title: The origins of insect metamorphosis.
abstract: 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.
authors.affiliation: Department of Zoology, University of Washington, Seattle 98195-1800, USA. jwt@u.washington.edu
authors.forename: J W
authors.initials: JW
authors.lastname: Truman
authors.forename: L M
authors.initials: LM
authors.lastname: Riddiford
mesh_terms: D000818:Animals; D005075:Biological Evolution; D007301:Insect Hormones / Q000502:physiology; D007313:Insecta / Q000145:classification / Q000196:embryology / Q000254:growth & development / Q000502:physiology*; D007605:Juvenile Hormones / Q000502:physiology; D008675:Metamorphosis, Biological; D009758:Nymph / Q000254:growth & development; D014921:Wings, Animal / Q000196:embryology
chemical_list: D007301:Insect Hormones; D007605:Juvenile Hormones