychaeta is a paraphyletic group, I determined almost the entire amino acid sequence of elongation factor-1 alpha from thirteen polychaetes, two oligochaetes, two hirudineans, two vestimentiferans, and two molluscs. Phylogenetic analysis by the neighbor-joining (NJ) method and the maximum likelihood (ML) method indicated the monophyly of Clitellata (the oligochaetes and hirudineans). In both the NJ and ML trees, vestimentiferans and clitellates were derived from polychaetes independently. The present results strongly suggest that Polychaeta is a paraphyletic group.