anagenesis

Anagenesis, also known as "phyletic transformation", is when the new morphospecies is a result of rapid evolution in the ancestral form without speciation taking place, such that there are no remaining other populations of the ancestor species and the species can be considered extinct. The ancestor species is therefore superseded by the new species it morphs into. Anagenesis is in contrast to the branching speciation known as cladogenesis. Anagenesis rejects animals related by convergent evolution and unlike the study of behavioral homologies permits the inclusion of animals related by parallel evolution (Yarczower & Hazlett 1977).