Evidence for Evolution

1. Evidence for Evolution • Fossil Record and Biogeography • Embryology • Body Structures (Anatomy) • Biochemistry

2. Fossil Record • Fossils are an important source of evolutionary evidence because they provide a record of early life and evolutionary history. • Ex. Whales descended from land-dwelling, doglike animals • Most of the fossil record is complete with intermediate forms (Figure 7 on page 382) • Fossils are found throughout the world

5. Biogeography • Biogeographyis the study of the locations of organisms around the world • Similar environments shape the evolution of organisms in similar ways

6. Anatomy • Homologous structures-structural features with a common evolutionary origin • They can be similar in arrangement, in function, or in both. • Figure 9 on page 384 shows the appendages of different organisms that have similar bones. The function of each appendage is different but the similar bone structure shows that the organisms came from a common ancestor.

7. Homologous Structures • Structural features with a common evolutionary origin • Same structure but different function

8. Analogous structures • Analogous structures-structures that are similar in function but do not have a common evolutionary origin • Ex. An insect and a bird both have wings to fly but the wings are made of different materials. An insect’s wing is made of chitin, a protein, whereas a bird’s wing is made of bone, flesh, and feathers. • There is no evolutionary tie between an insect and a bird and most likely adapted the ability to fly separately. • Same function but different structure.

9. Homologous structures versus Analogous structures

10. Vestigial Structures • Vestigial structures-a body structure that has no function presently but was probably useful to an ancestor • Even though the species does not need the feature, the structure is still inherited through genetics. • Ex. Eyes on blind mole-rats, flightless wings on an ostrich, appendix/tonsils on humans

11. Embryology • An embryo is the earliest stage of growth and development of plants and animals • Most embryos look very similar and have tail and gill slits

12. Embryology • This suggests a common ancestor. • As the embryos grow, the differences between organisms can be seen • Guess the Embryo!

13. Biochemistry • DNA, RNA, and proteins have been used to link organisms together into groups (page 384) • This is the basis of the classification system of organisms