<unk>  is a microevolutionary hypothesis that refers to a species that has "relative stasis over a considerable part of its total duration and underwent periodic, relatively rapid, morphologic change that did not lead to lineage branching". It is one of the three common models of evolution.
Punctuated gradualism
Affective spectrum
Modic changes
Stereotypy
Skew deviation
Hyperintensity
Baricity
Threshold expression