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Origin and Evolution of Insect Metamorphosis

  1. Xavier Belles

Published Online: 15 MAR 2011

DOI: 10.1002/9780470015902.a0022854

eLS

eLS

How to Cite

Belles, X. 2011. Origin and Evolution of Insect Metamorphosis. eLS. .

Author Information

  1. Institute of Evolutionary Biology (CSIC-UPF), Barcelona, Spain

Publication History

  1. Published Online: 15 MAR 2011

Abstract

Insect metamorphosis can be classified into three modalities: ametabolan (no changes), hemimetabolan (progressive changes) and holometabolan (dramatical changes at the end of the cycle). The metamorphic changes are mainly regulated by two hormones: the moulting hormone, which promotes the moults, and the juvenile hormone (JH), which represses the transformation into the adult. The action of these two hormones is mediated by a number of transcription factors, and the molecular mechanisms regulating the expression of these and of the corresponding target genes are finally refined by the action of micro ribonucleic acids. Among the different transcription factors involved, those of the Broad-Complex group are especially interesting because they have a differential expression and JH dependency in holometabolans and hemimetabolans. Holometabolan metamorphosis probably evolved from hemimetabolan ancestors, although the mechanisms underlying such a transition are still obscure.

Key Concepts:

  • Insect metamorphosis can be classified into three modalities: ametabolan, hemimetabolan and holometabolan.

  • The main hormones involved in the regulation of insect metamorphosis are the moulting hormone and the juvenile hormone.

  • The molecular mechanisms underlying the action of the moulting hormone are reasonably well known, but those related to juvenile hormone are much less understood.

  • Broad-Complex transcription factors are involved in the transduction of both, the moulting hormone and the juvenile hormone, but have a differential expression and juvenile hormone dependency in holometabolans and hemimetabolans.

  • Fossil record and phylogenetic reconstructions suggest that hemimetaboly evolved from ametabolan ancestors, whereas holometaboly derived from hemimetaboly.

  • Mechanisms underlying the evolutionary transitions from ametaboly to hemimetaboly and to holometaboly are still obscure and under debate.

Keywords:

  • metamorphosis;
  • insects;
  • holometaboly;
  • hemimetaboly;
  • ametaboly;
  • neometaboly;
  • prometaboly;
  • ecdysone;
  • juvenile hormone;
  • Broad-Complex