adaptive radiation

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun Diversification of a species or single ancestral type into several forms that are each adaptively specialized to a specific environmental niche.

from the GNU version of the Collaborative International Dictionary of English.

• noun (Palaeontology) the evolutionary generation of multiple specialized life forms from one ancestral form, evidenced in the fossil record. The inverse of extinction.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun biology the diversification of species into separate forms that each adapt to occupy a specific environmental niche

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun the development of many different forms from an originally homogeneous group of organisms as they fill different ecological niches