Zoology 10th Edition by Stephen Miller,John Harley

Exercise 11

The knowledge of evolutionary processes helps zoologists understand the great diversity of structure and function present in animals. Evolution also helps zoologists understand relationships among animals. These evolutionary relationships are ultimately based on shared DNA, they are reflected in inherited morphological characteristics, and they are represented by groupings in the classification system. The hierarchical nature of the naming system is reflected in groups becoming more inclusive as one moves from species to domain.
Why can taxonomists use similarities in DNA, similarities in morphological characteristics, or both when investigating taxonomic (evolutionary) relationships among animals?