Phylogeny of protostome worms derived from 18S rRNA sequences

Abstract

The phylogenetic relationships of protostome worms were studied by comparing new complete 185 rRNA sequences of Vestimentifera, Pogonophora, Sipuncula, Echiura, Nemertea, and Annelida with existing 185 rRNA sequences of Mollusca, Arthropoda, Chordata, and Platyhelminthes. Phylogenetic trees were inferred via neighbor-joining and maximum parsimony analyses. These suggest that (1) Sipuncula and Echiura are not sister groups; (2) Nemertea are protostomes; (3) Vestimentifera and Pogonophora are protostomes that have a common ancestor with Echiura; and (4) Vestimentifera and Pogonophora are a monophyletic clade.