When a single ancestral species gives rise to a number of different species, adaptive radiation has occurred. Each species diverges to the point that it is able to occupy a unique ecological nice. Going back to the finches we mentioned previously, they exhibit adaptive radiation b/c the single ancestor led to 13 distinct species, each of which has a specific environmental role that is not filled by another species. What would be the benefit of such rapid evolution? It decreases competition for limited resources.