Building Divergent Body Plans with Similar Genetic Pathways
656 Heredity (2006) 97, 23~-243 ~ 2006Nature Publishing Group Allrigh ts reserved 0018·067X/06 530.00 www.nature.com/hdy SHORT REVIEW • Building divergent body plans with similar genetic pathways BJ Swallau 3 'Center for Developmental Biology, Department of Biology, University of Wa shington, Seattle, WA 98195-1800, USA;' Friday Harbor Laboratories, University of Washingtoll, Friday Harbor, WA 98250-9299, USA; "Smithsonian Marine Station , 701 Seaway Drive, Fort Pierce, FL 34949-3140, llSA Deuterostome animals exhibit widely divergent body plans. second way of evolving a divergent body plan is to become Echinoderms have either radial or bilateral symmetry, colonial, as seen in hemichordates and tunicates. Early hemichordates include bilateral enteropneust worms and embryonic development and gastrulation are similar in all colonial pterobranchs, and chordates possess a defined deuterostomes, but, in chordates, the anterior-posterior dorsal-ventral axis imposed on their anterior-posterior axis. axis is established at right angles to the animal-vegetal Tunicates are chordates only as larvae, following meta axis, in contrast to hemichordates and indirect-developing morphosis the adults acquire a body plan unique for the echinoderms. Hox gene sequences and anterior-posterior deuterostomes. This paper examines larval and adult body expression patterns illuminate deuterostome phylogenetic plans in the deuterostomes and discusses two distinct ways relationships and the evolution of unique adult body plans of evolving divergent body plans. First,
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