switchback evolution

The recurrent reversals between alternative patterns of development during the evolution of particular groups of plants or animals. Insect ovary types (q.v.) provide an example. Reversions from the polytrophic to the panoistic type of oogenesis have occurred within the Mecoptera and the Neuroptera. Reversions from the telotrophic to the panoistic type have occurred within the Megaloptera and the Thysanoptera. See Classification, Eumetazoa, Bilateria, Coelomata, Arthropoda, Insecta.