Without the use of genetic methods, taxonomists would never be able to obtain any accurate information about species' degrees of relatedness to one another. The apparent degree of relatedness of some species, as determined by anatomical criteria, is not borne out by their degree of genetic similarity. The traditional anatomical methods by which taxonomists investigated the relatedness of species are incapable of any further refinement. The degree to which individuals of the same species are anatomically similar is determined more by their genetic codes than by such environmental factors as food supply.
New methods developed in genetic research have led taxonomists to revise their views on the evolutionary relationships between many species. Traditionally the relatedness of species has been ascertained by a close comparison of their anatomy. The new methods infer the closeness of any two species' relationship to each other directly from similarities between the species' genetic codes.
Which of the following conclusions is best supported by the information?