why is adaptive radiation so common a pattern in evolution
Adaptive radiation The evolution of a novel feature may permit a clade to diversify by making new areas of morphospace accessible. A classic example is the evolution of a fourth cusp in the mammalian tooth. This trait permits a vast increase in the range of foodstuffs which can be fed on. Evolution of this character has thus increased the number of ecological niches available to mammals. The trait arose a number of times in different groups during the Cenozoic, and in each instance was immediately followed by an adaptive radiation.[5] Birds find other ways to provide for each other, i.e. the evolution of flight opened new avenues for evolution to explore, initiating an adaptive radiation.[6] Other examples include placental gestation (for eutherian mammals), or bipedal locomotion (in hominins).[7]
Comparative anatomy Comparative anatomy has long served as evidence for evolution, now joined in that role by comparative genomics;[6] it indicates that organisms share a common ancestor.