PHYLOGENETIC ANALYSIS OF THE HSP70 SEQUENCES REVEALS THE MONOPHYLY OFMETAZOA AND SPECIFIC PHYLOGENETIC-RELATIONSHIPS BETWEEN ANIMALS AND FUNGI

To understand the early evolution of the Metazoa, it is necessary to d etermine the correct phylogenetic status of diploblastic animals. Desp ite cladistic studies of morphological characters and recent molecular phylogenetic studies, it remains uncertain whether diploblasts are mo nophyletic or paraphyletic, and how the phyla of diploblasts are phylo genetically related. The heat shock protein 70 (Hsp70) sequences, beca use of their ubiquity and high degree of conservation, could provide a useful model for phylogenetic analysis. We have sequenced almost the entire nucleic acid sequence of cytoplasmic Hsp70 from eight diploblas tic species. Our data support the monophyly of diploblastic animals. H owever, the phylogenetic relationships of the diploblast groups were n ot significantly resolved. Our phylogenetic trees also support the mon ophyly of Metazoa with high bootstrap values, indicating that animals form an extremely robust clade.