» "Phyletic evolution" redirects here. You may be looking for phyletic gradualism.Anagenesis, also known as "phyletic change,"'s the evolution of species involving an entire population rather than a branching event, as in cladogenesis. When enough mutations reach fixation in a population to significantly differentiate from an ancestral population, a new species name may be assigned. A key point's that the entire population's different from the ancestral population such that the ancestral popula… (More on Anagenesis)