Nature 401, 447-452 (30 September 1999) | doi:10.1038/46737

The origins of insect metamorphosis

James W. Truman & Lynn M. Riddiford


Insect metamorphosis is a fascinating and highly successful biological adaptation, but there is much uncertainty as to how it evolved. Ancestral insect species did not undergo metamorphosis and there are still some existing species that lack metamorphosis or undergo only partial metamorphosis. Based on endocrine studies and morphological comparisons of the development of insect species with and without metamorphosis, a novel hypothesis for the evolution of metamorphosis is proposed. Changes in the endocrinology of development are central to this hypothesis. The three stages of the ancestral insect species—pronymph, nymph and adult—are proposed to be equivalent to the larva, pupa and adult stages of insects with complete metamorphosis. This proposal has general implications for insect developmental biology.

  1. Department of Zoology, University of Washington, Box 351800, Seattle, Washington 98195-1800, USA

Correspondence to: James W. Truman Correspondence should be addressed to J.W.T. (e-mail: Email:  jwt@u.washington.edu).