Recent findings regarding the evolutionary origin of insects, their gas exchange physiology, wing development and flight ability are rapidly changing what we know and hypothesize about the history and biology of this major animal group. Hexapods now appear to be a sister taxon of branchiopod crustaceans, arising within the Pancrustacea. Developmental studies support the wings-from-gills hypothesis by identification of specific expression of orthologous genes during gill/wing formation in crustaceans and insects, and repression of abdominal appendages in modern insects by variants of genes that, in crustaceans, do not repress abdominal appendages. As gills evolved into wings, gas exchange physiology must have changed simultaneously and there is now evidence for this in both the origin of tracheae from cells in the wing primoridia, under control of wing-development genes, and in the discovery that some modern Plecoptera still express high levels of functional haemocyanin in their blood (i.e. insects that use both tracheal and blood-based gas exchange, similar to the overlap of dinosaur and avian traits in Archaeopteryx). Plecoptera and Ephemeroptera also display a wide range of mechanisms for aerodynamic locomotion across the surface of water, while their body weight is fully or partly supported by the water. These behaviours demonstrate a series of mechanically intermediate stages by which flapping gills could have evolved into flight-capable wings in an aquatic environment.
|Original language||English (US)|
|Title of host publication||Aquatic Insects|
|Subtitle of host publication||Challenges to Populations|
|Number of pages||20|
|State||Published - Jul 30 2008|
All Science Journal Classification (ASJC) codes
- Agricultural and Biological Sciences(all)