Origin of Pterygota in general and Odonata in particular

Community and Forum → Other questions. Insects topics → Origin of Pterygota in general and Odonata in particular

Karmiska, 18.12.2008 16:20

Who knows if meganevra is an ancestor of dragonflies or a convergent branch? And did meganevra larvae live on land? Land meganevra larvae seem unlikely to me for the simple reason that modern dragonfly larvae have gills, and no secondary aquatic organism (in my opinion) has regrown them. (Although it seems that there are beetles with secondary gills. Or not?)There are also easier ways to adapt to life in the water.
There are a lot of theories about the origin of wings, who thinks about this?
Perhaps the most common theories are the "paranotalny theory" of the origin of wings(i.e., the wing came from the paranota or free posterolateral part of the tergite, and the first flying insects were land hovering ones) and the "pleural"one. Here is a brief description of the latter:

"The wing is of pleural origin and is an appendage of the subcox, serially homologous to the gill plates of mayfly nymphs (Ephemerida1) and nymphs and imagos of some Protorthoptera (= Grylloblattida2). Mobile elytra with complex articulation, well-developed venation, and a distinctly corrugated surface existed long before flight and may have been inherited from the primordial aquatic arthropods, the ancestors of insects. Only much later, after the development of flight, did the wings merge with the tergite at the preimaginal stages as an adaptation to movement in shelters, among plants, etc. This was a response to the selection for a streamlined body shape. The function of the wings prior to flight acquisition is assumed to be diverse — ventilation or closure of the spiracles, retention of water necessary for breathing while out of the water, protection of the gills and their ventilation in the water, tactile and locomotor function (as a fin). The transition to flight occurred in the late Silurian - Early Devonian in amphibious conditions in an insect that climbed trees for feeding, mating, and dispersal. Flapping flight was present from the very beginning, but planning was probably used simultaneously as a way to save energy. Palaeoptera appeared first and were the ancestors of Neoptera. The main features of paleoptera (wings that do not fold back at rest over the abdomen, rectilinear wing articulation and complete corrugation of the wing surface, primarily with 6 convex and 6 concave main veins) are primitive. The backward - pointing position of the wings and wing buds appears independently in Paleopteran nymphs, Paleopteran imagos of the order Diaphanopterodea (= Diaphanopterida), and Neopteran nymphs and imagos. This position is achieved in different ways in each of these taxa by flexing the wing base in paleoptera nymphs and turning around the displaced third axillary in neoptera nymphs and imagos. Details of wing folding in Diaphanopterids are not known.
Kukalova-Peck also discusses other issues (the origin of metamorphosis, the irreversibility of evolution, taxonomic implications of its constructions), but only the origin of wings and flight are discussed here. In accordance with the Kukalova-Peck hypothesis, the pleural nature of the insect wing seems to be well justified by the fact that in insects from different orders it appears above the spiracle independently of the tergite and only later shifts to its lateral edge and merges with the paranota. The latter, therefore, has a complex origin (Bocharova-
Messner, 1959, 1965, 1968; Botscharova-Messner, 1971). This hypothesis seems particularly convincing, since it allows for continuous evolution of the insect wing as a locomotor organ: the wing can be considered as a complete or partial homologue of the preepipodite (mobile appendage of the subcox) of an aquatic arthropod, the ancestor of insects. The homology of the gill plates of mayflies and some aquatic grylloblattidae to the wing, rather than the leg, also seems well-founded. " A. P. Rasnitsyn

Who thinks what?