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Bilaterian Origins: Significance of New Experimental Observations

Peterson, Kevin J. and Cameron, R. Andrew and Davidson, Eric H. (2000) Bilaterian Origins: Significance of New Experimental Observations. Developmental Biology, 219 (1). pp. 1-17. ISSN 0012-1606. doi:10.1006/dbio.1999.9475.

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Several recent laboratory observations that bear on the origin of the Bilateria are reviewed and interpreted in light of our set-aside cell theory for bilaterian origins. We first discuss new data concerning the phylogeny of bilaterian phyla. Next, we use systematic, molecular, and paleontological lines of evidence to argue that the latest common ancestor of echinoderms plus hemichordates used a maximal indirect mode of development. Furthermore, the latest common ancestor of molluscs and annelids was also indirectly developing. Finally, we discuss new data on Hox gene expression patterns which suggest that both sea urchins and polychaete annelids use Hox genes in a very similar fashion. Neither utilizes the complete Hox complex in the development of the larva per se, while the Hox complex is expressed in the set-aside cells from which the adult body plan is formed. Our current views on the ancestry of the bilaterians are summarized in phylogenetic terms, incorporating the characters discussed in this paper.

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Cameron, R. Andrew0000-0003-3947-6041
Additional Information:© 2000 Academic Press. Received for publication June 25, 1999. Revised August 18, 1999. Accepted August 26, 1999. It is our great pleasure to acknowledge the contributions made by many of our colleagues for their perspicacious and critical comments, and for greatly improving various drafts of the manuscript. Among these we are particularly grateful to Dr. Steve Irvine of Yale University, Professor Mark Martindale of the University of Hawaii, Professor Greg Wray of SUNY Stony Brook, Professor Billy Swalla of the University of Washington, and Professor Ellen Rothenberg and Dr. Jonathan Rast of Caltech. This work was supported by grants from the NIH (HD-05753) to E.H.D. and the NSF (IBN-9604454) to R.A.C. K.J.P. was supported by a Caltech Geobiology Postdoctoral Fellowship.
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Caltech Geobiology Postdoctoral FellowshipUNSPECIFIED
Subject Keywords:metazoan; evolution; echinoderm; annelid; Hox genes; larva; indirect development
Issue or Number:1
Record Number:CaltechAUTHORS:20160122-095049693
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Official Citation:Kevin J. Peterson, R.Andrew Cameron, Eric H. Davidson, Bilaterian Origins: Significance of New Experimental Observations, Developmental Biology, Volume 219, Issue 1, 1 March 2000, Pages 1-17, ISSN 0012-1606, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:63874
Deposited By: Ruth Sustaita
Deposited On:22 Jan 2016 20:59
Last Modified:10 Nov 2021 23:22

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