Answer to Question #325646 in Zoology for JIMELYN MACULAM

Question

why are derived characteristics more useful in establishing evolutionary relationship than are shared characteristics? Use two groups of mammals to illustrate your answer. For example, compare horses ( order perissodactyla ) and camels ( order artiodactyla)

Answer 1

Shared (ancestral) traits are shared throughout the larger group. Derived traits are present only in a smaller group. The smaller group is defined and identified by having the derived trait.

Having derived traits is the most important evidence for evolutionary relationships. Organisms with the same derived traits (such as feathers) are grouped in the same clade. A derived trait is not necessarily an entirely new trait. More often it is a modified form of an ancestral trait. That's why they are more useful in establishing evolutionary relationships.

Both the camel and horse families originated in the Americas and migrated into Eurasia via the Bering Strait and have evolved from hoofed ancestors (shared traits).

On the other hand, according to molecular evidence and number of bones in the hooves and flippers respectively, the closest living relatives of whales are, quite surprisingly, the artiodactyls, a group of hoofed mammals that includes deer, cows, sheep, pigs, giraffes, camels and hippos, that also mean that whales and camels can have common ancestor (derived trait).