adaptive radiation(Why: mass extinctions reduce competition and allow for periods of rapid speciation.)

adaptive radiation(Why: Adaptive radiation is rapid speciation under conditions in which there is little competition.

adaptive radiation(Why: the appearance of an evolutionary novelty may allow for the exploitation of previously unexploited niches.)

adaptive radiation(Why: The finches that initially immigrated to the Galapagos Islands experienced little competition, the result of which was the promotion of speciation.