If a population separates into two reproductively isolated groups without geographic isolation, as with doubled chromosome numbers in some plants, this is called sympatric speciation . Adaptive Radiation a. Adaptive Radiation is proliferation of species by adaptation to new ways of life. Classic example is Darwin's finches. Different conditions on islands selected for variation while providing some isolation. Examples of little-changed organisms includes coelacanth, horseshoe crab, crocodile.
Stasis is a time of limited change in a lineage.