The Genomic and Cellular Foundations of Animal Origins

The first animals arose more than six hundred million years ago, yet they left little impression in the fossil record. Nonetheless, the cell biology and genome composition of the first animal, the Urmetazoan, can be reconstructed through the study of phylogenetically relevant living organisms. Compa...

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Bibliographic Details
Published in:Annual review of genetics 2013-01, Vol.47 (1), p.509-537
Main Authors: Richter, Daniel J, King, Nicole
Format: Article
Language:English
Subjects:
Animals
Biological Evolution
Cell Adhesion
Cell adhesion & migration
Cell Adhesion Molecules - genetics
Cell Adhesion Molecules - physiology
Cell differentiation
Cell division
Choanoflagellata - classification
Choanoflagellata - cytology
Choanoflagellata - genetics
choanoflagellate
Cnidaria - classification
Cnidaria - cytology
Cnidaria - embryology
Cnidaria - genetics
Comparative analysis
Ctenophora - classification
Ctenophora - cytology
Ctenophora - embryology
Ctenophora - genetics
Eukaryota - classification
Eukaryota - genetics
Eukaryota - physiology
evolution
Fossils
Gene-Environment Interaction
Genes
Genome
Genomes
multicellularity
Phylogenetics
Phylogeny
Porifera - classification
Porifera - cytology
Porifera - embryology
Porifera - genetics
Protein Structure, Tertiary
Protein-Tyrosine Kinases - genetics
Protein-Tyrosine Kinases - physiology
Structure-Activity Relationship
Urholozoan
Urmetazoan
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Summary:The first animals arose more than six hundred million years ago, yet they left little impression in the fossil record. Nonetheless, the cell biology and genome composition of the first animal, the Urmetazoan, can be reconstructed through the study of phylogenetically relevant living organisms. Comparisons among animals and their unicellular and colonial relatives reveal that the Urmetazoan likely possessed a layer of epithelium-like collar cells, preyed on bacteria, reproduced by sperm and egg, and developed through cell division, cell differentiation, and invagination. Although many genes involved in development, body patterning, immunity, and cell-type specification evolved in the animal stem lineage or after animal origins, several gene families critical for cell adhesion, signaling, and gene regulation predate the origin of animals. The ancestral functions of these and other genes may eventually be revealed through studies of gene and genome function in early-branching animals and their closest non-animal relatives.
ISSN:0066-4197
1545-2948
DOI:10.1146/annurev-genet-111212-133456