adaptive radiation

from WordNet (r) 3.0 (2006)

adaptive radiation
    n 1: the development of many different forms from an originally
         homogeneous group of organisms as they fill different
         ecological niches

from The Collaborative International Dictionary of English v.0.48

adaptive radiation \adaptive radiation\ n.
   1. (Palaeontology) the evolutionary generation of multiple
      specialized life forms from one ancestral form, evidenced
      in the fossil record. The inverse of {extinction}.
      [PJC]