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Deciphering deuterostome phylogeny: molecular, morphological and palaeontological perspectives
Billie J Swalla1, Andrew B Smith
1Department of Biology, University of Washington, Seattle, WA 98195-1800, USA. bjswalla@u-washington.edu
Summary
Deuterostome evolution traces back to the Precambrian, with key groups like vertebrates and ambulacrarians diverging early. Molecular and fossil data reveal ancestral traits including bilateral symmetry and specific gene expression patterns.
Area of Science:
- Zoology
- Evolutionary Biology
- Developmental Biology
Background:
- Deuterostomes represent a major animal lineage including vertebrates and invertebrates.
- Early fossil evidence suggests deuterostome divergence in the Late Precambrian.
Purpose of the Study:
- To reconstruct the evolutionary history and ancestral characteristics of deuterostomes.
- To clarify phylogenetic relationships among major deuterostome groups.
Main Methods:
- Analysis of fossil records from the Lower Cambrian.
- Molecular phylogenetics using ribosomal and mitochondrial genes.
- Genomic sequence analyses and gene network data interpretation.
Main Results:
- Echinoderms and hemichordates form the sister group Ambulacraria; Xenoturbellids are sister to Ambulacraria.
- Cephalochordates are the sister group to vertebrates, while tunicates are more distantly related.
- The deuterostome ancestor likely possessed bilateral symmetry, an anterior-posterior axis, and a dorsoventral gradient.
Conclusions:
- Deuterostome evolutionary divergence occurred in the Late Precambrian.
- Ancestral deuterostomes shared features like gill slits and acellular cartilage.
- Key developmental gene networks (Hox, Wnt, BMP/chordin, nodal) were established early in deuterostome evolution.
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