Clade emergence

Prospective versus Retrospective views of taxon emergence

Clade B arises from Clade A at time T₁ as a single new species. The clade subsequently undergoes extensive speciation as part of an adaptive radiation, resulting in a diversity of species with distinctive morphology at time T₂(the present). Given a recognition of this history and the present diversity of species in clade B, a present-day taxonomist would probably classify all of the B clade as a separate major taxon. However, a taxonomist living at time T₁ would not recongize the single ancestral species of the B clade as a distinct taxon.

Text material © 2005 by Steven M. Carr