This volume focuses on the origin of multicellular animals, Metazoa. Fossil records are scarce and morphological, biochemical or cytological evidence has not demonstrated an unequivocal phylogeny. Therefore, the question remains: Did Metazoa evolve from Protozoa only once, or several times? Is the origin of animals monophyletic or polyphyletic? Especially the relationships between the existing lower metazoan phyla, particularly the Porifera, are uncertain. In addition, phylogenetic analyses of nucleotide sequences of small and large ribosomal RNA also revealed no conclusive results with...
This volume focuses on the origin of multicellular animals, Metazoa. Fossil records are scarce and morphological, biochemical or cytological evidence ...
Recently, new genes and their proteins that revealed striking new insights into the early evolution of multicellular animals have been identified and characterized from members of the lowest metazoan phylum, the porifera (sponges). The unexpected result was that the sequences obtained from sponge displayed high similarity to those found in higher metazoa; in consequence, it was concluded that during the transition from protozoa to metazoa the major structural and regulatory proteins evolved only once. The data gathered are now powerful arguments to establish monophyly of metazoa; in addition,...
Recently, new genes and their proteins that revealed striking new insights into the early evolution of multicellular animals have been identified and ...