Phylogenomics revives traditional views on deep animal relationships.
The origin of many of the defining features of animal body plans, such as symmetry, nervous system, and the mesoderm, remains shrouded in mystery because of major uncertainty regarding the emergence order of the early branching taxa: the sponge groups, ctenophores, placozoans, cnidarians, and bilaterians. The "phylogenomic" approach [1] has recently provided a robust picture for intrabilaterian relationships [2, 3] but not yet for more early branching metazoan clades. We have assembled a comprehensive 128 gene data set including newly generated sequence data from ctenophores, cnidarians, and all four main sponge groups. The resulting phylogeny yields two significant conclusions reviving old views that have been challenged in the molecular era: (1) that the sponges (Porifera) are monophyletic and not paraphyletic as repeatedly proposed [4-9], thus undermining the idea that ancestral metazoans had a sponge-like body plan; (2) that the most likely position for the ctenophores is together with the cnidarians in a "coelenterate" clade. The Porifera and the Placozoa branch basally with respect to a moderately supported "eumetazoan" clade containing the three taxa with nervous system and muscle cells (Cnidaria, Ctenophora, and Bilateria). This new phylogeny provides a stimulating framework for exploring the important changes that shaped the body plans of the early diverging phyla.
Philippe
Hervé
H
Département de Biochimie, Centre Robert-Cedergren, Université de Montréal, Succursale Centre-Ville, Montréal, Québec, Canada.
Derelle
Romain
R
Lopez
Philippe
P
Pick
Kerstin
K
Borchiellini
Carole
C
Boury-Esnault
Nicole
N
Vacelet
Jean
J
Renard
Emmanuelle
E
Houliston
Evelyn
E
Quéinnec
Eric
E
Da Silva
Corinne
C
Wincker
Patrick
P
Le Guyader
Hervé
H
Leys
Sally
S
Jackson
Daniel J
DJ
Schreiber
Fabian
F
Erpenbeck
Dirk
D
Morgenstern
Burkhard
B
Wörheide
Gert
G
Manuel
Michaël
M
D000818:Animals; D005075:Biological Evolution; D019521:Body Patterning; D023281:Genomics; D009687:Nuclear Proteins / Q000145:classification / Q000235:genetics; D010802:Phylogeny; D011161:Porifera / Q000145:classification / Q000235:genetics
D009687:Nuclear Proteins