From embryo to adult--beyond the conventional periodization of arthropod development

The traditional framework for the description of arthropod development takes the molt-to-molt interval as the fundamental unit of periodization, which is similar to the morphological picture of the main body axis as a series of segments. Developmental time is described as the subdivision into a few...

Full description

Saved in:
Bibliographic Details
Published in:Development genes and evolution 2006-07, Vol.216 (7-8), p.373-383
Main Authors: Minelli, Alessandro, Brena, Carlo, Deflorian, Gianluca, Maruzzo, Diego, Fusco, Giuseppe
Format: Article
Language:English
Subjects:
Animals
Arthropoda
Arthropods - anatomy & histology
Arthropods - embryology
Arthropods - growth & development
Boundaries
Developmental stages
Embryo, Nonmammalian
Embryogenesis
Embryos
Evolution
Evolutionary genetics
Hatching
Molting
Ontogeny
Periodicity
Sexual maturity
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The traditional framework for the description of arthropod development takes the molt-to-molt interval as the fundamental unit of periodization, which is similar to the morphological picture of the main body axis as a series of segments. Developmental time is described as the subdivision into a few major stages of one or more instars each, which is similar to the subdivision of the main body axis into regions of one to many segments each. Parallel to recent criticisms to the segment as the fundamental building block of arthropod anatomy, we argue that, while a firm subdivision of development in stages is useful for describing arthropod ontogeny, this is limiting as a starting point for studying its evolution. Evolutionary change affects the association between different developmental processes, some of which are continuous in time whereas others are linked to the molting cycle. Events occurring but once in life (hatching; first achieving sexual maturity) are traditionally used to establish boundaries between major units of arthropod developmental time, but these boundaries are quite labile. The presence of embryonic molts, the 'gray zone' of development accompanying hatching (with the frequent delivery of an immature whose qualification as 'free-embryo' or ordinary postembryonic stage is arbitrary), and the frequent decoupling of growth and molting suggest a different view. Beyond the simple comparison of developmental schedules in terms of heterochrony, the flexible canvas we suggest for the analysis of arthropod development opens new vistas into its evolution. Examples are provided as to the origin of holometaboly and hypermetaboly within the insects.
ISSN:0949-944X
1432-041X
DOI:10.1007/s00427-006-0075-6