The Evolution of Multicellularity: A Minor Major Transition?

DOI Web Site 14 Citations
  • Richard K. Grosberg
    Center for Population Biology, College of Biological Sciences, University of California, Davis, California 95616;
  • Richard R. Strathmann
    Friday Harbor Laboratories, University of Washington, Friday Harbor, Washington 98250;

Bibliographic Information

Published
2007-12-01
DOI
  • 10.1146/annurev.ecolsys.36.102403.114735
Publisher
Annual Reviews

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<jats:p>Benefits of increased size and functional specialization of cells have repeatedly promoted the evolution of multicellular organisms from unicellular ancestors. Many requirements for multicellular organization (cell adhesion, cell-cell communication and coordination, programmed cell death) likely evolved in ancestral unicellular organisms. However, the evolution of multicellular organisms from unicellular ancestors may be opposed by genetic conflicts that arise when mutant cell lineages promote their own increase at the expense of the integrity of the multicellular organism. Numerous defenses limit such genetic conflicts, perhaps the most important being development from a unicell, which minimizes conflicts from selection among cell lineages, and redistributes genetic variation arising within multicellular individuals between individuals. With a unicellular bottleneck, defecting cell lineages rarely succeed beyond the life span of the multicellular individual. When multicellularity arises through aggregation of scattered cells or when multicellular organisms fuse to form genetic chimeras, there are more opportunities for propagation of defector cell lineages. Intraorganismal competition may partly explain why multicellular organisms that develop by aggregation generally exhibit less differentiation than organisms that develop clonally.</jats:p>

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