Deriving structure from evolution: metazoan segmentation

Mol Syst Biol. 2007:3:154. doi: 10.1038/msb4100192. Epub 2007 Dec 18.

Abstract

Segmentation is a common feature of disparate clades of metazoans, and its evolution is a central problem of evolutionary developmental biology. We evolved in silico regulatory networks by a mutation/selection process that just rewards the number of segment boundaries. For segmentation controlled by a static gradient, as in long-germ band insects, a cascade of adjacent repressors reminiscent of gap genes evolves. For sequential segmentation controlled by a moving gradient, similar to vertebrate somitogenesis, we invariably observe a very constrained evolutionary path or funnel. The evolved state is a cell autonomous 'clock and wavefront' model, with the new attribute of a separate bistable system driven by an autonomous clock. Early stages in the evolution of both modes of segmentation are functionally similar, and simulations suggest a possible path for their interconversion. Our computation illustrates how complex traits can evolve by the incremental addition of new functions on top of pre-existing traits.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Algorithms
  • Animals
  • Biological Evolution*
  • Body Patterning* / genetics
  • Computer Simulation*
  • Drosophila melanogaster / anatomy & histology
  • Drosophila melanogaster / embryology*
  • Drosophila melanogaster / genetics
  • Gene Regulatory Networks*
  • Hydrogen-Ion Concentration
  • Insect Proteins / physiology
  • Insecta / anatomy & histology
  • Insecta / embryology
  • Insecta / genetics
  • Models, Biological*
  • Models, Genetic
  • Mutation
  • Somites / anatomy & histology*
  • Transcription Factors
  • Vertebrates / anatomy & histology
  • Vertebrates / embryology*
  • Vertebrates / genetics

Substances

  • Insect Proteins
  • Transcription Factors