Evidence of Evolution Ch. 6 section 2

Interpreting the evidence Scientists have found a great deal of evidence supporting evolution. Fossils, patterns of early development, and similar body structures all provide evidence that organisms have changed over time.

Fossils Fossils show that organisms that lived in the past were very different from animals that live today.

Similarities in early development Opossum, chicken, fish, salamander All four animals look very similar in early development. (p.183) All four animals share a common ancestor.

Similarities in body structure Scientists look at body structures for clues in evolution. Most vertebrates have similar body structures. All of these animals probably inherited a similar structure from a vertebrate ancestor they shared. Homologous Structure: similar structures that relate species have a common ancestor.

Inferring species relationship Scientists have combined the evidence from DNA, protein structures, fossils, early development, and body structure to determine the evolutionary relationships among species.

Similarities in DNA Why do some species have similar body structures and development patterns? Species inherit many of the same genes from a common ancestor. Scientists compare N-bases in DNA. Ex. Elephant is closely related to a tiny elephant shrew. (p. 185)

Branching Tree Diagram that shows how scientists think different groups of organisms are related. Raccoons, lesser pandas, giant pandas, and bears may be related.

How do new species form? A new species can form when a group of individuals remains isolated from the rest of its species long enough to evolve different traits.