Latent homologues for the neural crest as an evolutionary novelty

Authors

  • Jon R. Stone,

    Corresponding author
    1. Biology Department, Dalhousie University, Life Sciences Building, Coburg Road, Halifax, Nova Scotia B3H 4J1, Canada
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    • 1Present address: Department of Biology, McMaster University, Life Sciences Building, 1280 Main Street West, Hamilton, Ontario L8S 4K1, Canada.

  • Brian K. Hall

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*Authors for correspondence (e-mail: bkh@dal.ca and jstoner@mcmaster.ca)

Summary

The neural crest is a craniate synapomorphy and a bona fide evolutionary novelty. Recently, researchers considering intriguingly similar patterns of gene expression, cell behaviors, and embryogenetic processes in noncraniate deuterostomes have suggested that cephalochordates, urochordates, and echinoderms or their ancestors might have possessed cells that were precursors to the neural crest or its constituent cells. To emphasize the caution with which similarities at genetic, cellular, or embryological levels should be interpreted as substantiations for cell, germ layer, or tissue homologies, we present and evaluate additional tantalizing evidence that could be considered as documenting neural crest precursors in precraniates. Furthermore, we propose an evolutionary context—latent homologue—within which these data should be interpreted.

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