Sprecher
Beschreibung
The origin of angiosperms is related to a singular evolutionary event, the origin of the carpel. To understand the origin of angiosperms may require novel approaches to how we think about the problem. The origin of the angiosperms may be considered as a series of existentially related events through the Mesozoic, beginning in the Triassic and culminating in a suite of angiosperm characters which contributed to their rapid diversification in the Lower / Upper Cretaceous. Genidentity (sensu Kurt Lewin 1922) events are diachronic, series of events that are causally connected and represent the same, continuously existing thing, even if that thing changes its properties through time. Using this concept, we discuss the evolutionary importance of morphological innovations related to male-male competition, mate choice and pollinator efficiency. We hypothesize there are six major events beginning in the Triassic and culminating in the Lower Cretaceous that define the origin of angiosperms using the concept of genidentity. The innovations include 1) the tectate-columellate reticulate exine structure (Triassic), 2) the origin of flies (Upper Triassic -Lower Jurassic), 3) the origin of the conduplicate carpel (stigma) (Upper Jurassic – Lower Cretaceous), 4) the origin of the Hymenoptera (specifically Apoidea) (Early Cretaceous), 5) the origin of the symmetrical positioned multi-aperturate pollen (Lower Cretaceous) and 6) the origin of the style as a transmitting tissue, (Upper Lower Cretaceous). We hypothesize that this series of related events all converged in the Lower Cretaceous and taken as a whole define the origin of angiosperms, not any one singular event.